Post by: Star One on 03/26/2014 05:41 pm
Post by: MP99 on 03/26/2014 06:34 pm
If this postulated object is "shepherding" Sedna and 2012 VP113, does that mean that it might fit within the definition of "planet" rather than "dwarf planet"?
Cheers, Martin
Post by: clongton on 03/26/2014 06:52 pm
ISTR that Pluto was demoted because it doesn't dominate it's orbit gravitationally (ISTR the Hill sphere came into it).
If this postulated object is "shepherding" Sedna and 2012 VP113, does that mean that it might fit within the definition of "planet" rather than "dwarf planet"?
Cheers, Martin
It's possible. For its gravitational effect to be large enough to shepherd these bodies like this it would need to be much larger, possibly Earth size or bigger. I doubt a dwarf planet would have that extensive an influence.
Post by: Star One on 03/26/2014 07:04 pm
ISTR that Pluto was demoted because it doesn't dominate it's orbit gravitationally (ISTR the Hill sphere came into it).
If this postulated object is "shepherding" Sedna and 2012 VP113, does that mean that it might fit within the definition of "planet" rather than "dwarf planet"?
Cheers, Martin
It's possible. For its gravitational effect to be large enough to shepherd these bodies like this it would need to be much larger, possibly Earth size or bigger. I doubt a dwarf planet would have that extensive an influence.
Super Earth of the title suggests a planet several times the size of the Earth, but would a body that large be needed to produce these effects?
Be funny if the textbooks had to be revised again back to nine planets.
Post by: Bubbinski on 03/26/2014 07:04 pm
If this leads to a "super-Earth" it could be our first glimpse of this kind of planet, there have been so many found orbiting other stars but not ours.
Post by: RanulfC on 03/26/2014 07:09 pm
Be funny if the textbooks had to be revised again back to nine planets.
Just name it "Pluto" and ignore the last fact we'd name a "dwarf" planet intead of the "right" one... Think of the cost savings by going back to older text books :)
Randy
Post by: Star One on 03/26/2014 07:24 pm
Be funny if the textbooks had to be revised again back to nine planets.
Just name it "Pluto" and ignore the last fact we'd name a "dwarf" planet intead of the "right" one... Think of the cost savings by going back to older text books :)
Randy
Good answer:)
Imagine trying to get a craft out to study it, you would have to invent some exotic technologies for that task.
Post by: Ben the Space Brit on 03/27/2014 12:36 pm
Post by: Nomadd on 03/27/2014 03:18 pm
Post by: Blackstar on 03/27/2014 03:28 pm
I remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out.
The Large Synoptic Survey Telescope (LSST) is under construction right now. You can Google it. When that becomes operational, you can expect the number of discoveries of these kinds of objects to increase quite a bit. As you can guess from the name, the point is that the LSST does a survey, meaning that it looks at a relatively wide bit of the sky. That's how you find small, faint moving objects. It is much harder to do with telescopes that have a very narrow field of view, because the object might be right outside of your field of view and you'll miss it.
Post by: Blackstar on 03/27/2014 04:46 pm
http://phenomena.nationalgeographic.com/2014/03/27/solar-system-surprises/
Post by: go4mars on 03/27/2014 05:58 pm
I keep seeing news reports referring to this as a "Dwarf planet". It's smaller than Vesta and doesn't seem likely to be spherical, so how is it a Dwarf?It means the planet is inhabited by Dwarf's. Just to clarify. :)
Post by: Star One on 03/27/2014 05:58 pm
I remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out.
The Large Synoptic Survey Telescope (LSST) is under construction right now. You can Google it. When that becomes operational, you can expect the number of discoveries of these kinds of objects to increase quite a bit. As you can guess from the name, the point is that the LSST does a survey, meaning that it looks at a relatively wide bit of the sky. That's how you find small, faint moving objects. It is much harder to do with telescopes that have a very narrow field of view, because the object might be right outside of your field of view and you'll miss it.
The LSST is covered in this article about the discovery.
http://www.astronomynow.com/news/n1403/27oortcloud/#.UzRzfycgGSM
It mentions that it may hopefully be able to discover the larger shepherding body if it exists.
Post by: go4mars on 03/27/2014 06:04 pm
Post by: Star One on 06/15/2014 02:46 pm
Quote
The monsters are multiplying. Just months after astronomers announced hints of a giant "Planet X" lurking beyond Pluto, a team in Spain says there may actually be two supersized planets hiding in the outer reaches of our solar system.
When potential dwarf planet 2012 VP113 was discovered in March, it joined a handful of unusual rocky objects known to reside beyond the orbit of Pluto. These small objects have curiously aligned orbits, which hints that an unseen planet even further out is influencing their behaviour. Scientists calculated that this world would be about 10 times the mass of Earth and would orbit at roughly 250 times Earth's distance from the sun.
Now Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid in Spain have taken another look at these distant bodies. As well as confirming their bizarre orbital alignment, the pair found additional puzzling patterns. Small groups of the objects have very similar orbital paths. Because they are not massive enough to be tugging on each other, the researchers think the objects are being "shepherded" by a larger object in a pattern known as orbital resonance.
http://www.newscientist.com/article/dn25711-two-giant-planets-may-cruise-unseen-beyond-pluto.html?utm_source=NSNS&utm_medium=SOC&utm_campaign=hoot&cmpid=SOC%7CNSNS%7C2013-GLOBAL-hoot#.U52wzIm9K0d
Here is the original paper.
http://arxiv.org/abs/1406.0715
Post by: Star One on 11/25/2014 07:03 pm
https://www.sciencenews.org/article/distant-planet-may-lurk-far-beyond-neptune?mode=magazine&context=189396
Post by: Ben the Space Brit on 11/30/2014 01:34 pm
Post by: NovaSilisko on 11/30/2014 05:38 pm
There is also the possibility that, as seems to be happening in the Fomalhaut system right now, the orbital distances of several major planets could have changed several times before re-stabilising. This would allow for large objects to be thrown out of the middle solar system (as I think of the area between Jupiter and Neptune's orbits) out into the Kuiper Belt and beyond.
That and the idea of them having been perturbed a long long time ago by other stars in a local stellar birth cluster are probably the best solutions.
Still, I can dream of Planet X, as have so many before.
Post by: mheney on 11/30/2014 05:46 pm
Post by: NovaSilisko on 11/30/2014 06:02 pm
Actually, Planet IX, ever since that whole Pluto thing ... ;)
IX and X then :P
Post by: Star One on 01/15/2015 06:52 pm
Quote
There could be at least two unknown dwarf planets hidden well beyond Pluto, whose gravitational influence determines the orbits and strange distribution of objects observed beyond Neptune. This has been revealed by numerical calculations. If confirmed, this hypothesis would revolutionize solar system models. Astronomers have spent decades debating whether some dark trans-Plutonian planet remains to be discovered within the solar system. According to scientists not only one, but at least two planets must exist to explain the orbital behavior of extreme trans-Neptunian objects.
http://www.sciencedaily.com/releases/2015/01/150115083036.htm
Heres one paper.
http://m.mnras.oxfordjournals.org/content/446/2/1867
Here is the other.
http://m.mnrasl.oxfordjournals.org/content/443/1/L59
Interesting abstract.
Quote
The existence of an outer planet beyond Pluto has been a matter of debate for decades and the recent discovery of 2012 VP113 has just revived the interest for this controversial topic. This Sedna-like object has the most distant perihelion of any known minor planet and the value of its argument of perihelion is close to 0°. This property appears to be shared by almost all known asteroids with semimajor axis greater than 150 au and perihelion greater than 30 au (the extreme trans-Neptunian objects or ETNOs), and this fact has been interpreted as evidence for the existence of a super-Earth at 250 au. In this scenario, a population of stable asteroids may be shepherded by a distant, undiscovered planet larger than the Earth that keeps the value of their argument of perihelion librating around 0° as a result of the Kozai mechanism. Here, we study the visibility of these ETNOs and confirm that the observed excess of objects reaching perihelion near the ascending node cannot be explained in terms of any observational biases. This excess must be a true feature of this population and its possible origin is explored in the framework of the Kozai effect. The analysis of several possible scenarios strongly suggest that at least two trans-Plutonian planets must exist.
Post by: Phil Stooke on 01/15/2015 07:06 pm
Also, it is really important to examine the effects of a close flyby of a brown dwarf or similar small object. What happens to distant orbits if a 100-Jupiter mass object passed 1 lightyear from the Sun a billion years ago? - and then we need to model the whole space, different masses, different distances, different times and speeds etc.. A distant planet might be possible, but I think we need to know a lot more before we assume it 'must be' present.
I expect some of this work has been done but I'm not aware of it.
Post by: llanitedave on 01/16/2015 04:50 am
This is one of the weaknesses in that IAU definition.
Post by: Star One on 01/16/2015 06:48 am
If I understand the current IAU definition of "planet", a Super-Earth located well beyond Pluto would not count as a planet, since at that distance with such a long orbital period, it would not yet have had time over the life of the Solar System to "clear it's orbital zone".
This is one of the weaknesses in that IAU definition.
They are going to look rather guilty of a logic fail if a planet larger than Earth is ever discovered out there, but still can't be classed as such because of the vagaries of the definition the IAU want to use as to what is and isn't a planet.
Post by: llanitedave on 01/16/2015 05:19 pm
If I understand the current IAU definition of "planet", a Super-Earth located well beyond Pluto would not count as a planet, since at that distance with such a long orbital period, it would not yet have had time over the life of the Solar System to "clear it's orbital zone".
This is one of the weaknesses in that IAU definition.
They are going to look rather guilty of a logic fail if a planet larger than Earth is ever discovered out there, but still can't be classed as such because of the vagaries of the definition the IAU want to use as to what is and isn't a planet.
Exactly. There are some good proposed definitions out there, and I know it's not the most important thing in the world, but I don't think the current definition is really helpful towards advancing the understanding and the science.
The best alternative that I've seen comes from David Russell, here:
http://arxiv.org/abs/1308.0616 (http://arxiv.org/abs/1308.0616)
It's more genetic and more extensible, and just needs traction, IMO.
Post by: tea monster on 02/11/2015 03:01 pm
Post by: Ben the Space Brit on 02/12/2015 09:32 am
Post by: Comga on 03/07/2015 12:24 am
Mathematics based on orbital perturbation is how Neptune was discovered.
It was also how Pluto was discovered but Pluto isnt big enough to cause the perturbations that motivated the search.
Sort of "What Phil Stooke said" above.
And can we leave the definition of "planet" to its own thread(s)? It pollutes all of these discussions.
Edit: While dynamisists are terrible at writing definitions they are terrific at dynamics. If they have the models it is beyond opinion to dismiss them.
Post by: ChrisWilson68 on 03/07/2015 02:19 am
Also, it is really important to examine the effects of a close flyby of a brown dwarf or similar small object. What happens to distant orbits if a 100-Jupiter mass object passed 1 lightyear from the Sun a billion years ago? - and then we need to model the whole space, different masses, different distances, different times and speeds etc.. A distant planet might be possible, but I think we need to know a lot more before we assume it 'must be' present.
A one-time visitor won't align orbits like that. A one-time visitor will tend to scatter them. This kind of alignment only happens over a very long term.
Post by: clongton on 03/07/2015 09:03 pm
Also, it is really important to examine the effects of a close flyby of a brown dwarf or similar small object. What happens to distant orbits if a 100-Jupiter mass object passed 1 lightyear from the Sun a billion years ago? - and then we need to model the whole space, different masses, different distances, different times and speeds etc.. A distant planet might be possible, but I think we need to know a lot more before we assume it 'must be' present.
A one-time visitor won't align orbits like that. A one-time visitor will tend to scatter them. This kind of alignment only happens over a very long term.
Without offering any opinion on authenticity, and just to provide an example for discussion, it could be an object similar to ancient Nibiru as found spoken of in the ancient Sumerian astrological tablets. It's a super-earth sized planet, about 4-5x earth, and it has an orbital period of 3,600 earth years. It's perigee is just inside the asteroid belt, its apogee is way out there, and it approaches from under the elliptic at a 30 degree angle to the elliptic. It passes the sun just under the elliptic, passes Mars orbit at the elliptic, continues up past the elliptic and reaches perigee in the asteroid belt, and then drops back below the elliptic. It also orbits clockwise, as opposed to everything else in the solar system, which orbits counterclockwise. It was said to be a captured rouge planet. The tablets say Nibiru stole Mar's air and water on one of its passes. Just saying. I brought this up just to make the point that a super earth doesn't need to be in the elliptic and doesn't need to have a more or less circular orbit. A large captured rouge planet with such orbital parameters could cause the same perturbations and then disappear for a while. It would be really hard to find until it got close.
Post by: Star One on 06/21/2015 09:31 pm
Grand Theft Sedna: how the sun might have stolen a mini-planet.
http://www.newscientist.com/article/dn27757-grand-theft-sedna-how-the-sun-might-have-stolen-a-miniplanet.html#.VYcnWXB4WrV
Here's a more detailed article on the above.
http://www.centauri-dreams.org/?p=33405
Post by: Star One on 11/11/2015 08:29 pm
Quote
Mike Brown, a planetary astronomer at the California Institute of Technology in Pasadena unaffiliated with the discovery, says that this is the allure of these extreme objects. “They carry the signature of whatever else happened,” he says. But until Sheppard pins down its orbit, V774104 may be interesting—or not, Brown says. “There’s no way to know what it means.” On the other hand, Brown acknowledges that he will have to give up the claim to having discovered the most distant solar system object, which came in 2005 when he found the dwarf planet Eris at a distance of 97 AU from the sun. “I have held the record for 10 years,” he says, jokingly. “I have to relinquish it. So I’m sad.”
http://news.sciencemag.org/space/2015/11/astronomers-spot-most-distant-object-solar-system-could-point-other-rogue-planets
Post by: Star One on 12/10/2015 08:55 am
http://arxiv.org/pdf/1512.02650v1.pdf
http://arxiv.org/pdf/1512.02652.pdf
Both are coming out of observations using ALMA which seems to be at the cutting edge for this kind of research.
Post by: Zed_Noir on 12/10/2015 03:24 pm
Another of these distant objects has been discovered that is even further out, but haven't yet had a chance to characterise its orbit.QuoteMike Brown, a planetary astronomer at the California Institute of Technology in Pasadena unaffiliated with the discovery, says that this is the allure of these extreme objects. “They carry the signature of whatever else happened,” he says. But until Sheppard pins down its orbit, V774104 may be interesting—or not, Brown says. “There’s no way to know what it means.” On the other hand, Brown acknowledges that he will have to give up the claim to having discovered the most distant solar system object, which came in 2005 when he found the dwarf planet Eris at a distance of 97 AU from the sun. “I have held the record for 10 years,” he says, jokingly. “I have to relinquish it. So I’m sad.”
http://news.sciencemag.org/space/2015/11/astronomers-spot-most-distant-object-solar-system-could-point-other-rogue-planets
FYI Mike Brown's twitter handle is @plutokiller (https://twitter.com/plutokiller)
He got a few recent twitter postings about objects in the outer Solar system.
Post by: NovaSilisko on 12/10/2015 04:42 pm
Couple of new papers on the possibility of large objects in the far outer solar system.
http://arxiv.org/pdf/1512.02650v1.pdf
http://arxiv.org/pdf/1512.02652.pdf
Both are coming out of observations using ALMA which seems to be at the cutting edge for this kind of research.
It should be pointed out both of those papers are apparently just submitted, not peer reviewed. Conclusion seems to be to take these both with a fist-sized lump of salt until followup observations are made by others. It was noted on twitter that a serendipitous discovery by ALMA of anything within its small field of view is astonishingly unlikely.
edit: Phil Plait has a good reasonable summary: http://www.slate.com/blogs/bad_astronomy/2015/12/10/extreme_tnos_very_distant_solar_system_objects_may_have_been_found.html
Post by: Star One on 12/10/2015 07:56 pm
Another of these distant objects has been discovered that is even further out, but haven't yet had a chance to characterise its orbit.QuoteMike Brown, a planetary astronomer at the California Institute of Technology in Pasadena unaffiliated with the discovery, says that this is the allure of these extreme objects. “They carry the signature of whatever else happened,” he says. But until Sheppard pins down its orbit, V774104 may be interesting—or not, Brown says. “There’s no way to know what it means.” On the other hand, Brown acknowledges that he will have to give up the claim to having discovered the most distant solar system object, which came in 2005 when he found the dwarf planet Eris at a distance of 97 AU from the sun. “I have held the record for 10 years,” he says, jokingly. “I have to relinquish it. So I’m sad.”
http://news.sciencemag.org/space/2015/11/astronomers-spot-most-distant-object-solar-system-could-point-other-rogue-planets
FYI Mike Brown's twitter handle is @plutokiller (https://twitter.com/plutokiller)
He got a few recent twitter postings about objects in the outer Solar system.
He's also received a degree of flack. Look at the comments on this article about these papers. Especially over his comments about 200,000 objects which he is criticised for making a sweeping rebuttal using a tiny dataset.
http://arstechnica.com/science/2015/12/astronomers-question-claim-of-super-planet-found-at-solar-systems-edge/
Post by: NovaSilisko on 12/10/2015 10:32 pm
Post by: Blackstar on 12/10/2015 10:53 pm
So, what, random comments on news articles are now considered a reliable source?
Also blogs. Comments on blogs are usually reliable and accurate and unbiased.
Post by: Alpha_Centauri on 12/10/2015 11:00 pm
Difficult one this.
Post by: Star One on 12/11/2015 06:40 am
Hmm, who should I believe? Expert on TNOs or random people with an opinion?
Difficult one this.
A not all the quotes are anonymous.
B You preclude the fact that some of the comments may also be by experts.
C Because of course Twitter is such an effective forum to debate scientific papers in the first place.
Post by: hop on 12/11/2015 06:12 pm
A not all the quotes are anonymous.You can quibble with how Brown worded it, but his basic point is obviously correct: These things being real requires that the ALMA observations got stupendously lucky, or an implausible population, or both.
B You preclude the fact that some of the comments may also be by experts.
C Because of course Twitter is such an effective forum to debate scientific papers in the first place.
The fact that the ALMA people claim to have seen two of these things (with at least one author common between the two papers) should really ring alarm bells. If you read the papers, you also find that additional unlikely coincidences are required to explain the apparent motion of these things and why these things weren't seen before.
Brown is far from the only outer solar system expert calling this out as implausible, pretty much everyone in the field I've seen comment has been similarly skeptical.
Post by: Star One on 12/11/2015 07:27 pm
A not all the quotes are anonymous.You can quibble with how Brown worded it, but his basic point is obviously correct: These things being real requires that the ALMA observations got stupendously lucky, or an implausible population, or both.
B You preclude the fact that some of the comments may also be by experts.
C Because of course Twitter is such an effective forum to debate scientific papers in the first place.
The fact that the ALMA people claim to have seen two of these things (with at least one author common between the two papers) should really ring alarm bells. If you read the papers, you also find that additional unlikely coincidences are required to explain the apparent motion of these things and why these things weren't seen before.
Brown is far from the only outer solar system expert calling this out as implausible, pretty much everyone in the field I've seen comment has been similarly skeptical.
It's not necessarily disagreeing with the basic point but rather with how it was delivered.
Post by: Moe Grills on 12/11/2015 07:32 pm
I remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out.
If this leads to a "super-Earth" it could be our first glimpse of this kind of planet, there have been so many found orbiting other stars but not ours.
A super-Earth way out there would likely have a dense atmosphere because of its strong gravity and brutal cold temperatures (example: Titan). A 22'd Century parachute probe anyone?
Post by: notsorandom on 12/11/2015 08:41 pm
It is so cold out that far that any atmosphere has likely frozen out long ago.I remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out.
If this leads to a "super-Earth" it could be our first glimpse of this kind of planet, there have been so many found orbiting other stars but not ours.
A super-Earth way out there would likely have a dense atmosphere because of its strong gravity and brutal cold temperatures (example: Titan). A 22'd Century parachute probe anyone?
Post by: Bob Shaw on 12/11/2015 09:23 pm
Also, it is really important to examine the effects of a close flyby of a brown dwarf or similar small object. What happens to distant orbits if a 100-Jupiter mass object passed 1 lightyear from the Sun a billion years ago?
A close pass by something reasonably massive has often been proposed as the cause of the Late Heavy Bombardment, but so far as I recall most such claims were made before the more recent descriptions of the presumed orbital migration of the outer planets and their consequent effects on smaller bodies - and these migrations don't seem to be caused by passing brown dwarfs. If there's a single thing to have come out of extrasolar planet discoveries it is the fact that not all star systems have the same distribution of bodies as our own, so things certainly are varied out there - star systems are no longer neat.
Having said that, the Sun orbits the Milky Way once every 250 million years, which opens up all sorts of opportunities for interactions with other stars and free-floating 'planets' and bigger 'things'. There's generally a logarithmic distribution of objects out there, as shown by crater sizes, so we should expect many, many times more small objects to be out there than big ones. If I was looking for non-radiating massive bodies then I'd start looking in areas like molecular clouds, where a transiting body might leave a turbulent trail.
One interesting question regarding Super Earths is the matter of internally generated heat; unlike gas giants and ice giants, radioactive decay should play a big part in keeping such bodies 'warm' internally. I doubt, however, if greenhouse gas effects will be very effective without an external radiant heat source and with an infinite cold trap sucking heat away, so the surface should still be generally cold. Nevertheless, a Super Earth might have volcanic activity, impact basins, and the rest - and perhaps even be an abode of life.
Post by: jgoldader on 12/12/2015 11:00 am
This could also be an astronomical analog of the irreproducible medical studies. With enough samples, eventually you'll get false hits. Nobody necessarily screwed up.
Post by: Star One on 12/12/2015 12:15 pm
Post by: as58 on 12/12/2015 12:49 pm
Is there any plans for another instrument similar to ALMA, then at least you might be able to get some independent secondary validation?
ALMA is by far the most expensive astronomical instrument on Earth (I think it has cost about $1.2B), so you won't be seeing a copy soon. The problem with these observations is that there's currently really nothing except ALMA that has the sensitivity and resolution to confirm (or disprove) this. Not sure if even JWST would help, if the objects are very cold.
All astrophysical explanations (extreme TNOs, rapidly varying background sources etc.) seem unlikely, so of course the possibility of some sort of artefact with ALMA or processing of observations must be considered (and that is also mentioned in the papers). On the other hand, the detections are fairly strong, so it'd be strange and disconcerting if ALMA produces such spurious sources.
Post by: Star One on 12/12/2015 06:34 pm
Is there any plans for another instrument similar to ALMA, then at least you might be able to get some independent secondary validation?
ALMA is by far the most expensive astronomical instrument on Earth (I think it has cost about $1.2B), so you won't be seeing a copy soon. The problem with these observations is that there's currently really nothing except ALMA that has the sensitivity and resolution to confirm (or disprove) this. Not sure if even JWST would help, if the objects are very cold.
All astrophysical explanations (extreme TNOs, rapidly varying background sources etc.) seem unlikely, so of course the possibility of some sort of artefact with ALMA or processing of observations must be considered (and that is also mentioned in the papers). On the other hand, the detections are fairly strong, so it'd be strange and disconcerting if ALMA produces such spurious sources.
I didn't realise it was so costly. Just must hope that technology might drive the cost down in future & someone may instigate another facility otherwise you're going to keep getting the issues associated with single source detections.
Post by: JamesG123 on 12/12/2015 11:30 pm
Also blogs. Comments on blogs are usually reliable and accurate and unbiased.
And Web discussion forums? ;)
This (the extent of the outer solar system/ort cloud) reminds me of that scene from "Finding Nemo" (yes, I have little kids) when they are going down into the abyss and Dory says, "It just keeps going doesn't it?"
Post by: AegeanBlue on 12/13/2015 03:02 am
ALMA is by far the most expensive astronomical instrument on Earth (I think it has cost about $1.2B), so you won't be seeing a copy soon. The problem with these observations is that there's currently really nothing except ALMA that has the sensitivity and resolution to confirm (or disprove) this. Not sure if even JWST would help, if the objects are very cold.
I was wondering if the Event Horizon Telescope would help. I know it is still in the making, getting all the telescopes all over the globe to actually work at the same time but perhaps it could help. The other telescope I am thinking would be the Allen Telescope Array after phase 4. I know that they have been having trouble fundraising to keep it running on phase one, let alone expand but perhaps it could rival ALMA when completed
Post by: Bubbinski on 12/13/2015 03:20 am
Post by: hop on 12/13/2015 04:06 am
The problem with these observations is that there's currently really nothing except ALMA that has the sensitivity and resolution to confirm (or disprove) this. Not sure if even JWST would help, if the objects are very cold.Should be noted this depends which on which of the scenarios you are looking at. Nothing can replicate the ALMA observations, but if "Gna" really is a ~200-800km centaur, it should be easily observable with existing ground based telescopes. In fact it would be bright enough to argue against this model, but it's possible something big slipped through the cracks.
The other problem for follow up is that the possible orbits are very poorly constrained. Even if JWST could detect say, a super earth in the inner Oort cloud, it would be very tough to argue for the time to do a large scale survey with it.
Post by: as58 on 12/13/2015 08:25 am
The problem with these observations is that there's currently really nothing except ALMA that has the sensitivity and resolution to confirm (or disprove) this. Not sure if even JWST would help, if the objects are very cold.Should be noted this depends which on which of the scenarios you are looking at. Nothing can replicate the ALMA observations, but if "Gna" really is a ~200-800km centaur, it should be easily observable with existing ground based telescopes. In fact it would be bright enough to argue against this model, but it's possible something big slipped through the cracks.
The other problem for follow up is that the possible orbits are very poorly constrained. Even if JWST could detect say, a super earth in the inner Oort cloud, it would be very tough to argue for the time to do a large scale survey with it.
Yeah, a large centaur should indeed be easy to detect and as you say, some strange coincidences would be needed to explain why it hasn't been seen before. I don't think anyone will (or should) get time for blind surveys for super-Earths in the Oort cloud with JWST (or ALMA for that matter), the small field of view makes such searches very inefficient.
As for what's next for these two possible objects, I guess if "Gna" is a super-centaur, it'll be seen in some large scale optical survey sooner or later. At least by LSST, if not before. If it's some other kind of Solar System object farther out, I think it's pretty much ALMA or nothing, but it's hard to argue for ALMA time without knowing where to look. The Alpha Centauri object is moving slower so maybe it could still be within ALMA field of view targeting Alpha Cen (I haven't checked the details though), so maybe a repeat observation in the nearish future could be useful. I guess people are also looking closely at the data to see if they could somehow explain the detection(s) as artefact(s).
Post by: as58 on 12/13/2015 08:44 am
I was wondering if the Event Horizon Telescope would help. I know it is still in the making, getting all the telescopes all over the globe to actually work at the same time but perhaps it could help. The other telescope I am thinking would be the Allen Telescope Array after phase 4. I know that they have been having trouble fundraising to keep it running on phase one, let alone expand but perhaps it could rival ALMA when completed
The two arrays you mentioned are working at much longer (radio) wavelengths. I don't think a cold outer Solar System object would emit much radiowaves. ATA is also too far north at least for Alpha Centauri observations.
Post by: jgoldader on 12/13/2015 12:08 pm
How could ALMA do a good follow up on this, if there's no other telescope like it that can be used? If a different team of scientists runs an observing program on ALMA and finds this same object a few months from now, in a slightly different location near where it was last observed, would that increase the confidence level?
That's a reasonable suggestion. In one of the two papers linked early on, the authors talked about funding the candidate in subsets of the data, which is about all they could be expected to do. (The other paper just accepted the detections as real.)
I'd hope they have a little director's discretionary time that could be used. I'd do two runs at different times of day, with slightly different pointings, and see if there's a detection at the same RA/DEC.
I'm wondering if this might be some kind of weird sidelobe issue, a "ghost" of a source outside the intended field of view. I never did array work, so have no direct experience with the issues you get with telescope arrays. One would suspect there'd have been work on characterizing that sort of thing during the commissioning phase.
Post by: Mongo62 on 12/17/2015 12:48 am
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Some of the scenarios envisaged for the possible new Solar System object, whose discovery with the ALMA facility has been recently claimed in the literature, are preliminarily put to the test by means of the orbital motions of some planets of the Solar System. It turns out that the current ranges of admissible values for any anomalous secular precession of the perihelion of Saturn, determined in the recent past with either the EPM2011 and the INPOP10a planetary ephemerides without modeling the action of such a potential new member of the Solar System, do not rule out the existence of a putative Neptune-like pointlike perturber at about 2500 au. Instead, both a super-Earth at some hundreds of au and a Jovian-type planet up to 4000 au are strongly disfavored. An Earth-sized body at 100 au would have a density as little as ∼0.1−0.01 g cm−3, while an unusually large Centaur or (Extreme) Trans Neptunian Object with linear size of 220−880 km at 12−25 au would have density much larger than ∼1 g cm−3.
So a Neptune-size body at around 2500 AU is not ruled out -- at least not by Saturn's orbital motions.
Post by: Star One on 12/17/2015 06:44 am
Tentative planetary orbital constraints of some scenarios for the possible new Solar System object recently discovered with ALMA (http://arxiv.org/abs/1512.05288)QuoteSome of the scenarios envisaged for the possible new Solar System object, whose discovery with the ALMA facility has been recently claimed in the literature, are preliminarily put to the test by means of the orbital motions of some planets of the Solar System. It turns out that the current ranges of admissible values for any anomalous secular precession of the perihelion of Saturn, determined in the recent past with either the EPM2011 and the INPOP10a planetary ephemerides without modeling the action of such a potential new member of the Solar System, do not rule out the existence of a putative Neptune-like pointlike perturber at about 2500 au. Instead, both a super-Earth at some hundreds of au and a Jovian-type planet up to 4000 au are strongly disfavored. An Earth-sized body at 100 au would have a density as little as ∼0.1−0.01 g cm−3, while an unusually large Centaur or (Extreme) Trans Neptunian Object with linear size of 220−880 km at 12−25 au would have density much larger than ∼1 g cm−3.
So a Neptune-size body at around 2500 AU is not ruled out -- at least not by Saturn's orbital motions.
Perhaps that's the missing gas giant that some believe was expelled from the Solar System.
http://blogs.discovermagazine.com/badastronomy/2011/11/16/did-jupiter-toss-a-giant-planet-out-of-the-solar-system/
Post by: redliox on 12/17/2015 07:13 am
So a Neptune-size body at around 2500 AU is not ruled out -- at least not by Saturn's orbital motions.
Perhaps that's the missing gas giant that some believe was expelled from the Solar System.
http://blogs.discovermagazine.com/badastronomy/2011/11/16/did-jupiter-toss-a-giant-planet-out-of-the-solar-system/
I'd call it a fair possibility. Whatever the object is, they might be able to compute its orbital history in the same way we learned that the gas giants migrated...with this would-be-planet being one of the casualties. If it's the size of Earth or greater odds are it more likely originated within the Solar System instead of the Oort cloud where it would have gained mass more swiftly.
Too early to say yet. It could still be a bright Kuiper-like body or even Alpha Centauri's planet.
Hopefully Hubble can swing into action to help as it did for New Horizons.
Post by: notsorandom on 12/17/2015 03:05 pm
According to WISE data (and Phil Plat) there can't be a Jupiter sized object closer than 20,000 AU or a Saturn sized object closer than 10,000 AU. Any object that big would be too warm to have escaped notice by WISE. These proposed objects discovered by ALMA if closer need to be smaller and cooler than a gas giant. A Neptune sized object would be smaller and cooler than Saturn but I am unsure if it could be as close at 2,500 AU and not be seen by WISE.So a Neptune-size body at around 2500 AU is not ruled out -- at least not by Saturn's orbital motions.
Perhaps that's the missing gas giant that some believe was expelled from the Solar System.
http://blogs.discovermagazine.com/badastronomy/2011/11/16/did-jupiter-toss-a-giant-planet-out-of-the-solar-system/
I'd call it a fair possibility. Whatever the object is, they might be able to compute its orbital history in the same way we learned that the gas giants migrated...with this would-be-planet being one of the casualties. If it's the size of Earth or greater odds are it more likely originated within the Solar System instead of the Oort cloud where it would have gained mass more swiftly.
Too early to say yet. It could still be a bright Kuiper-like body or even Alpha Centauri's planet.
Hopefully Hubble can swing into action to help as it did for New Horizons.
Post by: hop on 12/17/2015 08:35 pm
If it's the size of Earth or greater odds are it more likely originated within the Solar System instead of the Oort cloud where it would have gained mass more swiftly.FWIW, this is the accepted model for Oort objects as a whole, whether or not they are planetary size. In-situ formation at Oort cloud distances is hard. (Some models suggest a substantial number came from other stars in the solar birth cluster, but they still would have formed in the planetary region of those stars.)
My understanding is that the odds of outright ejection are higher than sticking around in the Oort cloud: Sticking around requires additional luck to lift perihelion out of the planetary region. So if you assume there was a third ice giant, it's more likely that it's long gone.
Quote
Hopefully Hubble can swing into action to help as it did for New Horizons.You don't get the kind of Hubble time needed to search large areas unless you have a much more compelling case. NH did, because it's a once in a lifetime opportunity to see a smaller KBO up close in it's native habitat.
Post by: clongton on 12/19/2015 12:09 am
If it's the size of Earth or greater odds are it more likely originated within the Solar System ...
Or it's a captured rogue planet, point of origin unknown.
Post by: jgoldader on 12/19/2015 10:54 am
If it's the size of Earth or greater odds are it more likely originated within the Solar System ...
Or it's a captured rogue planet, point of origin unknown.
You'd most likely need a 3-body interaction in a significant gravitational field, or a planet with a propulsion system to manage that. It's no different than having a passing spacecraft enter orbit, you still have to manage the momentum and energy.
Gravity being a conservative force, gravitational interactions are elastic (neglecting tidal heating and such; pesky complicated Real World!) conserving not only momentum but also kinetic energy. The discovery of binary asteroids gave the first reasonable explanation of all the tiny irregular satellites of the outer planets; a binary asteroid passing close to the planet gets disrupted, with the binary being split such that one member ends up in orbit around the planet and the second gets tossed away, carrying part of the first's original momentum and kinetic energy.
Unless a rogue planet was a binary and ended up close to one of "our" planets, it is hard to see how it could get captured. Most likely, anything very far out there in orbit around the Sun was born here, and scattered into that orbit via a gravitational interaction with one of the planets.
Post by: as58 on 12/19/2015 12:47 pm
Couple of new papers on the possibility of large objects in the far outer solar system.
http://arxiv.org/pdf/1512.02650v1.pdf
http://arxiv.org/pdf/1512.02652.pdf
Both are coming out of observations using ALMA which seems to be at the cutting edge for this kind of research.
Check the update to the second paper.
http://arxiv.org/abs/1512.02652
Post by: Star One on 12/19/2015 08:22 pm
Couple of new papers on the possibility of large objects in the far outer solar system.
http://arxiv.org/pdf/1512.02650v1.pdf
http://arxiv.org/pdf/1512.02652.pdf
Both are coming out of observations using ALMA which seems to be at the cutting edge for this kind of research.
Check the update to the second paper.
http://arxiv.org/abs/1512.02652
Is this update indicative of any particular type of object?
Post by: NovaSilisko on 12/20/2015 04:04 am
Comments: withdrawn until further data is available
Post by: jgoldader on 12/20/2015 10:33 am
Look closer.
Comments: withdrawn until further data is available
If you read the first paper, it looks like those authors reduced the data at least twice, using different software packages and techniques. I'd call that due diligence. As I suggested earlier, these "detections" could be some artefact of the system itself that might require software and/or data reduction strategy tweaks. Science in progress.
Post by: Johnnyhinbos on 12/20/2015 11:07 am
Post by: Bubbinski on 12/20/2015 06:43 pm
Seriously, if I'm reading that article right, they found something but need more info to deduce what it is. Will be watching this thread with interest.
Post by: hop on 12/20/2015 08:44 pm
Seriously, if I'm reading that article right, they found something but need more info to deduce what it is. Will be watching this thread with interest.They still think one of the signals is real, but there is no longer any suggestion of a moving object, so the already weak argument for solar system body is a lot weaker. If the remaining detection stands, it may be a distant transient astrophysical source. Or terrestrial ;)
Post by: Mongo62 on 01/20/2016 04:07 pm
Evidence for a Distant Giant Planet in the Solar System (http://"http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22/meta")
Konstantin Batygin and Michael E. Brown
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Abstract
Recent analyses have shown that distant orbits within the scattered disk population of the Kuiper Belt exhibit an unexpected clustering in their respective arguments of perihelion. While several hypotheses have been put forward to explain this alignment, to date, a theoretical model that can successfully account for the observations remains elusive. In this work we show that the orbits of distant Kuiper Belt objects (KBOs) cluster not only in argument of perihelion, but also in physical space. We demonstrate that the perihelion positions and orbital planes of the objects are tightly confined and that such a clustering has only a probability of 0.007% to be due to chance, thus requiring a dynamical origin. We find that the observed orbital alignment can be maintained by a distant eccentric planet with mass gsim10 m⊕ whose orbit lies in approximately the same plane as those of the distant KBOs, but whose perihelion is 180° away from the perihelia of the minor bodies. In addition to accounting for the observed orbital alignment, the existence of such a planet naturally explains the presence of high-perihelion Sedna-like objects, as well as the known collection of high semimajor axis objects with inclinations between 60° and 150° whose origin was previously unclear. Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet.
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6. SUMMARY
To date, the distinctive orbital alignment observed within the scattered disk population of the Kuiper Belt remains largely unexplained. Accordingly, the primary purpose of this study has been to identify a physical mechanism that can generate and maintain the peculiar clustering of orbital elements in the remote outskirts of the solar system. Here, we have proposed that the process of resonant coupling with a distant, planetary mass companion can explain the available data, and have outlined an observational test that can validate or refute our hypothesis.
We began our analysis with a re-examination of the available data. To this end, in addition to the previously known grouping of the arguments of perihelia (Trujillo & Sheppard 2014), we have identified ancillary clustering in the longitude of the ascending node of distant KBOs and showed that objects that are not actively scattering off of Neptune exhibit true orbital confinement in inertial space. The aim of subsequent calculations was then to establish whether gravitational perturbations arising from a yet-unidentified planetary-mass body that occupies an extended, but nevertheless bound, orbit can adequately explain the observational data.
The likely range of orbital properties of the distant perturber was motivated by analytic considerations, originating within the framework of octupole-order secular theory. By constructing secular phase-space portraits of a strictly planar system, we demonstrated that a highly eccentric distant perturber can drive significant modulation of particle eccentricities and libration of apsidal lines such that the perturber's orbit continuously encloses interior KBOs. Intriguingly, numerical reconstruction of the projected phase-space portraits revealed that, in addition to secular interactions, resonant coupling may strongly affect the dynamical evolution of KBOs residing within the relevant range of orbital parameters. More specifically, direct N-body calculations have shown that grossly overlapped, apsidally anti-aligned orbits can be maintained at nearly Neptune-crossing eccentricities by a highly elliptical perturber, resulting in persistent near-colinearity of KBO perihelia.
Having identified an illustrative set of orbital properties of the perturber in the planar case, we demonstrated that an inclined object with similar parameters can dynamically carve a population of particles that is confined both apsidally and nodally. Such sculpting leads to a family of orbits that is clustered in physical space, in agreement with the data. Although the model proposed herein is characterized by a multitude of quantities that are inherently degenerate with respect to one another, our calculations suggest that a perturber on an a' ~ 700 AU, e' ~ 0.6 orbit would have to be somewhat more massive (e.g., a factor of a few) than m' = 10 m⊕ to produce the desired effect.
A unique prediction that arises within the context of our resonant coupling model is that the perturber allows for the existence of an additional population of high-perihelion KBOs that do not exhibit the same type of orbital clustering as the identified objects. Observational efforts aimed at discovering such objects, as well as directly detecting the distant perturber itself constitute the best path toward testing our hypothesis.
So about the size of Neptune, if their hypothesis is correct.
Post by: llanitedave on 01/20/2016 04:18 pm
Post by: Bubbinski on 01/20/2016 04:27 pm
And is there any way that the ALMA data talked about in this thread could be relevant?
Post by: Retired Downrange on 01/20/2016 04:37 pm
"The thought of a hidden planet larger than Earth is intriguing,..... highly elliptical orbit. It might not make its closest approach of the sun more than once every 10,000 years, and even then it would remain far beyond the known planets.
...
It would be difficult to see the ninth planet if it's not at or near its closest approach to the sun. Brown doesn't believe the object is at that point, saying it would have been spotted by now. But he does think that the most powerful telescopes on the planet, if pointed in precisely the right direction, might be able to detect it even when it is most distant from the sun.
We've been looking for it for a while now, but the sky is pretty big," Brown said. "We know its path, but not where it is on that path."
https://www.washingtonpost.com/news/speaking-of-science/wp/2016/01/20/new-evidence-suggests-a-ninth-planet-lurking-at-the-edge-of-the-solar-system/
Post by: whitelancer64 on 01/20/2016 04:40 pm
Wow. A new planet in our solar system, at 10 earth masses plus? Which telescope would be best positioned to confirm this? And is the WISE data being looked at again?
And is there any way that the ALMA data talked about in this thread could be relevant?
The Keck Observatory or the Gran Telescopio Canarias would be needed if it is at the most distant point in its theorized orbit. If it is closer, there are many smaller (though still big) telescopes that would be able to spot it.
If it hasn't been found yet and the theory hasn't been shown to be wrong by 2025 (or even if it has been found by then), both the European Extremely Large Telescope and the Giant Magellan Telescope will easily be able to observe it. The Thirty Meter Telescope is currently on hold, but would also be more than capable of seeing it.
Post by: A8-3 on 01/20/2016 04:47 pm
http://www.sciencemag.org/news/2016/01/feature-astronomers-say-neptune-sized-planet-lurks-unseen-solar-system
Post by: Bynaus on 01/20/2016 05:22 pm
Quote
And is the WISE data being looked at again?
It is probably too cold to be imaged in the longest wavelength surveyed by WISE!
Post by: Star One on 01/20/2016 05:48 pm
http://m.caltech.edu/news/caltech-researchers-find-evidence-real-ninth-planet-49523
Post by: Alpha_Centauri on 01/20/2016 05:53 pm
Wow. A new planet in our solar system, at 10 earth masses plus? Which telescope would be best positioned to confirm this? And is the WISE data being looked at again?
And is there any way that the ALMA data talked about in this thread could be relevant?
In trying to find a faint object bigger isn't necessarily better. While the ELTs will be easily big enough to spot it, their corresponding tiny field-of-view makes a survey of the sky impractical. You need special wide field-of-view survey telescopes so that it wouldn't take forever to view the whole sky. Subaru has been looking for such objects for some time and not found anything, and to be honest I think it would be at the limit of its capability. I suspect we will only know when the LSST comes online in the next decade; http://www.lsst.org/lsst/
Re: ALMA, very very unlikely.
Post by: Star One on 01/20/2016 05:58 pm
Wow. A new planet in our solar system, at 10 earth masses plus? Which telescope would be best positioned to confirm this? And is the WISE data being looked at again?
And is there any way that the ALMA data talked about in this thread could be relevant?
In trying to find a faint object bigger isn't necessarily better. While the ELTs will be easily big enough to spot it, their corresponding tiny field-of-view makes a survey of the sky impractical. You need special wide field-of-view survey telescopes so that it wouldn't take forever to view the whole sky. Subaru has been looking for such objects for some time and not found anything, and to be honest I think it would be at the limit of its capability. I suspect we will only know when the LSST comes online in the next decade; http://www.lsst.org/lsst/
Re: ALMA, very very unlikely.
Would any of the current or forthcoming space telescopes be any use, or are their field of views too small?
This planet sounds like the fifth gas giant that Jupiter & Saturn ejected from our part of the solar system.
Post by: JasonAW3 on 01/20/2016 06:07 pm
As current theories about the current orbits of the various planets and the formation of the Moon involve a sort of "Billiard Balls" type of dynamics, planets thrown into extreme orbits actually make a good deal of sense.
Post by: Lee Jay on 01/20/2016 06:23 pm
Would any of the current or forthcoming space telescopes be any use, or are their field of views too small?
JWST will be good once we know where the thing is, but probably not before that.
Post by: Star One on 01/20/2016 06:50 pm
Considering the number of planets that were likely thrown about in the early days after the sun ignited, I would not be too suprised if there are a number of Oort Cloud and somehat beyond large planets of Earth size or slightly larger.
As current theories about the current orbits of the various planets and the formation of the Moon involve a sort of "Billiard Balls" type of dynamics, planets thrown into extreme orbits actually make a good deal of sense.
This planet seems to boss around a lot of objects out that way.
I wonder if it had any hand in things like Ceres ending up where it is rather than the Kuiper belt where it may have originated and also why Neptune has a Kuiper belt object for a moon.
Post by: Mongo62 on 01/20/2016 07:02 pm
Would any of the current or forthcoming space telescopes be any use, or are their field of views too small?
WFIRST (Wide Field Infrared Survey Telescope) sounds perfect for this job, but it would not be in orbit for quite a while yet.
Post by: Star One on 01/20/2016 07:10 pm
https://youtu.be/42GeoCVaZQg
Post by: meekGee on 01/20/2016 07:22 pm
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Post by: Star One on 01/20/2016 07:30 pm
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
As I said up the thread I wonder if this is the missing fifth gas giant that it is theorised that Jupiter & Saturn hurled outwards.
Post by: whitelancer64 on 01/20/2016 07:30 pm
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
Post by: meekGee on 01/20/2016 07:33 pm
Yeah, that's what I remembered too.Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
Post by: Phil Stooke on 01/20/2016 08:00 pm
I would think that a big object, multi-Earth masses big, would be detectable by its gravitational effect on those trajectories. I would regard that as the best way to confirm a big object right now. The question is, are there any unexplained components of Voyager or Pioneer motion that might be explained by a large object in that general region of the sky?
Large planets are sources of radio emissions as well. Are there radio astronomy results relevant to this story?
I hope some of these other techniques can be used here. We are not solely reliant on visible or IR imaging.
Post by: alk3997 on 01/20/2016 08:06 pm
So..., we have four distant spacecraft, two still being tracked (Voyagers) and two tracked for less time, but their data still available for analysis (Pioneers). I'm not counting NH for this. The old Pioneer anomaly story shows how exquisitely precisely we can track these things. And all heading out in different directions.
I would think that a big object, multi-Earth masses big, would be detectable by its gravitational effect on those trajectories. I would regard that as the best way to confirm a big object right now. The question is, are there any unexplained components of Voyager or Pioneer motion that might be explained by a large object in that general region of the sky?
Large planets are sources of radio emissions as well. Are there radio astronomy results relevant to this story?
I hope some of these other techniques can be used here. We are not solely reliant on visible or IR imaging.
Space is very big...Voyager 1 hasn't even reached the proposed orbit of "Planet 9".
The area of the entire solar system from Neptune inward would fit in the area that this 10 earth mass planet could be in. Can an Earth orbiting spacecraft detect, by gravity, the presence of a 10 Earth mass planet at Neptune? That would likely be easier.
We would have to be very very lucky for any of those tiny spacecraft to be close enough to have their trajectories changed when they actually get out there. The odds of any instrument on those spacecraft detecting the supposed planet is as close to null as possible.
http://www.gannett-cdn.com/usatoday/editorial/graphics/2016/01/012016-new-planet-mobile1.jpg
Andy
Post by: rocx on 01/20/2016 08:10 pm
Because they spend a lot of time orbiting together, long enough for resonance effects to become visible.
Post by: ChrisGebhardt on 01/20/2016 08:23 pm
Yeah, that's what I remembered too.Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
The official IAU (International Astronomical Union) definition of a planet is:
An astronomical object that
- is in orbit around the Sun,
- has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
- has "cleared the neighborhood" around its orbit.
Now, as has been stated many times - even by the IAU - this is the definition reached in 2006 based on known information and a growing understanding of the outer solar system. This definition can be amended with new information.
I would also add that so little is known about this region that it's possible this not-mathematically-disproved Planet Nine has indeed cleared its "neighbouring region" enough to qualify for major planet status. It's also possible that it hasn't.
Regardless, it is far too early to speculate where it may fall in the definitional realm of planet-hood. We need to find it, observe it, and concretely determine its orbit first.
That said (and what I'm sure some people will claim otherwise), it is highly unlikely that Planet Nine would - if found - in anyway result in Pluto being added back into the major planet class -- not with all of the similar objects it shares the Kuiper Belt and its orbit with. (There, I said it. :D)
Post by: Bynaus on 01/20/2016 08:37 pm
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I would also add that so little is known about this region that it's possible this not-mathematically-disproved Planet Nine has indeed cleared its "neighbouring region" enough to qualify for major planet status. It's also possible that it hasn't.
"Clearing the neighborhood" should not be taken that literal. The Earth's neighborhood is not completely cleared, nor is Jupiter's (think of the Trojan asteroids or the Jupiter family comets), yet these two remain planets under the new definition. The point is, a planet is an object that is gravitationally dominating on its orbit.
That new object, if it exists, will be gravitationally dominant. See this article by one of the authors of the discovery paper: http://www.findplanetnine.com/2016/01/is-planet-nine-planet.html
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That said (and what I'm sure some people will claim otherwise), it is highly unlikely that Planet Nine would - if found - in anyway result in Pluto being added back into the major planet class
Second that. Not a comet's chance in the inner corona.
Post by: meekGee on 01/20/2016 08:49 pm
Not a comet's chance in the inner corona.I need to remember that one.
Post by: Star One on 01/20/2016 08:55 pm
According to this article this it could even be a super Earth rather than mini Neptune.
http://news.nationalgeographic.com/2016/01/150119-new-ninth-planet-solar-system-space/
Post by: Mongo62 on 01/20/2016 08:56 pm
Which would make it, at that distance, a dwarf planet under IAU rules.
Co-author Mike Brown, who supported the demotion of Pluto to "Dwarf Planet", thinks that this object qualifies as a full planet. From the New Yorker article (http://www.newyorker.com/tech/elements/discovering-planet-nine):
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I asked Brown whether “planet” was the right word for it. “It is a planet—there’s virtually no doubt,” he said. “What we now call planets are objects that can gravitationally dominate their neighborhood. Pluto is a slave to the gravitational influence of Neptune. By area, Planet Nine dominates more of the solar system than any other known planet—it’s only because of this that we can infer its existence. And because of this we’re pretty sure it’s not a small object: it’s at least ten times more massive than Earth and five thousand times more massive than Pluto. In many ways, you could argue that this is more of a planet than anything else in the solar system.”
"Clearing the neighborhood" is a virtually meaningless term. There are still asteroids next to Earth and even Jupiter. But gravitationally dominating an area is quite possible, and this object, unlike any of the known dwarf planets, would do so, if it exists.
Post by: Lee Jay on 01/20/2016 09:03 pm
Post by: gospacex on 01/20/2016 09:09 pm
Post by: Star One on 01/20/2016 09:09 pm
http://www.findplanetnine.com/p/blog-page.html?m=1
Post by: Bynaus on 01/20/2016 09:12 pm
What's the rationale for assuming it's likely composition is that of a gas giant and not a large rock?
None at all, at this moment. We don't have a good handle on its mass. Something 5-15 Earth masses would certainly work. Perhaps a bit lower. Perhaps a big higher still. If its on the lower end, its likely rocky/icy. If its at the upper end, it will have a lot of gas too. We'll have to see - when they find it.
Post by: Star One on 01/20/2016 09:17 pm
What's the rationale for assuming it's likely composition is that of a gas giant and not a large rock?
None at all, at this moment. We don't have a good handle on its mass. Something 5-15 Earth masses would certainly work. Perhaps a bit lower. Perhaps a big higher still. If its on the lower end, its likely rocky/icy. If its at the upper end, it will have a lot of gas too. We'll have to see - when they find it.
An expert quoted in that National Geographic article suggested it was just as likely a super Earth as mini Neptune. Also it would mean this thread title was correct;)
By the way is there any kind of already preset limitation on what this planet could be called of found, would it have to be a name that followed the other planets naming?
Post by: Bynaus on 01/20/2016 09:39 pm
Perhaps an idea: Mike Brown once suggested to name all objects in that region after arctic gods of the deep sea (like Sedna). I don't know if anything comes to mind... EDIT: Perhaps Anguta (https://en.wikipedia.org/wiki/Anguta)?
Post by: ChrisGebhardt on 01/20/2016 09:41 pm
By the way is there any kind of already preset limitation on what this planet could be called of found, would it have to be a babe that followed the other planets naming?
Way too early for anything about a potential name. But it would logically follow the naming schemes of the other eight planets.
Post by: Lee Jay on 01/20/2016 09:51 pm
At New Horizons speed, it would take around 300 years to get there.
To get there in a year, it would have to average around 4750km/s which is about 1.6% of the speed of light.
That's assuming it exists. And we find it.
A big space-based optical interferometer would probably be faster.
Post by: meekGee on 01/20/2016 10:01 pm
Is it at all possible to not repeat "dwarf planet debate" in this thread?Empirical evidence seems to suggest the opposite.
.. And actually for a good reason... It shows that the definition of a "regular" planet does in fact allow for new bodies, and the exclusion of Pluto was not arbitrary.
Buy sure, we can take that to the Pluto thread, if it's still alive.
Post by: Mongo62 on 01/20/2016 10:03 pm
By the way is there any kind of already preset limitation on what this planet could be called of found, would it have to be a babe that followed the other planets naming?
Way too early for anything about a potential name. But it would logically follow the naming schemes of the other eight planets.
If it is found by a team led by Mike Brown, it might be quite a while after discovery before it gets named. 2007 OR10 (https://en.wikipedia.org/wiki/(225088)_2007_OR10) was discovered by Brown in 2007 (as its designation suggests) and has still not been named:
Quote
(225088) 2007 OR10 is currently the largest known object in the Solar System without an official name. In 2011 Brown decided he finally had enough information to justify giving it one, because the discovery of water ice and the possibility of methane makes it noteworthy enough to warrant further study. However, as of 2015, Brown had yet to propose a name, though he notes that in 2017 anyone will be able to make a proposal.
Post by: Star One on 01/20/2016 10:05 pm
Also from her blog.
Quote
I did read the paper, and one thing in the discussion caught my eye: the work does not explain the "Kuiper cliff," the lack of objects with orbit semimajor axes between 50 and 70 AU. It would be very nice (from an aesthetic standpoint, anyway) if the same planet could also be blamed for those apparently missing worlds. But it can't, at least not yet:
Another curious feature of the distant scattered disk is the lack of objects with perihelion distance in the range q = 50–70 AU. It is yet unclear if this property of the observational sample can be accounted for by invoking a distant eccentric perturber such as the one discussed herein. Indeed, answering these questions comprises an important avenue toward further characterization of our model.
http://www.planetary.org/blogs/emily-lakdawalla/2016/01200955-theoretical-evidence-for-planet-9.html
Post by: ChrisGebhardt on 01/20/2016 10:12 pm
By the way is there any kind of already preset limitation on what this planet could be called of found, would it have to be a babe that followed the other planets naming?
Way too early for anything about a potential name. But it would logically follow the naming schemes of the other eight planets.
If it is found by a team led by Mike Brown, it might be quite a while after discovery before it gets named. 2007 OR10 (https://en.wikipedia.org/wiki/(225088)_2007_OR10) was discovered by Brown in 2007 (as its designation suggests) and has still not been named:Quote(225088) 2007 OR10 is currently the largest known object in the Solar System without an official name. In 2011 Brown decided he finally had enough information to justify giving it one, because the discovery of water ice and the possibility of methane makes it noteworthy enough to warrant further study. However, as of 2015, Brown had yet to propose a name, though he notes that in 2017 anyone will be able to make a proposal.
IF found, the fact that it would in all likelihood be a bonafide planet would probably accelerate its naming.
To counter your point, Sedna was discovered on 14 November 2003 and officially named in September 2004. There's really no way to predict how quickly something can be named. But names can be proposed and accepted quite quickly.
Moreover, Pluto was discovered in March 1930 and officially named on 1 May 1930 -- less than two months after its discovery.
Post by: llanitedave on 01/21/2016 12:03 am
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
The distance from the Sun has quite a bit to do with it. The farther a body is from the Sun, the longer it will take to clear out its orbit, and the more massive it must be in order to be considered a planet. Under a formula created by Jean-Luc Margot (https://en.wikipedia.org/wiki/Clearing_the_neighbourhood), an Earth-mass body greater than 390 a.u. distant would not have cleared out its orbit during the Sun's main-sequence lifetime, and thus would not be a planet.
Post by: meekGee on 01/21/2016 01:02 am
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
The distance from the Sun has quite a bit to do with it. The farther a body is from the Sun, the longer it will take to clear out its orbit, and the more massive it must be in order to be considered a planet. Under a formula created by Jean-Luc Margot (https://en.wikipedia.org/wiki/Clearing_the_neighbourhood), an Earth-mass body greater than 390 a.u. distant would not have cleared out its orbit during the Sun's main-sequence lifetime, and thus would not be a planet.
Which is why "gravitationally dominant" makes for better phrasing. Same idea though.
Post by: a_langwich on 01/21/2016 02:01 am
Hopefull, that boundary will expand rapidly over the next few decades, and not shrink as human spaceflight distance capabilities have.
Post by: wxmeddler on 01/21/2016 02:23 am
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
The distance from the Sun has quite a bit to do with it. The farther a body is from the Sun, the longer it will take to clear out its orbit, and the more massive it must be in order to be considered a planet. Under a formula created by Jean-Luc Margot (https://en.wikipedia.org/wiki/Clearing_the_neighbourhood), an Earth-mass body greater than 390 a.u. distant would not have cleared out its orbit during the Sun's main-sequence lifetime, and thus would not be a planet.
Found this off of the planet nine blog from Mike Brown, one of the co-authors..
(http://3.bp.blogspot.com/-ikiYAW0Ktn8/Vp6JDNN4OUI/AAAAAAAANno/RP1KsA6YolY/s1600/margot.png)
Post by: AegeanBlue on 01/21/2016 03:23 am
Post by: CuddlyRocket on 01/21/2016 03:49 am
Which would make it, at that distance, a dwarf planet under IAU rules.
It stands to reason that with a discovery like this, they can modify the definition.
It also stands to reason that they'll keep differentiating a body like this from bodies like Pluto, Sedna, and the rest of that population, which are clearly in a family of their own.
I wonder if they could show that this planet formed in the giant belt and got ejected at some point.
Well, it should gravitationally dominate its orbit, making it a planet regardless. The distance it is from the Sun has nothing to do with it.
The distance from the Sun has quite a bit to do with it. The farther a body is from the Sun, the longer it will take to clear out its orbit, and the more massive it must be in order to be considered a planet. Under a formula created by Jean-Luc Margot (https://en.wikipedia.org/wiki/Clearing_the_neighbourhood), an Earth-mass body greater than 390 a.u. distant would not have cleared out its orbit during the Sun's main-sequence lifetime, and thus would not be a planet.
Which is why "gravitationally dominant" makes for better phrasing. Same idea though.
Margot seems to prefer the phrase 'dynamical-dominance'. Though, as you say, they all express the same underlying idea, the terminology of 'dominance' seems less prone to misinterpretation than that of 'clearing the neighbourhood'!
The IAU definition of planet within the Solar System does not define clearing the neighbourhood. It simply asserts that the Big 8 objects are planets and Ceres, Pluto and Eris are not. Thus people are free to come up with various definitions whilst still conforming to the IAU definition. The three that seem to have traction within the astronomical community are that by Margot; and earlier one by Stern and Levinson, and one by Soter. (Alan Stern, famously, regards all the Big 8 and Smaller 3 as planets; but he does recognise a distinction between the dynamically important Big 8 and the others. Levinson and his formula for so distinguishing additional objects can therefore also be used to distinguish between planets and dwarf planets.)
Soter requires the object to have a mass 100 times greater than all other objects in its orbital zone. To be accurate that requires a census of all other objects, which is going to be difficult (!) at the distance of this putative planet. However, the mass of the Kuiper belt is estimated at 0.033+/-0.115 that of Earth. So an object of 10 times the mass of Earth would be at least 67 times the mass of the whole Kuiper belt, most of which would not be in its orbital zone in any event.
An object of a given mass will satisfy the Stern-Levinson criteria at a greater orbital distance than that of Margot's, so if it's a planet according to the latter it will also be one according to the former. As stated, an object the mass of Earth satisfies Margot's criteria up to an orbit of 390 AU. But an object the mass of Uranus (14.5 times the mass of Earth) satisfies it out to 4,200 AU. So an object 10 times the mass of Earth orbiting 20 times further than Neptune on average (i.e. about 600 AU) will almost certainly satisfy Margot's criteria.
But the object proposed appears to be dynamically dominant in any event; after all, that's the basis of the argument for its existence! So if it didn't satisfy either Soter's or Margot's criteria, what's likely to happen is that those criteria are shifted until it does! :)
Post by: meekGee on 01/21/2016 04:05 am
I honestly don't care of dwarf planets are considered planets.
But you need a sub category, because the number of dwarf planets is likely rather large.
Post by: testguy on 01/21/2016 01:58 pm
Post by: Graham on 01/21/2016 02:25 pm
Has anyone seen any data on the planets orbital plane? Wondering if it is the same as the other 8 planets indicating it was formed along with our solar system. If it is in a different plane, might it be a captured rouge planet formed in conjunction with a different star at an other time. How cool would that be?
It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.
As for the inclination, it is predicted to be on the same plane as the other Sedna- esque KBOs. For reference Sedna is ~12 degrees to the ecliptic
Post by: Lee Jay on 01/21/2016 02:34 pm
It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.
But if it's ejected, wouldn't only aphelion rise during the process (I mean, beyond Neptune's orbit)? I'm not knowledgeable in this long-term planetary mechanics stuff, but I'm struggling to understand the mechanism for raising perihelion to such an enormous value. Wouldn't that require impulse to be applied far away from perihelion? What could do that that doesn't come from outside the system?
Post by: Zed_Noir on 01/21/2016 03:40 pm
Has anyone seen any data on the planets orbital plane? Wondering if it is the same as the other 8 planets indicating it was formed along with our solar system. If it is in a different plane, might it be a captured rouge planet formed in conjunction with a different star at an other time. How cool would that be?
Video clip (https://youtu.be/6poHQ2h00ZA?t=28s) from Caltech showing the orbits of the outer systen in rotating viewpoint from about 0:28 to 0:59 seconds. Mike Brown (aka @plutokiller (https://twitter.com/plutokiller/with_replies) on twitter) give an overview talk during that clip segment.
Post by: Mongo62 on 01/21/2016 03:56 pm
Has anyone seen any data on the planets orbital plane? Wondering if it is the same as the other 8 planets indicating it was formed along with our solar system. If it is in a different plane, might it be a captured rouge planet formed in conjunction with a different star at an other time. How cool would that be?
From the paper:
For our nominal simulation, we adopted a′=700 AU, e′=0.6, and m′=10 m⊕, as before, and set the inclination and initial argument of perihelion of the perturber to i′=30° and ω′=150°, respectively.
Post by: Star One on 01/21/2016 08:56 pm
Quote
Alan Stern, principal scientist for New Horizons, is withholding judgment on Brown and Batygin's prediction.
"This kind of thing comes around every few years. To date, none of those predicts have been borne out by discoveries," Stern said in an email Wednesday. "I'd be very happy if the Brown-Batygin were the exception to the rule, but we'll have to wait and see. Prediction is not discovery."
Brown realizes skepticism will exist until the planet is actually observed.
"It's such a long history of people being basically wrong that standing up and saying we're right this time makes us almost look crazy," Brown said. "Except I'm going to stand up and say we're actually right this time. The evidence for the first time is actually very good that this thing is actually out there."
http://www.denverpost.com/nationworld/ci_29408753/scientists-good-evidence-9th-planet-solar-system
Quote
@scifri
We'll be talking to the @Caltech researchers who found evidence for Planet Nine this Friday
https://twitter.com/scifri/status/689836208042741760
Post by: Lars-J on 01/22/2016 01:21 am
Post by: Helodriver on 01/22/2016 03:15 am
How close a pass between the bodies would need to happen to impart such an impulse and would it have been a one time event or a series of passes in resonance over time that did it? Some fascinating questions to be figured out in this story.
Post by: Dalhousie on 01/22/2016 04:46 am
Post by: meekGee on 01/22/2016 06:08 am
I'm pretty skeptical as well. The wide range of projected planet mass, orbital period, and expected location (anywhere in 1/3rd of the hemisphere?) just seems to be the a shot in the dark. But what do I know...
Since all they have to work with is the orbits of a handful of KBOs, there's no way they can pin point it.
The placed the constrains they have, and came up with a probabilistic estimate that is pretty specific - but of course is only probabilistic...
Let's call it a shot in the dark aimed at a moving target that made a noise... You think you know what it was, and you think you know roughly where you're aiming... Luckily, in this scenario, you won't end up shooting your cat...
Post by: Star One on 01/22/2016 06:32 am
For a planet of 10X Earth mass to get flung from our solar system into such a distant and inclined orbit, an extremely high energy interaction would have to have occurred. I wonder if such an encounter might explain the 98 degree axial tilt of Uranus or even the 26 degree tilt of Saturn. (Jupiter has only a 3 degree tilt for comparison.)
How close a pass between the bodies would need to happen to impart such an impulse and would it have been a one time event or a series of passes in resonance over time that did it? Some fascinating questions to be figured out in this story.
The explanation I saw pointed the finger at both Uranus & Neptune being involved in its ejection from the inner Solar System. I would have thought between them there would be sufficient energy to do the job.
I am glad that people likeJim Green are attempting to add a note of caution to this announcement when it comes to the wider public.
http://www.cnet.com/uk/news/science-is-ready-to-brawl-again-over-a-totally-different-ninth-planet/ (http://www.cnet.com/uk/news/science-is-ready-to-brawl-again-over-a-totally-different-ninth-planet/)
Post by: Mongo62 on 01/22/2016 11:30 am
The suggested orbit also overlaps with several KBOs, so having not cleared it's orbit it's only a dwarf planet, no matter how large
That is not how the definition works. If you go by that meaning of the definition, Jupiter itself has not "cleared its orbit" and is therefore only a dwarf planet.
One of the three accepted wordings of the definition is that a full planet is gravitationally dominant over its region of the Solar System. So other bodies can exist there, but their orbits are set by the gravitational influence of the planet (i.e. resonances or Trojan orbits) while conversely, the other bodies have little effect on the orbit of the planet itself.
By that definition (which I repeat is one of the three accepted wordings of the official definition) Pluto is NOT a full planet, but only a dwarf planet. Planet Nine, however, would certainly qualify as a full planet, since it would be by far the dominant gravitational influence in its region of the Solar System.
Post by: Ben the Space Brit on 01/22/2016 12:06 pm
The hypothetical Sol-J object being involved or associated in some way in the Ice Giant migration to the outer solar system is interesting. IF (and that 's a huge 'if', the existence of this object is verified, then I think we might end up, via its characteristics, answering several questions about the structure and development of the solar system as we know it today.
Post by: Star One on 01/22/2016 12:38 pm
A quick glance at the 'where to look' blog linked further up-thread made my eyebrows go up. Trying to locate a very, very faint and slow-moving object against the Milky Way star clouds. Lovely. Maybe they can whistle up an optical-wavelength visible dark matter 'star' whilst they're at it?
The hypothetical Sol-J object being involved or associated in some way in the Ice Giant migration to the outer solar system is interesting. IF (and that 's a huge 'if', the existence of this object is verified, then I think we might end up, via its characteristics, answering several questions about the structure and development of the solar system as we know it today.
But it's not a completely impossible task. Or we will have to wait for the Large Synoptic Survey Telescope to come online in 2021.
Post by: JasonAW3 on 01/22/2016 01:40 pm
Seriously though.
One could make a very good case for establishing a high velocity Linear Accelerator on the Moon, to be able to launch a significant payload, including fuel, towards this supposed Ninth Planet. Using slingshot maneuvers and a fairly high velocity launch, one could, in theory, launch a large payload to this planet, braking into orbit via ion propulsion.
The further benefit would be, after construction and first use, having the ability to send payloads around the far solar system at a fraction of the time and cost that it would normally cost. (Assuming, that is, the majority of the manufacturing and assembly of said payloads, are accomplished on the Moon). This would also allow priority payloads to be sent to Mars, as needed.
Mind you, this would ONLY be for cargo and non-living payloads only as the acceleration would likely be significantly more than a living organism could withstand. (Can we say chunky salsa?)
Post by: Graham on 01/22/2016 02:07 pm
It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.
But if it's ejected, wouldn't only aphelion rise during the process (I mean, beyond Neptune's orbit)? I'm not knowledgeable in this long-term planetary mechanics stuff, but I'm struggling to understand the mechanism for raising perihelion to such an enormous value. Wouldn't that require impulse to be applied far away from perihelion? What could do that that doesn't come from outside the system?
If the event was energetic enough I would assume it could kick up both the perihelion and the aphelion (obviously one more than the other), with other, smaller encounters kicking the aphelion up further.
Post by: Lee Jay on 01/22/2016 02:22 pm
It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.
But if it's ejected, wouldn't only aphelion rise during the process (I mean, beyond Neptune's orbit)? I'm not knowledgeable in this long-term planetary mechanics stuff, but I'm struggling to understand the mechanism for raising perihelion to such an enormous value. Wouldn't that require impulse to be applied far away from perihelion? What could do that that doesn't come from outside the system?
If the event was energetic enough I would assume it could kick up both the perihelion and the aphelion (obviously one more than the other), with other, smaller encounters kicking the aphelion up further.
How? If you give something a short burst of impulse say, from the Jupiter/Saturn/Neptune vicinity, it either escapes entirely or comes right back to where you hit it (albeit with a much higher aphelion) , doesn't it? I mean, you can't raise perigee from perigee, can you?
Post by: Ben the Space Brit on 01/22/2016 03:59 pm
Post by: Star One on 01/22/2016 06:54 pm
http://m.xkcd.com/1633/
Also this from The Atlantic.
Planet Nine May Help Us Slingshot Our Way to Interstellar Space
http://www.theatlantic.com/science/archive/2016/01/planet-nine-may-help-us-slingshot-our-way-to-the-stars/425010/?utm_source=atl-daily-newsletter
It also comes up with a good possible name for this planet if found.
Quote
Perhaps it will be Nox, the seldom-seen Roman goddess of night and shadow.
Post by: redliox on 01/23/2016 01:22 am
It also comes up with a good possible name for this planet if found.QuotePerhaps it will be Nox, the seldom-seen Roman goddess of night and shadow.
Nix, which I'm pretty sure is the same goddess, has already been taken by one of Pluto's moons. Tyche seems to one suggested by scientists just prior to the announcement of 'indirect evidence,' and I believe there was some popularity tying that goddess to Jupiter/Zeus.
Personally two other names come to mind: Morpheus or Hercules. Hercules (or Herakles) was one of the official 12 pantheon gods in addition to being Jupiter/Zeus' son, so barring complications with asteroids bearing the name that should be a title for the roster. Morpheus was a deity of dreams and the night, so a distant dark planet in an overlooked part of space coupled with planet X being 'a dream' of sorts seems fitting too.
Post by: Kryten on 01/23/2016 01:27 am
Tyche, Morpheus, and Heracles are already taken; by asteroids 258, 4197, and 5143 respectively.It also comes up with a good possible name for this planet if found.QuotePerhaps it will be Nox, the seldom-seen Roman goddess of night and shadow.
Nix, which I'm pretty sure is the same goddess, has already been taken by one of Pluto's moons. Tyche seems to one suggested by scientists just prior to the announcement of 'indirect evidence,' and I believe there was some popularity tying that goddess to Jupiter/Zeus.
Personally two other names come to mind: Morpheus or Hercules. Hercules (or Herakles) was one of the official 12 pantheon gods in addition to being Jupiter/Zeus' son, so barring complications with asteroids bearing the name that should be a title for the roster. Morpheus was a deity of dreams and the night, so a distant dark planet in an overlooked part of space coupled with planet X being 'a dream' of sorts seems fitting too.
Post by: Star One on 01/23/2016 02:05 am
On another topic I wonder if we could have already imaged this object and not even realised it, sitting around on a data drive somewhere.
Post by: AegeanBlue on 01/23/2016 02:32 am
I am certain that there are precovery images of said planet somewhere faintly moving across a starry field. If a volunteer slave a.k.a. graduate student is willing to combine the PAN-STARRS dataset with the not yet released Gaia dataset something might pop up
Post by: KelvinZero on 01/23/2016 03:20 am
Pluto was pretty well named for a planet so far away from the sun, though Hades might be a bit grim.. :)
Post by: CuddlyRocket on 01/23/2016 05:04 am
It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.
But if it's ejected, wouldn't only aphelion rise during the process (I mean, beyond Neptune's orbit)? I'm not knowledgeable in this long-term planetary mechanics stuff, but I'm struggling to understand the mechanism for raising perihelion to such an enormous value. Wouldn't that require impulse to be applied far away from perihelion? What could do that that doesn't come from outside the system?
This article (http://link.springer.com/article/10.1007%2Fs10569-004-4623-y#page-1) suggests that the Kozai mechanism coupled with mean motion resonances is responsible for raising the perihelia of various scattered disc objects. (Actually, they say it's 'mainly' responsible, so presumably there are other mechanisms!)
Post by: Zed_Noir on 01/23/2016 06:23 pm
Post by: AegeanBlue on 01/23/2016 06:38 pm
What about Cronus as name for the the planet?
That is Saturn, already taken
Post by: jgoldader on 01/23/2016 07:11 pm
It occurs to me that, distant or not, at 10x ME, the thing would have considerable internal heat and would probably stick out like a sore thumb at certain infrared wavelengths assuming favourable background conditions. Is there a particular wavelength band that cries out 'planetary object/small brown dwarf' and not 'molecular cloud' or 'proto-star'?
Well, if it's radiating like a blackbody, the peak wavelength is 3000 microns divided by the temperature in kelvins. Neptune's temperature at the 1 bar pressure level is about 70K, so Neptune would be brightest at about 43 microns or so. But there'd be spectral features due to (probably) rotational emissions lines from the gases, so the spectrum would not be a perfect blackbody. You'd need pretty good spatial resolution and good sensitivity in a space telescope; that wavelength range is inaccessible from the ground and source confusion would be a big problem.
Post by: clongton on 01/23/2016 07:20 pm
It occurs to me that, distant or not, at 10x ME, the thing would have considerable internal heat and would probably stick out like a sore thumb at certain infrared wavelengths assuming favourable background conditions. Is there a particular wavelength band that cries out 'planetary object/small brown dwarf' and not 'molecular cloud' or 'proto-star'?
I believe it was stated somewhere upthread that 10x earth mass was an estimate based on the object being a gas giant like Uranus and Neptune. Conversely it may also be a rocky planet, in which case it would be 5x the mass of earth. And yes, if it's a small brown dwarf it should be easier to locate if the search includes objects in the infrared.
Post by: clongton on 01/23/2016 07:28 pm
...that wavelength range is inaccessible from the ground and source confusion would be a big problem.
Upthread I suggested an array at SEL-2. Smaller telescopes are easier to build, especially if you're making multiple copies, and if you array them so they act as one you will easily outperform any ground based facility.
Post by: as58 on 01/23/2016 07:30 pm
I am certain that there are precovery images of said planet somewhere faintly moving across a starry field. If a volunteer slave a.k.a. graduate student is willing to combine the PAN-STARRS dataset with the not yet released Gaia dataset something might pop up
Gaia most likely won't see it, the survey only goes to ~20th magnitude and in the yet to be ruled out part of its orbit the planet would be fainter than that.
Post by: as58 on 01/23/2016 07:38 pm
...that wavelength range is inaccessible from the ground and source confusion would be a big problem.
Upthread I suggested an array at SEL-2. Smaller telescopes are easier to build, especially if you're making multiple copies, and if you array them so they act as one you will easily outperform any ground based facility.
Small telescopes at far-infrared wavelengths would have very poor resolution, which would lead to massive source confusion as jgoldader mentioned.
And if you suggest interferometry, it no longer easy and cheap.
Post by: Star One on 01/23/2016 07:38 pm
Quote
That is why Dr. Brown keeps coming back to Hawaii – to look for objects beyond Neptune’s orbit, in the outermost reaches of the Solar System. His next observation will use the Subaru Telescope in March. It is a time exchange program between the Subaru Telescope and the W. M. Keck Observatory. What is the camera of his choice at Subaru? Yes – it will be the Hyper Suprime-Cam (HSC) with sensitive CCDs, offering a very wide field of view equivalent of nine full moon areas. This makes it extremely suitable for finding a faint object if you are not sure of where it is, but have rough idea where it can be.
Dr. Chad Trujillo based at Gemini Observatory, is an expert on objects in the outer Solar System and says, "I'd be surprised if all of the telescopes on Maunakea aren't involved in studies of the 9-th Planet." He adds that large telescopes with wide-field capabilities will be needed to find the planet in the first place since it is probably very faint. "Once discovered, virtually every telescope on Maunakea, and around our planet, will be involved in characterizing the planet to learn properties such as its mass and composition," says Trujillo.
http://www.naoj.org/Topics/2016/01/21/index.html
Post by: Skamp_X on 01/23/2016 08:59 pm
So the general rule is , early on lots of planets formed , some collided and some got kicked out of the solar system.
So that would mean there are planets floating around between the stars.
Remaining planets settled in there orbits in mostly a even plane , I assume because of long term gravity effects from the sun and other neighbouring planets.
Some others have others have eccentric orbits , possibly due to lower gravity affects from longer distances or gravity interference from planets like Jupiter.
But if were talking about billions of years isn't the chance of our sun grabbing one of these rogue planets pretty real?
Could mean there might be a few more planets out there to explore in our own solar system (and within reach of probes).
And they might end up been much older then any planet in our solar system.
Post by: Star One on 01/23/2016 09:02 pm
Up thread I believe there was one earlier paper indicating there being at least two super Earths.
Post by: clongton on 01/23/2016 09:58 pm
Something I can't help wonder about,
So the general rule is , early on lots of planets formed , some collided and some got kicked out of the solar system. So that would mean there are planets floating around between the stars.
<snip>
But if were talking about billions of years isn't the chance of our sun grabbing one of these rogue planets pretty real? Could mean there might be a few more planets out there to explore in our own solar system (and within reach of probes). And they might end up been much older then any planet in our solar system.
To your thought of how common these bodies may be there was an article at Space.com dated 2011-03-31 that spoke to this. The thrust of the article was about the search for alien life but I quote it here, not for that, but to speak to how common these bodies may be in light of your comment.
http://www.space.com/11268-alien-life-brown-dwarfs-failed-stars.html (http://www.space.com/11268-alien-life-brown-dwarfs-failed-stars.html)
Quote
The search for alien life usually focuses on planets around other stars. But a lesser-known possibility is that life has sprung up on planets that somehow were ejected from their original solar systems and became free-floating in the universe, as well as on small bodies called sub-brown dwarfs, which are stars so small and dim they are not really stars at all, but function more like planets.
Studies show these bodies could potentially host atmospheres and surfaces where some form of extraterrestial life of could take hold.
As to how many there are:
Quote
Ultimately, free-floating planets (FFP) and sub-brown dwarfs (SBD) could prove a fertile place to look for extraterrestrial creatures. Besides their habitable qualities, these bodies seem to be quite common in the universe. Sub-brown dwarfs weighing between 1 and 13 Jupiter masses may be about as common as stars, Badescu said. "The total number of FFPs and SBDs may exceed the number of stars by two orders of magnitude, although most of them should be low-mass rock/ice planetary embryos ejected from planetary systems in formation," i.e. not the type with large gaseous atmospheres that would retain the heat required for life, Badescu said.
Interesting that there may be an awful lot of them, and yes I suppose there could be others that were captured into solar orbit sometime in the distant past, especially in that astronomers who have looked into this seem to think that they may even be older than our own solar system, which at 4 billion years is short compared to the believed age of the universe to be in excess of 10 billion years.
Like I said I don't necessarily subscribe to the assumption that life may be on them, although never say never, but I thought it interesting that some prominent scientists believe these bodies may be very common.
YMMV
Post by: cscott on 01/23/2016 10:44 pm
They are roughly as common as stars. The nearest star is 4.4 light years away.
Post by: Skamp_X on 01/24/2016 02:24 am
billions of stars in 1 galaxy ..... space doesn't feel so empty all of the sudden,
could be trillions of small and big planets floating along with the stars.
Post by: KelvinZero on 01/24/2016 02:55 am
Re frequency of rogue planets, see http://blogs.discovermagazine.com/badastronomy/2011/05/19/are-we-in-danger-from-a-rogue-planet/Btw that refers to jupiter sized rogue planets. There was also a mention that the size distribution was a bit unexpected. Another interesting statistic would be how many worlds big enough to be round (or in hydrostatic equilibrium if you like :) ).
They are roughly as common as stars. The nearest star is 4.4 light years away.
Post by: CuddlyRocket on 01/24/2016 06:09 pm
But if were talking about billions of years isn't the chance of our sun grabbing one of these rogue planets pretty real?
Rogue planets, stars, even stellar systems are small compared to the gap between the stars. Even when whole galaxies collide, the odds are heavily against any star or wandering planet colliding. The odds that a rogue planet has run into the solar system - or had the solar system run into it - are vanishingly small. Also, even if they did enter the solar system they're likely to be on a hyperbolic orbit and would simply zoom straight back out again.
Capturing an object into orbit is actually quite difficult. Generally it needs the object to be one of a pair in mutual orbit around each other - one gets ejected at high speed or crashes into the primary, the other goes into orbit. How a double rogue planet got ejected into interstellar space is an interesting question!
Post by: Star One on 01/24/2016 09:34 pm
http://phenomena.nationalgeographic.com/2016/01/22/how-can-we-find-planet-nine-and-other-burning-questions/ (http://phenomena.nationalgeographic.com/2016/01/22/how-can-we-find-planet-nine-and-other-burning-questions/)
Like Alan Stern's quote in it about "Apparently Caltech can't count."
The search for planet nine blog has recently been updated.
http://www.findplanetnine.com/2016/01/the-long-and-winding-history-of-planet-x.html?m=1
Post by: Star One on 01/25/2016 05:06 pm
http://www.cbc.ca/radio/quirks/quirks-quarks-for-jan-23-2016-1.3415772/planet-9-from-outer-space-1.3415785
Post by: Blackstar on 01/25/2016 06:36 pm
The devil’s planet
by Dwayne Day
Monday, January 25, 2016
Last Wednesday, Caltech scientists Konstantin Batygin and Mike Brown made a startling announcement: they had found evidence of a possible massive new planet on the far edges of our solar system. The evidence is in the form of perturbations in the orbits of several observed Kuiper Belt Objects, or KBOs, which themselves are beyond the orbit of Pluto. What are needed now, the scientists admit, are observations of their theorized planet, which a number of other astronomers are doubtful exists. Observations will not be easy because if there is another large planet lurking way out there in the black, it is barely receiving any photons from our Sun that it can reflect back to telescopes.
The hunt for “Planet X” or the tenth planet, or whatever terminology has been used, goes back over a century. Neptune was discovered after scientists noted irregularities in Uranus’ orbit. Similarly, Clyde Tombaugh found Pluto while chasing a theory that even with Neptune found, Uranus’ orbit was still odd enough to indicate there was a planet tugging on it. The theory was wrong, but Tombaugh found Pluto—a combination of mistaken inspiration and a hell of a lot of hard work.
The hunt for a distant planet, and occasionally its discovery, has also inspired various works of fiction. One such example was the story “Lucifer Rising” by Yukinobu Hoshino, in his 1984 manga series 2001 Nights, which had a clever and unique storyline. (You can read part 1 here and part 2 here.) 2001 Nights was eventually translated into English and published in the United States in the 1990s, and Hoshino was clearly inspired both by American and British science fiction, particularly Arthur C. Clarke. Much of Hoshino’s artwork was influenced by 2001: A Space Odyssey, and along with the storylines depicts hard, scientifically-based science fiction. A lot of the hardware and spaceships in Hoshino’s stories look like they could exist in the universe of Stanley Kubrick’s classic film.
Post by: hop on 01/25/2016 07:59 pm
Post by: Star One on 01/26/2016 09:36 pm
http://www.scientificamerican.com/article/hidden-planet-x-could-orbit-in-outer-solar-system/
Post by: meekGee on 01/26/2016 09:59 pm
But if were talking about billions of years isn't the chance of our sun grabbing one of these rogue planets pretty real?
Rogue planets, stars, even stellar systems are small compared to the gap between the stars. Even when whole galaxies collide, the odds are heavily against any star or wandering planet colliding. The odds that a rogue planet has run into the solar system - or had the solar system run into it - are vanishingly small. Also, even if they did enter the solar system they're likely to be on a hyperbolic orbit and would simply zoom straight back out again.
Capturing an object into orbit is actually quite difficult. Generally it needs the object to be one of a pair in mutual orbit around each other - one gets ejected at high speed or crashes into the primary, the other goes into orbit. How a double rogue planet got ejected into interstellar space is an interesting question!
Strictly speaking, stars are small, but star systems are not small. Look up how large the Oort cloud is - a good fraction of the distance to the Alpha Centauri.
So rogue bodies will encounter star systems quite often. The thing is, in order to get captured, they need to interact with a relatively massive body within those solar system, and the solar systems are largely empty.
So it's not that star systems are small, but rather that star systems are empty.
All of which makes you wonder - how often does a rogue planet pass through our solar system?
Post by: Star One on 01/26/2016 10:22 pm
http://www.findplanetnine.com/2016/01/as-you-will-see-in-next-post-i-think.html?m=1
Post by: whitelancer64 on 01/26/2016 10:59 pm
It really deserves the name of some major greek or roman deity, even if we have to appropriate it off some asteroid or other. Im surprised there is no Athena at the moment? (though there is a 93 Minerva)
Pluto was pretty well named for a planet so far away from the sun, though Hades might be a bit grim.. :)
We don't need to be limited to the Greeks and Romans.
https://en.wikipedia.org/wiki/List_of_night_deities
Nott strikes me as particularly appropriate.
Post by: the_other_Doug on 01/27/2016 03:11 am
It really deserves the name of some major greek or roman deity, even if we have to appropriate it off some asteroid or other. Im surprised there is no Athena at the moment? (though there is a 93 Minerva)
Pluto was pretty well named for a planet so far away from the sun, though Hades might be a bit grim.. :)
Well, the simplest thing would be to rename the body New Horizons just flew past something like "Tombaugh" and name this new ninth planet Pluto.
Means we don't have to destroy all of those old grade school textbooks, right...?
;)
We don't need to be limited to the Greeks and Romans.
https://en.wikipedia.org/wiki/List_of_night_deities
Nott strikes me as particularly appropriate.
Post by: RotoSequence on 01/27/2016 06:34 am
Post by: NovaSilisko on 01/27/2016 08:15 am
Why Planet Nine might not exist
http://www.findplanetnine.com/2016/01/as-you-will-see-in-next-post-i-think.html?m=1
Makes me glad to see the authors being skeptical as well. As they should.
Post by: KelvinZero on 01/27/2016 08:59 am
Why Planet Nine might not exist
http://www.findplanetnine.com/2016/01/as-you-will-see-in-next-post-i-think.html?m=1
Makes me glad to see the authors being skeptical as well. As they should.
Also establishing some ways it can be disproved/discounted. Future kuiper belt finds should establish if this pattern is real with ever more confidence. Im guessing we will find them at an ever accelerating rate.
Post by: Star One on 01/29/2016 05:17 pm
https://mobile.twitter.com/chrislintott/status/692802978894319617
A sceptical piece about the possibility of a ninth planet.
https://medium.com/starts-with-a-bang/not-so-fast-why-there-likely-isn-t-a-large-planet-beyond-pluto-f75ea974465b#.tp5qqpba5
Post by: Star One on 01/31/2016 09:26 pm
http://youtu.be/bzmjfulVESA
Post by: redliox on 02/01/2016 09:02 am
We don't need to be limited to the Greeks and Romans.
https://en.wikipedia.org/wiki/List_of_night_deities
Nott strikes me as particularly appropriate.
I'd say the Etruscan goddess Artume might be a suitable compromise for a non-Roman name.
I like Morpheus. ;D
Seconded, although I suggested him alongside Hercules for possibilities earlier. :)
Post by: meekGee on 02/02/2016 02:34 pm
If they name planet 9 as "Pluto", that will solve the other debate as well...
Post by: Star One on 02/05/2016 10:00 am
http://www.space.com/31817-planet-nine-existence-question.html
Post by: Bynaus on 02/05/2016 10:45 am
https://www.reddit.com/r/IAmA/comments/42mxxr/iama_blank_we_are_konstantin_batygin_and_mike/#czbix18
Post by: Star One on 02/05/2016 12:05 pm
On the recent AMA, Batygin answered to this idea:
https://www.reddit.com/r/IAmA/comments/42mxxr/iama_blank_we_are_konstantin_batygin_and_mike/#czbix18
You've a better memory than me as I had read all the way through that Reddit & had forgotten that.:)
How Planet 9 Would Make Ours a More Typical Solar System
http://www.manyworlds.space/index.php/2016/02/04/how-planet-9-would-make-us-a-more-typical-solar-system/
Argues planet nine could be a wandering exoplanet gathered up by our sun to add to its planetary collection.
Post by: cscott on 02/06/2016 06:12 pm
I'm pretty sure that theory was addressed by brown and batygin as well --- the odds for capturing an exoplanet are fairly low. The odds for encountering one are low to start with (they are about as common as stars, so only one or so likely to be present in the four or so light years surrounding us), and then the odds for capture (opposed to scatter) are lower still.On the recent AMA, Batygin answered to this idea:
https://www.reddit.com/r/IAmA/comments/42mxxr/iama_blank_we_are_konstantin_batygin_and_mike/#czbix18
You've a better memory than me as I had read all the way through that Reddit & had forgotten that.:)
How Planet 9 Would Make Ours a More Typical Solar System
http://www.manyworlds.space/index.php/2016/02/04/how-planet-9-would-make-us-a-more-typical-solar-system/
Argues planet nine could be a wandering exoplanet gathered up by our sun to add to its planetary collection.
They suspect planet nine would be a sibling of the other giant planets in our solar system.
Post by: John-H on 02/06/2016 06:29 pm
John
Post by: Phil Stooke on 02/06/2016 06:45 pm
Post by: Hobbes-22 on 02/07/2016 03:41 pm
I keep hearing that wandering planets are about as common as stars - how would anyone know that? There is no way to observe them,
Not quite. 8 wandering planets have been found so far: https://en.wikipedia.org/wiki/Rogue_planet#Known_or_possible_rogue_planets (https://en.wikipedia.org/wiki/Rogue_planet#Known_or_possible_rogue_planets)
Post by: CuddlyRocket on 02/07/2016 10:30 pm
I keep hearing that wandering planets are about as common as stars - how would anyone know that?
Remember; to astronomers 'about' means a factor of ten either way! :)
Estimates derive from simulations of planetary systems formation; how many planet-sized objects get ejected on average etc.
Post by: Star One on 02/09/2016 08:31 pm
http://www.planetary.org/multimedia/planetary-radio/show/2016/0208-planet-9-brown-batygin.html
Post by: Star One on 02/12/2016 09:33 pm
http://www.findplanetnine.com/2016/02/why-i-believe-in-planet-nine.html?m=1
Reading the comments underneath it seems he has another paper coming soon.
Post by: Star One on 02/13/2016 09:47 pm
A Stranger at Home
Quote
Cumulatively, a distinct picture of the Galactic planetary census is beginning emerge, wherein the ordered orbits of the known planets of the solar system are starting to appear increasingly abnormal. On the other hand, with a characteristic mass approximately 10 times greater than the Earth and an eccentricity of ~0.6, Planet Nine fits into this extrasolar planetary album seamlessly. Intriguingly, this yet-unseen world may provide the closest link between our solar system, and the extrasolar realm. Indeed, Planet Nine may constitute the closest thing to the solar system’s very own extrasolar planet.
http://www.findplanetnine.com/2016/02/a-stranger-at-home.html?m=1
Just a reminder for UK posters the Sky At Night is covering planet nine on the show at 8pm tomorrow night on BBC Four.
Post by: Quagga on 02/14/2016 03:50 pm
Post by: JamesG123 on 02/14/2016 07:45 pm
I wonder if our solar system really is that different from others. If we looked at a clone of the solar system, which planets would we be able to detect? Jupiter?
Currently none. Jupiter is in to long an orbit for us to detect its effect on the star, and yet too close for us to resolve it separately.
Post by: Bynaus on 02/14/2016 08:06 pm
I wonder if our solar system really is that different from others. If we looked at a clone of the solar system, which planets would we be able to detect? Jupiter?
Currently none. Jupiter is in to long an orbit for us to detect its effect on the star, and yet too close for us to resolve it separately.
This ist not true. There have been multi-decadal surveys which have found multiple Jupiter analogs around other stars. E.g., see here: http://arxiv.org/abs/1601.05465 Such systems are relatively rare, on the order of 6%. So in that respect, the solar system is not very typical in having a "Jupiter". We are also not very typical in having no planets closer to the sun than Mercury, and for the very circular orbits of the planets.
For a perfect solar system analog (rather a clone), we could find Jupiter if we looked long enough, possibly even Saturn. We could (barely) find Venus with Kepler by transit if the inclination was right.
Post by: Star One on 02/15/2016 04:46 pm
http://www.bbc.co.uk/programmes/p03jcl64
Post by: Star One on 02/24/2016 07:45 pm
Quote
Laskar and his team have reduced the search area by 50 percent by eliminating two zones in which they say the modelling does not match reality.
"We have cut the work in half," he told AFP.
http://m.phys.org/news/2016-02-narrows-planet.html
Post by: Star One on 03/08/2016 07:07 pm
Quote
When Konstantin Batygin and Mike Brown announced the possible existence of a distant planet, my first question was "what do the dynamicists think?" Several were quoted in the media surrounding the announcement, but yesterday leading dynamicist Renu Malhotra (with coauthors Kat Volk and Xianyu Wang) posted to ArXiv the first formal response I've seen. In brief, Malhotra and coauthors are on board with the idea of a possible outer planet, and found that it may have shaped the orbits of extremely distant Kuiper belt objects in another way beyond the several ways that Batygin and Brown proposed.
Before I continue with the story, I want to mention that you can hear from Batygin and Brown directly tonight through a Planetary Radio Live webcast! I'll be onstage as well.
http://www.planetary.org/blogs/emily-lakdawalla/2016/03080928-planet-nine-update.html
Post by: whitelancer64 on 03/08/2016 07:53 pm
Search narrows for Planet NineQuoteLaskar and his team have reduced the search area by 50 percent by eliminating two zones in which they say the modelling does not match reality.
"We have cut the work in half," he told AFP.
http://m.phys.org/news/2016-02-narrows-planet.html
"Laskar and his team said the search field can be further narrowed if Cassini, due to finish its mission next year, is extended to 2020."
Why is that?
Post by: Star One on 03/08/2016 07:56 pm
Search narrows for Planet NineQuoteLaskar and his team have reduced the search area by 50 percent by eliminating two zones in which they say the modelling does not match reality.
"We have cut the work in half," he told AFP.
http://m.phys.org/news/2016-02-narrows-planet.html
"Laskar and his team said the search field can be further narrowed if Cassini, due to finish its mission next year, is extended to 2020."
Why is that?
Good question?
Post by: ISP on 03/08/2016 08:17 pm
Better explained by an article I happened to have bookmarked a bit ago:
http://www.space.com/32037-saturn-probe-cassini-planet-nine-search.html
Post by: Torbjorn Larsson, OM on 03/08/2016 08:21 pm
This article (http://link.springer.com/article/10.1007%2Fs10569-004-4623-y#page-1) suggests that the Kozai mechanism coupled with mean motion resonances is responsible for raising the perihelia of various scattered disc objects. (Actually, they say it's 'mainly' responsible, so presumably there are other mechanisms!)It is unlikely to be an interstellar capture. Brown and Batygin believe it to be an ejected ice giant core.But if it's ejected, wouldn't only aphelion rise during the process (I mean, beyond Neptune's orbit)? I'm not knowledgeable in this long-term planetary mechanics stuff, but I'm struggling to understand the mechanism for raising perihelion to such an enormous value. Wouldn't that require impulse to be applied far away from perihelion? What could do that that doesn't come from outside the system?
Batygin favors an early ejection within 10 Myrs. [In the video interview with him, I think.]
That means, if I understand him correctly, that the solar system was gravitationally much smaller, pre-Oort cloud, since it was still located in the scattering open star cluster that it was associated with after its birth. And there were plenty of gravitational disturbers further out.
It also means there was a still dispersing gas disk that could have placed PN by drag mechanisms.
I keep hearing that wandering planets are about as common as stars - how would anyone know that?
Remember; to astronomers 'about' means a factor of ten either way! :)
Estimates derive from simulations of planetary systems formation; how many planet-sized objects get ejected on average etc.
Confirming that there was also an early microlensing survey that got the same number (and lousy statistics). At the very least WFIRST will improve on that estimate.
*************
Re Cassini, ninja'ed.
Post by: Star One on 03/17/2016 10:21 pm
Quote
At the time we published our paper on Planet Nine, we were working on a companion paper, that we had hoped to finish that same day, that would tell you where to look for Planet Nine. Finally, only two months later than anticipated, we have finally finished the paper.
I'll be writing in more depth about where we think Planet Nine is, how we constrain it, and how we're going about trying to find it, but, first, I want to simply put in a link to the paper, so you can go read it yourself:
http://www.findplanetnine.com/2016/03/where-is-planet-nine.html?m=1
Post by: Star One on 03/24/2016 08:38 pm
Quote
Mike Brown – @plutokiller
Hey Planet Nine fans, a new eccentric KBO was discovered. And it is exactly where Planet Nine says it should be.
https://mobile.twitter.com/plutokiller/status/713111594197061632/photo/1
https://mobile.twitter.com/plutokiller/status/713111594197061632Quotethe new one is uo3L91; slide from a just-posted talk at the SETI institute. Discovery from OSSOS survey on the CFHTQuoteI haven't done the statistics yet, but I suspect this takes the probability of this being a statistical fluke down to ~.001% or so.
Post by: hop on 03/25/2016 03:22 am
Is there an exoplanet in the Solar System? (http://arxiv.org/abs/1603.07247)
Quote
We investigate the prospects for the capture of the proposed Planet 9 from other stars in the Sun's birth cluster.
...
While the existence of Planet 9 remains unproven, we consider capture from one of the Sun's young brethren a plausible route to explain such an object's orbit. Capture appears to predict a large population of Trans-Neptunian Objects (TNOs) whose orbits are aligned with the captured planet, and we propose that different formation mechanisms will be distinguishable based on their imprint on the distribution of TNOs.
Post by: CuddlyRocket on 03/26/2016 07:30 am
https://www.youtube.com/watch?v=_w9N6yABAW4
Post by: Star One on 03/30/2016 04:57 pm
Quote
FAYETTEVILLE, Ark. – Periodic mass extinctions on Earth, as indicated in the global fossil record, could be linked to a suspected ninth planet, according to research published by a faculty member of the University of Arkansas Department of Mathematical Sciences.
Daniel Whitmire, a retired professor of astrophysics now working as a math instructor, published findings in the January issue of Monthly Notices of the Royal Astronomical Society that the as yet undiscovered “Planet X” triggers comet showers linked to mass extinctions on Earth at intervals of approximately 27 million years.
http://news.uark.edu/articles/34087/u-of-a-researcher-links-mass-extinctions-to-planet-x-
Post by: NovaSilisko on 03/31/2016 08:13 pm
edit: Oh great, now it's showing up elsewhere http://www.space.com/32429-could-planet-x-cause-comet-catastrophes-on-earth.html
This is just going to cause confusion and needlessly scare people.
Post by: Star One on 04/01/2016 06:40 am
I think they've got the wrong Planet X.
edit: Oh great, now it's showing up elsewhere http://www.space.com/32429-could-planet-x-cause-comet-catastrophes-on-earth.html
This is just going to cause confusion and needlessly scare people.
You're a bit late with that concern as it was widely reported online not long after I linked to that original article.
Post by: Bynaus on 04/01/2016 07:09 am
Quote
U of A Researcher Links Mass Extinctions to 'Planet X'
Whitmire's "Planet X" would have to be at a distance of ~100 AU on an inclined (~25-35°) orbit, and have a mass of a few Earth masses at most. He shows that such a world would undergo orbital oscillations with a period of 27 Ma, in accordance with what has been claimed (and disputed) for decades to be evidence for periodic mass extinctions. Whitmire speculates that if this planet (still called "X") were very dark, it might not have been detected so far. He also speculates, without any simulations, that this planet could be responsible for the alignment of extreme SDO orbits. A lot of hot air blown into an old hypothesis, if you ask me.
Post by: NovaSilisko on 04/01/2016 07:16 am
You're a bit late with that concern as it was widely reported online not long after I linked to that original article.
Well, I won't lie, I end up sort of avoiding the sorts of places that are likely to hype about it.
Post by: Star One on 04/01/2016 11:12 am
You're a bit late with that concern as it was widely reported online not long after I linked to that original article.
Well, I won't lie, I end up sort of avoiding the sorts of places that are likely to hype about it.
I am talking mainstream news/science sites.
Post by: Alpha_Centauri on 04/01/2016 12:22 pm
Post by: yg1968 on 04/01/2016 05:57 pm
I think they've got the wrong Planet X.
edit: Oh great, now it's showing up elsewhere http://www.space.com/32429-could-planet-x-cause-comet-catastrophes-on-earth.html
This is just going to cause confusion and needlessly scare people.
The conclusion in the Space.com article states exactly what you said in your post above:
Quote
This research assumes that Planet Nine has a huge orbital period — it would need to pass through the Kuiper belt every 26 million years for this theory to hold water. In an interview with the MailOnline, Brown pointed out that the Planet Nine he is looking for most likely isn't the Planet X Whitmire and Matese hopes it is.
"Whitmire has been speculating for decades about a very distant very massive planet pushing comets around. It has to have an orbital period of something like 27 million years," said Brown. "While that idea may or may not make sense, it definitely has nothing to do with Planet Nine, which is much closer to the sun and thus 'only' takes 15,000 years to go around."
"The evidence for Planet Nine says nothing about whether or not there is a more distant Planet X."
See: http://www.space.com/32429-could-planet-x-cause-comet-catastrophes-on-earth.html#sthash.YLeFOT4d.dpuf
Post by: as58 on 04/01/2016 06:22 pm
Post by: Star One on 04/01/2016 08:33 pm
I'm not sure if prof. Brown has even read Whitmire's new paper. Whitmire's latest model has an orbit precession period of 27 million years, not orbital period. Indeed, Whitmere's Planet X would be in an even closer orbit than Brown's Planet Nine. On the other hand, Whitmire's paper(s) make me feel that he's very much in love with his "periodic extinctions due to comet showers" theory and will interpret pretty much everything as being in favour of that.
It's been brought to his attention.
Mike Brown
Mike Brown – @plutokiller
@astroengine what I meant to say was: WE'RE DOOMED! RUN FOR THE HIL
https://mobile.twitter.com/plutokiller/status/715268903153348608
Post by: Star One on 04/06/2016 09:25 am
Mysterious Gravitational Tug on Orbiter May Help Find Planet Nine
Astronomers are homing in on the whereabouts of a hidden giant planet in our solar system, and could discover the unseen beast in roughly a year
Quote
So Fienga and her colleagues compared the updated model, which placed Planet Nine at various points in its hypothetical orbit, with the data. They found a sweet spot—with Planet Nine 600 astronomical units (about 90 billion kilometers) away toward the constellation Cetus—that can explain Cassini’s orbit quite well. Although Fienga is not yet convinced that she has found the culprit for the probe’s odd movements, most outside experts are blown away. “It’s a brilliant analysis,” says Greg Laughlin, an astronomer at Lick Observatory, who was not involved in the study. “It’s completely amazing that they were able to do that so quickly.” Gerdes agrees: “That’s a beautiful paper.”
Quote
The good news does not end there. If Planet Nine is located toward the constellation Cetus, then it could be picked up by the Dark Energy Survey, a Southern Hemisphere observation project designed to probe the acceleration of the universe. “It turns out fortuitously that the favored region from Cassini is smack dab in the middle of our survey footprint,” says Gerdes, who is working on the cosmology survey. “We could not have designed our survey any better.” Although the survey was not planned to search for solar system objects, Gerdes has discovered some (including one of the icy objects that led Batygin and Brown to conclude Planet Nine exists in the first place).
http://www.scientificamerican.com/article/mysterious-gravitational-tug-on-orbiter-may-help-find-planet-nine/
Post by: clongton on 04/07/2016 12:29 am
Post by: Star One on 04/07/2016 08:07 am
This is awesome news.
It's amazing to me that what must be the tiny influence it has on a spacecraft orbiting Saturn may help find it.
Post by: mikelepage on 04/07/2016 09:04 am
From what I understand of the Grand Tack hypothesis, you've got proto-Jupiter having coalesced out at 5+ AU, and the remnant nebula gas is providing just enough drag that it is spiraling inwards, well on it's way to becoming a hot Jupiter, then, somehow, resonance with Saturn manages to pull it back out again to it's present position. I guess don't see how smaller Saturn gets close enough to Jupiter to do this - I mean - hasn't Jupiter already swept up most of the gas from it's original orbit inwards? What is it that causes Saturn to come in close enough to have such an effect?
Instead, what if planet nine actually formed internal to Jupiter's orbit? and accounted for the "missing mass" that people have talked about (ie Mercury+Venus+Earth+Mars+belt aren't anywhere near as massive as they "should be"). You'd have Jupiter coming inwards and peturbing the smaller planet's orbit, and eventually kicking it out. In the (very basic) simulators I've played with, I have seen smaller, internally orbiting bodies get into some very chaotic momentum exchanges with larger bodies before being ejected at speed, so intuitively it seems possible to me.
It would also mean that planet nine had already swept up most of the gas inside a certain orbital distance, so Jupiter would have come in to a given distance, but not had anything forcing it in any further (allowing remnant planetoids to coalesce into the current 4 rocky planets+belt).
Post by: Bynaus on 04/07/2016 09:26 am
Quote
From what I understand of the Grand Tack hypothesis, you've got proto-Jupiter having coalesced out at 5+ AU, and the remnant nebula gas is providing just enough drag that it is spiraling inwards, well on it's way to becoming a hot Jupiter, then, somehow, resonance with Saturn manages to pull it back out again to it's present position. I guess don't see how smaller Saturn gets close enough to Jupiter to do this - I mean - hasn't Jupiter already swept up most of the gas from it's original orbit inwards? What is it that causes Saturn to come in close enough to have such an effect?
Jupiter, after it forms, feels a "torque" from the disk: a large outer disk relative to which it moves faster (ahead) and a small inner disk relative to which it moves slower (behind). The torque from the external disk, which slows Jupiter down, overpowers the torque from the inner disk, which speeds Jupiter up, so overall, Jupiter is slowed down, resulting in its migration towards the sun. Saturn forms in its wake, and because it has a lower mass (much of the material has already been swept up by Jupiter), it migrates too, but faster. Therefore, it eventually catches up with Jupiter and they enter a resonance when Jupiter is at approximately 1.5 AU (thereby "cutting off" the inner disk at about 1 AU). The outer disk further dissipates, and is further depleted by the formation of two gas giants (plus, supposedly, the ice giants). So now, the torques switch sides: the increasingly missing torque from the outer disk starts to act such that Saturn tends to migrate outwards again, but the "lock" established by the resonance results in Jupiter being draged along too.
Quote
Instead, what if planet nine actually formed internal to Jupiter's orbit? and accounted for the "missing mass" that people have talked about (ie Mercury+Venus+Earth+Mars+belt aren't anywhere near as massive as they "should be"). You'd have Jupiter coming inwards and peturbing the smaller planet's orbit, and eventually kicking it out. In the (very basic) simulators I've played with, I have seen smaller, internally orbiting bodies get into some very chaotic momentum exchanges with larger bodies before being ejected at speed, so intuitively it seems possible to me.
The missing mass is essentially inside Mercury's orbit ("missing" compared to many Kepler systems). It would seem difficult for Jupiter to extract a world from there (there have been simulations of this, e.g. http://arxiv.org/abs/1502.06558, so mostly Jupiters migration seems to result in the destruction of an interior system of planets by dropping them into the sun). However, there should be many large objects forming in the outer disk, and it seems a fifth gas giant (third ice giant) forming out there can explain many things (e.g., http://arxiv.org/abs/1109.2949 or http://arxiv.org/abs/1509.05397).
Another problem is that you need to circularize the orbit of the ejected object quite quickly - otherwise it will encounter other planets and might either be ejected completely, or dropped into the star, or result in a collision. This is easier to do if it originates in the outer disk, because its initial orbit has it encountering less planets, as an object initially ejected from the innermost part of the system would (there's a similar argument against any "Nibiru"-type object: any planet crossing into the inner solar system as proposed for "Nibiru" would, at some point in the history of the solar system, have had a close encounter with Jupiter or Saturn, which would have resulted in its ejection/destruction).
Hope that helps!
Post by: Ben the Space Brit on 04/07/2016 10:31 am
Post by: Star One on 04/07/2016 11:26 am
To me, what really strikes me about the hypothetical Sol-IX is that it might literally turn all existing theories about the formation of the solar system on their heads. After thousands of years of studying the skies, it turns out that we didn't even know all of the major bodies creating large-scale gravitational influence!
Not so much if it is a planet that the Sun stole from another solar system perhaps when it was still in its stellar cluster.
Post by: Bynaus on 04/07/2016 01:07 pm
To me, what really strikes me about the hypothetical Sol-IX is that it might literally turn all existing theories about the formation of the solar system on their heads. After thousands of years of studying the skies, it turns out that we didn't even know all of the major bodies creating large-scale gravitational influence!
Not really. Most of these 1000s of years, we didn't have telescopes (and anything beyond Saturn, or Uranus if you want to be very delicate, is invisible to the human eye). And even after we had them, P9 (if it exists) is so far away that its influence on the orbits of the other planets is extremly feeble. Its perihelion is at about 300 AU or so, 10 times farther out than Neptune.
As discussed above, since the "Nice models" were put forward and discussed, and the realization came (from studying exoplanets) that migration of gas giants might be a common phenomenon in planet forming disks, the idea that such migrations and planet-planet encounters (even ejections) might have happened in the solar system as well have been discussed for several years now. The solar system does indeed show signs of earlier (comparatively mild) chaos - so an additional gas giant on a remote, eccentric orbit? Why not.
Post by: NovaSilisko on 04/07/2016 04:07 pm
The missing mass is essentially inside Mercury's orbit ("missing" compared to many Kepler systems).
Hold on, what's that supposed to mean? We really can't take Kepler's data as indications of some sort of "rule" for mass distribution vs distance from a star because it's inherently and strongly biased toward finding massive, close-in objects just due to how the transit method works. Or am I missing your real meaning?
Post by: CuddlyRocket on 04/07/2016 06:56 pm
It's amazing to me that what must be the tiny influence it has on a spacecraft orbiting Saturn may help find it.
It's actually the influence P9 has on the orbit of Saturn; Cassini is just along for the ride - although its presence enables a more accurate determination of Saturn's orbit.
Post by: Bynaus on 04/07/2016 07:29 pm
The missing mass is essentially inside Mercury's orbit ("missing" compared to many Kepler systems).
Hold on, what's that supposed to mean? We really can't take Kepler's data as indications of some sort of "rule" for mass distribution vs distance from a star because it's inherently and strongly biased toward finding massive, close-in objects just due to how the transit method works. Or am I missing your real meaning?
There is a bias, but since it's primarily geometric, you can correct for it ("de-biasing"). You can also correct for incompletenss due to the difficulty of finding very small planets. Doing all this, we find that about half of all stars have at least one planet with at least the size of the Earth inside Mercury's orbit. Therefore, there is a true deficit of such planets in the inner-most solar system. See e.g. http://www.drewexmachina.com/2015/11/03/the-prevalence-of-earth-size-planets-around-sun-like-stars/
Quote
Petigura determined that 41.7% (+6.8%/-5.9%) of Sun-like stars have planets with radii greater than 1 RE in orbits with periods ranging from 5 to 50 days. This confirms the view that our Solar System is somewhat unusual in not having planets in short-period orbits
(remember also that planet occurrence increases strongly at smaller radii - i.e., if so many stars already have Earths at these distances, many more should have Marses and Mercuries).
Post by: llanitedave on 04/07/2016 07:33 pm
Post by: Mark K on 04/07/2016 07:47 pm
If we can detect an effect on Cassini, what about Pioneer or the Voyagers?
I believe the Cassini data will be used to see if there is an effect on the orbit of Saturn. That is why Pioneer or Voyagers wouldn't be appropriate in this case.
Post by: as58 on 04/07/2016 07:53 pm
I think that the previous poster is right, they're looking for an effect in Saturn's orbit, which can be determined very accurately thanks to Cassini.
Post by: Star One on 04/07/2016 08:02 pm
Quote
Astrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm
Post by: HarryM on 04/07/2016 10:13 pm
https://en.wikipedia.org/wiki/Thule
Quote
...The term ultima Thule in medieval geographies denotes any distant place located beyond the "borders of the known world"...
Post by: whitelancer64 on 04/07/2016 10:27 pm
In Norse mythology, she is night personified, and also is the grandmother of Thor.
Post by: Star One on 04/07/2016 10:49 pm
Post by: NovaSilisko on 04/08/2016 04:06 am
The missing mass is essentially inside Mercury's orbit ("missing" compared to many Kepler systems).
Hold on, what's that supposed to mean? We really can't take Kepler's data as indications of some sort of "rule" for mass distribution vs distance from a star because it's inherently and strongly biased toward finding massive, close-in objects just due to how the transit method works. Or am I missing your real meaning?
There is a bias, but since it's primarily geometric, you can correct for it ("de-biasing"). You can also correct for incompletenss due to the difficulty of finding very small planets. Doing all this, we find that about half of all stars have at least one planet with at least the size of the Earth inside Mercury's orbit. Therefore, there is a true deficit of such planets in the inner-most solar system. See e.g. http://www.drewexmachina.com/2015/11/03/the-prevalence-of-earth-size-planets-around-sun-like-stars/QuotePetigura determined that 41.7% (+6.8%/-5.9%) of Sun-like stars have planets with radii greater than 1 RE in orbits with periods ranging from 5 to 50 days. This confirms the view that our Solar System is somewhat unusual in not having planets in short-period orbits
(remember also that planet occurrence increases strongly at smaller radii - i.e., if so many stars already have Earths at these distances, many more should have Marses and Mercuries).
I just recently encountered something by David Kipping about the biases being stronger than originally thought. I wish I could remember where it was, though...
Or what it said. [headdesk]
Post by: Bynaus on 04/08/2016 06:12 am
I'd favor Enatos as a name for the new world. Which just means "The Ninth". It is very likely to be the ninth planet in sequence of distance to the sun, and also the ninth "true" planet we have discovered (Pluto should never have been a planet). It also speaks of a certain pragmatism, and a turn away from the old figures of mythology.
I just recently encountered something by David Kipping about the biases being stronger than originally thought. I wish I could remember where it was, though...
Or what it said. [headdesk]
Well, in any case, you can also look at it this way: if there is a space mission that can tell us reliably what types of planets there are around stars within the orbit of Mercury (and how frequent they are), then Kepler is the one. If the solar system were a typical system (in that respect), we should have found fewer planets than we actually have. And biases always work towards finding fewer planets than there actually are, not finding more of them... (unless there is something deeply flawed with your methodology, i.e., you are getting a lot of false-positives)
Post by: Ben the Space Brit on 04/08/2016 12:14 pm
I suggest Nótt (Old Norse "night") as a name.
In Norse mythology, she is night personified, and also is the grandmother of Thor.
I like this name, mostly because at the projected orbital distance of this object, the Sun would look more like an extremely bright background star. Out where Sol-IX turns, the night is forever.
Post by: Star One on 04/08/2016 07:35 pm
Can we use a 'snowbank orbit' maneuver to put a payload into orbit around Planet 9? Adam Crowl speculates:
http://www.centauri-dreams.org/?p=35392
Post by: Blackstar on 04/08/2016 08:26 pm
Post by: meekGee on 04/09/2016 05:25 am
And I still say we call it Pluto.
Post by: Nomadd on 04/09/2016 05:56 am
"Contrary to recent reports, NASA's Cassini spacecraft is not experiencing unexplained deviations in its orbit around Saturn, according to mission managers and orbit determination experts at NASA's Jet Propulsion Laboratory in Pasadena, California."
"Although we'd love it if Cassini could help detect a new planet in the solar system, we do not see any perturbations in our orbit that we cannot explain with our current models," said Earl Maize, Cassini project manager at JPL.
Post by: Star One on 04/09/2016 09:42 am
http://www.nasa.gov/feature/jpl/saturn-spacecraft-not-affected-by-hypothetical-planet-9
"Contrary to recent reports, NASA's Cassini spacecraft is not experiencing unexplained deviations in its orbit around Saturn, according to mission managers and orbit determination experts at NASA's Jet Propulsion Laboratory in Pasadena, California."
"Although we'd love it if Cassini could help detect a new planet in the solar system, we do not see any perturbations in our orbit that we cannot explain with our current models," said Earl Maize, Cassini project manager at JPL.
Odd as I thought this deviation was a well known and long running effect.
Post by: NovaSilisko on 04/09/2016 04:58 pm
Or is it saying that Cassini's trajectory shows there's no deviation to Saturn's? If so, where the hell did the idea come from? Are they suggesting the authors of the paper just made it up? Or had bad info?
And, no deviation as compared to what? A model that already has the error in place?
This is just adding confusion to an already complicated subject.
Post by: Cherokee43v6 on 04/09/2016 05:25 pm
I suggest Ultima Thule as a name.
https://en.wikipedia.org/wiki/ThuleQuote...The term ultima Thule in medieval geographies denotes any distant place located beyond the "borders of the known world"...
Ah, just call it Pern... ;) as in 'Here be dragons' :P
Post by: MP99 on 04/09/2016 05:41 pm
Red Star is in an eccentric orbit, more like this object.I suggest Ultima Thule as a name.
https://en.wikipedia.org/wiki/ThuleQuote...The term ultima Thule in medieval geographies denotes any distant place located beyond the "borders of the known world"...
Ah, just call it Pern... ;) as in 'Here be dragons'
Cheers, Martin
Post by: clongton on 04/09/2016 06:05 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
Post by: as58 on 04/09/2016 06:05 pm
I don't get what that JPL article is trying to say. It seems to suggest that the paper in question was saying that Planet Nine would be affecting Cassini's orbit around Saturn, when it had been talking about Saturn's orbit around the sun. They go on to say that a new planet... would indeed affect Saturn's orbit but not Cassini's?
Or is it saying that Cassini's trajectory shows there's no deviation to Saturn's? If so, where the hell did the idea come from? Are they suggesting the authors of the paper just made it up? Or had bad info?
And, no deviation as compared to what? A model that already has the error in place?
This is just adding confusion to an already complicated subject.
There's a correction (dated yesterday) in the Scientific American article. Originally it claimed that disturbances in Cassini's orbit around Saturn was used to study where Planet Nine could be. I guess JPL's response is to the original article.
Post by: Star One on 04/09/2016 06:09 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
Post by: NovaSilisko on 04/09/2016 07:24 pm
There's a correction (dated yesterday) in the Scientific American article. Originally it claimed that disturbances in Cassini's orbit around Saturn was used to study where Planet Nine could be. I guess JPL's response is to the original article.
But after re-reading the JPL article, it seems to be saying there's no deviation in Saturn's orbit. I don't get what's going on either.
Post by: as58 on 04/09/2016 07:50 pm
There's a correction (dated yesterday) in the Scientific American article. Originally it claimed that disturbances in Cassini's orbit around Saturn was used to study where Planet Nine could be. I guess JPL's response is to the original article.
But after re-reading the JPL article, it seems to be saying there's no deviation in Saturn's orbit. I don't get what's going on either.
I agree that JPL's response is a bit strange. William Folkner and Earl Maize say that there's no signature of Planet Nine in Cassini's orbit, but that was only ever claimed in the now-corrected Scientific American article. Folkner says that the change would be seen in Saturn's orbit, which is exactly what Fienga et al. have looked at. It almost feels like the JPL people didn't read properly the original Fienga et al. article.
Post by: Star One on 04/09/2016 08:07 pm
There's a correction (dated yesterday) in the Scientific American article. Originally it claimed that disturbances in Cassini's orbit around Saturn was used to study where Planet Nine could be. I guess JPL's response is to the original article.
But after re-reading the JPL article, it seems to be saying there's no deviation in Saturn's orbit. I don't get what's going on either.
I don't understand all of this as are they saying that the original paper is utterly wrong, as they seem to be implying the underlying basis of the whole paper is incorrect.
Post by: clongton on 04/09/2016 08:44 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
To the contrary, WISE has indicated that there is no detectable infrared signature of a brown dwarf at the location it was looking at. But they are not even sure they are looking in the right place. Even if they were it is too far away to be able to take any measurements of any kind, especially any brown dwarf signature of a small, relatively cool object. In addition, without being able to pinpoint a location in any way, shape or form, it is physically impossible to say what an object may or may not be. I repeat, my advise is to not assume anything until we know more about this object. One of the things we absolutely must know before we can say anything about the object beyond its gravitational disturbances (which to date is the only thing noticed) is its location. Only then will the readings of any sensor make any sense wrt an unknown, undetected celestial object.
Post by: Star One on 04/09/2016 09:05 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
To the contrary, WISE has indicated that there is no detectable infrared signature of a brown dwarf at the location it was looking at. But they are not even sure they are looking in the right place. Even if they were it is too far away to be able to take any measurements of any kind, especially any brown dwarf signature of a small, relatively cool object. In addition, without being able to pinpoint a location in any way, shape or form, it is physically impossible to say what an object may or may not be. I repeat, my advise is to not assume anything until we know more about this object. One of the things we absolutely must know before we can say anything about the object beyond its gravitational disturbances (which to date is the only thing noticed) is its location. Only then will the readings of any sensor make any sense wrt an unknown, undetected celestial object.
I am pretty certain from following his Twitter Feed that Brown has eliminated the possibility of it being a brown dwarf.
Post by: clongton on 04/09/2016 09:09 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
To the contrary, WISE has indicated that there is no detectable infrared signature of a brown dwarf at the location it was looking at. But they are not even sure they are looking in the right place. Even if they were it is too far away to be able to take any measurements of any kind, especially any brown dwarf signature of a small, relatively cool object. In addition, without being able to pinpoint a location in any way, shape or form, it is physically impossible to say what an object may or may not be. I repeat, my advise is to not assume anything until we know more about this object. One of the things we absolutely must know before we can say anything about the object beyond its gravitational disturbances (which to date is the only thing noticed) is its location. Only then will the readings of any sensor make any sense wrt an unknown, undetected celestial object.
I am pretty certain from following his Twitter Feed that Brown has eliminated the possibility of it being a brown dwarf.
One cannot know what it is or isn't until one can pinpoint it in order to focus the instruments that might reveal what it is or isn't. To date that hasn't happened. Thus everything about it is only opinion, unsubstantiated by any demonstrable fact. One might believe that it is or isn't a brown dwarf, but until it can be directly measured and examined based on those measurements one cannot say if it is or isn't a brown dwarf.
Post by: as58 on 04/09/2016 09:12 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
To the contrary, WISE has indicated that there is no detectable infrared signature of a brown dwarf at the location it was looking at. But they are not even sure they are looking in the right place. Even if they were it is too far away to be able to take any measurements of any kind, especially any brown dwarf signature of a small, relatively cool object. In addition, without being able to pinpoint a location in any way, shape or form, it is physically impossible to say what an object may or may not be. I repeat, my advise is to not assume anything until we know more about this object. One of the things we absolutely must know before we can say anything about the object beyond its gravitational disturbances (which to date is the only thing noticed) is its location. Only then will the readings of any sensor make any sense wrt an unknown, undetected celestial object.
WISE was an all-sky survey. Where exactly is this location they didn't look at?
Post by: gospacex on 04/09/2016 09:23 pm
Planet 9 takes shape: Newfound planet in our outer solar system simulatedQuoteAstrophysicists have modeled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.
https://www.sciencedaily.com/releases/2016/04/160407092944.htm (https://www.sciencedaily.com/releases/2016/04/160407092944.htm)
Estimate of planetary radius may be relatively accurate but it is much too early to estimate the temperature, which *assumes*, with no basis of any kind, that the planet is another icy giant. There are other astrophysicists who believe the planet *might* be a captured brown dwarf, not native to our solar system at all. At the very least it is a plausible theory, and if true would raise the surface temperature by a significant amount. My advise is to not assume anything until we know more about this object.
WISE has ruled out the possibility of a brown dwarf. All the papers I have read have taken this as read and therefore stated it must be a smaller body.
To the contrary, WISE has indicated that there is no detectable infrared signature of a brown dwarf at the location it was looking at. But they are not even sure they are looking in the right place. Even if they were it is too far away to be able to take any measurements of any kind, especially any brown dwarf signature of a small, relatively cool object.
WISE scanned entire sky, most of it 16 times or more. Its data was processed by several independent teams, and they _did_ find many brown dwarfs. Sadly, closest ones were a bit farther from us than Alpha Centauri.
Some BDs are hot. Some are cool, but only "relatively" cool. For WISE, all types of of them are bright enough to be detected.
The only chance for BD to be missed by WISE is to hide in a very dense star field, like galactic bulge.
Post by: NovaSilisko on 04/09/2016 10:12 pm
There's a correction (dated yesterday) in the Scientific American article. Originally it claimed that disturbances in Cassini's orbit around Saturn was used to study where Planet Nine could be. I guess JPL's response is to the original article.
But after re-reading the JPL article, it seems to be saying there's no deviation in Saturn's orbit. I don't get what's going on either.
I don't understand all of this as are they saying that the original paper is utterly wrong, as they seem to be implying the underlying basis of the whole paper is incorrect.
I feel like someone needs to contact the people at JPL and ask for specific clarification. If we really want to disprove the perturbation hypothesis, then it shold be done more thoroughly than a "no we looked, it's ok"
Post by: Robotbeat on 04/10/2016 02:53 am
I agree also we shouldn't declare the end of the solar system just yet. Also names implying large distances should be avoided - otherwise we might end up in the situation where the closest "inner Oort cloud" planet gets a name referring to its extreme distance...Disagree. There's never been a good case to why it shouldn't be a planet except an after-the-fact arbitrary orbital mechanics cut-off that is biased towards the inner solar system. A lot of very intelligent people favor the geologic definition of planet. It'd be kind of lame to name a planet just after its somewhat arbitrary ordering.
I'd favor Enatos as a name for the new world. Which just means "The Ninth". It is very likely to be the ninth planet in sequence of distance to the sun, and also the ninth "true" planet we have discovered (Pluto should never have been a planet)...
Post by: clongton on 04/10/2016 11:17 am
Post by: Star One on 04/10/2016 06:15 pm
Stop Blaming Everything On Planet Nine
http://motherboard.vice.com/read/stop-blaming-everything-on-planet-nine
Post by: jgoldader on 04/10/2016 07:54 pm
Post by: Bynaus on 04/10/2016 08:18 pm
@jgoldader: for gas giants with a large heat flux, yes. Ice giants like Uranus and Neptune (and, supposedly, Planet Nine) are much colder and are thus more difficult to exclude using WISE (e.g., WISE can only barely make out Neptune).
Post by: Star One on 04/10/2016 08:28 pm
@Robobeat: I don't actually want to open the Pluto planet debate can-of-worms again. I will just say that the "geologic" argument - disregarding place and/or dynamic status in the solar system - would logically make all large satellites (including the Moon) planets as well. To me, a planet is a dynamic role (planetai = "wanderers"), not necessarily a geologic one, so I prefer a definition that is based on a dynamic criterion (but "clearing the neighborhood" is deeply flawed as a definition).
@jgoldader: for gas giants with a large heat flux, yes. Ice giants like Uranus and Neptune (and, supposedly, Planet Nine) are much colder and are thus more difficult to exclude using WISE (e.g., WISE can only barely make out Neptune).
And it wouldn't have been able to see a sub-Neptune class planet like the proposed planet nine at all.
Post by: Archibald on 04/11/2016 12:33 pm
https://en.wikipedia.org/wiki/Arda_%28Tolkien%29
Post by: Mongo62 on 04/11/2016 03:26 pm
Call it Arda - the name Tolkien gave to his world
https://en.wikipedia.org/wiki/Arda_%28Tolkien%29
I would save that name for an actual Earth-like exoplanet.
In this case, I would choose a name associated with extreme cold. How about the Norse goddess Hel?
Post by: cartman on 04/11/2016 04:11 pm
I'd favor Enatos as a name for the new world. Which just means "The Ninth". It is very likely to be the ninth planet in sequence of distance to the sun, and also the ninth "true" planet we have discovered (Pluto should never have been a planet). It also speaks of a certain pragmatism, and a turn away from the old figures of mythology.Well i disagree, for the same reason we didn't call the other planets Ogdoos, Ebdomos etc. Also Enatos sounds a bit weak in Greek, at least for a planet. A mythological name like Hades or Erebus sounds much better and would continue the tradition of naming the major planets after Greek/Roman deities.
Post by: NovaSilisko on 04/11/2016 05:40 pm
would continue the tradition of naming the major planets after Greek/Roman deities.
Personally, I'd like to see a break from that tradition. We might, depending on what team discovers it and suggests a name to the IAU.
Post by: as58 on 04/11/2016 06:48 pm
Post by: NovaSilisko on 04/11/2016 06:50 pm
Maybe I'm in the minority, but IMO whatever name the (possible) object will be given is the second least interesting thing about it. The only thing I care less about is whether it should be called a planet or dwarf planet or something else.
I think I'll join you in your minority. I'll roll with whatever name is picked, and planet status is at the absolute bottom of my priorities.
It would be fascinating to figure out how this object got there in the first place.
Post by: Star One on 04/11/2016 07:05 pm
Maybe I'm in the minority, but IMO whatever name the (possible) object will be given is the second least interesting thing about it. The only thing I care less about is whether it should be called a planet or dwarf planet or something else.
It might be less interesting to you but for the general populace it will be one of the most interesting aspects. Anyway since when do we have to start ranking its attributes.
Post by: clongton on 04/13/2016 07:28 am
Patience. It will still be there in a few years when we may be able to actually figure out what it really is. THEN we can name it, when the name actually means something instead of all this fantasy stuff.
The only thing it needs right now is a designation, the same as any other body in the catalog.
Post by: Star One on 04/13/2016 10:33 am
I really wouldn't call *it* anything yet. We really don't even know what *it* is yet. For all we know *it* might not even be a member of our solar system but just a visitor passing thru. THAT's how little we *actually* know about *it*.
Patience. It will still be there in a few years when we may be able to actually figure out what it really is. THEN we can name it, when the name actually means something instead of all this fantasy stuff.
The only thing it needs right now is a designation, the same as any other body in the catalog.
It cannot be a visitor just passing through as to maintain the other objects in their current orbits would require a persistent presence over a lengthy period of time. In fact your whole post is full of wrong as if you read any of the various papers on planet nine would become clear.
Post by: gospacex on 04/13/2016 12:28 pm
I wonder what's going on on Subaru telescope now. To my (limited in this field) knowledge, its HSC camera is the most capable instrument in the world for this kind of wide-field search.
Post by: gospacex on 04/13/2016 12:37 pm
After reading about it, I learned that tiled CCD detectors (many CCDs with small gaps between them) cause surprising amounts of PITA when you have to use them. IOW: huge single-die CCDs are a bigger deal that I thought.
More here: http://www2.lowell.edu/rsch/LMI/Overview.html
Post by: Star One on 04/13/2016 01:37 pm
Pity that astronomers tend to be quite silent when they are participating in a search program for a new planet ;)
I wonder what's going on on Subaru telescope now. To my (limited in this field) knowledge, its HSC camera is the most capable instrument in the world for this kind of wide-field search.
Mike Brown is waiting to hear back on his request for twenty days observing time on Subaru according to his Twitter account, apparently this is extremely large amount of time to ask for.
Post by: as58 on 04/13/2016 08:20 pm
Post by: CuddlyRocket on 04/13/2016 10:46 pm
The latest arxiv listing had another paper on using Cassini ranging data to constraint the location of Planet Nine: http://arxiv.org/abs/1604.03180. They seem to agree with the earlier Cassini data paper and using a different method they are able to set tighter constraints on possible locations.
Holman and Payne note that extensive, highly precise range measurements to Mars-orbiting spacecraft have been collected and suggest analysing that data to more precisely constrain the location of Planet Nine.
Post by: Vultur on 04/14/2016 06:48 am
About the only way a big gas giant/ice giant could have escaped the survey
This wouldn't be one, though. 10 Earth masses is a small ice giant or large "mini-Neptune", significantly smaller than Uranus which is about 15.
Post by: Ben the Space Brit on 04/14/2016 09:48 am
In The Pirate Planet, Mondas was a near-Earth Twin that was ejected from the inner solar system due to some gravitational interaction with a massive object. The world ended up in an extreme elliptical orbit with an apihelion of >10,000AU and an orbital period in the millennia. The planet's native inhabitants had already developed a 20th Century-level of technology and, as the planet froze and the ecosphere collapsed, they were able to use technology to compensate. Eventually, the only way they were able to survive was to completely replace all their organic components with ever more sophisticated prostheses that could survive the extreme conditions and low-organic resource environment in their subterranean cities. Ultimately, the Modasians became the first Cybermen.
One possible history of Sol-IX (a mid-system object migrating out to the extreme outer solar system due to gravitational interactions) and its likely sub-giant size just made me think of Mondas and the tragic history of its inhabitants.
Post by: gospacex on 04/14/2016 11:05 am
Pity that astronomers tend to be quite silent when they are participating in a search program for a new planet ;)
I wonder what's going on on Subaru telescope now. To my (limited in this field) knowledge, its HSC camera is the most capable instrument in the world for this kind of wide-field search.
Mike Brown is waiting to hear back on his request for twenty days observing time on Subaru according to his Twitter account, apparently this is extremely large amount of time to ask for.
My google-fu says that HSC should be able to detect objects down to 24-27 magnitude. At least about 500 square degrees need to be searched, at least two exposures per field for parallax detection, but usually more exposures are needed for noise detection and CCD gap filling (I assume at least x3 more). HSC FOV is 2.25 sq.deg. In all, some 1500 good HSC exposures are needed as bare minimum.
Post by: Star One on 04/14/2016 09:35 pm
Quote
Ben Montet
6h6 hours ago
Ben Montet @benmontet
@plutokiller what about correlated residuals in Gaia astrometry? Don't they have to correct for positions of outer planets?
Mike Brown
Mike Brown – @plutokiller
@benmontet turns out the P9 orbit is ideal for this; crosses the galactic plane at the ecliptic, so good Gaia observations. Been pondering..
Post by: Star One on 04/18/2016 09:14 pm
Round up of the types of planet it could be.
http://m.dailykos.com/stories/2016/4/17/1513422/-The-race-to-find-Planet-Nine
Post by: clongton on 04/19/2016 12:50 am
The race to find Planet Nine
Round up of the types of planet it could be.
http://m.dailykos.com/stories/2016/4/17/1513422/-The-race-to-find-Planet-Nine (http://m.dailykos.com/stories/2016/4/17/1513422/-The-race-to-find-Planet-Nine)
At least the writer of this article has stated what I have been inferring all along, but in a far better way than my poor efforts. We do NOT know what this object is, nor do we know what this object is not. It is the height of conceit to be proclaiming that the object is this or that and rushing headlong into naming discussions, when we don't even know if this object actually even exists at all. All we have really are gravitational pertubences that indicate *something* is causing misalignment of certain previously well understood orbital mechanics of some well known celestial objects. That's it folks. That's ALL we really have. There is no smoking gun. Hell there isn't even a smoking toy cap pistol. Maybe it's a planet. Maybe it's a sub-brown dwarf. Maybe it's a small black hole. Maybe it's something else entirely. The point is that we really have no idea at all, beyond utter speculation (which I have seen a LOT of in this thread) what this "thing" is or is not. As such, it does not deserve a name. The best we can, or should offer is nothing more than a designation to assist conversation and points of study, until we actually do (1) confirm its existence and (2) identify what this "object" actually is. Then we can leave the realm of science fantasy behind and actually think about what name to give it.
Post by: hop on 04/19/2016 02:38 am
We do NOT know what this object is, nor do we know what this object is not. It is the height of conceit to be proclaiming that the object is this or that and rushing headlong into naming discussions, when we don't even know if this object actually even exists at all. All we have really are gravitational pertubences that indicate *something* is causing misalignment of certain previously well understood orbital mechanics of some well known celestial objects. That's it folks. That's ALL we really have.This is not correct. Aside from the observed apparent perturbation of some KBOs, we have a huge body of existing observations which very strongly constrain the kinds of things that could go undetected while still satisfying the "planet 9 hypothesis". Many of these constraints are substantially more robust than the supposed alignment of the KBOs.
Quote
Maybe it's a sub-brown dwarf. Maybe it's a small black hole.No. If it exists, it pretty much has to be significantly more massive than Earth, and less massive then Saturn. That puts it firmly in the "planetary" range. It can't be a brown dwarf, because anything Jupiter mass or larger would already have been detected.
Post by: NovaSilisko on 04/19/2016 04:38 am
Post by: Star One on 04/19/2016 07:18 am
I feel like everyone coming into this thread should be mentally prefixing every post with "If planet nine exists..." just as a general rule.That goes without saying. Though the likelihood of it not existing has declined slightly since it started due to the discovery of another of those aligned objects.
Post by: Hobbes-22 on 04/19/2016 08:33 am
At least the writer of this article has stated what I have been inferring all along, but in a far better way than my poor efforts. We do NOT know what this object is, nor do we know what this object is not.
We do know what the object is not. We can rule out several possibilities because if planet 9 were one of them, we'd have found it by now.
see http://www.xkcd.com/1633/
Post by: Star One on 04/20/2016 07:24 pm
Submarine Vet @rnolter
@plutokiller I thought the small perturbations in Saturn's orbit have been dismissed by NASA as rumor and not true. Your take??
Mike Brown – @plutokiller
@rnolter unclear. the NASA press release was not very informative. trying to get the real data myself.
Post by: CuddlyRocket on 04/21/2016 03:46 am
When NASA is talking about Cassini's orbit they're talking about its orbit around Saturn (more precisely, within the Saturnian system), not its orbit around the Sun. After all, the former is what they're interested in when maneuvering Cassini about. NASA says there's no unexplained anomalies in that orbit, whether due to P9 or otherwise. But then, you wouldn't expect any anomalies caused by P9, because any perturbations induced by P9, or any other planet, would affect both Saturn and Cassini equally (combine F=ma with F=GMm/r^2).
Fienga et al in their paper weren't considering the orbit of Cassini at all; they were considering the orbit of Saturn. How Cassini comes into it is that ranging data to the spacecraft enabled a more accurate determination of Saturn's orbit for the period the probe has been in the Saturnian system. This can then be combined with all the historical data for Saturn and the other planets and run through a model to see what orbits are consistent with the effect of the planets on each other given the uncertainties caused by measurement inaccuracy.
They then asked what is the effect if you add P9 to the model; what orbits of P9 with its affects on the other planets doesn't result in it shifting the other planets' orbits outside the residual uncertainty; and going further, actually reduces that residual uncertainty?
Post by: Star One on 04/21/2016 08:14 am
Confusion seems to be arising because of some miscommunication and misunderstandings.
When NASA is talking about Cassini's orbit they're talking about its orbit around Saturn (more precisely, within the Saturnian system), not its orbit around the Sun. After all, the former is what they're interested in when maneuvering Cassini about. NASA says there's no unexplained anomalies in that orbit, whether due to P9 or otherwise. But then, you wouldn't expect any anomalies caused by P9, because any perturbations induced by P9, or any other planet, would affect both Saturn and Cassini equally (combine F=ma with F=GMm/r^2).
Fienga et al in their paper weren't considering the orbit of Cassini at all; they were considering the orbit of Saturn. How Cassini comes into it is that ranging data to the spacecraft enabled a more accurate determination of Saturn's orbit for the period the probe has been in the Saturnian system. This can then be combined with all the historical data for Saturn and the other planets and run through a model to see what orbits are consistent with the effect of the planets on each other given the uncertainties caused by measurement inaccuracy.
They then asked what is the effect if you add P9 to the model; what orbits of P9 with its affects on the other planets doesn't result in it shifting the other planets' orbits outside the residual uncertainty; and going further, actually reduces that residual uncertainty?
Well how is that NASA have misunderstood that?
Post by: Alpha_Centauri on 04/21/2016 12:22 pm
Quote
"An undiscovered planet outside the orbit of Neptune, 10 times the mass of Earth, would affect the orbit of Saturn, not Cassini," said William Folkner, a planetary scientist at JPL. Folkner develops planetary orbit information used for NASA's high-precision spacecraft navigation. "This could produce a signature in the measurements of Cassini while in orbit about Saturn if the planet was close enough to the sun. But we do not see any unexplained signature above the level of the measurement noise in Cassini data taken from 2004 to 2016."
That was the confusing bit, because it appears to directly contradict Fienga, and now Holman (although the later does use the same INPOP model as Fienga as the basis). They were not simply making a semantic point about Cassini vs. Saturn's orbit. IMO it's not good form to make such a claim if you're not going to submit your analysis to peer review, I hope we see a paper on it.
Of course they could be making a semantic point about an "unexplained signature", since the addition of planet nine may reduce residuals producing a better fit, but that is not the same as needing planet nine to explain Saturn's motion.
Post by: Star One on 04/21/2016 12:35 pm
Quote
However, Nasa notes that "Cassini's mission is planned to end in late 2017, when the spacecraft – too low on fuel to continue on a longer mission – will plunge into Saturn's atmosphere." Some reports added an element of confusion by claiming that the mystery planet was affecting Cassini's orbit, rather than those of other bodies, a claim that Nasa had to debunk.
http://www.wired.co.uk/news/archive/2016-04/20/planet-nine-location-narrowed-down-cassini
Post by: CuddlyRocket on 04/22/2016 02:14 am
The NASA press release clearly says;Quote"An undiscovered planet outside the orbit of Neptune, 10 times the mass of Earth, would affect the orbit of Saturn, not Cassini," said William Folkner, a planetary scientist at JPL. Folkner develops planetary orbit information used for NASA's high-precision spacecraft navigation. "This could produce a signature in the measurements of Cassini while in orbit about Saturn if the planet was close enough to the sun. But we do not see any unexplained signature above the level of the measurement noise in Cassini data taken from 2004 to 2016."
That was the confusing bit, because it appears to directly contradict Fienga, and now Holman (although the later does use the same INPOP model as Fienga as the basis). They were not simply making a semantic point about Cassini vs. Saturn's orbit. IMO it's not good form to make such a claim if you're not going to submit your analysis to peer review, I hope we see a paper on it.
Folkner's comments look as if they were made on the hoof as they are rather slipshod; I expect he'd have made a much better job of it if he'd had time to think about things!
He says that P9 would affect the orbit of Saturn (presumably about the Sun), not Cassini (presumably about Saturn). Of course, P9 would affect the motion of both Saturn and Cassini but as it affects them both equally it won't affect the orbit of Cassini about Saturn. However, 'equally' is not precisely true as Cassini is at a different and varying distance from P9 than Saturn is; at P9's presumed distance - much, much greater than any such difference - this is probably not measurable but if P9 got close enough (to Saturn/Cassini, but 'to the Sun' is close enough; I'm assuming that 'the planet' means P9 not Saturn) it would be.
Quote
Of course they could be making a semantic point about an "unexplained signature", since the addition of planet nine may reduce residuals producing a better fit, but that is not the same as needing planet nine to explain Saturn's motion.
More slipshod language by Folkner. I think that when he's talking about Cassini data he means the data as to the shape of Cassini's orbit around Saturn not the data as to the shape of Saturn's orbit around the Sun (both of which are deduced using the ranging data between Earth and Cassini). So he means there's no unexplained signature in Cassini's orbit around Saturn not that there's no unexplained signature in Saturn's orbit around the Sun. Then he fails to point out, as you say, that Fienga's paper is based on assuming no such signature!
Post by: Phil Stooke on 04/22/2016 02:50 am
Post by: Mongo62 on 04/22/2016 05:19 pm
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
That is correct, Fienga said that the lack of observable deviations in Saturn's orbit since Cassini arrived rules out Planet 9 being in certain portions of its conjectured orbit, but the rest of the locations along the orbit are still not ruled out. Folkner states that there are no observed deviations of Saturn's orbit during that time span, agreeing with Fienga.
Post by: Star One on 04/22/2016 07:01 pm
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
That is correct, Fienga said that the lack of observable deviations in Saturn's orbit since Cassini arrived rules out Planet 9 being in certain portions of its conjectured orbit, but the rest of the locations along the orbit are still not ruled out. Folkner states that there are no observed deviations of Saturn's orbit during that time span, agreeing with Fienga.
It's all a matter of semantics as the way this has been written about elsewhere is this helps narrow the search down as to where it could be, rather than where it isn't.
Post by: clongton on 04/22/2016 11:38 pm
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
My sentiments exactly
Post by: Star One on 04/23/2016 12:03 am
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
My sentiments exactly
So this has now devolved into people arguing about semantics...
Post by: Alpha_Centauri on 04/23/2016 12:33 am
Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data.
Um, then you must be reading a different paper because that is not what Fienga concludes.
http://arxiv.org/abs/1602.06116
Quote
6. Conclusions
The Cassini data provides an exceptional set of measures that acts as a very sensitive device for testing the possibility of an additional massive body in the solar system. With the data accumulated until 2014.4, we can exclude the possibility that P9 is in the section of the orbit depicted in red in Fig.6, with a true anomaly v in [−130◦ :−100◦]∪[−65◦ : 85◦]. We thus contradict the affirmation of Iorio (2016), who states that a body of 10 M⊕ is excluded if it resides closer to 1000 AU of the Sun. Iorio (2016) does not properly consider how much the presence of an additional body can be absorbed by the fit of all the other parameters in the solar system ephemerides. The global fit that we present here avoids this drawback. Moreover, we found that the presence of P9 could significantly decrease the Cassini residuals if v is in the interval [108◦ : 129◦], with a most probable position at v = 117.8◦+11◦
The two principle findings are emboldened. Yes part of the analysis rules out (only for this one particular set of orbital characteristics) certain zones where it couldn't be, but the other part also highlights a zone where the fitting is significantly improved over the current model. That is evidence for a new planet. It is only circumstantial evidence however, granted, as the level of significance is not so high it couldn't end up evaporating with improved models but it is still evidence.
Post by: clongton on 04/23/2016 12:56 am
So this has now devolved into people arguing about semantics...Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.My sentiments exactly
No. It's the point I have been trying to make all along while people poo pooed me and continued on in fanciful flights of fantasies about the big planet, its atmosphere and what to call it. We do not even know yet what "it" is.
Post by: CuddlyRocket on 04/23/2016 09:54 am
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
Of course I've read the paper.
Fienga doesn't say there's no evidence for P9; she doesn't contradict Batygin and Brown, after all. She merely puts limits on its possible orbit and current position based on what we know about the orbits of the other objects in the Solar system.
Folkner doesn't even mention Fienga's paper!
That is correct, Fienga said that the lack of observable deviations in Saturn's orbit since Cassini arrived rules out Planet 9 being in certain portions of its conjectured orbit, but the rest of the locations along the orbit are still not ruled out. Folkner states that there are no observed deviations of Saturn's orbit during that time span, agreeing with Fienga.
Lack of deviations exceeding uncertainties in the orbits of all the planets (and other objects) based on measurements of the planets' positions since records began. Cassini comes into it by enabling a more accurate determination of Saturn's orbit around the Sun since it has been in orbit around Saturn; this reduces the uncertainties in Saturn's orbit throughout history and consequentially those of all the other planets as well. Presumably without the Cassini ranging data the uncertainties in the planets' orbits would be so large as to mask any potential perturbations from P9.
Folkner doesn't mention any deviations of Saturn's orbit; he's talking about Cassini's orbit about Saturn. It's the fact that there's so much confusion as to what actually he's talking about which leads me to describe his language as slipshod; it would have been helpful if he had been more precise.
Post by: Star One on 04/23/2016 11:12 am
Not slipshod. Read the paper and you will see that Fienga concludes there is no evidence for the presence of the 'new' planet, at least in the parts of its orbit where it might be detected with current data. Folkner said it exactly right. And he did NOT contradict Fienga, he agreed with the paper and was disagreeing with uninformed comment about the paper. If you're looking for slipshod, look at the uninformed comment.
Of course I've read the paper.
Fienga doesn't say there's no evidence for P9; she doesn't contradict Batygin and Brown, after all. She merely puts limits on its possible orbit and current position based on what we know about the orbits of the other objects in the Solar system.
Folkner doesn't even mention Fienga's paper!That is correct, Fienga said that the lack of observable deviations in Saturn's orbit since Cassini arrived rules out Planet 9 being in certain portions of its conjectured orbit, but the rest of the locations along the orbit are still not ruled out. Folkner states that there are no observed deviations of Saturn's orbit during that time span, agreeing with Fienga.
Lack of deviations exceeding uncertainties in the orbits of all the planets (and other objects) based on measurements of the planets' positions since records began. Cassini comes into it by enabling a more accurate determination of Saturn's orbit around the Sun since it has been in orbit around Saturn; this reduces the uncertainties in Saturn's orbit throughout history and consequentially those of all the other planets as well. Presumably without the Cassini ranging data the uncertainties in the planets' orbits would be so large as to mask any potential perturbations from P9.
Folkner doesn't mention any deviations of Saturn's orbit; he's talking about Cassini's orbit about Saturn. It's the fact that there's so much confusion as to what actually he's talking about which leads me to describe his language as slipshod; it would have been helpful if he had been more precise.
I would describe your OP as confusing as from the way I read it and clearly others reading it as well that's not the impression you gave.
Post by: Bynaus on 04/23/2016 11:52 am
Btw, the work by Fienga has now been re-done with much more scrutiny by Holman & Payne: http://arxiv.org/abs/1604.03180 They not only look at the nominal orbit as Fienga did, but at a whole series of possible orbits. They are able to constrain the sky position of P9 - if it exists - fairly well.
Post by: hop on 04/23/2016 07:03 pm
Btw, the work by Fienga has now been re-done with much more scrutiny by Holman & Payne: http://arxiv.org/abs/1604.03180 They not only look at the nominal orbit as Fienga did, but at a whole series of possible orbits. They are able to constrain the sky position of P9 - if it exists - fairly well.From what I understand Holman & Payne take much of Fienga's work as a given. They do a more thorough exploration of the possible orbits of P9, but don't do much to further verify that the supposed perturbation of Saturn's orbit is real.
Quote
Our results rely entirely upon the residuals from the detailed, unperturbed ephemeris model of F16. Without their careful work, as well as their insight into the sensitivity of the Cassini range measurements to the gravitational perturbations from Planet Nine , we would not be able to carry out the present investigation. Furthermore, if the ephemeris models of F16 are incorrect, our results will be too./quote]
Post by: Alpha_Centauri on 04/23/2016 08:44 pm
Post by: llanitedave on 04/24/2016 09:03 pm
Confusion seems to be arising because of some miscommunication and misunderstandings.
When NASA is talking about Cassini's orbit they're talking about its orbit around Saturn (more precisely, within the Saturnian system), not its orbit around the Sun. After all, the former is what they're interested in when maneuvering Cassini about. NASA says there's no unexplained anomalies in that orbit, whether due to P9 or otherwise. But then, you wouldn't expect any anomalies caused by P9, because any perturbations induced by P9, or any other planet, would affect both Saturn and Cassini equally (combine F=ma with F=GMm/r^2).
Fienga et al in their paper weren't considering the orbit of Cassini at all; they were considering the orbit of Saturn. How Cassini comes into it is that ranging data to the spacecraft enabled a more accurate determination of Saturn's orbit for the period the probe has been in the Saturnian system. This can then be combined with all the historical data for Saturn and the other planets and run through a model to see what orbits are consistent with the effect of the planets on each other given the uncertainties caused by measurement inaccuracy.
They then asked what is the effect if you add P9 to the model; what orbits of P9 with its affects on the other planets doesn't result in it shifting the other planets' orbits outside the residual uncertainty; and going further, actually reduces that residual uncertainty?
I'm still not clear, then, how they can measure these anomalies from Cassini and not from the Voyagers.
Post by: ugordan on 04/24/2016 09:35 pm
Voyagers are 3-axis stabilized via RCS so are probably completely useless for any precision measurements, like they were for the Pioneer anomaly.
Post by: llanitedave on 04/25/2016 12:28 am
I'm thinking it would have something to do with the fact Cassini relies on reaction wheels most of the time, only doing periodical desaturation via RCS. In addition, perturbative effects (like solar radiation pressure) can probably also be accounted for given the observed changes in Cassini's orbital parameters as it's being tracked so it might help out separate actual Saturnian system "drift" from just Cassini's orbit being perturbed.
Voyagers are 3-axis stabilized via RCS so are probably completely useless for any precision measurements, like they were for the Pioneer anomaly.
That does make very good sense.
Post by: cscott on 04/25/2016 12:17 pm
Post by: CuddlyRocket on 04/26/2016 09:51 pm
The Saturn data helps in particular to constrain the uncertainties in Uranus and Neptune's orbits; which planets would be most perturbed by P9.
Post by: Star One on 04/27/2016 08:50 pm
Thee Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability
We investigate the physical characteristics of the Solar System's proposed Planet Nine using modeling tools with a strong heritage in studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic Teff, from ~35-50 K for masses of 5-20 M_Earth. Possible planetary radii could readily span from 3 to 6 R_Earth depending on the mass fraction of any H/He envelope. We model the atmospheric temperature structure and spectra. Given its cold temperature, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like expectations. We find the atmosphere is strongly depleted in molecular absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere with a high geometric albedo of 0.75. We highlight two diagnostics for the atmosphere's temperature structure, the first being the value of the methane mixing ratio above the methane cloud. The second is the wavelength at which cloud scattering can be seen, which yields the cloud-top pressure. Surface reflection may be seen if the atmosphere is thin. Due to collision-induced opacity of H2 in the infrared, the planet would be extremely blue (instead of red) in the shortest wavelength WISE colors if methane is depleted, and would, in some cases, exist on the verge of detectability by WISE. For a range of models, thermal fluxes from ~3-5 microns are ~20 orders of magnitude larger than blackbody expectations. We report a search of the AllWISE Source Catalog for Planet Nine, but find no detection.
http://arxiv.org/abs/1604.07424
Post by: Alpha_Centauri on 04/27/2016 08:58 pm
Quote
We are currently sifting this 428,787,253-line database for candidates.
Poor grad student.
Post by: CuddlyRocket on 04/28/2016 02:50 am
QuoteWe are currently sifting this 428,787,253-line database for candidates.
Poor grad student.
Seems like a job for citizen science - perhaps Planet Hunters (https://www.planethunters.org/)? ;)
Post by: Star One on 05/03/2016 07:50 pm
Release No.:
2016-11
For Release:
Tuesday, May 3, 2016 - 9:00am
Cambridge, MA -
Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. Since then theorists have puzzled over how this planet could end up in such a distant orbit.
New research by astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) examines a number of scenarios and finds that most of them have low probabilities. Therefore, the presence of Planet Nine remains a bit of a mystery.
"The evidence points to Planet Nine existing, but we can't explain for certain how it was produced," says CfA astronomer Gongjie Li, lead author on a paper accepted for publication in the Astrophysical Journal Letters.
Planet Nine circles our Sun at a distance of about 40 billion to 140 billion miles, or 400 - 1500 astronomical units. (An astronomical unit or A.U. is the average distance of the Earth from the Sun, or 93 million miles.) This places it far beyond all the other planets in our solar system. The question becomes: did it form there, or did it form elsewhere and land in its unusual orbit later?
Li and her co-author Fred Adams (University of Michigan) conducted millions of computer simulations in order to consider three possibilities. The first and most likely involves a passing star that tugs Planet Nine outward. Such an interaction would not only nudge the planet into a wider orbit but also make that orbit more elliptical. And since the Sun formed in a star cluster with several thousand neighbors, such stellar encounters were more common in the early history of our solar system.
However, an interloping star is more likely to pull Planet Nine away completely and eject it from the solar system. Li and Adams find only a 10 percent probability, at best, of Planet Nine landing in its current orbit. Moreover, the planet would have had to start at an improbably large distance to begin with.
CfA astronomer Scott Kenyon believes he may have the solution to that difficulty. In two papers submitted to the Astrophysical Journal, Kenyon and his co-author Benjamin Bromley (University of Utah) use computer simulations to construct plausible scenarios for the formation of Planet Nine in a wide orbit.
"The simplest solution is for the solar system to make an extra gas giant," says Kenyon.
They propose that Planet Nine formed much closer to the Sun and then interacted with the other gas giants, particularly Jupiter and Saturn. A series of gravitational kicks then could have boosted the planet into a larger and more elliptical orbit over time.
"Think of it like pushing a kid on a swing. If you give them a shove at the right time, over and over, they'll go higher and higher," explains Kenyon. "Then the challenge becomes not shoving the planet so much that you eject it from the solar system."
That could be avoided by interactions with the solar system's gaseous disk, he suggests.
Kenyon and Bromley also examine the possibility that Planet Nine actually formed at a great distance to begin with. They find that the right combination of initial disk mass and disk lifetime could potentially create Planet Nine in time for it to be nudged by Li's passing star.
"The nice thing about these scenarios is that they're observationally testable," Kenyon points out. "A scattered gas giant will look like a cold Neptune, while a planet that formed in place will resemble a giant Pluto with no gas."
Li's work also helps constrain the timing for Planet Nine's formation or migration. The Sun was born in a cluster where encounters with other stars were more frequent. Planet Nine's wide orbit would leave it vulnerable to ejection during such encounters. Therefore, Planet Nine is likely to be a latecomer that arrived in its current orbit after the Sun left its birth cluster.
Finally, Li and Adams looked at two wilder possibilities: that Planet Nine is an exoplanet that was captured from a passing star system, or a free-floating planet that was captured when it drifted close by our solar system. However, they conclude that the chances of either scenario are less than 2 percent.
Li and Adams' paper has been accepted for publication in the Astrophysical Journal Letters and is available online. Kenyon and Bromley have submitted their findings to the Astrophysical Journal in two papers available online: one on in-situ formation and one on gas-giant scattering.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
For more information, contact:
Christine Pulliam
Media Relations Manager
Harvard-Smithsonian Center for Astrophysics
617-495-7463
[email protected]
https://www.cfa.harvard.edu/news/2016-11
Post by: CuddlyRocket on 05/05/2016 02:18 am
Interaction Cross Sections and Survival Rates for Proposed Solar System Member Planet Nine (http://arxiv.org/abs/1602.08496)
Making Planet Nine: Pebble Accretion at 250--750 AU in a Gravitationally Unstable Ring (http://arxiv.org/abs/1603.08008)
Making Planet Nine: A Scattered Giant in the Outer Solar System (http://arxiv.org/abs/1603.08010)
Post by: Don2 on 05/06/2016 05:46 am
Post by: Star One on 05/06/2016 07:00 pm
https://paw.princeton.edu/article/there-ninth-planet
Post by: CuddlyRocket on 05/07/2016 07:13 pm
New interview with Mike Brown
https://paw.princeton.edu/article/there-ninth-planet
Quote
Who would get to name it?
There’s no answer to that because there aren’t supposed to be any more planets. The International Astronomical Union will probably claim the right, but it will be interesting to see if that works for them. When William Herschel discovered Uranus in 1781, he wanted to name it after King George III, but of course no one listened. It was nearly 70 years, though, before “Uranus” stuck.
There were similar disputes over Neptune's name (http://dioi.org/kn/NeptuneName.pdf). Stopping such disputes was one of the reasons the IAU was founded. But the IAU doesn't come up with names itself; normally someone else - often the discoverer - comes up with a name and then the IAU puts its imprimatur on it and makes it 'official'.
Post by: Star One on 05/12/2016 08:40 am
Post by: Alpha_Centauri on 05/12/2016 09:19 am
Post by: as58 on 05/12/2016 09:25 am
Edit: Another thing is that full-frame images are not (cannot be due to bandwidth limitations) downloaded, only stamps around pre-determined targets, so it's not effective as a survey instrument.
Post by: clongton on 05/12/2016 09:42 am
Would the K2 mission be any use in the hunt for Planet Nine, as I know it has been doing observation work on distant bodies in the Solar System?
Shepherded objects are off the ecliptic indicating object 9 is as well. K2 would not be able to find it except by blind luck.
Post by: Star One on 05/12/2016 11:32 am
Post by: Star One on 05/16/2016 01:06 pm
Russell Kerbel @DrKerbel
@plutokiller Could Planet 9 be anywhere in its orbit right now based on your calculations? Or can it be narrowed down mathematically?
Mike Brown – @plutokiller
@DrKerbel we have a paper on that coming out shortly....
5:32 p.m. - 15 May 2016
Post by: Alpha_Centauri on 05/24/2016 05:26 am
http://arxiv.org/abs/1605.06575
Post by: cscott on 05/24/2016 01:39 pm
Post by: Alpha_Centauri on 05/24/2016 02:20 pm
Post by: Star One on 05/31/2016 08:30 pm
Quote
An extrasolar planet, or exoplanet, is by definition a planet located outside our solar system. Now it appears that this definition is no longer viable. According to astronomers in Lund, there is a lot to indicate that Planet 9 was captured by the young Sun and has been a part of our solar system completely undetected ever since.
“It is almost ironic that while astronomers often find exoplanets hundreds of light-years away in other solar systems, there’s probably one hiding in our own backyard,” says Alexander Mustill, astronomer at Lund University.
Stars are born in clusters and often pass by one another. It is during these encounters that a star can “steal” one or more planets in orbit around another star. This is probably what happened when our own Sun captured Planet 9.
http://astronomynow.com/2016/05/31/did-the-young-sun-steal-planet-9-from-another-star/
Here's the paper.
http://m.mnrasl.oxfordjournals.org/content/460/1/L109
Post by: NovaSilisko on 05/31/2016 08:31 pm
Post by: CuddlyRocket on 05/31/2016 09:14 pm
Quote
An extrasolar planet, or exoplanet, is by definition a planet located outside our solar system. Now it appears that this definition is no longer viable. According to astronomers in Lund, there is a lot to indicate that Planet 9 was captured by the young Sun and has been a part of our solar system completely undetected ever since.
This doesn't make any sense. If an exoplanet is by definition a planet located outside our solar system then Planet 9 is not an exoplanet whether or not it formed around the Sun or around some other star.
Whether or not this is the most appropriate definition for 'exoplanet' is another matter. Personally, I'd abolish the term and just call them all planets.
Post by: clongton on 06/01/2016 12:37 am
Did the young Sun steal Planet 9 from another star?QuoteAn extrasolar planet, or exoplanet, is by definition a planet located outside our solar system. Now it appears that this definition is no longer viable. According to astronomers in Lund, there is a lot to indicate that Planet 9 was captured by the young Sun and has been a part of our solar system completely undetected ever since.
“It is almost ironic that while astronomers often find exoplanets hundreds of light-years away in other solar systems, there’s probably one hiding in our own backyard,” says Alexander Mustill, astronomer at Lund University.
Stars are born in clusters and often pass by one another. It is during these encounters that a star can “steal” one or more planets in orbit around another star. This is probably what happened when our own Sun captured Planet 9.
http://astronomynow.com/2016/05/31/did-the-young-sun-steal-planet-9-from-another-star/ (http://astronomynow.com/2016/05/31/did-the-young-sun-steal-planet-9-from-another-star/)
Here's the paper.
http://m.mnrasl.oxfordjournals.org/content/460/1/L109 (http://m.mnrasl.oxfordjournals.org/content/460/1/L109)
I got seriously pooh-poohed a couple of months ago by all the experts on here for suggesting that this was a possibility. Looks like it's not such a far-fetched idea after all.
Post by: hop on 06/01/2016 05:41 am
The means of proving such hypothesis is difficult with current orbital integration, so this is a "head of the pin" kind of situation. You spend much of your effort in tracking down floating point error effects, finding ways to cancel them out, and then finding similar astrometric issues affecting your N-body simulation ... and so on.FWIW Mustill et al aren't claiming to prove the specific case of Planet 9, all they are doing looking at how likely such a capture is, and whether it is compatible with known objects and the specific orbit hypothesized for Planet 9. Getting a good statistical sense for this kind of thing is does not require mathematical perfection.
So the issue is "how" real are such captures, given the extremely difficult mathematical environment. Its hard to peer review this, in either direction of "too easy" or "too hard".
They do suggest that the capture scenario could leave a distinct orbital population, but it's as explicitly a direction for further study rather than a firm conclusion. Even if this population were found, it probably wouldn't close the case, but it would be more compelling that just Planet 9 itself.
Contrary to clongton's suggestion, capture from the solar birth cluster is not a new, far out idea. It is well known as one of the more favorable pathways to capture bodies that formed elsewhere, and has previously been suggested for Sedna.
Post by: clongton on 06/01/2016 09:35 am
Contrary to clongton's suggestion, capture from the solar birth cluster is not a new, far out idea. It is well known as one of the more favorable pathways to capture bodies that formed elsewhere, and has previously been suggested for Sedna.
I didn't suggest it was a "new, far out idea". I was referring to the heat I took for even suggesting that capture of a non-solar planet was possible. It was dismissed as being ludicrous and far fetched, hence my use of the term in my post above referring to the previous roasting of me by some so-called experts.
Post by: as58 on 06/01/2016 11:09 am
Contrary to clongton's suggestion, capture from the solar birth cluster is not a new, far out idea. It is well known as one of the more favorable pathways to capture bodies that formed elsewhere, and has previously been suggested for Sedna.
I didn't suggest it was a "new, far out idea". I was referring to the heat I took for even suggesting that capture of a non-solar planet was possible. It was dismissed as being ludicrous and far fetched, hence my use of the term in my post above referring to the previous roasting of me by some so-called experts.
This discussion is a bit pointless, but I recall that you were not taking heat for suggesting the capture hypothesis, but because of your claims that we have no idea what the planet is like. As was pointed out by many posters, that is simply not true. We don't know if the planet exists at all, but we know a lot about what and where it can't be (a brown dwarf for example - that would've already been seen).
Post by: Archibald on 06/01/2016 04:57 pm
That's always been my favored hypothesis for how such an object could get to that position, good to see some serious thought put toward it.
Now imagine if we explore it and found some ancient hieroglyphes on a wall cave...
Post by: RonM on 06/01/2016 08:57 pm
QuoteAn extrasolar planet, or exoplanet, is by definition a planet located outside our solar system. Now it appears that this definition is no longer viable. According to astronomers in Lund, there is a lot to indicate that Planet 9 was captured by the young Sun and has been a part of our solar system completely undetected ever since.
This doesn't make any sense. If an exoplanet is by definition a planet located outside our solar system then Planet 9 is not an exoplanet whether or not it formed around the Sun or around some other star.
Whether or not this is the most appropriate definition for 'exoplanet' is another matter. Personally, I'd abolish the term and just call them all planets.
Planet 9 is now an ex-exoplanet. :)
Yes, I think the terminology needs some work.
Post by: clongton on 06/02/2016 09:26 pm
Contrary to clongton's suggestion, capture from the solar birth cluster is not a new, far out idea. It is well known as one of the more favorable pathways to capture bodies that formed elsewhere, and has previously been suggested for Sedna.
I didn't suggest it was a "new, far out idea". I was referring to the heat I took for even suggesting that capture of a non-solar planet was possible. It was dismissed as being ludicrous and far fetched, hence my use of the term in my post above referring to the previous roasting of me by some so-called experts.
This discussion is a bit pointless, but I recall that you were not taking heat for suggesting the capture hypothesis, but because of your claims that we have no idea what the planet is like. As was pointed out by many posters, that is simply not true. We don't know if the planet exists at all, but we know a lot about what and where it can't be (a brown dwarf for example - that would've already been seen).
You didn't read back far enough
Post by: cscott on 06/02/2016 10:42 pm
Post by: Star One on 06/13/2016 08:42 pm
Quote
Now, however, brothers Carlos and Raúl de la Fuente Marcos, two freelance Spanish astronomers, together with scientist Sverre J. Aarseth from the Institute of Astronomy of the University of Cambridge (United Kingdom), have considered the question the other way around: How would the orbits of these six ETNOs evolve if a Planet Nine such as the one proposed by K. Batygin and M. Brown really did exist? The answer to this important question has been published in the journal Monthly Notices of the Royal Astronomical Society.
“With the orbit indicated by the Caltech astronomers for Planet Nine, our calculations show that the six ETNOs, which they consider to be the Rosetta Stone in the solution to this mystery, would move in lengthy, unstable orbits,” warns Carlos de la Fuente Marcos.
”These objects would escape from the solar system in less than 1.5 billion years,” he adds, “and in the case of 2004 VN112, 2007 TG422 and 2013 RF98 they could abandon it in less than 300 million years; what is more important, their orbits would become really unstable in just 10 million years, a really short amount of time in astronomical terms.”
Quote
According to this new study, also based on numerical (N-body) simulations, the orbit of the new planet proposed by Batygin and Brown would have to be modified slightly so that the orbits of the six ETNOs analysed would be really stable for a long time.
These results also lead to a new question: Are the ETNOs a transient and unstable population or, on the contrary, are they permanent and stable? The fact that these objects behave in one way or another affects the evolution of their orbits and also the numerical modelling.
“If the ETNOs are transient, they are being continuously ejected and must have a stable source located beyond 1,000 astronomical units (in the Oort cloud) where they come from,” notes Carlos de la Fuente Marcos. “But if they are stable in the long term, then there could be many in similar orbits although we have not observed them yet”.
In any case, the statistical and numerical evidence obtained by the authors, both through this and previous work, leads them to suggest that the most stable scenario is one in which there is not just one planet, but rather several more beyond Pluto, in mutual resonance, which best explains the results. “That is to say we believe that in addition to a Planet Nine, there could also be a Planet Ten and even more,” the Spanish astronomer points out.
http://astronomynow.com/2016/06/13/extreme-trans-neptunian-objects-lead-the-way-to-planet-nine/
Also Mike Brown's new paper on searching for planet nine.
https://arxiv.org/abs/1603.05712
Post by: Star One on 07/10/2016 01:55 pm
https://mobile.twitter.com/plutokiller/status/751539312076791808/photo/1
https://mobile.twitter.com/plutokiller/status/751539773542629377
Post by: Star One on 07/11/2016 08:12 pm
Quote
An international team of astronomers have discovered a new dwarf planet orbiting in the disc of small icy worlds beyond Neptune. The new object is roughly 700 kilometres (435 miles) in size and has one of the largest orbits for a dwarf planet. Designated 2015 RR245 by the International Astronomical Union’s Minor Planet Center, it was found using the Canada-France-Hawaii Telescope on Maunakea, Hawaii, as part of the ongoing Outer solar system Origins Survey (OSSOS).
“The icy worlds beyond Neptune trace how the giant planets formed and then moved out from the Sun. They let us piece together the history of our solar system. But almost all of these icy worlds are painfully small and faint: it’s really exciting to find one that’s large and bright enough that we can study it in detail,” said Dr. Michele Bannister of the University of Victoria in British Columbia, who is a postdoctoral fellow with the survey.
National Research Council of Canada’s Dr. JJ Kavelaars first sighted RR245 in February 2016 in the OSSOS images from September 2015. “There it was on the screen — this dot of light moving so slowly that it had to be at least twice as far as Neptune from the Sun,” said Bannister.
The team became even more excited when they realised that the object’s orbit takes it more than 120 times further from the Sun than Earth. The size of RR245 is not yet exactly known, as its surface properties need further measurement. “It’s either small and shiny, or large and dull,” said Bannister.
https://astronomynow.com/2016/07/11/new-distant-dwarf-planet-found-beyond-neptune/
Post by: Bynaus on 07/11/2016 08:56 pm
It is currently NOT part of the enigmatic group of dynamically detached objects which led to the Planet Nine hypothesis. However, if P9 exists, it might change the orbit of the new object into periodically joining the group (before leaving again, etc).
Post by: redliox on 07/11/2016 10:42 pm
It is currently NOT part of the enigmatic group of dynamically detached objects which led to the Planet Nine hypothesis. However, if P9 exists, it might change the orbit of the new object into periodically joining the group (before leaving again, etc).
In other words, it might be evidence against the hypothetical Planet Nine then? I know telescopic surveys have ruled out anything the size of Saturn or larger roaming, and I would assume the JWST and newer ground scopes could find a new Ice Giant (if pointed in right direction naturally). Frankly, I'd just be impressed to hear about a new Pluto-size body. If a few of those are found, coupled with this new body, it would disprove there's a 5th gas giant lurking. Time will ultimately tell.
Post by: Alpha_Centauri on 07/11/2016 11:17 pm
From the information released it doesn't look like there is anything to suggest this is evidence against Planet Nine as proposed.
Post by: hop on 07/12/2016 03:58 am
In other words, it might be evidence against the hypothetical Planet Nine then?As far as I understand, it really doesn't add much either way by itself. Things on orbits like 2015 RR245 are expected regardless.
Michele Bannister (of the OSSOS team which discovered 2015 RR245) tweeted
https://twitter.com/astrokiwi/status/752624569953886208
Quote
FAQ: does 2015 RR245 help answer the idea of a ninth planet?
Short answer: No.
Long: only with lots of its friends http://arxiv.org/abs/1605.06575
Post by: Bynaus on 07/12/2016 05:13 am
Regarding JWST should be able to see P9: yes, but so do many other telescopes in operation today. The problem is not catching its reflected light, its knowing where to point your telescope! This is why the primary telescope to search for P9 is Subaru: not the biggest and best, but the big one with the largest field of view.
Post by: Star One on 07/12/2016 05:59 am
Yup, Alpha_Centauri is right, I should have mentioned that, we are talking probably 100s of Ma period cycles here. I just wanted to point out that this object by itself does not help (nor does it disprove) the P9 hypothesis (the thread title).
Regarding JWST should be able to see P9: yes, but so do many other telescopes in operation today. The problem is not catching its reflected light, its knowing where to point your telescope! This is why the primary telescope to search for P9 is Subaru: not the biggest and best, but the big one with the largest field of view.
Which is where Mike Brown is at the moment, as it appears he got granted his twenty days (or at least an amount of observing time on it to look for it) on the Subaru telescope.
Post by: Star One on 07/12/2016 07:43 pm
Quote
Chris Lindsay @MrChrisWrites
@plutokiller Hi Mike. Will the discovery of 2015 RR245 impact on your data for finding Planet 9?
Mike Brown
Mike Brown – @plutokiller
@MrChrisWrites no, it's not far enough away to be affected by Planet Nine, sadly.
Post by: Mongo62 on 07/15/2016 12:52 am
Quote
The six-degree obliquity of the sun suggests that either an asymmetry was present in the solar system's formation environment, or an external torque has misaligned the angular momentum vectors of the sun and the planets. However, the exact origin of this obliquity remains an open question. Batygin & Brown (2016) have recently shown that the physical alignment of distant Kuiper Belt orbits can be explained by a 5-20 Earth-mass planet on a distant, eccentric, and inclined orbit, with an approximate perihelion distance of ~250 AU. Using an analytic model for secular interactions between Planet Nine and the remaining giant planets, here we show that a planet with similar parameters can naturally generate the observed obliquity as well as the specific pole position of the sun's spin axis, from a nearly aligned initial state. Thus, Planet Nine offers a testable explanation for the otherwise mysterious spin-orbit misalignment of the solar system.
Post by: Star One on 07/15/2016 07:58 am
Post by: Alpha_Centauri on 07/15/2016 09:35 am
Post by: Star One on 07/15/2016 04:25 pm
Quote
We’re reminded that we have not just Kuiper Belt Objects to contend with but scattered disk objects as well (scattered disk objects are considered to be KBOs with large orbital eccentricities), and beyond them the so-called Sednoids. This has implications for the conjectured Planet Nine, whose existence has been inferred through the clustering of a small number of Sednoid objects. Siegel has his doubts, and they’re reinforced by 2015 RR245:
But it’s also possible, as scattered disk objects and elliptical KBOs show, that there are a huge variety of objects with tremendously varied orbits out there, and we’re only seeing a tiny fraction of them. If the objects we’re seeing have even a slight bias to them, it could lead us to jump to all sorts of incorrect conclusions, just as we did decades ago claiming periodic mass extinctions due to asteroid impacts and the Nemesis theory of a second Sun. Incomplete data is what we’ve got, and the first results of OSSOS and the discovery of 2015 RR245 should remind us all of how much more there is — not just in the Universe but even in our Solar System — still left to discover.
http://www.centauri-dreams.org/?p=35987
Post by: CuddlyRocket on 07/16/2016 03:22 am
QuoteThus, Planet Nine offers a testable explanation for the otherwise mysterious spin-orbit misalignment of the solar system.
As Mike Brown noted, it's always a good sign for a hypothesis that it turns out to explain things other than that for which it was created in the first place. That's two now for the P9 hypothesis - but they still need to actually find it!
Added 20 July: Another group independently came to the same conclusion (they submitted their paper to arXiv four days later - must have been annoying! :) ).
The inclination of the planetary system relative to the solar equator may be explained by the presence of Planet 9 (http://arxiv.org/abs/1607.05111)
Quote
We evaluate the effects of a distant planet, commonly known as planet 9, on the dynamics of the giant planets of the Solar System. We find that, given the large distance of planet 9, the dynamics of the inner giant planets can be decomposed into a classic Lagrange-Laplace dynamics relative to their own invariant plane (the plane orthogonal to their total angular momentum vector) and a slow precession of said plane relative to the total angular momentum vector of the Solar System, including planet 9. Under some specific configurations for planet 9, this precession can explain the current tilt of approximately 6 degrees between the invariant plane of the giant planets and the solar equator. An analytical model is developed to map the evolution of the inclination of the inner giant planets' invariant plane as a function of the planet 9's mass, inclination, eccentricity and semimajor axis, and some numerical simulations of the equations of motion of the giant planets and planet 9 are performed to validate our analytical approach. The longitude of the ascending node of planet 9 is found to be linked to the longitude of the ascending node of the giant planets' invariant plane, which also constrain the longitude of the node of planet 9 on the ecliptic. Some of the planet 9 configurations that allow explaining the current solar tilt are compatible with those proposed to explain the orbital confinement of the most distant Kuiper belt objects. Thus, this work on the one hand gives an elegant explanation for the current tilt between the invariant plane of the inner giant planets and the solar equator and, on the other hand, adds new constraints to the orbital elements of planet 9.
Post by: Star One on 07/21/2016 08:34 pm
Quote
The search for distant solar system objects has found two more small worlds far outside the orbit of Neptune. The new objects are located beyond the Kuiper Belt, which is a belt of small icy objects just beyond Neptune, of which Pluto is a member. They have the third and fourth most-distant perihelia, which is when an object has its closest approach distance to the Sun, of any known solar system objects.
In addition, the orbital motions of these objects are in resonance with Neptune’s orbit, which was somewhat unexpected. Their orbital paths imply that these worlds either have interacted with Neptune in the past or are continuing to do so – despite their great distances from the ice giant planet.
This latest discovery is based on observations made with the Subaru Telescope in Hawai'i and Cerro Tololo Inter-American Observatory (CTIO) telescope in Chile, and is described in a paper published in the July 2016 edition of Astrophysical Journal Letters.
Dr. Scott S. Sheppard (Carnegie Institution for Science) and his collaborators Dr. Chadwick Trujillo (Gemini Observatory at the time of the research) and Dr. David J. Tholen (University of Hawai'i) have been conducting the widest, deepest survey ever to search out distant solar system objects. The team members started their survey using the Suprime-Cam imager at the Subaru Telescope several years ago. Their main goal is to find extreme Trans-Neptunian objects and they already have successfully found several. Now with the new Hyper Suprime-Cam on Subaru, they are able to cover a lot more of the sky than in the past in their searches for faint distant worlds.
The Story Behind the Discovery
In 2014, the team predicted the existence of a Super-Earth-mass planet orbiting beyond a few hundred astronomical units (AU) away from the Sun. Its gravitational influence appears to be pushing the extreme Trans-Neptunian objects into similar types of orbits. The team is continuing a survey looking for this massive distant planet, but need to find more of the smaller objects, which can then lead them to the bigger object.
In their paper, the team members describe the discovery of the two new objects, and how these two new objects have very distant perihelia but don't have extreme semi-major axes or eccentricities like the other high-perihelion extreme trans-Neptunian objects (TNOs) such as Sedna and 2012 VP113. In fact, these newly found worlds occupy a region of space just beyond what is known as the "Kuiper Belt edge," which lies about 50 AU from the Sun. Until this most recent discovery, only one object was known to have a low-to-moderate semi-major axis and a perihelion beyond this edge. The team discovered several more of these objects with high perihelion but moderately eccentric orbits. Their semi-major axes are in the range of about 60 to 100 AUs.
What was surprising is that these new objects are all near Neptune Mean Motion Resonances (that is, the locations of their orbits have specific period ratios with respect to that of Neptune). One of the new objects goes around the Sun once every time Neptune goes around 4 times, while the other new objects go around once every time Neptune goes around 3 times. The new objects also have significant inclinations in their orbits and thus are effected by the Kozai resonance, which was first shown to effect high inclination objects by Yoshihide Kozai in 1962. This finding suggests these worlds were captured into this rare orbital region through interactions with Neptune while that planet was migrating outwards in the solar system in the distant past. Neptune was born much closer to the Sun than its current position, and its migration outwards disturbed other, smaller objects into these distant orbits we see today. Thus, these objects give us insights into the movement of Neptune during the very early history of the solar system.
The discovery and characterization of these objects and their orbits are described in the "Beyond the Kuiper Belt edge: New high perihelion Trans-Neptunian Objects with moderate semimajor axes and eccentricities" by Scott S. Sheppard, Chadwick Trujillo, and David J. Tholen, published July 1, 2016 in Astrophysical Journal Letters (Volume 825).
http://www.naoj.org/Pressrelease/2016/07/20/index.html
Post by: Star One on 07/23/2016 01:51 pm
Post by: gospacex on 07/23/2016 04:30 pm
Post by: Mongo62 on 07/24/2016 05:19 pm
Mike Brown is already somewhat famous for his discoveries of Eris et al. If the planet will indeed be found, he will jump several rungs up on that ladder. If *he* will discover it, even more so.
I would say that he is already in the top tier of current solar system scientists, due to the numerous very large KBOs he has discovered. He is perhaps already the most famous solar system scientist, for the above reason and because of his successful campaign to demote Pluto to "Dwarf Planet" status. If "Planet 9" is found where he says it is, and especially if he leads the team that discovers it, he would be instantly catapulted into the ranks of the most famous solar system scientists of all time, in my opinion.
Post by: Star One on 07/24/2016 06:10 pm
Mike Brown is already somewhat famous for his discoveries of Eris et al. If the planet will indeed be found, he will jump several rungs up on that ladder. If *he* will discover it, even more so.
I would say that he is already in the top tier of current solar system scientists, due to the numerous very large KBOs he has discovered. He is perhaps already the most famous solar system scientist, for the above reason and because of his successful campaign to demote Pluto to "Dwarf Planet" status. If "Planet 9" is found where he says it is, and especially if he leads the team that discovers it, he would be instantly catapulted into the ranks of the most famous solar system scientists of all time, in my opinion.
Just a shame that he and Alan Stern, another scientist in the same area with high name recognition, have such an acrimonious relationship.
Post by: hop on 07/27/2016 07:12 am
Talking about the inclination being explained by planet nine, couldn't it also be explained by a large star passing close by earlier on the Solar System's existence?Yes, the Bailey et. al paper specifically mentions that there are several other viable explanations:
Quote
In principle, solar obliquity could have been excited through a temporary, extrinsic gravitational torque early in the solar system's lifetime. That is, an encounter with a passing star or molecular cloud could have tilted the disc or planets with respect to the sun (Heller 1993; Adams 2010). Alternatively, the sun may have had a primordial stellar companion, capable of early star-disc misalignment (Batygin 2012; Spalding & Batygin 2014; Lai 2014).That fact that the observed obliquity is within the range compatible with Planet 9 is nice, but it doesn't seem like very strong evidence.
Post by: Star One on 07/29/2016 07:03 pm
Quote
ESA’s Gaia satellite is scanning the entire sky, detecting objects as faint as 20.7 magnitudes, but Planet Nine is likely to be fainter. Even if Gaia did see it, it probably would not be immediately recognized as a Solar System object, as its apparent motion (about 0.2 arcsecs per hour) is also below the current threshold for the Gaia data processing to immediately recognize it as a moving solar system object, but large enough to cause the planet to appear as a new “star” at a different position of the sky during subsequent Gaia observations.
But Gaia might not need to see Planet Nine to find it.
Like all massive objects, an otherwise invisible planet hiding in the outer reaches of the Solar System deforms the fabric of space-time around it, and the light from distant stars passing by the planet would be ever-so-slightly deflected. Measuring this deflection as the hidden planet passes in front of distant stars could reveal its presence, even if the planet itself is too faint to be seen. (See the animation below.) This temporary deflection is the less-well-known astrometric aspect of a phenomenon called microlensing, which also causes a temporary brightening of background sources (not shown in the animation).
Quote
Unfortunately it appears from their study that such a detection by Gaia is also unlikely. The expected deviation of a star’s direction for a 10 Earth mass planet at about 700 AU is incredibly tiny: about 3 milliarcsecs if the star is within 10 milliarcsecs of the planet’s position. (One milliarcsec is 1/1000 of an arcsecond, which is 1/3600 of a degree: That’s about the apparent height of Neil Armstrong standing on the Moon as seen from Earth.) Not only that, given the apparent motion of Planet Nine on the sky, such microlensing events would have a very short duration. Essentially a star would have to be within about 10 milliarcsecs of Planet Nine at the moment that Gaia observes it.
Regardless of how Planet Nine is found (if it exists), measurements of microlensing events by the planet will likely be the only means to directly measure its mass, as any moons revolving around Planet Nine will be far too faint even for our most powerful telescopes. And while such microlensing events might be observable with other telescopes, only Gaia will be able to provide an accurate enough map of the sky to be able to accurately foresee such microlensing events.
https://www.linkedin.com/pulse/gaia-points-planet-nine-ronald-drimmel
Post by: Star One on 08/08/2016 09:04 pm
Quote
Mike Brown – @plutokiller
Just heard today that we're going to get to take a look at Orcus and Vanth with ALMA. Should be east to resolve them. Super fun.
https://mobile.twitter.com/plutokiller/status/762690032335331333
Post by: Ben the Space Brit on 08/09/2016 08:45 am
Post by: Star One on 08/11/2016 05:57 am
Mystery object in weird orbit beyond Neptune cannot be explained
Quote
"I hope everyone has buckled their seatbelts because the outer solar system just got a lot weirder.” That’s what Michele Bannister, an astronomer at Queens University, Belfast tweeted on Monday.
She was referring to the discovery of a TNO or trans-Neptunian object, something which sits beyond Neptune in the outer solar system. This one is 160,000 times fainter than Neptune, which means the icy world could be less than 200 kilometres in diameter. It’s currently above the plane of the solar system and with every passing day, it’s moving upwards – a fact that makes it an oddity.
The TNO orbits in a plane that’s tilted 110 degrees to the plane of the solar system. What’s more, it swings around the sun backwards unlike most of the other objects in the solar system. With this in mind, the team that discovered the TNO nicknamed it “Niku” after the Chinese adjective for rebellious.
https://www.newscientist.com/article/2100700-mystery-object-in-weird-orbit-beyond-neptune-cannot-be-explained/
Here's the relevant paper.
http://arxiv.org/abs/1608.01808
Post by: Ben the Space Brit on 08/11/2016 09:16 am
Post by: the_other_Doug on 08/11/2016 05:21 pm
I'm wondering whether at least some of these large TNOs in extreme orbits are large Oort Cloud objects knocked into closer orbits that just never get close enough to the sun to appear as comets. There may be thousands of these objcts.
Or they could be gas giant moons, or seeds of ice giants, ejected into odd high-inclination orbits during gravitic interactions with Big Planets on the Move around 4.5 GY ago...
Post by: Star One on 08/11/2016 06:44 pm
I'm wondering whether at least some of these large TNOs in extreme orbits are large Oort Cloud objects knocked into closer orbits that just never get close enough to the sun to appear as comets. There may be thousands of these objcts.
Or they could be gas giant moons, or seeds of ice giants, ejected into odd high-inclination orbits during gravitic interactions with Big Planets on the Move around 4.5 GY ago...
I imagine if planet nine exists that an ice giant could cause a lot of disruption on its way out to its present orbit if it was ejected from the inner solar system by the other giant planets.
Post by: the_other_Doug on 08/11/2016 06:54 pm
I'm wondering whether at least some of these large TNOs in extreme orbits are large Oort Cloud objects knocked into closer orbits that just never get close enough to the sun to appear as comets. There may be thousands of these objcts.
Or they could be gas giant moons, or seeds of ice giants, ejected into odd high-inclination orbits during gravitic interactions with Big Planets on the Move around 4.5 GY ago...
I imagine if planet nine exists that an ice giant could cause a lot of disruption on its way out to its present orbit if it was ejected from the inner solar system by the other giant planets.
Agreed, though the theories I've read (and I know there are many) in re outer planet movement is that the original order of the planets was Mercury, Venus, Earth, Mars, Neptune, Uranus, Jupiter and Saturn. As Jupiter began to move in due to friction with the remaining stellar accretion disk, it forced Uranus and Neptune out, and then it was pulled back out farther from the Sun via its orbital resonance with Saturn.
This all means that, if true, Jupiter formed a ways further out than it is now -- there had to be room for Uranus and Neptune to form outside the frost line if they were, indeed, ice giants at the time of their ejection out to the outer system.
I can imagine all of this movement over the first gigayear or so of the existence of the solar system could well have ejected some decent-sized worlds from solar influence entirely, and placed others in very odd, high-inclination orbits. It also wouldn't surprise me if ejection of worlds of various sizes could have been the disruption of the Oort cloud needed to trigger the Late Heavy Bombardment. No interloper stars or planets required... ;)
Post by: Star One on 08/11/2016 07:32 pm
I'm wondering whether at least some of these large TNOs in extreme orbits are large Oort Cloud objects knocked into closer orbits that just never get close enough to the sun to appear as comets. There may be thousands of these objcts.
Or they could be gas giant moons, or seeds of ice giants, ejected into odd high-inclination orbits during gravitic interactions with Big Planets on the Move around 4.5 GY ago...
I imagine if planet nine exists that an ice giant could cause a lot of disruption on its way out to its present orbit if it was ejected from the inner solar system by the other giant planets.
Agreed, though the theories I've read (and I know there are many) in re outer planet movement is that the original order of the planets was Mercury, Venus, Earth, Mars, Neptune, Uranus, Jupiter and Saturn. As Jupiter began to move in due to friction with the remaining stellar accretion disk, it forced Uranus and Neptune out, and then it was pulled back out farther from the Sun via its orbital resonance with Saturn.
This all means that, if true, Jupiter formed a ways further out than it is now -- there had to be room for Uranus and Neptune to form outside the frost line if they were, indeed, ice giants at the time of their ejection out to the outer system.
I can imagine all of this movement over the first gigayear or so of the existence of the solar system could well have ejected some decent-sized worlds from solar influence entirely, and placed others in very odd, high-inclination orbits. It also wouldn't surprise me if ejection of worlds of various sizes could have been the disruption of the Oort cloud needed to trigger the Late Heavy Bombardment. No interloper stars or planets required... ;)
Is there still a belief that there could be a Mars sized body within the Kuiper belt or has that theory been superseded by more data?
Post by: Star One on 08/13/2016 09:21 pm
http://www.npr.org/2016/08/13/489815076/astronomers-are-on-a-celestial-treasure-hunt-the-prize-planet-nine
Post by: Star One on 08/15/2016 04:59 pm
http://www.centauri-dreams.org/?p=36121
Post by: Star One on 08/26/2016 08:07 pm
Quote
Mike Brown
3h
Mike Brown @plutokiller
@Rickie99_ I predict within 3 years it'll be found.
https://mobile.twitter.com/plutokiller
What say people on this prediction?
Post by: CuddlyRocket on 08/27/2016 02:40 am
Mike Brown sticks his neck out as regards planet nine.QuoteMike Brown
3h
Mike Brown @plutokiller
@Rickie99_ I predict within 3 years it'll be found.
https://mobile.twitter.com/plutokiller
What say people on this prediction?
It will either be right or wrong! :)
Mike probably has a pretty good idea of what search capacity is going to be available and therefore how long a search capable of detecting P9 is going to take to cover the entire presumed area. And he may as well be optimistic on the likelihood of success!
Post by: Star One on 08/27/2016 07:20 am
I was just surprised to see him come out in public with such a specific figure. Since reading the recent book on the vexed history of the planet that never was Vulcan, I've wondered if planet nine could be yet another example of this, though our mathematical modeling has improved greatly and we now know about relativity I can't help wondering.Mike Brown sticks his neck out as regards planet nine.QuoteMike Brown
3h
Mike Brown @plutokiller
@Rickie99_ I predict within 3 years it'll be found.
https://mobile.twitter.com/plutokiller
What say people on this prediction?
It will either be right or wrong! :)
Mike probably has a pretty good idea of what search capacity is going to be available and therefore how long a search capable of detecting P9 is going to take to cover the entire presumed area. And he may as well be optimistic on the likelihood of success!
Post by: clongton on 08/27/2016 06:04 pm
Post by: gospacex on 08/27/2016 07:45 pm
Post by: hop on 08/27/2016 09:13 pm
I was just surprised to see him come out in public with such a specific figure. Since reading the recent book on the vexed history of the planet that never was Vulcan, I've wondered if planet nine could be yet another example of this, though our mathematical modeling has improved greatly and we now know about relativity I can't help wondering.FWIW, he has been saying he expects it to be found in the next few years pretty much from the start.
Post by: leovinus on 08/27/2016 09:28 pm
Other areas are excluded by previous searches.
In case anyone missed it, background info on the search and excluded area's at http://www.findplanetnine.com
Post by: clongton on 08/28/2016 01:08 am
Other areas are excluded by previous searches.
I know that. But in those areas, and in the current one, they are looking for an object that they have pretty much defined. My point is that if P9 ends up not conforming to that definition, they may never find it at all, having already missed it in those other areas, as well as the current - because - they didn't recognize it.
All I am saying is that it is counterproductive to be making such a prediction when everything they are doing is based on supposition; suppositions based, I agree, on observations but suppositions none-the-less.
Post by: Phil Stooke on 08/28/2016 01:34 am
Post by: hop on 08/28/2016 01:35 am
I know that. But in those areas, and in the current one, they are looking for an object that they have pretty much defined. My point is that if P9 ends up not conforming to that definition, they may never find it at all, having already missed it in those other areas, as well as the current - because - they didn't recognize it.Beyond a certain point if it doesn't conform to the definitions, it's not the "Planet 9" they predicted. The whole reason "Planet 9" is more interesting than many previous "something big could be out there" type predictions is that it's fairly specific.
Of course it's possible that Planet 9 was missed due to bad luck in one of the regions thought to be ruled out, but by definition the odds of that are low. If the surveys of the highest probability areas turn up empty and no other data invalidates the Planet 9 hypothesis, people will likely go back and look harder at the others. If all else fails, LSST will likely answer the question definitively.
Post by: zubenelgenubi on 08/28/2016 01:53 am
Mike Brown sticks his neck out as regards planet nine.QuoteMike Brown
3h
Mike Brown @plutokiller
@Rickie99_ I predict within 3 years it'll be found.
https://mobile.twitter.com/plutokiller
What say people on this prediction?
Reminds me of Babe Ruth...pointing to center field before hitting a home run over the Wrigley Field center field fence in the 1932 World Series.
Is it possible that Brown's team has already found a candidate object and are making follow-up observations?
Post by: jgoldader on 08/28/2016 03:07 am
Is it possible that Brown's team has already found a candidate object and are making follow-up observations?
Maybe.
You wouldn't need more than several days, a couple of weeks at most, I'd think, to get confirmation of a very distant object. Images a day or two apart easily show Kuiper Belt objects. For distant objects, most of the angular motion is due to parallax, because the velocity of Earth is so much greater than the velocity of an object on a distant heliocentric orbit. It only takes a few observations to get the heliocentric distance pretty accurately, as I recall. Multiple oppositions would be needed to accurately pin down the details of the orbit. More likely, he has just done the math for how big the survey area is, and the rate at which it's being covered.
However, if he does have a candidate, he'd have to have access to a couple years' data (which could include pre-discovery observations) to pin down the Longitude of the ascending node and argument of perihelion, and those are what would make the putative planet 9 stand out from other distant objects. I'm pretty sure Phil can correct me if I'm wrong. I did some work on this, but it was about... Goodness... 15 years ago (I'm getting old).
He'd be gambling on keeping something a few hundred AUs away under his hat for years, that nobody else would find it and announce it first. Big gamble, but go big or go home.
Post by: Bynaus on 08/28/2016 10:30 am
Post by: Star One on 08/28/2016 11:51 am
Hm, Mike Brown just told another user on twitter that P9 is "definetly real". That could - but perhaps shouldn't - be read as them having found a promising candidate. Or it could just be a figure of speech.
I would caution that you need to look at the context of the enquiry there, but who knows.
If he did find a strong candidate how many independent observing teams would have to verify it for him to announce its discovery, what I mean is there an agreed number of independent observations that you need for this?
Post by: jgoldader on 08/28/2016 01:39 pm
Hm, Mike Brown just told another user on twitter that P9 is "definetly real". That could - but perhaps shouldn't - be read as them having found a promising candidate. Or it could just be a figure of speech.
I would caution that you need to look at the context of the enquiry there, but who knows.
If he did find a strong candidate how many independent observing teams would have to verify it for him to announce its discovery, what I mean is there an agreed number of independent observations that you need for this?
Only one team is needed; Brown's bona fides are well-established. What's needed are several observations over a long enough arc of time to establish the orbital parameters. Like I said above, my guess is data spanning a few years. You can get distances with short arcs (few days) but Brown's looking for not just the semimajor axis, but the orientation of the orbit. In essence, you have to wait until the curvature of the orbit is measured well enough that you can accurately fit an ellipse to it.
Post by: Star One on 08/28/2016 01:45 pm
Hm, Mike Brown just told another user on twitter that P9 is "definetly real". That could - but perhaps shouldn't - be read as them having found a promising candidate. Or it could just be a figure of speech.
I would caution that you need to look at the context of the enquiry there, but who knows.
If he did find a strong candidate how many independent observing teams would have to verify it for him to announce its discovery, what I mean is there an agreed number of independent observations that you need for this?
Only one team is needed; Brown's bona fides are well-established. What's needed are several observations over a long enough arc of time to establish the orbital parameters. Like I said above, my guess is data spanning a few years. You can get distances with short arcs (few days) but Brown's looking for not just the semimajor axis, but the orientation of the orbit. In essence, you have to wait until the curvature of the orbit is measured well enough that you can accurately fit an ellipse to it.
Thank you. So he could have already found it but would need to observe it for a long space of time to confirm it. So much for my desire for a quick answer on this.
Post by: hop on 08/28/2016 08:36 pm
Hm, Mike Brown just told another user on twitter that P9 is "definetly real". That could - but perhaps shouldn't - be read as them having found a promising candidate. Or it could just be a figure of speech.As I mentioned before, he has been expressing confidence that it is real and will be found in the next several years ever since the announcement. I wouldn't read more into statements like this.
Post by: CuddlyRocket on 08/29/2016 05:49 am
If he did find a strong candidate how many independent observing teams would have to verify it for him to announce its discovery, what I mean is there an agreed number of independent observations that you need for this?
Only one team is needed; Brown's bona fides are well-established. What's needed are several observations over a long enough arc of time to establish the orbital parameters. Like I said above, my guess is data spanning a few years. You can get distances with short arcs (few days) but Brown's looking for not just the semimajor axis, but the orientation of the orbit. In essence, you have to wait until the curvature of the orbit is measured well enough that you can accurately fit an ellipse to it.
Thank you. So he could have already found it but would need to observe it for a long space of time to confirm it. So much for my desire for a quick answer on this.
He could announce it well before determining the orbital parameters. If it's anything like the size mooted, it will be obviously a planet. There are plenty of things you can establish about such an object - including whether it has a moon and therefore its mass - without knowing the orbit.
Post by: Alpha_Centauri on 08/29/2016 02:15 pm
https://carnegiescience.edu/news/hunt-ninth-planet-reveals-new-extremely-distant-solar-system-objects
Quote
Hunt for ninth planet reveals new extremely distant Solar System objects
...2013 FT28 shows similar clustering in some of these parameters (its semi-major axis, eccentricity, inclination, and argument of perihelion angle, for angle enthusiasts out there) but one of these parameters, an angle called the longitude of perihelion, is different from that of the other extreme objects, which makes that particular clustering trend less strong...
(https://carnegiescience.edu/sites/carnegiescience.edu/files/resize/imagepicker/74/NewExtremeObjectsPic4_0-964x709.jpg)
Edit: They added a new image with the third object. Looks reminiscent of the still unpublished one from Michelle Bannister's team.
(https://carnegiescience.edu/sites/carnegiescience.edu/files/imagepicker/74/20160829-newobjects-oort-6.jpg)
Post by: Star One on 08/29/2016 03:13 pm
Post by: CuddlyRocket on 08/29/2016 05:20 pm
So what does this mean for planet nine, does it mean it's less likely to exist or its location is different to that calculated by Mike Brown.
The article managed to avoid talking about Brown & Batygin entirely! We may have to wait for the paper to get the details, but what they do say is:
Quote
The orbit of an object is defined by six parameters. The clustering of several of these parameters is the main argument for a ninth planet to exist in the outer solar system. 2013 FT28 shows similar clustering in some of these parameters (its semi-major axis, eccentricity, inclination, and argument of perihelion angle, for angle enthusiasts out there) but one of these parameters, an angle called the longitude of perihelion, is different from that of the other extreme objects, which makes that particular clustering trend less strong.
It sounds like a case of six of one and half-a-dozen of the other!
Post by: Star One on 08/29/2016 05:48 pm
So what does this mean for planet nine, does it mean it's less likely to exist or its location is different to that calculated by Mike Brown.
The article managed to avoid talking about Brown & Batygin entirely! We may have to wait for the paper to get the details, but what they do say is:QuoteThe orbit of an object is defined by six parameters. The clustering of several of these parameters is the main argument for a ninth planet to exist in the outer solar system. 2013 FT28 shows similar clustering in some of these parameters (its semi-major axis, eccentricity, inclination, and argument of perihelion angle, for angle enthusiasts out there) but one of these parameters, an angle called the longitude of perihelion, is different from that of the other extreme objects, which makes that particular clustering trend less strong.
It sounds like a case of six of one and half-a-dozen of the other!
I noticed that too there was an avoidance of any reference to them which I found curious.
Post by: jgoldader on 08/29/2016 08:32 pm
I noticed that too there was an avoidance of any reference to them which I found curious.
Generally, scientists play nice together. Generally. It's not only Brown looking for "Planet 9," and whoever finds it first will be the ones remembered for it. That alone would be reason for a little competitiveness.
Post by: as58 on 08/29/2016 08:41 pm
I noticed that too there was an avoidance of any reference to them which I found curious.
Generally, scientists play nice together. Generally. It's not only Brown looking for "Planet 9," and whoever finds it first will be the ones remembered for it. That alone would be reason for a little competitiveness.
If Planet 9 (meaning the specific prediction of Batygin&Brown, not just any new planet) is found, I'm pretty sure that they (B&B) would be remembered at least as well as the actual discoverers. Just like with Neptune: Adams and Le Verrier are at least as famous as Galle.
Post by: Alpha_Centauri on 08/30/2016 08:58 am
So what does this mean for planet nine, does it mean it's less likely to exist or its location is different to that calculated by Mike Brown.
Something must be influencing the extreme TNOs, the question is its precise properties.
The press release doesn't give the ephemerides of these new objects so it's hard to tell. I haven't had time to check if they are on the circulars. It would appear however there could be a reason to explain why 2103 FT28 doesn't quite fit. The Space.com article explains their thinking;
http://www.space.com/33890-planet-nine-existence-evidence-grows.html
Quote
They also discovered two 125-mile-wide (200 km) objects, known as 2014 SR349 and 2013 FT28, that "cluster" in one of the key orbital parameters (known as argument of perihelion), furthering strengthening the case for Planet Nine's existence. (The objects' names reflect the years that they were first spotted in the survey; their discovery is being announced in the new study.)
"We have 15 or so of these extreme objects now, and all of them cluster in this argument of perihelion angle," Sheppard said.
Furthermore, he added, the five most distant of these 15 extreme objects share similarities in another orbital characteristic as well, one called longitude of perihelion. Significantly, the far-flung five are too distant to be realistically affected by any gravitational tugs from Neptune (whose influence could be the reason the other 10 objects' longitudes of perihelion don't line up).
So I'm guessing from this that 2013 FT28 has a relatively low perihelion.
Edit: It is up on MPC and yes 2013 FT28 has a relatively low perihelion of 43.6 AU so it isn't one of those furthest five. Seems like a borderline case so perhaps is close enough that Neptune will very gradually influence its orbit.
http://www.minorplanetcenter.net/mpec/K16/K16Q39.html
Post by: Mongo62 on 09/01/2016 12:39 am
We are conducting a wide and deep survey for extreme distant solar system objects. Our goal is to understand the high perihelion objects Sedna and 2012 VP113 and determine if an unknown massive planet exists in the outer solar system. The discovery of new extreme objects from our survey of some 1080 square degrees of sky to over 24th magnitude in the r-band are reported. Two of the new objects, 2014 SR349 and 2013 FT28, are extreme detached trans-Neptunian objects, which have semi-major axes greater than 150 AU and perihelia well beyond Neptune (q>40 AU). Both new objects have orbits with arguments of perihelia within the range of the clustering of this angle seen in the other known extreme objects. One of these objects, 2014 SR349, has a longitude of perihelion similar to the other extreme objects, but 2013 FT28, which may have more significant Neptune interactions, is about 180 degrees away or anti-aligned in its longitude of perihelion. We also discovered the first outer Oort cloud object with a perihelion beyond Neptune, 2014 FE72. We discuss these and other interesting objects discovered in our ongoing survey. All the high semi-major axis (a>150 AU) and high perihelion (q>35 AU) bodies follow the previously identified argument of perihelion clustering between 290 and 40 degrees as first reported and explained as being from an unknown massive planet by Trujillo and Sheppard (2014), which some have called Planet X or Planet 9. We also report objects with lower perihelia (q<35 AU) and a>200 AU show arguments of perihelia clustering at the opposite angles between 100 and 200 degrees. Finally, we find that the longitude of perihelion is significantly correlated with the argument of perihelion for all extreme objects.
Post by: Star One on 09/02/2016 03:44 pm
Quote
Mike Brown – @plutokiller
@TheEightPlanet putting finishing touches on it over next 2 weeks!
https://mobile.twitter.com/plutokiller/status/771508282674417664
Post by: K-P on 09/02/2016 06:52 pm
Dr. Mark Powell: "I'm not worried. It's just that I'm only familiar with nine planets."
Prot: "Well, actually, there are ten, but that doesn't matter. I'm not from your solar system. K-PAX is about 1,000 of your light-years away from here in what you would call your constellation Lyra."
Post by: Star One on 09/20/2016 08:27 pm
http://events.berkeley.edu/?event_ID=101152&date=2016-09-21&tab=lectures
Post by: Alpha_Centauri on 09/26/2016 03:23 pm
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The new season of Finding Planet Nine starts at the Subaru telescope TONIGHT.
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Also, FWIW, we think of this as a ~3 year Planet Nine finding campaign. So don't get your hopes up just yet....
Post by: Star One on 09/27/2016 09:56 pm
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Mike Brown @plutokiller 6h6 hours ago
We [me, @kbatygin and our fabulous Japanese collaborators] just finished our first night at Subaru looking for P9. Let's hope we get lucky.
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@elvan_yaln @kbatygin it'll take a while to process all of the tons of data we are collecting!
https://twitter.com/plutokiller/status/780838293797609472
Post by: Star One on 09/28/2016 08:33 pm
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Mike Brown – @plutokiller
@spaceVtime we've cut our search area by about a factor of 100 by calculations. Not so bad, I think.
https://mobile.twitter.com/plutokiller/status/781217066233716744
Post by: Star One on 09/29/2016 07:47 pm
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Mike Brown – @plutokiller
Night 3 of the Planet Nine search is officially underway. Also I am officially tired.
https://mobile.twitter.com/plutokiller/status/781439445643984896
Post by: Star One on 09/30/2016 07:48 pm
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Gus @gusparagus
@plutokiller how many nights on the subarau do you have approved and lined up right now?
Mike Brown – @plutokiller
@gusparagus 6. 3 more to go.
https://mobile.twitter.com/plutokiller/status/781612132005715968
Post by: gospacex on 09/30/2016 08:20 pm
Also, after collecting the data, Mike Brown will likely need some time to fix/adapt/improve his search software for processing specifically Subaru's data.
Post by: Star One on 10/01/2016 10:14 am
Post by: jgoldader on 10/01/2016 12:42 pm
Just out of interest is it possible that WISE could have missed any, for want of a better phrase, hyper cold large objects close or just within the limits of the solar system, what was its detection limits? Can we have high confidence that there aren't any closer brown dwarfs than the ones it detected as they are turning out to be very common objects?
Sure. The classic way to miss something is to have it moving through a crowded field so that the software misses it moving. Maybe it's "on top of" a star every time you look at it, for example, so the software doesn't notice a moving thing. There could be who-knows-what hiding out in Sagittarius.
If you are after flux limits, i'm pretty sure there was a paper a couple of years ago about looking for large planets in particular... Think it excluded gas/ice giants out to pretty great distances. But I'd have to go looking for it.
Edit- found mention of the paper with the money graphic
http://www.space.com/24989-planet-x-search-nasa-telescope.html
Post by: Alpha_Centauri on 10/01/2016 12:54 pm
http://iopscience.iop.org/article/10.1088/0004-637X/781/1/4/meta;jsessionid=14FEAC9286419A672B0DC9124758DAF2.c3.iopscience.cld.iop.org
Post by: Star One on 10/01/2016 02:11 pm
Post by: hop on 10/01/2016 07:06 pm
Thank you both. What do you think of the theory that brown dwarfs are so numerous that they make up a percentage of the hidden mass in the galaxy?If you mean a substantial fraction of dark matter, no, that (and pretty much every other MACHO flavor (https://en.wikipedia.org/wiki/Massive_compact_halo_object)) is ruled out by multiple independent observations. WISE may have missed a few nearby BDs, but it still put very strong constraints on the overall occurrence rate in our neighborhood. If BDs were a substantial fraction of the mass of the galaxy they would also show up in microlensing.
It should be noted that while WISE and other surveys *could* have missed something, the odds pretty low, likely lower than the "Planet" KBO alignment happening by chance. Both options are physically possible, but neither would be a good bet.
For more massive objects, there are other constraints too, e.g. something Jupiter mass or larger in the orbit suggested for Planet 9 would affect the orbits of the known planets.
Post by: Star One on 10/01/2016 07:31 pm
Thank you both. What do you think of the theory that brown dwarfs are so numerous that they make up a percentage of the hidden mass in the galaxy?If you mean a substantial fraction of dark matter, no, that (and pretty much every other MACHO flavor (https://en.wikipedia.org/wiki/Massive_compact_halo_object)) is ruled out by multiple independent observations. WISE may have missed a few nearby BDs, but it still put very strong constraints on the overall occurrence rate in our neighborhood. If BDs were a substantial fraction of the mass of the galaxy they would also show up in microlensing.
It should be noted that while WISE and other surveys *could* have missed something, the odds pretty low, likely lower than the "Planet" KBO alignment happening by chance. Both options are physically possible, but neither would be a good bet.
For more massive objects, there are other constraints too, e.g. something Jupiter mass or larger in the orbit suggested for Planet 9 would affect the orbits of the known planets.
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?
Post by: Star One on 10/01/2016 09:57 pm
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Safir @safirjamil
@plutokiller Software used for this analysis, same as before? Any major changes/calibration required specifically for P9?
Mike Brown – @plutokiller
@safirjamil same idea, all new software a decade later. in some ways P9 is **easier** because it is so far away and moving so slowly.
https://mobile.twitter.com/plutokiller/status/782005491387895808
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Mike Brown – @plutokiller
@omcintyre @kbatygin 6 nights. 3 good, 1 lost, 2 to go.
https://mobile.twitter.com/plutokiller/status/782005296621203456
Post by: jgoldader on 10/01/2016 10:48 pm
Thank you both. What do you think of the theory that brown dwarfs are so numerous that they make up a percentage of the hidden mass in the galaxy?If you mean a substantial fraction of dark matter, no, that (and pretty much every other MACHO flavor (https://en.wikipedia.org/wiki/Massive_compact_halo_object)) is ruled out by multiple independent observations. WISE may have missed a few nearby BDs, but it still put very strong constraints on the overall occurrence rate in our neighborhood. If BDs were a substantial fraction of the mass of the galaxy they would also show up in microlensing.
It should be noted that while WISE and other surveys *could* have missed something, the odds pretty low, likely lower than the "Planet" KBO alignment happening by chance. Both options are physically possible, but neither would be a good bet.
For more massive objects, there are other constraints too, e.g. something Jupiter mass or larger in the orbit suggested for Planet 9 would affect the orbits of the known planets.
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?
The stability of, e.g., Pluto's orbit places limits on close, massive things. I'd imagine the N-body code people have worked on the possibility of a brown dwarf or other massive thing coming near the Sun. But I didn't follow those things closely.
On brown dwarfs making up a significant part of dark matter, I think microlensing surveys more or less ruled that out. IIRC, the amount of "missing" baryons is not the problem it once was, with the X-ray observations of galaxy clusters finding enough hot gas to account for a big part of that. It's the non-baryons that are the problem now.
Post by: Star One on 10/02/2016 08:19 am
Thank you both. What do you think of the theory that brown dwarfs are so numerous that they make up a percentage of the hidden mass in the galaxy?If you mean a substantial fraction of dark matter, no, that (and pretty much every other MACHO flavor (https://en.wikipedia.org/wiki/Massive_compact_halo_object)) is ruled out by multiple independent observations. WISE may have missed a few nearby BDs, but it still put very strong constraints on the overall occurrence rate in our neighborhood. If BDs were a substantial fraction of the mass of the galaxy they would also show up in microlensing.
It should be noted that while WISE and other surveys *could* have missed something, the odds pretty low, likely lower than the "Planet" KBO alignment happening by chance. Both options are physically possible, but neither would be a good bet.
For more massive objects, there are other constraints too, e.g. something Jupiter mass or larger in the orbit suggested for Planet 9 would affect the orbits of the known planets.
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?
The stability of, e.g., Pluto's orbit places limits on close, massive things. I'd imagine the N-body code people have worked on the possibility of a brown dwarf or other massive thing coming near the Sun. But I didn't follow those things closely.
On brown dwarfs making up a significant part of dark matter, I think microlensing surveys more or less ruled that out. IIRC, the amount of "missing" baryons is not the problem it once was, with the X-ray observations of galaxy clusters finding enough hot gas to account for a big part of that. It's the non-baryons that are the problem now.
What about the DXL results finding an unexpected source of X Rays?
http://www.astrowatch.net/2016/09/nasa-funded-sounding-rocket-solves-one.html?m=1
Post by: jgoldader on 10/02/2016 12:02 pm
What about the DXL results finding an unexpected source of X Rays?
http://www.astrowatch.net/2016/09/nasa-funded-sounding-rocket-solves-one.html?m=1
High energy X-rays are made by hot things; brown dwarfs are cold.
Post by: Star One on 10/02/2016 01:58 pm
What about the DXL results finding an unexpected source of X Rays?
http://www.astrowatch.net/2016/09/nasa-funded-sounding-rocket-solves-one.html?m=1
High energy X-rays are made by hot things; brown dwarfs are cold.
Thanks. Was seeing some online claiming this was evidence of such an object and I couldn't see the connection myself.
Post by: jgoldader on 10/02/2016 02:44 pm
What about the DXL results finding an unexpected source of X Rays?
http://www.astrowatch.net/2016/09/nasa-funded-sounding-rocket-solves-one.html?m=1
High energy X-rays are made by hot things; brown dwarfs are cold.
Thanks. Was seeing some online claiming this was evidence of such an object and I couldn't see the connection myself.
Low-mass stars can make X-rays from flares and such (Prox Cen is a case in point). But because the flaring region is small, their X-ray luminosities are low and variable. Some brown dwarfs show H-alpha emission, but that's from auroras and such, I believe, which won't produce much in the way of X-rays. You typically need 10^6-10^7 K gas to make serious X-rays. A brown dwarf's main energy source would be gravitational contraction, and they just don't have that kind of energy lying around. And I thought much of the diffuse X-ray background had been resolved, so brown dwarfs are fighting for a percentage of whatever percentage hasn't been resolved.
Post by: Star One on 10/02/2016 03:52 pm
What about the DXL results finding an unexpected source of X Rays?
http://www.astrowatch.net/2016/09/nasa-funded-sounding-rocket-solves-one.html?m=1
High energy X-rays are made by hot things; brown dwarfs are cold.
Thanks. Was seeing some online claiming this was evidence of such an object and I couldn't see the connection myself.
Low-mass stars can make X-rays from flares and such (Prox Cen is a case in point). But because the flaring region is small, their X-ray luminosities are low and variable. Some brown dwarfs show H-alpha emission, but that's from auroras and such, I believe, which won't produce much in the way of X-rays. You typically need 10^6-10^7 K gas to make serious X-rays. A brown dwarf's main energy source would be gravitational contraction, and they just don't have that kind of energy lying around. And I thought much of the diffuse X-ray background had been resolved, so brown dwarfs are fighting for a percentage of whatever percentage hasn't been resolved.
I am not quite sure why some people are so keen on the idea of there being a brown dwarf in the solar system. I can only think it's a variant of the debunked idea that the Sun has a companion star called Nemesis.
Post by: hop on 10/02/2016 06:44 pm
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?I'm not sure what the limits are, I'd expect the WISE papers mentioned up thread to cite some of that work. However, even if a BD or super-Jupiter could be hiding at say 50,000 AU, that doesn't necessarily mean it would be a candidate for "Planet 9". To be "Planet 9", it needs to be in an orbit that produces the observed alignment of KBOs while not affecting the rest of the solar system in ways we would observe. I don't know if this is possible or not, but it's certainly not a given that it is.
Post by: Bynaus on 10/02/2016 06:57 pm
Post by: jgoldader on 10/02/2016 07:23 pm
Post by: Bob Shaw on 10/02/2016 09:47 pm
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?I'm not sure what the limits are, I'd expect the WISE papers mentioned up thread to cite some of that work. However, even if a BD or super-Jupiter could be hiding at say 50,000 AU, that doesn't necessarily mean it would be a candidate for "Planet 9". To be "Planet 9", it needs to be in an orbit that produces the observed alignment of KBOs while not affecting the rest of the solar system in ways we would observe. I don't know if this is possible or not, but it's certainly not a given that it is.
Nor would it have 'cleared' the orbit it inhabits, so even if it was twice as big as Jupiter it would not be a planet. This demonstrates once more how futile rules and regulations are in science.
Post by: gospacex on 10/02/2016 11:39 pm
Just out of interest is it possible that WISE could have missed any, for want of a better phrase, hyper cold large objects close or just within the limits of the solar system, what was its detection limits? Can we have high confidence that there aren't any closer brown dwarfs than the ones it detected as they are turning out to be very common objects?
Sure. The classic way to miss something is to have it moving through a crowded field so that the software misses it moving. Maybe it's "on top of" a star every time you look at it, for example, so the software doesn't notice a moving thing. There could be who-knows-what hiding out in Sagittarius.
If you are after flux limits, i'm pretty sure there was a paper a couple of years ago about looking for large planets in particular... Think it excluded gas/ice giants out to pretty great distances. But I'd have to go looking for it.
Edit- found mention of the paper with the money graphic
http://www.space.com/24989-planet-x-search-nasa-telescope.html
Kevin Luhman's discovery papers of brown dwarfs and even one "sub-brown dwarf" (in other words, super-Jupiter free-floating planet), are very interesting read. He really pulled everything possible to tease them out of WISE data - and aliasing to background stars was an issue for both his discoveries!
WISE 0855−0714 is a 3-10 Mjup object 7.2ly away. It's approx -30 Celsius.
WISE data almost excludes Jupiter-Saturn mass objects to very large distances (tens of thousands of AU); but smaller planets, ones which were not able to retain significant heat for 4 bn years and therefore ones which do not glow in IR, are not excluded.
Post by: CuddlyRocket on 10/03/2016 07:37 pm
As far as influencing objects in the Solar System would that still be the case if a brown dwarf was out at close to Oort Cloud distance?I'm not sure what the limits are, I'd expect the WISE papers mentioned up thread to cite some of that work. However, even if a BD or super-Jupiter could be hiding at say 50,000 AU, that doesn't necessarily mean it would be a candidate for "Planet 9". To be "Planet 9", it needs to be in an orbit that produces the observed alignment of KBOs while not affecting the rest of the solar system in ways we would observe. I don't know if this is possible or not, but it's certainly not a given that it is.
Nor would it have 'cleared' the orbit it inhabits, so even if it was twice as big as Jupiter it would not be a planet. This demonstrates once more how futile rules and regulations are in science.
If you use Jean-Luc Margot's planetary discriminant as a measure of ability to clear its orbit, Jupiter would have to be further than 64,000 AU before it ceased to be a planet.
Post by: Star One on 10/05/2016 07:18 pm
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Mike Brown
Mike Brown – @plutokiller
Tonight is the season finale of The Search for Planet Nine. Forecast is for 100% fog. Going home to make tacos for my family.
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@Jehochman we got good stuff. just not quite as much good stuff as we would have preferred.
https://mobile.twitter.com/plutokiller/status/783462067189579776
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Navin Weeraratne
19h
Navin Weeraratne @NavinScifi
@plutokiller Sorry to hear it's been a bust. When do you get another observation window?
Mike Brown
Mike Brown – @plutokiller
@NavinScifi next year :(
https://mobile.twitter.com/plutokiller/status/783467232722419714
There must be other teams looking for it?
Post by: Alpha_Centauri on 10/05/2016 09:00 pm
Post by: as58 on 10/06/2016 06:24 am
What's worse is usually you pay for the telescope time regardless of whether you are actually able to use it.
Is there a (large) facility where the users really have to pay themselves? I can't think of any. Subaru at least is fully funded by the Japanese government.
Post by: Star One on 10/06/2016 06:30 am
What's worse is usually you pay for the telescope time regardless of whether you are actually able to use it.
Is there a (large) facility where the users really have to pay themselves? I can't think of any. Subaru at least is fully funded by the Japanese government.
Would it be a case of him then making a proposal for time on it and then its management group saying yay or nay?
Or is it a more complex negotiation over the time they get allocated?
Post by: as58 on 10/06/2016 06:54 am
What's worse is usually you pay for the telescope time regardless of whether you are actually able to use it.
Is there a (large) facility where the users really have to pay themselves? I can't think of any. Subaru at least is fully funded by the Japanese government.
Would it be a case of him then making a proposal for time on it and then its management group saying yay or nay?
Or is it a more complex negotiation over the time they get allocated?
Usually people write proposals and then telescope Time Allocation Committee decides which ones are granted time. People on TAC are other astronomers, and generally telescope management has nothing to do with the decisions (though usually there's a ~10% fraction of time reserved as Directors Discretionary Time, which he/she can grant).
Who gets to propose is, of course, subject to negotiations, In case of Subaru I think most of the time is reserved for proposals with Japan-based (co-)PI, but some fraction is open for everyone to apply for. Other large telescopes are similar: time is mostly reserved for people from countries/institutions that fund the observatory, but there may also be open time. It's also often possible to find a colleague working in the 'right' country/institution who is willing to join the proposal as a co-PI to get around the limitations.
Post by: Star One on 10/06/2016 11:48 am
Post by: CuddlyRocket on 10/06/2016 05:08 pm
Who gets to propose is, of course, subject to negotiations, In case of Subaru I think most of the time is reserved for proposals with Japan-based (co-)PI, but some fraction is open for everyone to apply for. Other large telescopes are similar: time is mostly reserved for people from countries/institutions that fund the observatory, but there may also be open time. It's also often possible to find a colleague working in the 'right' country/institution who is willing to join the proposal as a co-PI to get around the limitations.
I believe there is an arrangement to swap observing time on the Subaru telescope with such time on the nearby Keck telescopes, which are Caltech instruments.
Post by: Star One on 10/07/2016 07:01 pm
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Mike Brown – @plutokiller
Hey, @kbatygin, I just finished the draft of the paper about some cool things that Planet Nine does. Check it out.
https://mobile.twitter.com/plutokiller/status/784184244083896320
He's sounding increasingly certain on this planet's existence, well he is to my ears.
Post by: Star One on 10/08/2016 08:56 pm
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Mike Brown – @plutokiller
@JenZomederis we're looking for a little dot moving across the sky. the analysis will take a few weeks, though, so give us a second here...
https://mobile.twitter.com/plutokiller/status/784542366678061056
Post by: CuddlyRocket on 10/09/2016 07:10 am
Is this mostly done by software these days, that he made reference to a few days earlier?
Such software is usually used to flag things up for human inspection. But, I imagine Mike Brown will look anyway - imagine if you missed it!
Geoff Marcy and his colleagues had the data to discover the first exoplanet, but relied on software to spot the periodicity. Unfortunately, it was set to ignore such a short period. If only they'd looked! (As they did shortly after the announcement, which is why they were able to confirm the discovery so quickly.)
Post by: clongton on 10/10/2016 11:59 pm
Post by: as58 on 10/11/2016 05:09 am
How far above and below solar horizontal does WISE search?
What is solar horizontal? Anyway, WISE survey was all-sky, so the answer is 90 degrees. See http://wise2.ipac.caltech.edu/docs/release/allsky/ for details.
Post by: gospacex on 10/11/2016 07:32 am
Is this mostly done by software these days, that he made reference to a few days earlier?
Such software is usually used to flag things up for human inspection. But, I imagine Mike Brown will look anyway - imagine if you missed it!
With the amount of data one gets from 25 mag deep imaging of tens of sq.deg. of the sky, it may be impractical to search all that data by human eye (would take some 10 years). Software is a great help. That's one of the reasons why asteroid discoveries have such dramatic increase in the last ~15 years.
Post by: Star One on 10/11/2016 08:58 am
Is this mostly done by software these days, that he made reference to a few days earlier?
Such software is usually used to flag things up for human inspection. But, I imagine Mike Brown will look anyway - imagine if you missed it!
With the amount of data one gets from 25 mag deep imaging of tens of sq.deg. of the sky, it may be impractical to search all that data by human eye (would take some 10 years). Software is a great help. That's one of the reasons why asteroid discoveries have such dramatic increase in the last ~15 years.
He mentioned on his Twitter feed that it would take several weeks. Would the software be customised by Mike Brown to specifically look for this object and if it is how would the parameters of that search be defined?
Post by: Star One on 10/11/2016 06:58 pm
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Dear all,
Surely this will hit the news later to day or tomorrow, but for fair warning 2014 UZ224 was announced only an hour ago as another distant TNO: This one blows the others out of the water, however. Its current distance is around 90.8 AU, second only to Eris's 96.2.
Furthermore, it's a definite member of the planet Nine group, and now the second largest known after Sedna, with an absolute magnitude of 3.5, furthermore making it the largest object discovered since 2013 FY27 in 2013! This asteroid sets many records, and hopefully will set many more as it travels closer to the Sun, and more importantly more recovery observations are made of it.
~Sam
https://groups.yahoo.com/neo/groups/mpml/conversations/messages/32366
More here.
http://www.npr.org/sections/thetwo-way/2016/10/11/497071139/a-friend-for-pluto-astronomers-find-new-dwarf-planet-in-our-solar-system
Post by: Star One on 10/12/2016 06:57 pm
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Mike Brown – @plutokiller
Last night ALMA made the first of our observations of Orcus and Vanth. Whoo hoooo! Dwarf planets FTW. Can't. wait. to. see. the. data.
https://mobile.twitter.com/plutokiller/status/786260056337633280
Post by: Star One on 10/15/2016 09:44 pm
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Mike Brown – @plutokiller
@DenzildeanNY I'd say that there's a good chance that it will be within 2 years. but might take longer.
https://mobile.twitter.com/plutokiller/status/787329992166219776
Post by: Alpha_Centauri on 10/18/2016 07:15 am
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New icy world with 20,000-year orbit could point to Planet Nine.
And new paper from Batygin and Brown.
https://arxiv.org/pdf/1610.04992.pdf
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GENERATION OF HIGHLY INCLINED TRANS-NEPTUNIAN OBJECTS BY PLANET NINE
Post by: Star One on 10/18/2016 10:31 am
Post by: jgoldader on 10/18/2016 11:47 am
It almost seems like a new distant object is discovered every few weeks at the moment.
Cameras with crazy big numbers of pixels and large fields of view are really efficient at strip-mining the sky. And with the discovery that many TNOs have high-inclination orbits, people are looking away from the ecliptic, finding things that old ecliptic-based surveys would not have seen (unless the object was crossing the ecliptic, of course).
Post by: Star One on 10/19/2016 06:51 pm
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2007 OR10 has stood out as the largest known trans-Neptunian object lacking a Moon. Most of the other big worlds have at least one: Pluto has Charon, Styx, Nix, Hydra and Kerberos; Eris has Dysnomia; Makemake has one discovered this year; Haumea has Hi'iaka and Namaka; Orcus has Vanth; Quaoar has Weywot. Now Sedna is the largest known object out there for which we have not -- yet -- discovered a moon. (Hopefully somebody will look!)
With a slow rotation period of 45 hours, astronomers have suspected for a while that 2007 OR10 had a moon, whose tidal interactions with the primary would have been responsible for slowing its rotation. Marton et al report the discovery in a set of older Hubble WFC3 images taken in September 2010. The new moon likely has a diameter of roughly 300 kilometers (roughly Hyperion-sized), as compared to 2007 OR10's roughly 1575 kilometers (roughly Rhea-sized). Although 300 kilometers is fully 20% of the diameter of the primary, Marton and coworkers state that, given a likely very dark surface, it doesn't contribute enough reflected light to 2007 OR10's signal to affect diameter estimates for the larger body. It is also too far from the parent body for the two to be in mutually synchronous rotation.
http://www.planetary.org/blogs/emily-lakdawalla/2016/10190940-dpsepsc-update-2007-or10.html
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Mike Brown – @plutokiller
Today's #DPSEPSC session was mostly a Planet Nine love fest. With a few thoughts from the Planet Nine haters, too. S'OK. Balance is good.
https://mobile.twitter.com/plutokiller/status/788585714472611840
Post by: Star One on 10/20/2016 06:39 am
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In their paper, "Corralling a Distant Planet with Extreme Resonant Kuiper Belt Objects," Malhotra and her co-authors, Kathryn Volk and Xianyu Wang, point out peculiarities of the orbits of the extreme KBOs that went unnoticed until now: they found that the orbital period ratios of these objects are close to ratios of small whole numbers. An example of this would be one KBO traveling around the Sun once while another takes twice as long, or three times as long, or four times as long etc., but not, say, 2.7 times as long.
According to the authors, such ratios could arise most naturally if the extreme KBOs' orbital periods are in small whole number ratios with a massive planet, which would help to stabilize the highly elliptical orbits of eKBOs.
http://m.phys.org/news/2016-10-evidence-ninth-planet-roaming-solar.html
Paper
https://arxiv.org/abs/1603.02196
We've heard this before but the paper has now been accepted for publication in an upcoming issue of the Astrophysical Journal.
Curious tilt of the sun traced to undiscovered planet
http://m.phys.org/news/2016-10-curious-tilt-sun-undiscovered-planet.html
Post by: Star One on 10/20/2016 07:09 pm
Darn Mike Brown reckons he will have found it by winter next year.
Can anyone expand on the idea for me that a planet no matter how large has so much torque because of its orbit that it can tilt the Sun.
Post by: denis on 10/20/2016 08:01 pm
Darn Mike Brown reckons he will have found it by winter next year.
Can anyone expand on the idea for me that a planet no matter how large has so much torque because of its orbit that it can tilt the Sun.
I'm not sure to really understand, but I think what they are saying is that Planet 9 moved the disk (i.e. all the other planets + everything else) by 6 degree compared to the where it should be (i.e. aligned with the Sun equator). So it moved all the planets' orbits with respect to the Sun, it didn't tilt the Sun.
Post by: Star One on 10/20/2016 08:07 pm
Darn Mike Brown reckons he will have found it by winter next year.
Can anyone expand on the idea for me that a planet no matter how large has so much torque because of its orbit that it can tilt the Sun.
I'm not sure to really understand, but I think what they are saying is that Planet 9 moved the disk (i.e. all the other planets + everything else) by 6 degree compared to the where it should be (i.e. aligned with the Sun equator). So it moved all the planets' orbits with respect to the Sun, it didn't tilt the Sun.
Thanks. Perhaps I am just misunderstanding badly but it really sounded like the meant it tilted the sun, but your explanation sounds far more likely.
Post by: CuddlyRocket on 10/20/2016 09:31 pm
Darn Mike Brown reckons he will have found it by winter next year.
Can anyone expand on the idea for me that a planet no matter how large has so much torque because of its orbit that it can tilt the Sun.
I'm not sure to really understand, but I think what they are saying is that Planet 9 moved the disk (i.e. all the other planets + everything else) by 6 degree compared to the where it should be (i.e. aligned with the Sun equator). So it moved all the planets' orbits with respect to the Sun, it didn't tilt the Sun.
Thanks. Perhaps I am just misunderstanding badly but it really sounded like the meant it tilted the sun, but your explanation sounds far more likely.
Actually, the Sun tilting rather than the disc is the most likely. Although the Sun holds 99.8% of the mass in the solar system it has only 1% of the total angular momentum (much less if Planet Nine is included), and it's changes in angular momentum that are being considered.
Post by: Star One on 10/21/2016 06:55 am
Darn Mike Brown reckons he will have found it by winter next year.
Can anyone expand on the idea for me that a planet no matter how large has so much torque because of its orbit that it can tilt the Sun.
I'm not sure to really understand, but I think what they are saying is that Planet 9 moved the disk (i.e. all the other planets + everything else) by 6 degree compared to the where it should be (i.e. aligned with the Sun equator). So it moved all the planets' orbits with respect to the Sun, it didn't tilt the Sun.
Thanks. Perhaps I am just misunderstanding badly but it really sounded like the meant it tilted the sun, but your explanation sounds far more likely.
Actually, the Sun tilting rather than the disc is the most likely. Although the Sun holds 99.8% of the mass in the solar system it has only 1% of the total angular momentum (much less if Planet Nine is included), and it's changes in angular momentum that are being considered.
Yes they remarked in the video that it could have as much angular momentum as the rest of the solar system combined.
The other thing I took from the video is that Mike Brown seems pretty certain that he is close to finding his quarry. First time that I've am aware of him shaving down the estimated time window for locating it.
Post by: jgoldader on 10/21/2016 02:30 pm
Post by: Alpha_Centauri on 10/21/2016 02:39 pm
https://arxiv.org/abs/1610.04251
Post by: Star One on 10/21/2016 03:14 pm
And there's by no means unanimity that the current evidence is consistent with there being a planet nine;
https://arxiv.org/abs/1610.04251
Mike Brown has mentioned differing opinions certainly in connection to his recent talk on the matter, but I would still hedge my money on him being right.
Quote
Mike Brown – @plutokiller
Today's #DPSEPSC session was mostly a Planet Nine love fest. With a few thoughts from the Planet Nine haters, too. S'OK. Balance is good.
https://mobile.twitter.com/plutokiller/status/788585714472611840
Post by: Star One on 10/23/2016 06:42 pm
Preliminary constraints on the location of Telisto/Planet Nine from planetary orbital dynamics
https://arxiv.org/abs/1512.05288
Post by: Orbiter on 10/23/2016 06:50 pm
Post by: Star One on 10/23/2016 07:07 pm
I've never heard of "Telisto", is that a Roman/Greek God or Goddess?
Bit too close to Telos for my liking.;)
https://en.m.wikipedia.org/wiki/Telos_(Doctor_Who) (https://en.m.wikipedia.org/wiki/Telos_(Doctor_Who))
Post by: Kryten on 10/23/2016 07:21 pm
I've never heard of "Telisto", is that a Roman/Greek God or Goddess?To quote another paper from the same author (https://arxiv.org/abs/1512.05288v2), it's;
Quote
'From τηλιστος ´ : farthest, most remote.'the paper makes it clear that this author came up with the name. As far as I can tell nobody else uses it, and there's nothing to indicate this man has any right to formally name the object or has made any attempt to do so.
Post by: Star One on 10/27/2016 08:43 pm
New distant objects? Unseen planets? The unexplored region of our solar system
http://www.astronomy.com/news/2016/10/the-outer-solar-system-keeps-getting-weirder
Post by: Star One on 10/28/2016 08:23 pm
Quote
Mike Brown – @plutokiller
New Planet Nine paper submitted! Coming to your inbox soon. If you're one of the scientists doing the peer review. Otherwise: patience.....
https://mobile.twitter.com/plutokiller/status/792077053281472512
Follow up answer.
Quote
Mike Brown – @plutokiller
@StartsWithABang oh hey it answers your argument of perihelion question. which is nice.
https://mobile.twitter.com/plutokiller/status/792084649333788673
Quote
Armando Lopez Jr @Vegasmarine223
@plutokiller we name planets offor of mythical gods but we can't name a super large planet with an irregular orbit off of the name Nibiru?
Mike Brown – @plutokiller
@Vegasmarine223 probably not. it would freak out too many people who would be convinced it was going to destroy the world.
https://mobile.twitter.com/plutokiller/status/791762463431589888
Post by: arnuz on 10/30/2016 03:58 pm
Post by: Star One on 11/04/2016 07:55 pm
Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images
Status Report From: arXiv.org e-Print archive
Posted: Wednesday, November 2, 2016
Aaron M. Meisner, Benjamin C. Bromley, Peter E. Nugent, David J. Schlegel, Scott J. Kenyon, Edward F. Schlafly, Kyle S. Dawson
(Submitted on 31 Oct 2016)
A distant, as yet unseen ninth planet has been invoked to explain various observations of the outer solar system. While such a 'Planet Nine', if it exists, is most likely to be discovered via reflected light in the optical, it may emit much more strongly at 3−5μm than simple blackbody predictions would suggest, depending on its atmospheric properties (Fortney et al. 2016). As a result, Planet Nine may be detectable at 3.4μm with WISE, but single exposures are too shallow except at relatively small distances (d9≲430 AU). We develop a method to search for Planet Nine far beyond the W1 single-exposure sensitivity, to distances as large as 800 AU, using inertial coadds of W1 exposures binned into ∼1 day intervals. We apply our methodology to ∼2000 square degrees of sky identified by Holman & Payne (2016) as a potentially likely Planet Nine location, based on the Fienga et al. (2016) Cassini ranging analysis. We do not detect a plausible Planet Nine candidate, but are able to derive a detailed completeness curve, ruling out its presence within the parameter space searched at W1<16.66 (90% completeness). Our method uses all publicly available W1 imaging, spanning 2010 January to 2015 December, and will become more sensitive with future NEOWISE-Reactivation releases of additional W1 exposures. We anticipate that our method will be applicable to the entire high Galactic latitude sky, and we will extend our search to that full footprint in the near future.
Comments: as submitted to AAS Journals on 4 October 2016
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:1611.00015 [astro-ph.EP] (or arXiv:1611.00015v1 [astro-ph.EP] for this version)
Submission history
From: Aaron Meisner
[v1] Mon, 31 Oct 2016 20:00:43 GMT (829kb)
https://arxiv.org/abs/1611.00015
// end //
http://spaceref.com/news/viewsr.html?pid=49537
Post by: Star One on 12/09/2016 07:11 pm
Quote
Mike Brown – @plutokiller
Home from Arizona with ideas two new ways to look for Planet Nine. I'm going to start on method #1 right this very second.....
https://mobile.twitter.com/plutokiller/status/807293681443053568
Anyone want to hazard a guess as to what these could be?
Post by: Star One on 12/13/2016 07:35 pm
Quote
Mike Brown @plutokiller
The ALMA radio telescope/interferometer detects the heat coming from Orcus ~4 billion miles away and separately from its moon Vanth. FTW. pic.twitter.com/5GHGFFTBR8 (http://pic.twitter.com/5GHGFFTBR8)
Post by: Star One on 12/22/2016 07:16 pm
https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1
Post by: Bynaus on 12/23/2016 04:11 pm
New preprint by Mullholland and Laughlin today. They build upon Malhotra's argument of possible mean motion resonances between P9 and the TNOs it shepherds, developing it into an elaborate attempt to better constrain possible sky positions. Interesting!
They suggest a = 654 AU, e = 0.4, i = 30 deg, m = 6 - 10 M_earth as the most likely values. That they find such a low mass raised my brow a bit - that would be far more interesting than "just" another Uranus/Neptune, because it would give us the opportunity to explore the most common type of exoplanet (according to Kepler, at least) from up-close!
Post by: jgoldader on 12/23/2016 06:16 pm
Mike Brown posted this picture of his workstation. What exactly are all these figures and the like and how do they relate to astronomy?
https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1
It looks like he's observing. Left two screens are camera control and maybe telescope status? Image on far left one could be location of the field in some big survey image or maybe from the auto guider. The big numbers on the right-hand screen appear to be: top row, UT time and date, second and third rows field center (maybe desired and actual?) in RA/DEC. Second line says epoch 2000.0 coordinates. Image on right panel might be from the guide camera, I'd guess.
Post by: Star One on 12/23/2016 06:50 pm
Mike Brown posted this picture of his workstation. What exactly are all these figures and the like and how do they relate to astronomy?
https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1
It looks like he's observing. Left two screens are camera control and maybe telescope status? Image on far left one could be location of the field in some big survey image or maybe from the auto guider. The big numbers on the right-hand screen appear to be: top row, UT time and date, second and third rows field center (maybe desired and actual?) in RA/DEC. Second line says epoch 2000.0 coordinates. Image on right panel might be from the guide camera, I'd guess.
Thank you very much.
How different is the life of the modern astronomer from his forbearers.
Post by: jgoldader on 12/23/2016 08:16 pm
How different is the life of the modern astronomer from his forbearers.
That's for sure! Gone are the days of Edwin Hubble in his jacket sitting in the cage atop the 100-inch.
I was an observer, and I guess I got out just in time. Sitting at a computer monitoring a telescope a continent or two away doesn't sound like nearly as much fun as freezing your *** off all night at 32F with near 50 mph winds at 14,000 feet, only to find in the morning that the truck you needed to get down the mountain had a flat tire. Nobody's going to be impressed by observing stories like, "So then I had to go move the laundry..."
Post by: Bynaus on 12/23/2016 08:19 pm
Quote
a continent or two away
Or in orbit, for that matter...
Post by: jgoldader on 12/24/2016 11:46 am
Quotea continent or two away
Or in orbit, for that matter...
With HST, there's no real-time interaction at all for observers (at least, there wasn't when I used it). When your proposal is granted time, you fill in a template with all the observation info (coordinates, instrument, mode/exposure/etc.), then you just wait, usually for months. You watch the schedule to see when your program is getting some of its orbits, then you wait for an e-mail saying you have data, then you get to work. Getting that e-mail was like Christmas morning, wondering if you'd been good or naughty, were you getting a puppy or a lump of coal?
Post by: as58 on 12/24/2016 01:26 pm
Quotea continent or two away
Or in orbit, for that matter...
With HST, there's no real-time interaction at all for observers (at least, there wasn't when I used it). When your proposal is granted time, you fill in a template with all the observation info (coordinates, instrument, mode/exposure/etc.), then you just wait, usually for months. You watch the schedule to see when your program is getting some of its orbits, then you wait for an e-mail saying you have data, then you get to work. Getting that e-mail was like Christmas morning, wondering if you'd been good or naughty, were you getting a puppy or a lump of coal?
Service mode operations are becoming the norm even for large ground-based observatories. When you have a billion dollar telescope, it's better (or at least more efficient) to have the observations done by people who know the ins and outs of the instrument.
Post by: Star One on 12/24/2016 02:15 pm
Quotea continent or two away
Or in orbit, for that matter...
With HST, there's no real-time interaction at all for observers (at least, there wasn't when I used it). When your proposal is granted time, you fill in a template with all the observation info (coordinates, instrument, mode/exposure/etc.), then you just wait, usually for months. You watch the schedule to see when your program is getting some of its orbits, then you wait for an e-mail saying you have data, then you get to work. Getting that e-mail was like Christmas morning, wondering if you'd been good or naughty, were you getting a puppy or a lump of coal?
Service mode operations are becoming the norm even for large ground-based observatories. When you have a billion dollar telescope, it's better (or at least more efficient) to have the observations done by people who know the ins and outs of the instrument.
When Mike Brown was talking about using the Subaru telescope to look for planet nine last year it sounded like he was actually out in Japan.
Post by: Bynaus on 12/24/2016 02:34 pm
Quotea continent or two away
Or in orbit, for that matter...
With HST, there's no real-time interaction at all for observers (at least, there wasn't when I used it). When your proposal is granted time, you fill in a template with all the observation info (coordinates, instrument, mode/exposure/etc.), then you just wait, usually for months. You watch the schedule to see when your program is getting some of its orbits, then you wait for an e-mail saying you have data, then you get to work. Getting that e-mail was like Christmas morning, wondering if you'd been good or naughty, were you getting a puppy or a lump of coal?
Service mode operations are becoming the norm even for large ground-based observatories. When you have a billion dollar telescope, it's better (or at least more efficient) to have the observations done by people who know the ins and outs of the instrument.
When Mike Brown was talking about using the Subaru telescope to look for planet nine last year it sounded like he was actually out in Japan.
He was - in Hawai'i (where the Subaru is located (http://subarutelescope.org/)).
Post by: david1971 on 12/24/2016 10:45 pm
Quotea continent or two away
Or in orbit, for that matter...
With HST, there's no real-time interaction at all for observers (at least, there wasn't when I used it). When your proposal is granted time, you fill in a template with all the observation info (coordinates, instrument, mode/exposure/etc.), then you just wait, usually for months. You watch the schedule to see when your program is getting some of its orbits, then you wait for an e-mail saying you have data, then you get to work. Getting that e-mail was like Christmas morning, wondering if you'd been good or naughty, were you getting a puppy or a lump of coal?
Service mode operations are becoming the norm even for large ground-based observatories. When you have a billion dollar telescope, it's better (or at least more efficient) to have the observations done by people who know the ins and outs of the instrument.
I flew two flights on SOFIA. There was an "outside" astronomer on one of the two flights, accounting for maybe 5% of the observing time. Once the telescope operators know where you want them to point the telescope, there isn't any more input needed from the person putting in the request. Why spend budget on getting to the physical location of the telescope?
Post by: llanitedave on 12/25/2016 03:15 pm
Mike Brown posted this picture of his workstation. What exactly are all these figures and the like and how do they relate to astronomy?
https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1 (https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1)
It looks like he's observing. Left two screens are camera control and maybe telescope status? Image on far left one could be location of the field in some big survey image or maybe from the auto guider. The big numbers on the right-hand screen appear to be: top row, UT time and date, second and third rows field center (maybe desired and actual?) in RA/DEC. Second line says epoch 2000.0 coordinates. Image on right panel might be from the guide camera, I'd guess.
Is that a Linux desktop shown on the big screens?
Post by: Star One on 12/26/2016 07:35 pm
https://arxiv.org/abs/1612.07774
New preprint by Mullholland and Laughlin today. They build upon Malhotra's argument of possible mean motion resonances between P9 and the TNOs it shepherds, developing it into an elaborate attempt to better constrain possible sky positions. Interesting!
They suggest a = 654 AU, e = 0.4, i = 30 deg, m = 6 - 10 M_earth as the most likely values. That they find such a low mass raised my brow a bit - that would be far more interesting than "just" another Uranus/Neptune, because it would give us the opportunity to explore the most common type of exoplanet (according to Kepler, at least) from up-close!
It would still be a gas/ice giant at that mass though?
Post by: hop on 12/26/2016 08:06 pm
It would still be a gas/ice giant at that mass though?Not necessarily. Super earths are generally taken as <= ~10 M_earth, and can be rocky, "water worlds" or have significant hydrogen envelope.
Post by: Star One on 12/26/2016 10:23 pm
It would still be a gas/ice giant at that mass though?Not necessarily. Super earths are generally taken as <= ~10 M_earth, and can be rocky, "water worlds" or have significant hydrogen envelope.
That far out I imagine any water will be frozen like rock. You make it sound like a giant Pluto.
Post by: hop on 12/27/2016 12:37 am
That far out I imagine any water will be frozen like rock. You make it sound like a giant Pluto.I wouldn't assume that. Something in this mass range would very likely have a > M_earth rocky core, which would produce a lot of radiogenic heat, as well as having significant heat leftover from formation.
There are serious suggestions that Pluto might still have an ocean, and we're talking about something 3000+ times more massive.
Post by: Robotbeat on 12/27/2016 02:37 pm
Post by: Bynaus on 12/28/2016 08:28 am
And yes, of course, such a world could have relatively large moons. If the characteristic 1:5000 ratio between planet and moon mass holds (as it does for all the gas giants), we would expect it to have moons with a total mass of about 10% of the Earth's moon (or about 8x Ceres). On the other hand, whatever process kicked planet 9 to where it orbits now might also have (partially?) stripped it of its original moons, leaving it only with a few irregular/captured ones on remote and inclined orbits.
Post by: clongton on 12/28/2016 01:09 pm
1. Something that massive likely has a great deal of internal heat, enough to sustain a substantial atmosphere.
2. Something that massive might have enough internal heat to maintain liquid water on its surface, even that far from the sun.
3. Something that massive and warm enough to have an atmosphere and liquid surface water might harbor life.
4. I understand the mechanics of planetary migration but coupling that with its likely highly eccentric orbit I am having a great deal of trouble accepting that something that massive would have migrated that far from the inner system into that eccentric an orbit. For me it is easier to accept that it is a captured rogue planet. That would explain everything.
We have learned more about solar system and planetary formation in the last 50 years than the last 5,000, but nothing we know today adequately explains why something that massive orbits the sun with such an eccentric orbit. I suspect that learning ever more about P9 will increase our knowledge about how systems form in a similar jump in knowledge.
Post by: Star One on 12/28/2016 02:05 pm
Post by: clongton on 12/28/2016 02:17 pm
If it is less massive would it take it beyond our current limits of detection?
Large or small, figuring out exactly where to look is the key to confirmable discovery.
Post by: Robotbeat on 12/28/2016 02:34 pm
Post by: Bynaus on 12/28/2016 02:57 pm
Some admittedly wild speculation:
1. Something that massive likely has a great deal of internal heat, enough to sustain a substantial atmosphere.
2. Something that massive might have enough internal heat to maintain liquid water on its surface, even that far from the sun.
3. Something that massive and warm enough to have an atmosphere and liquid surface water might harbor life.
4. I understand the mechanics of planetary migration but coupling that with its likely highly eccentric orbit I am having a great deal of trouble accepting that something that massive would have migrated that far from the inner system into that eccentric an orbit. For me it is easier to accept that it is a captured rogue planet. That would explain everything.
We have learned more about solar system and planetary formation in the last 50 years than the last 5,000, but nothing we know today adequately explains why something that massive orbits the sun with such an eccentric orbit. I suspect that learning ever more about P9 will increase our knowledge about how systems form in a similar jump in knowledge.
Regarding points 1-3, that is not crazy at all. Suggestions like these have long been made (e.g., by Stevenson, 1999 (http://adsabs.harvard.edu/abs/1999Natur.400...32S)), although usually they are made for objects smaller than P9. But it all depends on the H2 pressure - if it's around 200 bars, a liquid water solid surface is possible. But that would also mean a very small H2 fraction, which, as said above, seems unlikely.
Regarding 4., remember that on interstellar scales, P9 is still orbiting very deep in the gravity well of the sun. While it's not impossible that P9 is a captured rogue, it does not seem particularly likely either. You would need a plausible capture mechanism, e.g., the escape of a massive companion object, but that, too, seems unlikely (P9-sized objects do not have companions of comparable mass - this is why capture is more plausible for Triton: we know that many KBOs have companions of comparable mass).
On the other hand, we know from exoplanet systems that close encounters between gas giants are an important factor determining the fate and stability of planetary systems. Also, many things in the solar system make more sense if there once was a light-weight "fifth gas giant" which was later ejected (https://en.wikipedia.org/wiki/Five-planet_Nice_model) - to infinity, so everyone thought, but perhaps not entirely: just to a very eccentric orbit reaching from the giant planet region (5-30 AU) to a few 1000 AU or so. The presence of an extended, weak disk of gas might then well have circularized the orbit of such an object, fast enough so that it would not likely have another encounter with a gas giant before the disk dissipated completely, leaving P9 on an eccentric, but not too eccentric orbit in which it survived for 4.5 billion years. This is the default scenario Braun and Batygin are talking about in their publication from January 2016.
Post by: hop on 12/28/2016 05:50 pm
nothing we know today adequately explains why something that massive orbits the sun with such an eccentric orbit.There have been a number of papers on this, including
Interaction Cross Sections and Survival Rates for Proposed Solar System Member Planet Nine - Gongjie Li, Fred C. Adams (https://arxiv.org/abs/1602.08496)
Is there an exoplanet in the Solar System? - Alexander J. Mustill, Sean N. Raymond, Melvyn B. Davies (https://arxiv.org/abs/1603.07247)
The bottom line seems to be that both formation in the solar system and capture are viable, although the odds might not be quite as high as one would like.
Post by: CuddlyRocket on 12/29/2016 05:15 pm
It would still be a gas/ice giant at that mass though?Not necessarily. Super earths are generally taken as <= ~10 M_earth, and can be rocky, "water worlds" or have significant hydrogen envelope.
Whether Planet Nine is a super-Earth or a mini-Neptune depends on its constituents. If it's a rocky or rocky/ice body with a modest atmosphere, it will be the former; if it has a substantial gas envelope, it will be the latter.
A plot of radius against mass for known worlds shows a transition at about 2 Earth-masses, which is taken as indicating the accretion of substantial gas envelopes. Thus, as the mass of an object rises above 2 Earth-masses, the object is increasingly likely to be a mini-Neptune.
Post by: clongton on 12/29/2016 05:57 pm
Whether Planet Nine is a super-Earth or a mini-Neptune depends on its constituents. If it's a rocky or rocky/ice body with a modest atmosphere, it will be the former; if it has a substantial gas envelope, it will be the latter.It would still be a gas/ice giant at that mass though?Not necessarily. Super earths are generally taken as <= ~10 M_earth, and can be rocky, "water worlds" or have significant hydrogen envelope.
A plot of radius against mass for known worlds shows a transition at about 2 Earth-masses, which is taken as indicating the accretion of substantial gas envelopes. Thus, as the mass of an object rises above 2 Earth-masses, the object is increasingly likely to be a mini-Neptune
And yet a few exoplanets have been identified estimated at ~4-5 Earth Masses which are rocky worlds, one even in it's solar Goldilocks zone.
Post by: Bynaus on 12/29/2016 06:56 pm
Of course, these "Mega-Earths" (Kepler 10c is another one) are very rare and all have been found very close to their stars, so the chance of P9 being such a world is probably low. But it's not impossible.
Post by: clongton on 12/29/2016 07:29 pm
Rocky planets even get more massive than that. BD+20594b is a 16-Earth mass rocky planet... (density 7.8 g/cm3!) https://arxiv.org/abs/1601.07608
42 day orbit around its host star. Wow.
Post by: CuddlyRocket on 12/30/2016 04:51 pm
Whether Planet Nine is a super-Earth or a mini-Neptune depends on its constituents. If it's a rocky or rocky/ice body with a modest atmosphere, it will be the former; if it has a substantial gas envelope, it will be the latter.It would still be a gas/ice giant at that mass though?Not necessarily. Super earths are generally taken as <= ~10 M_earth, and can be rocky, "water worlds" or have significant hydrogen envelope.
A plot of radius against mass for known worlds shows a transition at about 2 Earth-masses, which is taken as indicating the accretion of substantial gas envelopes. Thus, as the mass of an object rises above 2 Earth-masses, the object is increasingly likely to be a mini-Neptune
And yet a few exoplanets have been identified estimated at ~4-5 Earth Masses which are rocky worlds, one even in it's solar Goldilocks zone.
Probability is not certainty. 'Increasingly likely to be' leaves open the possibility of not being!
Rocky planets even get more massive than that. BD+20594b is a 16-Earth mass rocky planet... (density 7.8 g/cm3!) https://arxiv.org/abs/1601.07608
Of course, these "Mega-Earths" (Kepler 10c is another one) are very rare and all have been found very close to their stars, so the chance of P9 being such a world is probably low. But it's not impossible.
As you say, not impossible. For very large rocky planets close to their host stars, the possibility arises of them having had a substantial gaseous envelope at some point that has been evaporated by the heat of the star and its stellar wind (though that no doubt takes some time!).
42 day orbit around its host star. Wow.
At 16.3 times the mass of the Earth, it lies between Uranus and Neptune in mass. The host star has 88% the luminosity of the Sun and the planet orbits at 0.24 AU, compared with 0.39 AU for Mercury - so it'll be hot! Perhaps it's the remnant of a hot Jupiter?
Post by: Bynaus on 12/30/2016 05:58 pm
(...) Perhaps it's the remnant of a hot Jupiter?
Virtually every article on that idea has come to the conclusion that it's unfeasable to fully "evaporate" a typical Hot Jupiter by irradiation during the life-time of a sun-like star, no matter the distance, even with the help of Roche-lobe overfilling. Their escape velocities are just too high. See, e.g., here: https://arxiv.org/abs/1401.2511
That said, there is a conspicious gap in the mass-vs.-irradiation diagram of close-in exoplanets, which has been interpreted as the region where some large Hot Neptunes might lose their atmospheres to irradiation and become rocky super-Earths instead. See this paper: http://www.nature.com/articles/ncomms11201
From the paper:
Quote
We do not find any exoplanets with radii between 2.2 and 3.8 Earth radii with incident flux above 650 times the incident flux on Earth. This gap in the population of exoplanets is explained by evaporation of volatile elements and thus supports the predictions.
So it seems you can "boil down" a sub-Neptune to Neptune-sized planet to a rocky core at very high stellar fluxes. How does the "Mega-Earth" above compare? At 0.24 AU distance and 88% of the sun's luminosity, the flux is about 15 times the flux on Earth, i.e., a far cry from the lower limit mentioned above. So I don't think it formed by evaporation, unless the planet migrated out again for some reason. If I had to guess, I would think that you can form these super-massive rocky planets by a collision of two Neptunes.
Post by: KelvinZero on 12/31/2016 02:26 am
42 day orbit around its host star. Wow.I might be jumping in out of context, but https://en.wikipedia.org/wiki/Proxima_Centauri_b has an orbital period of about 11 days and is in habitable zone. It is an interesting factoid anyway.
Post by: Bynaus on 12/31/2016 06:52 am
42 day orbit around its host star. Wow.I might be jumping in out of context, but https://en.wikipedia.org/wiki/Proxima_Centauri_b has an orbital period of about 11 days and is in habitable zone. It is an interesting factoid anyway.
And indeed, there are planets with even shorter periods. If you sort the list found on this site (http://www.exoplanet.eu/catalog/) by period, you will see that there are plenty of known exoplanets with orbital periods shorter than a single (Earth) day... And now let us return to that object with a period on the order of a few 10 000 years. :)
Post by: Star One on 01/02/2017 08:12 pm
https://mobile.twitter.com/plutokiller/status/815689415385198592
Post by: Lee Jay on 01/02/2017 08:19 pm
If and when he finds Planet Nine Mike Brown is going to set JWST on it.🙂
https://mobile.twitter.com/plutokiller/status/815689415385198592
It seems obvious to me, that if it's found, that every large instrument everywhere will be pointed at it within days or at most weeks of it being available to them in the night sky.
Post by: Star One on 01/03/2017 07:30 pm
Quote
@plutokiller
@FishEcon our predicted location on the sky is getting smaller and smaller. So if we don't find it soon we'll have some explaining to do....
Post by: Star One on 01/03/2017 07:30 pm
Quote
@plutokiller
@FishEcon our predicted location on the sky is getting smaller and smaller. So if we don't find it soon we'll have some explaining to do....
Post by: Ben the Space Brit on 01/04/2017 12:07 pm
Post by: Star One on 01/06/2017 06:41 pm
Quote
Adler Planetarium – @AdlerPlanet
Planet Nine is out there and we're getting closer to finding it. Tune in to @60Minutes featuring @plutokiller this Sunday at 6pm CST.
https://mobile.twitter.com/AdlerPlanet/status/817424829620113412
Post by: Bynaus on 01/12/2017 03:05 pm
http://phys.org/news/2017-01-simulations-planet-rogue.html
I am not so sure about the phrase "They presented evidence suggesting that if Planet Nine is out there, it is likely a rogue" in the article. Note that the abstract doesn't say so, only that they speculate about that possibility, after showing that Jupiter-sized Rogues can be constrained by the fact that our system is not disturbed. You can make P9 by capturing a Rogue, but whether that is more likely than a planet ejected from the inner solar system is a very different question.
Post by: TakeOff on 01/12/2017 05:30 pm
Post by: Space Ghost 1962 on 01/12/2017 05:36 pm
Planet Nein being rougePlanet No being red? ::) Didn't quite get that ...
Yes, anything big and heavy that far out has to be snagged from elsewhere in an interesting manner.
Post by: Star One on 01/12/2017 10:04 pm
Quote
7h
Matt Hewes @ghsdkgb
Doesn't this run counter to @plutokiller and @kbatygin 's initial estimates?
Simulations suggest Planet Nine may have been a roguephys.org
in reply to @ghsdkgb
Mike Brown @plutokiller
@ghsdkgb @kbatygin no, sounds about right.
Post by: Star One on 01/21/2017 09:47 pm
BEYOND PLUTO: THE HUNT FOR A MASSIVE PLANET X
http://europeanastrofest.com/beyond-pluto-the-hunt-for-a-massive-planet-x
Post by: Robotbeat on 01/23/2017 12:52 pm
Post by: meekGee on 01/23/2017 01:03 pm
I vote that if it's not found, they have to Make Pluto a Planet Again.Joking, right? It's the same researcher, but Pluto was demoted not because of P9, but because of the abundance of Plutoids in the Kuiper belt, some being equal or larger than Pluto.
P9 has to do only with their distribution..
Post by: Star One on 02/08/2017 07:46 pm
The search for the Ninth Planet
http://www.nbi.ku.dk/Besoeg_os/niels_bohr_lectures/2017/michael_e_brown/
Post by: as58 on 02/08/2017 08:08 pm
Post by: Star One on 02/08/2017 08:19 pm
I guess I'm getting old and grumpy, but I'm getting a bit weary of professor Brown's constant promotion of this hypothetical planet.
Oh for heavens sake give him a chance to find it, he said himself it might take a while. I'd suggest if you don't have anything constructive to post here maybe think twice in future before adding to the noise to signal ratio.
Post by: jg on 02/10/2017 07:08 pm
Mike Brown posted this picture of his workstation. What exactly are all these figures and the like and how do they relate to astronomy?
https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1 (https://mobile.twitter.com/plutokiller/status/811805159575658500/photo/1)
It looks like he's observing. Left two screens are camera control and maybe telescope status? Image on far left one could be location of the field in some big survey image or maybe from the auto guider. The big numbers on the right-hand screen appear to be: top row, UT time and date, second and third rows field center (maybe desired and actual?) in RA/DEC. Second line says epoch 2000.0 coordinates. Image on right panel might be from the guide camera, I'd guess.
Is that a Linux desktop shown on the big screens?
Looks like my favorite window system to me ;), as far as I can tell.... Probably a gnome desktop on Fedora or RHEL Linux, from what I can see from the iconography.
Post by: Star One on 02/17/2017 07:37 pm
Quote
3h
Meghan Kowalski @meghan1943
.@plutokiller I just got tix to your talk at the Smithsonian. What are the odds you'll have found Planet 9 before you arrive? #CuriousMinds
in reply to @meghan1943
Mike Brown @plutokiller
@meghan1943 pretty small, sadly. i think it's up in the fall sky, so we have to wait again.
Post by: Star One on 02/19/2017 09:17 am
http://mashable.com/2017/02/16/planet-nine-database-hunt
Post by: CuddlyRocket on 02/22/2017 02:31 am
Quote
The scientists have made the first spectroscopic observations of 2004 VN112 and 2013 RF98, both of them particularly interesting dynamically because their orbits are almost identical and the poles of the orbits are separated by a very small angle. This suggest a common origin, and their present-day orbits could be the result of a past interaction with the hypothetical Planet Nine. This study, recently published in Monthly Notices of the Royal Astronomical Society, suggests that this pair of ETNOs was a binary asteroid which separated after an encounter with a planet beyond the orbit of Pluto.
Quote
"We are proposing the possibility that they were previously a binary asteroid which became unbound during an encounter with a more massive object". To validate this hypothesis, the team performed thousands of numerical simulations to see how the poles of the orbits would separate as time went on. The results of these simulations suggest that a possible Planet Nine, with a mass of between 10 and 20 Earth masses orbiting the Sun at a distance between 300 and 600 AU could have deviated the pair 2004 VN112 - 2013 RF98 around 5 and 10 million years ago.
You can read the published paper here (https://academic.oup.com/mnrasl/article-lookup/doi/10.1093/mnrasl/slx003).
Post by: Star One on 03/05/2017 08:37 pm
When I am not searching for Planet Nine, I am teaching classes here at Caltech and throughout the world. The most fun class is my online class The Science of the Solar System. It is a 100% free online class hosted at Coursera for anyone in the world. I've been running the class for several years now, and I finally got around to updating the class to include a short lecture on Planet Nine. For fun I thought I would post a copy here just to keep everyone up to date on my favorite yet-unseen planet. It's about 20 minutes long, and extra amusing if you watch it at double speed. CLICK HERE to watch it on Youtube,
https://www.youtube.com/watch?v=v-ktWBtt7sc
Post by: Star One on 03/31/2017 08:16 am
https://mobile.twitter.com/plutokiller/status/847657846892146689
Post by: CuddlyRocket on 03/31/2017 12:00 pm
Interesting Twitter exchange about the hunt for planet nine.
https://mobile.twitter.com/plutokiller/status/847657846892146689
This was a citizen science project involving the viewers of the BBC Stargazing programme. You can find details about it at https://www.zooniverse.org/projects/skymap/planet-9.
Post by: Star One on 03/31/2017 12:06 pm
Interesting Twitter exchange about the hunt for planet nine.
https://mobile.twitter.com/plutokiller/status/847657846892146689
This was a citizen science project involving the viewers of the BBC Stargazing programme. You can find details about it at https://www.zooniverse.org/projects/skymap/planet-9.
Yep I was watching it here.
That particular hunt is closed for now but you can find one here.
https://www.zooniverse.org/projects/marckuchner/backyard-worlds-planet-9
Post by: Star One on 03/31/2017 11:34 pm
https://anu.prezly.com/four-unknown-objects-being-investigated-in-planet-9-search#
Post by: hop on 04/07/2017 06:15 pm
Quote
We report the discovery of the minor planet 2013 SY99, on an exceptionally distant, highly eccentric orbit. With a perihelion of 50.0 au, 2013 SY99's orbit has a semi-major axis of 730±40 au, the largest known for a high-perihelion trans-Neptunian object (TNO), well beyond those of (90377) Sedna and 2012 VP113. Yet, with an aphelion of 1420±90 au, 2013 SY99's orbit is interior to the region influenced by Galactic tides. Such TNOs are not thought to be produced in the current known planetary architecture of the Solar System, and they have informed the recent debate on the existence of a distant giant planet. Photometry from the Canada-France-Hawaii Telescope, Gemini North and Subaru indicate 2013 SY99 is ∼250 km in diameter and moderately red in colour, similar to other dynamically excited TNOs. Our dynamical simulations show that Neptune's weak influence during 2013 SY99's perihelia encounters drives diffusion in its semi-major axis of hundreds of astronomical units over 4 Gyr. The overall symmetry of random walks in semi-major axis allow diffusion to populate 2013 SY99's orbital parameter space from the 1000-2000 au inner fringe of the Oort cloud. Diffusion affects other known TNOs on orbits with perihelia of 45 to 49 au and semi-major axes beyond 250 au, providing a formation mechanism that implies an extended population, gently cycling into and returning from the inner fringe of the Oort cloud.
This one is not particularly positive for the Planet 9 hypothesis, although it doesn't rule it out either. The orbit would be unstable in the presence of Planet 9 unless in resonance, while without Planet 9 it is easy to produce and stable for the age of the solar system.
Post by: clongton on 04/09/2017 02:39 pm
OSSOS: V. Diffusion in the orbit of a high-perihelion distant Solar System object (https://arxiv.org/abs/1704.01952)QuoteWe report the discovery of the minor planet 2013 SY99, on an exceptionally distant, highly eccentric orbit. With a perihelion of 50.0 au, 2013 SY99's orbit has a semi-major axis of 730±40 au, the largest known for a high-perihelion trans-Neptunian object (TNO), well beyond those of (90377) Sedna and 2012 VP113. Yet, with an aphelion of 1420±90 au, 2013 SY99's orbit is interior to the region influenced by Galactic tides. Such TNOs are not thought to be produced in the current known planetary architecture of the Solar System, and they have informed the recent debate on the existence of a distant giant planet. Photometry from the Canada-France-Hawaii Telescope, Gemini North and Subaru indicate 2013 SY99 is ∼250 km in diameter and moderately red in colour, similar to other dynamically excited TNOs. Our dynamical simulations show that Neptune's weak influence during 2013 SY99's perihelia encounters drives diffusion in its semi-major axis of hundreds of astronomical units over 4 Gyr. The overall symmetry of random walks in semi-major axis allow diffusion to populate 2013 SY99's orbital parameter space from the 1000-2000 au inner fringe of the Oort cloud. Diffusion affects other known TNOs on orbits with perihelia of 45 to 49 au and semi-major axes beyond 250 au, providing a formation mechanism that implies an extended population, gently cycling into and returning from the inner fringe of the Oort cloud.
This one is not particularly positive for the Planet 9 hypothesis, although it doesn't rule it out either. The orbit would be unstable in the presence of Planet 9 unless in resonance, while without Planet 9 it is easy to produce and stable for the age of the solar system.
If one assumes it is in resonance, what does that say about the orbit of P9?
Post by: hop on 04/09/2017 07:48 pm
I one assumes it is in resonance, what does that say about the orbit of P9?The authors address this. Currently, the uncertainties in 2013 SY99's orbit are too large to really say anything about that case:
Quote
With appropriate external planet parameters, 2013 SY99 could be phase-protected in a mean-motion resonance (Batygin & Brown 2016; Malhotra et al. 2016), though this is not strictly required (Beust 2016). However, the present orbit of 2013 SY99 is too uncertain to discuss potential resonances with an external planet as in Malhotra et al. (2016); de la Fuente Marcos & de la Fuente Marcos (2016); Millholland & Laughlin (2017). Several years of further observation will be needed to constrain the semi-major axis to within the width of a potential resonance. There are substantial compounding uncertainties: the technically infinite number of potential resonances, the widths of resonances, the a uncertainties in the extreme TNO sample, and the exible range for the potential planet's semi-major axis. Any potential proximity even to low-order resonances is thus currently not significant.
Post by: Star One on 04/11/2017 08:16 pm
Quote
We measured the mean plane of the Kuiper belt as a function of semi-major axis. For the classical Kuiper belt as a whole (the non-resonant objects in the semi-major axis range 42-48 au), we find a mean plane of inclination im=1.8∘+0.7∘−0.4∘ and longitude of ascending node Ωm=77∘+18∘−14∘ (in the J2000 ecliptic-equinox coordinate system), in accord with theoretical expectations of the secular effects of the known planets. With finer semi-major axis bins, we see evidence for the expected warp of the mean plane near semi-major axes 40-42 au, owed to the ν18 nodal secular resonance. For the more distant Kuiper belt objects of semi-major axes in the range 50-80 au, the expected mean plane is close to the invariable plane of the solar system, but the measured mean plane deviates greatly from this: it has inclination im=9.1∘+6.6∘−3.8∘ and longitude of ascending node Ωm=227∘+18∘−44∘. We estimate this deviation from the expected mean plane to be statistically significant at the ∼97−99% confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in, low-mass unseen planet in the outer solar system is responsible for the warping.
https://arxiv.org/abs/1704.02444
Post by: Star One on 04/13/2017 11:00 pm
http://www.centauri-dreams.org/?p=37498
Post by: Star One on 04/18/2017 09:29 pm
Quote
The existence of significant anisotropies in the distributions of the directions of perihelia and orbital poles of the known extreme trans-Neptunian objects (ETNOs) has been used to claim that trans-Plutonian planets may exist. Among the known ETNOs, the pair (474640) 2004 VN112–2013 RF98 stands out. Their orbital poles and the directions of their perihelia and their velocities at perihelion/aphelion are separated by a few degrees, but orbital similarity does not necessarily imply common physical origin. In an attempt to unravel their physical nature, visible spectroscopy of both targets was obtained using the OSIRIS camera-spectrograph at the 10.4 m Gran Telescopio Canarias (GTC). From the spectral analysis, we find that 474640–2013 RF98 have similar spectral slopes (12 versus 15 per cent/0.1 μm), very different from Sedna's but compatible with those of (148209) 2000 CR105 and 2012 VP113. These five ETNOs belong to the group of seven linked to the Planet Nine hypothesis. A dynamical pathway consistent with these findings is dissociation of a binary asteroid during a close encounter with a planet and we confirm its plausibility using N-body simulations. We thus conclude that both the dynamical and spectroscopic properties of 474640–2013 RF98 favour a genetic link and their current orbits suggest that the pair was kicked by a perturber near aphelion.
https://academic.oup.com/mnrasl/article-lookup/doi/10.1093/mnrasl/slx003
Post by: Star One on 04/19/2017 11:28 am
Quote
23h
Neil Mandam @NeilMandam
@chrislintott will there be any updates on Sky at Night on Sunday re the search for planet 9 carried out on Stargazing live.
chrislintott @chrislintott
Replying to @NeilMandam
We're still where we were - @btucker22 and his team are looking at candidates. Sky at Night's already pretty packed.
1:22 pm · 18 Apr 2017
https://mobile.twitter.com/chrislintott/status/854309131422924800
Post by: Star One on 04/26/2017 07:24 pm
Quote
Researchers at Yale and elsewhere are drawing tantalizingly close to finding the location of the much-discussed Planet Nine, a planet thought to be orbiting in a remote part of our solar system.
On Saturday, April 29, at 2 p.m., California Institute of Technology astronomer Konstantin Batygin will give a free public talk, “Planet Nine From Outer Space,” at Davies Auditorium, 15 Prospect St.
YaleNews recently asked Yale astronomy professor Gregory Laughlin to talk about the upcoming lecture and about Yale’s research on Planet Nine.
Quote
Can you put your own research into context with other efforts that are ongoing?
Over the past year here at Yale, I’ve collaborated with astronomy graduate student Sarah Millholland in an effort to pin down Planet Nine’s sky position. Sarah has shown that the ratios of the orbital periods of the most distant Kuiper Belt objects are very close to integer ratios. This suggests that they are all in gravitational “resonance” with a more distant massive object, which we hypothesize is Planet Nine. Using a large suite of simulations, done over the course of two months with Yale’s High-Performance Computing resources, we think we’ve potentially isolated the patch of sky where it’s most likely to be.
What was your most recent finding?
If Planet Nine is out there, and of course that’s a big “if,” we think it’s located in the direction of the constellation Cetus. Sarah has made a nice interactive web demonstration that shows our model of its three-dimensional orbit.
http://news.yale.edu/2017/04/25/plan-planet-nine-lecture-saturday
Post by: Star One on 04/27/2017 05:01 pm
Quote
Still, not everyone is confident that Planet 9 will be found any time soon—or at all. A new study from a team of scientists at Queen’s University in Belfast asserts that the discovery of a minor planet called 2013 SY99—which is, at its closest, 50 AU—might dash our hopes of ever discovering the world. After running computer models of the solar system, the researchers concluded that if Planet 9 did exist, it likely would have altered SY99's orbit so much we would not be able to view it.
“Computer models do show that a Planet Nine would be an unfriendly neighbor to tiny worlds like SY99: its gravitational influence would starkly change its orbit – throwing it from the solar system entirely, or poking it into an orbit so highly inclined and distant that we wouldn’t be able to see it,” Michele Bannister, an author on the study, wrote in The Conversation. “SY99 would have to be one of an utterly vast throng of small worlds, continuously being sucked in and cast out by the planet.”
Bannister told Gizmodo that while her team’s findings don’t entirely disprove the idea of Planet 9, it calls the hypothetical world’s legitimacy into question.
“The planet 9 idea is a fun idea, it’s exciting, but it’s taking a bit of the oxygen at the moment,” she told Gizmodo. “We have this interesting problem…and the very shiny solution at the moment is called planet 9.”
Brown, on the other hand, read Bannister’s paper and said he and Batgyin had predicted that astronomers would discover objects just like SY99. He said that finding these objects actually reinforces the idea that Planet 9 is out there.
“The reason that we initially thought Planet 9 existed—there are a lot more reasons now—but the initial reasons were that the most distant Kuiper Belt objects were on these very eccentric orbits that are all pointing off in the same direction,” he told Gizmodo. “One of the things we said when we first announced this a year ago was that, ‘We predict that as you continue to find more and more distant Kuiper Belt objects, they too will be pushed off in this one direction. So we’ve been waiting for all these discoveries to come in—this one is exactly where it’s predicted.”
http://gizmodo.com/when-the-hell-will-we-find-planet-nine-1794681137
Post by: Star One on 05/09/2017 06:43 pm
https://www.forbes.com/sites/startswithabang/2017/05/09/the-scientific-truth-about-planet-nine-so-far/amp/
Post by: KelvinZero on 05/11/2017 12:03 pm
Scientists need your help to find the mysterious planet they suspect is lurking in our solar systemHave they considered walking backwards slowly? That always works in horror movies :)
http://mashable.com/2017/02/16/planet-nine-database-hunt
Post by: Star One on 05/15/2017 07:34 pm
Quote
Mike Brown @plutokiller
Replying to @DesslerAlex
Why the clustering of distant eccentric KBOs is not an observational bias (I'll show you Thursday!)
https://mobile.twitter.com/plutokiller/status/863907009258692608
Post by: Star One on 05/18/2017 07:05 pm
Quote
The combined power of three space observatories, including NASA’s Hubble Space Telescope, has helped astronomers uncover a moon orbiting the third largest dwarf planet, catalogued as 2007 OR10. The pair resides in the frigid outskirts of our solar system called the Kuiper Belt, a realm of icy debris left over from our solar system’s formation 4.6 billion years ago.
https://astronomynow.com/2017/05/18/hubble-spots-moon-around-third-largest-dwarf-planet/
Post by: Star One on 06/13/2017 08:21 pm
Quote
Mike Brown @plutokiller
tomorrow's paper will answer the age old question: does observational bias explain the clustering of distant KBOs? (spoiler: no)
https://mobile.twitter.com/plutokiller/status/874685485930602496
Post by: CuddlyRocket on 06/14/2017 04:50 am
Observational bias and the clustering of distant eccentric Kuiper belt objects (https://arxiv.org/pdf/1706.04175.pdf) (arXiv pdf)
Quote
(Abstract)
The hypothesis that a massive Planet Nine exists in the outer solar system on a distant eccentric orbit was inspired by observations showing that the objects with the most distant eccentric orbits in the Kuiper belt have orbits which are physically aligned, that is, they are clustered in longitude of perihelion and have similar orbital planes. Questions have remained, however, about the effects of observational bias on these observations, particularly on the longitudes of perihelion. Specifically, distant eccentric Kuiper belt objects tend to be faint and only observable near their perihelia, suggesting that the longitudes of perihelion of the known distant objects could be strongly biased by the limited number of locations in the sky where deep surveys have been carried out. We have developed a method to rigorously estimate the longitude of perihelion bias for Kuiper belt observations. We find that the probability that the 10 known Kuiper belt objects with semimajor axis beyond 230 AU are drawn from a population with uniform longitude of perihelion is 1.2%. Combined with the observation that the orbital poles of these object are also clustered, the overall probability of detecting these two independent clusterings in a randomly distributed sample is 0.025%. While observational bias is clearly present in these observations, it is unlikely to explain the observed alignment of the distant eccentric Kuiper belt objects.
Post by: Star One on 06/14/2017 08:19 am
Post by: Bynaus on 06/19/2017 09:22 am
https://arxiv.org/abs/1706.05348
Quote
OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects
The accumulating, but small, set of large semi-major axis trans-Neptunian objects (TNOs) shows an apparent clustering in the orientations of their orbits. This clustering must either be representative of the intrinsic distribution of these TNOs, or else arise as a result of observation biases and/or statistically expected variations for such a small set of detected objects. The clustered TNOs were detected across different and independent surveys, which has led to claims that the detections are therefore free of observational bias. This apparent clustering has led to the so-called "Planet 9" hypothesis that a super-Earth currently resides in the distant solar system and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a large program that ran on the Canada-France-Hawaii Telescope from 2013--2017, discovering more than 800 new TNOs. One of the primary design goals of OSSOS was the careful determination of observational biases that would manifest within the detected sample. We demonstrate the striking and non-intuitive biases that exist for the detection of TNOs with large semi-major axes. The eight large semi-major axis OSSOS detections are an independent dataset, of comparable size to the conglomerate samples used in previous studies. We conclude that the orbital distribution of the OSSOS sample is consistent with being detected from a uniform underlying angular distribution.
Post by: CuddlyRocket on 06/20/2017 05:41 am
Mike Brown @plutokiller 12h12 hours ago
Planet Nine fans! OK, so I'm on vacation but I haven't quite left for the airport yet, so a quick take on the new OSSOS paper.
Mike Brown @plutokiller
they demonstrate nicely that their survey is strongly biased. I would 100% agree; they look in limited places in the sky, that makes biases.
Mike Brown @plutokiller 12h12 hours ago
the take home message is that, sadly, OSSOS is not so good for understanding perihelion clustering. which makes sense.
Mike Brown @plutokiller 12h12 hours ago
they then make the leap to say that therefore it is probably true that NO survey is good for understanding perihelion clustering.
Mike Brown @plutokiller 12h12 hours ago
Luckily, just last week I posted that paper showing, in fact, that the combination of previous surveys does a great job w/perihelion cluster
Mike Brown @plutokiller 12h12 hours ago
so I'd say the OSSOS paper is relatively neutral for Planet Nine. Which is too bad. A different survey strategy could have been definite.
Mike Brown @plutokiller 12h12 hours ago
But no one was thinking about P9 back when their survey was designed.
Post by: Star One on 06/22/2017 08:34 pm
The curious case of the warped Kuiper Belt
https://astronomynow.com/2017/06/22/the-curious-case-of-the-warped-kuiper-belt/
Here's the original press release.
https://uanews.arizona.edu/story/ua-scientists-and-curious-case-warped-kuiper-belt
I suppose there's no chance New Horizons might spot this?
Post by: CuddlyRocket on 06/23/2017 02:22 am
Though whether this is another planet gets caught up in how we define planets now.
I will cross-post this to the Pluto-Planet debate discussion thread to deal with that aspect!
Quote
I suppose there's no chance New Horizons got spot this?
Very slim - space is big and Mars-sized objects are small!
Post by: kevin-rf on 06/24/2017 03:57 pm
I suppose there's no chance New Horizons might spot this?
More fun would be it having enough hydrazine for a flyby.
Post by: Star One on 06/24/2017 04:01 pm
Post by: ugordan on 06/24/2017 04:04 pm
Is there anyway from the way objects in the Kuiper belt are being twisted of trying to estimate where this body might be lurking?
Mike Brown already addressed that at one point, it's not possible because you need to have a long tracking arc to pick up perturbations to Keplerian orbits. Kuiper belt objects, by the very fact they're so far out, move in their orbits glacially slowly.
Interestingly enough, they did try using Cassini's precision measurements of Saturn's location over the last decade or so to see if any large object noticeably perturbed it. Inconclusive results IIRC.
Post by: Star One on 06/24/2017 04:08 pm
Is there anyway from the way objects in the Kuiper belt are being twisted of trying to estimate where this body might be lurking?
Mike Brown already addressed that at one point, it's not possible because you need to have a long tracking arc to pick up perturbations to Keplerian orbits. Kuiper belt objects, by the very fact they're so far out, move in their orbits glacially slowly.
Interestingly enough, they did try using Cassini's precision measurements of Saturn's location over the last decade or so to see if any large object noticeably perturbed it. Inconclusive results IIRC.
Wasn't that in reference to planet 9 rather than this object?
Post by: ugordan on 06/24/2017 04:15 pm
Post by: gospacex on 06/24/2017 04:45 pm
Interestingly enough, they did try using Cassini's precision measurements of Saturn's location over the last decade or so to see if any large object noticeably perturbed it. Inconclusive results IIRC.
Actually, analysis of Cassini data does have a hint at a perturbation is a specific direction. It's just quite close to noise floor, so they can't with confidence say that "something is definitely there". Also, the precision of that direction is quite low, so it's not really helping astronomers to limit the search area.
Post by: Star One on 06/24/2017 07:13 pm
Interestingly enough, they did try using Cassini's precision measurements of Saturn's location over the last decade or so to see if any large object noticeably perturbed it. Inconclusive results IIRC.
Actually, analysis of Cassini data does have a hint at a perturbation is a specific direction. It's just quite close to noise floor, so they can't with confidence say that "something is definitely there". Also, the precision of that direction is quite low, so it's not really helping astronomers to limit the search area.
Did it indicate this body might be the galactic plane?
Post by: gospacex on 06/24/2017 07:33 pm
Post by: Star One on 06/24/2017 07:37 pm
Galactic plane pulls all bodies in Solar System equally, Saturn and Earth including. Timing of Cassini signals wouldn't detect that.
Well the belief seems to be we haven't seen it when we should have because it's hidden against the galactic plane.
Post by: gospacex on 06/24/2017 07:45 pm
I think this is the paper:
https://www.aanda.org/articles/aa/pdf/2016/03/aa28227-16.pdf
https://arxiv.org/pdf/1602.06116.pdf
Post by: Star One on 06/24/2017 08:19 pm
I'll stop paraphrasing my vague recollections and give you the source.
I think this is the paper:
https://www.aanda.org/articles/aa/pdf/2016/03/aa28227-16.pdf
https://arxiv.org/pdf/1602.06116.pdf
Thank you for the links.
Post by: hop on 06/28/2017 06:15 am
Quote
Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for Np(q) perihelion passages with perihelion distance q<2.5 au. The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with Np(2.5)=500 and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution (with only a slight preference for prograde orbits). In our model, the HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing Np, but the existing observational data are not good enough to constrain Np from orbital fits. Np(2.5)>1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.
Mostly about comets, but some implications for P9
Post by: hop on 06/28/2017 05:40 pm
If you're talking about that recent OSSOS paper and Planet Nine, Mike Brown very effectively demolished it's conclusions on his Twitter feed before he went on break and said he would talk more about it in July.TBH, I generally find Browns comments even handed and insightful, but I thought this critique came off as dismissive and didn't address the core point of the paper.
OSSOS, with very well characterized biases, showed that their observations are consistent with no special alignment. Saying OSSOS is biased does not negate this. A biased sample with well characterized biases can still tell you a lot about the underlying population, especially one like OSSOS which has some sensitivity across a large part of the parameter space. The main "out" for P9 seems to be that the statistics are small, but then again the statistics justifying P9 are also pretty small too. One might also argue with the selection criteria.
The assertion that other surveys would not suffer similar biases also seems unjustified. Several of the biases identified in the paper (like those induced by the galactic bulge or the weather patterns at Mauna Kea) very likely apply to other surveys. Moreover, the paper shows pretty well that the biases are unintuitive and very difficult to quantify in cases where you can't use simulations like OSSOS did.
There's certainly still room for P9 (or something sort of like it) to be out there, but between OSSOS paper and the last one I linked, my personal betting odds have gone down a fair bit.
Post by: CuddlyRocket on 06/29/2017 03:41 am
Quote
However, Brown and Batygin argue that the OSSOS results can be interpreted as good, or at the very least inconclusive, for the Planet Nine hypothesis.
Post by: Star One on 06/29/2017 04:12 am
From the other thread:Well considering the guy was just going on holiday and he did say these were just his initial tweeted impressions, and that he would be dealing with it more when he returned in July it's not surprising that he may not have covered everything.If you're talking about that recent OSSOS paper and Planet Nine, Mike Brown very effectively demolished it's conclusions on his Twitter feed before he went on break and said he would talk more about it in July.TBH, I generally find Browns comments even handed and insightful, but I thought this critique came off as dismissive and didn't address the core point of the paper.
OSSOS, with very well characterized biases, showed that their observations are consistent with no special alignment. Saying OSSOS is biased does not negate this. A biased sample with well characterized biases can still tell you a lot about the underlying population, especially one like OSSOS which has some sensitivity across a large part of the parameter space. The main "out" for P9 seems to be that the statistics are small, but then again the statistics justifying P9 are also pretty small too. One might also argue with the selection criteria.
The assertion that other surveys would not suffer similar biases also seems unjustified. Several of the biases identified in the paper (like those induced by the galactic bulge or the weather patterns at Mauna Kea) very likely apply to other surveys. Moreover, the paper shows pretty well that the biases are unintuitive and very difficult to quantify in cases where you can't use simulations like OSSOS did.
There's certainly still room for P9 (or something sort of like it) to be out there, but between OSSOS paper and the last one I linked, my personal betting odds have gone down a fair bit.
Second have you read his own very recent paper on observational bias?
Here it is just in case you haven't.
https://arxiv.org/abs/1706.04175
I mention this because a lot of the reporting of the OSSOS paper completely fails to mention Mike Brown's paper and therefore in my view is inherently biased.
Post by: Star One on 06/29/2017 04:57 pm
https://mobile.twitter.com/kbatygin/status/877735541650804739
Post by: CuddlyRocket on 07/01/2017 03:14 am
Status Update (Part 1) (http://www.findplanetnine.com/2017/06/status-update-part-1.html?spref=tw)
Edit: Status Update (Part 2) added (http://www.findplanetnine.com/2017/07/status-update-part-2.html?spref=tw)
Post by: Star One on 07/03/2017 04:28 pm
Konstantin going into more detail on the findplanetnine.com blog:
Status Update (Part 1) (http://www.findplanetnine.com/2017/06/status-update-part-1.html?spref=tw)
Edit: Status Update (Part 2) added (http://www.findplanetnine.com/2017/07/status-update-part-2.html?spref=tw)
So it looks like it must be an ice giant if does exist to have that level of influence. I assume it's liable to be clone of Neptune just a bit smaller?
Also there was an interesting comment about this possible planet 10.
Quote
P10 would have to answer two questions: how does it coexist with Eris which orbits nearby, and how did it get where neither Neptune nor P9 could reach it?
Post by: Alpha_Centauri on 07/13/2017 12:06 am
https://www.eurekalert.org/pub_releases/2017-07/f-sf-nei071217.php
Quote
New evidence in support of the Planet Nine hypothesis
Last year, the existence of an unknown planet in our Solar system was announced. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they point out that there is something perturbing them: a planet located at a distance between 300 to 400 times the Earth-Sun separation.
Something interesting near the bottom,
Quote
De la Fuente Marcos explains that the hypothetical Planet Nine suggested in this study has nothing to do with another possible planet or planetoid situated much closer to us, and hinted at by other recent findings....
... "In any case, we are convinced that Volk and Malhotra's work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence"
Pre-print;
https://arxiv.org/pdf/1706.06981.pdf
Post by: as58 on 07/13/2017 07:13 am
Surprised this one has been missed as it's been on arxiv a month.
https://www.eurekalert.org/pub_releases/2017-07/f-sf-nei071217.phpQuoteNew evidence in support of the Planet Nine hypothesisPre-print;
Last year, the existence of an unknown planet in our Solar system was announced. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they point out that there is something perturbing them: a planet located at a distance between 300 to 400 times the Earth-Sun separation.
https://arxiv.org/pdf/1706.06981.pdf
Their hypothesised Planet Nine has a quite small semimajor axis of 300 to 400 AU, which is in some tension with Brown & Batygin predictions.
Post by: Bynaus on 07/13/2017 07:32 am
1) Planet Nine by Brown & Batygin, at 600-900 AU, eccentric, inclined orbit, sub-Neptune to Neptune mass
2) The object postulated by Volk & Malhotra (the "Mars-mass body at 60 AU" giving its name to another thread in this forum)
These two objects could easily co-exist (dynamically).
The new object suggested by the de la Fuente Marcos brothers seems to be a variant of P9, with a lower semi-major axis of 300 - 400 AU, but also with a mass in the sub-Neptune to Neptune range, but compared to the P9 hypothesis, which has several independent observations pointing in the same direction, their argument seems relatively weak. Note also that there have been other objects (like super-Earths at ~100-200 AU) suggested by other workers in the field. Some (or even most) of these objects might actually be mutually exclusive (perhaps unless they are in some kind of resonance). Its probably best to take all of these studies with a medium-sized grain of salt.
Post by: Star One on 07/13/2017 08:28 am
Surprised this one has been missed as it's been on arxiv a month.
https://www.eurekalert.org/pub_releases/2017-07/f-sf-nei071217.phpQuoteNew evidence in support of the Planet Nine hypothesis
Last year, the existence of an unknown planet in our Solar system was announced. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they point out that there is something perturbing them: a planet located at a distance between 300 to 400 times the Earth-Sun separation.
Something interesting near the bottom,QuoteDe la Fuente Marcos explains that the hypothetical Planet Nine suggested in this study has nothing to do with another possible planet or planetoid situated much closer to us, and hinted at by other recent findings....
... "In any case, we are convinced that Volk and Malhotra's work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence"
Pre-print;
https://arxiv.org/pdf/1706.06981.pdf
This article appeared in a British broadsheet newspaper over a year ago yet appears to refer to the work that produced the above paper. It puts forward the idea there might be planets nine, ten & eleven.
http://www.telegraph.co.uk/science/2016/06/13/solar-system-may-hold-ten-planets-or-more-say-scientists/
Post by: as58 on 07/13/2017 11:59 am
This article appeared in a British broadsheet newspaper over a year ago yet appears to refer to the work that produced the above paper. It puts forward the idea there might be planets nine, ten & eleven.
http://www.telegraph.co.uk/science/2016/06/13/solar-system-may-hold-ten-planets-or-more-say-scientists/
The Telegraph article seems to be mostly about an earlier paper http://adsabs.harvard.edu/abs/2016MNRAS.460L.123D (though this newest paper is of course closely related).
Post by: Alpha_Centauri on 07/13/2017 12:02 pm
Their hypothesised Planet Nine has a quite small semimajor axis of 300 to 400 AU, which is in some tension with Brown & Batygin predictions.
Yes that is interesting, though i'm not sure the semi-major axis is well constrained as it is built upon some assumptions.
One thing I'm not sure about is why they are assuming the node avoidance region they find has to be at 3:2 or 2:1. Why not 5:2? That would push the semi-major axis further out.
This article appeared in a British broadsheet newspaper over a year ago yet appears to refer to the work that produced the above paper. It puts forward the idea there might be planets nine, ten & eleven.
http://www.telegraph.co.uk/science/2016/06/13/solar-system-may-hold-ten-planets-or-more-say-scientists/
That is referring to an earlier study by the same researchers;
https://arxiv.org/pdf/1604.06241.pdf
Post by: as58 on 07/13/2017 12:15 pm
Yes, its getting a bit complicated here:
1) Planet Nine by Brown & Batygin, at 600-900 AU, eccentric, inclined orbit, sub-Neptune to Neptune mass
2) The object postulated by Volk & Malhotra (the "Mars-mass body at 60 AU" giving its name to another thread in this forum)
These two objects could easily co-exist (dynamically).
The new object suggested by the de la Fuente Marcos brothers seems to be a variant of P9, with a lower semi-major axis of 300 - 400 AU, but also with a mass in the sub-Neptune to Neptune range, but compared to the P9 hypothesis, which has several independent observations pointing in the same direction, their argument seems relatively weak. Note also that there have been other objects (like super-Earths at ~100-200 AU) suggested by other workers in the field. Some (or even most) of these objects might actually be mutually exclusive (perhaps unless they are in some kind of resonance). Its probably best to take all of these studies with a medium-sized grain of salt.
Yes, I doubt all these proposed objects are mutually compatible. Also, if there really were that many planets out there, it would be very strange that they _all_ have been able to escape detection by surveys.
Post by: MATTBLAK on 07/13/2017 12:29 pm
Post by: Star One on 07/13/2017 01:26 pm
Yes, its getting a bit complicated here:
1) Planet Nine by Brown & Batygin, at 600-900 AU, eccentric, inclined orbit, sub-Neptune to Neptune mass
2) The object postulated by Volk & Malhotra (the "Mars-mass body at 60 AU" giving its name to another thread in this forum)
These two objects could easily co-exist (dynamically).
The new object suggested by the de la Fuente Marcos brothers seems to be a variant of P9, with a lower semi-major axis of 300 - 400 AU, but also with a mass in the sub-Neptune to Neptune range, but compared to the P9 hypothesis, which has several independent observations pointing in the same direction, their argument seems relatively weak. Note also that there have been other objects (like super-Earths at ~100-200 AU) suggested by other workers in the field. Some (or even most) of these objects might actually be mutually exclusive (perhaps unless they are in some kind of resonance). Its probably best to take all of these studies with a medium-sized grain of salt.
Yes, I doubt all these proposed objects are mutually compatible. Also, if there really were that many planets out there, it would be very strange that they _all_ have been able to escape detection by surveys.
You well know that our observations of the outer solar system have actually been quite limited and we don't really know that much about it in comparison to the inner Solar System. The fact that there could be over 40,000 Kuiper Belt Objects discovered by LSST alone tells you all you need to know.
I don't even have faith now that we haven't overlooked something as massive as a Brown Dwarf comparatively close at hand, closer that is than Proxima Centauri considering how high their population in the galaxy seems to be. Their proposed population numbers seem at odds with the discovery numbers by WISE, which does make you question how effective WISE actually was in this area.
Post by: Bynaus on 07/13/2017 08:58 pm
I don't even have faith now that we haven't overlooked something as massive as a Brown Dwarf comparatively close at hand, closer that is than Proxima Centauri considering how high their population in the galaxy seems to be. Their proposed population numbers seem at odds with the discovery numbers by WISE, which does make you question how effective WISE actually was in this area.
WISE has discovered plenty of near-by, cool dwarfs (brown & red), but indeed nothing closer than Proxima. Even if the WISE observations were incomplete, it would seem strange that it would have overlooked primarily the closest (and thus brightest) objects from these classes.
What makes you think the WISE result is at odds with proposed population numbers? And even if there is a statistically significant discrepancy, shouldn't the actual observation (or non-observation, in that case) be given priority above model-dependent population numbers?
Post by: Star One on 07/13/2017 09:00 pm
I don't even have faith now that we haven't overlooked something as massive as a Brown Dwarf comparatively close at hand, closer that is than Proxima Centauri considering how high their population in the galaxy seems to be. Their proposed population numbers seem at odds with the discovery numbers by WISE, which does make you question how effective WISE actually was in this area.
WISE has discovered plenty of near-by, cool dwarfs (brown & red), but indeed nothing closer than Proxima. Even if the WISE observations were incomplete, it would seem strange that it would have overlooked primarily the closest (and thus brightest) objects from these classes.
What makes you think the WISE result is at odds with proposed population numbers? And even if there is a statistically significant discrepancy, shouldn't the actual observation (or non-observation, in that case) be given priority above model-dependent population numbers?
Well does a possible population of 100 billion Brown Dwarfs in the Milky Way seem in line with the WISE observations to you?
Post by: Bynaus on 07/13/2017 09:45 pm
I don't even have faith now that we haven't overlooked something as massive as a Brown Dwarf comparatively close at hand, closer that is than Proxima Centauri considering how high their population in the galaxy seems to be. Their proposed population numbers seem at odds with the discovery numbers by WISE, which does make you question how effective WISE actually was in this area.
WISE has discovered plenty of near-by, cool dwarfs (brown & red), but indeed nothing closer than Proxima. Even if the WISE observations were incomplete, it would seem strange that it would have overlooked primarily the closest (and thus brightest) objects from these classes.
What makes you think the WISE result is at odds with proposed population numbers? And even if there is a statistically significant discrepancy, shouldn't the actual observation (or non-observation, in that case) be given priority above model-dependent population numbers?
Well does a possible population of 100 billion Brown Dwarfs in the Milky Way seem in line with the WISE observations to you?
I guess you are referring to that recent suggestion that the Milky Way might contain between 25 and 100 billion Brown Dwarfs (BDs) (https://arxiv.org/abs/1707.00277). Their suggested star / BD ratio is in the region of 2-5. This range is compatible with the WISE results:
If we look at the 10 nearest star systems (https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs) (plus the sun), there are 13 stars vs. 3 BDs (all discovered by WISE), so the ratio is within the range given above. If we look at the 20 closest systems, there are 28 stars and 6 BDs (3 of which have been discovered by WISE), again a ratio <5. If we go to the 30 closest systems, there are 37 stars and 8 BDs (4 from WISE), again a ratio <5. It is well possible that WISE overlooked a few objects (especially some old, dark BDs), which might drive the true star / BD ratio in the solar neighborhood closer to the center of the estimated range above. On this page (https://www.nasa.gov/mission_pages/WISE/news/wise20120608.html), a similar conclusion was reached: WISE results suggest about six stars per BD. While this is lower than earlier figures (which had suggested a star / BD ratio of up to one), it is roughly in agreement with the suggested 25-100 billion BDs in the Milky Way galaxy.
Post by: Star One on 07/13/2017 09:47 pm
I don't even have faith now that we haven't overlooked something as massive as a Brown Dwarf comparatively close at hand, closer that is than Proxima Centauri considering how high their population in the galaxy seems to be. Their proposed population numbers seem at odds with the discovery numbers by WISE, which does make you question how effective WISE actually was in this area.
WISE has discovered plenty of near-by, cool dwarfs (brown & red), but indeed nothing closer than Proxima. Even if the WISE observations were incomplete, it would seem strange that it would have overlooked primarily the closest (and thus brightest) objects from these classes.
What makes you think the WISE result is at odds with proposed population numbers? And even if there is a statistically significant discrepancy, shouldn't the actual observation (or non-observation, in that case) be given priority above model-dependent population numbers?
Well does a possible population of 100 billion Brown Dwarfs in the Milky Way seem in line with the WISE observations to you?
I guess you are referring to that recent suggestion that the Milky Way might contain between 25 and 100 billion Brown Dwarfs (BDs) (https://arxiv.org/abs/1707.00277). Their suggested star / BD ratio is in the region of 2-5. This range is compatible with the WISE results:
If we look at the 10 nearest star systems (https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs) (plus the sun), there are 13 stars vs. 3 BDs (all discovered by WISE), so the ratio is within the range given above. If we look at the 20 closest systems, there are 28 stars and 6 BDs (3 of which have been discovered by WISE), again a ratio <5. If we go to the 30 closest systems, there are 37 stars and 8 BDs (4 from WISE), again a ratio <5. It is well possible that WISE overlooked a few objects (especially some old, dark BDs), which might drive the true star / BD ratio in the solar neighborhood closer to the center of the estimated range above. On this page (https://www.nasa.gov/mission_pages/WISE/news/wise20120608.html), a similar conclusion was reached: WISE results suggest about six stars per BD. While this is lower than earlier figures (which had suggested a star / BD ratio of up to one), it is roughly in agreement with the suggested 25-100 billion BDs in the Milky Way galaxy.
Thank you for that. I had read some commentary suggesting the two weren't compatible.
But I should add a caveat here that part of the argument was that BDs may come in much smaller sizes than previously thought and that this may cause an issue with the WISE results.
Post by: Star One on 07/15/2017 07:37 pm
Quote
It seems that the outer Solar System is getting more crowded with every passing year. And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t. If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!
https://www.universetoday.com/136450/evidence-mounts-existence-planet-nine/amp/
Post by: Dao Angkan on 07/15/2017 08:06 pm
Evidence Mounts for the Existence of Planet NineQuoteIt seems that the outer Solar System is getting more crowded with every passing year. And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t. If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!
https://www.universetoday.com/136450/evidence-mounts-existence-planet-nine/amp/
If it's that crowded, then how come no Kuiper Belt dwarf planets have been discovered for years, even though many more people have been searching for them since the initial wave were discovered? Anyway, it's just a debate about semantics, which exoplanet discoveries are making largely redundant. What's the point of a definition of a planet which only applies to our own system and not the possibly infinite amount of other systems, or indeed planemos not attached to a system?
Post by: Dao Angkan on 07/15/2017 08:18 pm
Personally, I don't care what Pluto and other KBOs are defined as, just that it should apply to all planemos, not just the ones in our own solar system.
As for planet 9/10/X ... it's possible, but we've seen so many different theories on this for so many years, that I take it with a pinch of salt until we see actual evidence.
Edit: This was a response to a post which must have been deleted before I replied.
Post by: CuddlyRocket on 07/16/2017 12:31 am
Evidence Mounts for the Existence of Planet NineQuoteIt seems that the outer Solar System is getting more crowded with every passing year. And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t. If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!
https://www.universetoday.com/136450/evidence-mounts-existence-planet-nine/amp/
I think that depends on how big they are and where they are. If they're the 'right' side of the line, there'll be hardly a murmur! Which line? Well, Margot's planetary discriminant seems to be favourite at present.
Anyway, it's just a debate about semantics, which exoplanet discoveries are making largely redundant.
It's partly about semantics, but there is a difference between gravitationally dominant bodies in a system and the rest, which exoplanet discoveries doesn't affect.
Quote
What's the point of a definition of a planet which only applies to our own system and not the possibly infinite amount of other systems, or indeed planemos not attached to a system?
I agree that the definition should cover other stellar systems, but it need not cover free-floating planemos.
Post by: Star One on 08/01/2017 07:32 pm
Is There a Giant Planet Lurking Beyond Pluto?
Quote
Huge telescopes on Earth have been scanning the skies for months now. Brown and Batygin have been observing on Japan’s Subaru telescope on Mauna Kea—as have veteran minor-planet hunters Chad Trujillo of Northern Arizona University and Scott Sheppard of the Carnegie Institution for Science—to exploit that observatory’s giant mirror (8.2 meters across) and its 3-metric-ton, 870-megapixel camera. Meanwhile other astronomers, both professional and amateur, are digging through archives of images in hopes of finding this needle in a hayfield.
Any of them could get lucky. But the smart money is on software, either to deliver the quarry or reveal it to be an illusion. Simulations running on supercomputers and in the cloud are modeling billions of years of celestial mechanics to pin down Planet Nine’s likeliest path. Engineers at the Jet Propulsion Laboratory, in Pasadena, have been analyzing telemetry from the Cassini spacecraft for clues to the current position of the putative planet within its enormous orbit. And an ambitious pair of graduate students is preparing to deploy machine-learning software on a petaflop-scale Cray XC40 supercomputer. Their strategy aims to cleverly combine multiple images in which Planet Nine is hidden within the noise to yield one image in which it shines unmistakably.
Although many astronomers share Brown’s enthusiasm at the prospect of finding a planet bigger than Earth for the first time in 170 years, some worry about being fooled by subtle biases or simple coincidences in the data. “My instinct—completely unjustifiable—is that there’s a two-thirds chance it’s really there,” Laughlin says.
Quote
Those odds are now steeper because the list of relevant oddball planetoids known to haunt the outer reaches of our solar system has lengthened: from 6 in early 2016 to 20, Trujillo says. About a dozen of these objects orbit within the same vertically tilted plane as Planet Nine does, but they sweep away from the sun in the opposite direction of the planet; a couple of others are aligned with the planet. Then there are a handful of planetoids circling crazily at almost right angles to everything else in the solar system; a couple of these even travel backward around the sun. “They all fit in beautifully,” Batygin says. “As time has gone on, the evidence has only increased.”
Quote
With the idea of a big but undiscovered planet in our cosmic backyard moving from possible to plausible, Planet Nine hunters now have to face their biggest challenge: deciding where to point their telescopes. “We don’t actually know where the planet is today in its orbit,” Batygin says. To narrow the search, his team and other astronomers are sifting clues from computer simulations that recapitulate billion-year segments of the solar system’s past or predict its far future.
Quote
“I’m running 12 integrations of the real objects in the outer solar system and how they would behave over the next billion years with Planet Nine, given different values for the seven parameters,” he says. The combinations of values are guesses, guided mainly by his intuition. “If one ever happens to work”—meaning that the virtual solar system keeps humming along for the next billion years without the new planet wreaking havoc—“I can jump up and down,” he smiles.
It takes his workstation just two days to model the celestial interactions of 200 tracer objects over a billion years, thanks to advances in technology. Moore’s Law has obviously helped. But the early 1990s also brought a big breakthrough in an algorithm, known as symplectic integration, that reduced computational times by an order of magnitude. Then came multicore and massively parallel computing systems, which are ideally suited for what Brown calls “embarrassingly parallel” problems like tracing how the orbits of many objects evolve over a wide range of starting conditions.
Quote
Symplectic integration is so complicated that even Brown admits he doesn’t fully understand the math. “But the key idea,” he explains, “is to take advantage of the fact that you already know that any object circling the sun mostly follows a simple orbit,” as described by Kepler’s laws of planetary motion—plus some minor perturbations. Because symplectic integrators don’t waste time rediscovering Kepler’s laws over and over, they run orbital simulations hundreds of times as fast as older methods do. One of the most popular symplectic modeling platforms is called Mercury (not to be confused with the planet), and it has become the tool of choice for several of the planet-hunting teams, including Brown and Batygin.
At Yale, Laughlin and his graduate student Sarah Millholland enhanced Mercury last autumn with a Markov-chain Monte Carlo algorithm to home in more quickly on promising orbits. Using the 1,000-core supercomputing cluster at Yale, they were able in a month to simulate a total of 1019 years of orbital mechanics, tracking not only 11 extreme trans-Neptunian objects but also uncertainties in their observations.
“We got orbital parameters that agree well with Brown’s and Batygin’s values,” Laughlin says. “But our simulation gives a more precise place in the sky to look for it.” Their paper, published in February, as well as more recent supercomputer simulations presented in April by Trujillo, puts Planet Nine somewhere in the constellation Cetus (the whale) or Eridanus (the river), at about 28 times the current distance to Pluto. “It’s still a vast search area,” Trujillo says.
Quote
Initial results seemed encouraging: Extreme TNO orbits lined up just as others had found. “It showed that Planet Nine could be responsible for that,” Nesvorný says. But things didn’t work out as well when he then focused on how Planet Nine would affect a certain class of comets.
“My model nicely reproduces all orbital parameters for these comets—until I add Planet Nine,” he says. In the model, the new planet tilts the so-called scattered disk, where Jupiter-family comets originate, causing the virtual comets to enter the solar system more steeply than the real ones do.
More caveats to Planet Nine’s theorized existence come from the Cassini probe, which has orbited Saturn since 2004. From minute changes in the spacecraft’s speed and other telemetry, the Cassini team calculates the distance from Earth to Saturn to within 3 meters. Those range measurements could reveal even small deviations in Saturn’s orbit due to the pull from Planet Nine, but only if it is close or large enough. William Folkner, a principal engineer at JPL, says he and coworkers examined the data and saw no perceptible distortion of Saturn’s orbit. So, if Planet Nine exists and is 10 times Earth’s mass, it must be within 25 degrees of the farthest point in its hypothetical orbit, he says. A smaller Planet Nine—Brown now favors a mass eight times that of Earth—would have 40 degrees of wiggle room to hide in.
The results, positive and negative, aid the handful of observers now hunting for Planet Nine on telescopes. In addition to the groups working on Subaru, Sheppard and Trujillo are leading searches in the high desert of Chile, in case the planet is easier to see from the Southern Hemisphere. There, both the 570-megapixel Dark Energy Camera (DECam) on the 4-meter Blanco telescope and the 6.5-meter Magellan telescopes are contributing to the hunt.
Quote
“I actually think we will not discover Planet Nine by scanning the sky,” Brown says. “We could, but I think somebody will find it first in archival data,” from surveys that have already photographed huge swathes of the heavens. After Uranus and Neptune were discovered, astronomers noticed that earlier stargazers had already recorded the two worlds many times but not recognized them for what they were. Now at least four efforts are under way to find a new planet in old photos.
David Gerdes of the University of Michigan has been combing through the archive of DECam’s survey observations to find images of the planet. By coincidence, Brown notes, “our predicted path for the planet goes right through the Dark Energy Survey’s field of view.”
An army of amateurs has jumped into the game as well. In February, Marc Kuchner of NASA’s Goddard Space Flight Center helped launch a crowdsourced effort to compare successive infrared images made by the Wide-field Infrared Survey Explorer space telescope of the same spot in the sky. By July, the project had recruited 40,000 volunteers, who had thoroughly reviewed over 125,000 chunks of space. A southern-sky version, launched in March with data from the Australian SkyMapper telescope, blew through 106,000 search regions in just three days. Laudable as these citizen-science projects are, their odds of success are low because the small telescopes involved typically cannot gather enough light to see something as dim and distant as Planet Nine is thought to be.
Michael Medford and Danny Goldstein, graduate students at the University of California, Berkeley, think they have a solution to that problem. Drawing on hundreds of thousands of images covering the search area for Planet Nine—all shot from 2009 to 2016 using a 1.2-meter telescope in the mountains north of San Diego—their system will combine multiple images in an ingenious way that should brighten the faint flickers of light from Planet Nine enough to distinguish them from background noise.
“Because the planet is moving with respect to the background stars, you can’t just add overlapping images together,” Medford points out. Instead, their software selects each of the many distinct plausible orbits for Planet Nine, projects the planet’s movement onto the relevant patch of sky, and then offsets successive images to superimpose—and brighten—any pixels corresponding to the planet. A pipeline of software written with Peter Nugent, their faculty advisor, performs the overlapping and subtracts known objects such as stars.
The computational task is enormous because the planet’s orbit is still so uncertain. To do a 98 percent complete search, Medford estimates, they will need to perform 10 billion image comparisons. Fortunately, Nugent has time allocated on the Cori supercomputer, a new Cray XC40 system that recently ranked as the fifth most powerful in the world.
http://spectrum.ieee.org/aerospace/satellites/is-there-a-giant-planet-lurking-beyond-pluto.amp.html
Post by: Star One on 09/05/2017 09:53 pm
Was #PlanetNine captured in the Sun's natal star-forming region? (link: https://arxiv.org/pdf/1709.00418.pdf) arxiv.org/pdf/1709.00418… [spoiler alert: nah...]
Post by: Star One on 09/06/2017 07:21 pm
Quote
Mike Brown @plutokiller
Replying to @leosutic
thanks; off to the telescope in 2 weeks!
https://mobile.twitter.com/plutokiller/status/905464596403691521
Post by: Star One on 09/08/2017 06:51 pm
https://mobile.twitter.com/KarinaVoggel/status/90620221071065088
Planet 9 Probably Isn’t an Exoplanet, After All
Quote
Scientists thought Planet 9 might be an exoplanet captured by the Sun in its early days, but new mathematical applications have proven that the likelihood of planet-swapping for the potential new solar sister is near zero. This raises the question: how could the big planet have gotten so far out there?
https://futurism.com/planet-9-probably-isnt-an-exoplanet-after-all/
Post by: Bynaus on 09/08/2017 07:54 pm
Post by: Star One on 09/08/2017 08:33 pm
Ha, interesting, about the candidates. Watch that space, I guess.
It made me laugh when Mike Brown pretended he knew nothing about it.
Post by: Alpha_Centauri on 09/08/2017 09:02 pm
Post by: Star One on 09/08/2017 09:50 pm
I'm one of the ones searching the Neowise data with Aaron and others. I've not heard anything concrete; frankly i doubt it will have been found yet, even in the best case scenario from Fortney et al. (2016) (https://arxiv.org/pdf/1604.07424.pdf) it would be at the edge of detectability and with really unhelpful motion between the epochs in-hand. There is new reprocessed Neowise data coming soon which will make finding it a little easier though.
But would you have heard anything though as I'd of thought something like this they would keep under their hats until they were ready to say something definitive.
Post by: Alpha_Centauri on 09/08/2017 09:58 pm
Post by: CuddlyRocket on 09/08/2017 10:49 pm
Some tweets regarding Aaron Meisner's search for planet nine. Apparently they have candidates but no final result.
https://mobile.twitter.com/KarinaVoggel/status/90620221071065088
"Sorry, that page doesn't exist!" Interesting. (Of course, there's many possible explanations - but I like the 'premature disclosure' one best! :) )
Post by: Star One on 09/08/2017 10:51 pm
Some tweets regarding Aaron Meisner's search for planet nine. Apparently they have candidates but no final result.
https://mobile.twitter.com/KarinaVoggel/status/90620221071065088
"Sorry, that page doesn't exist!" Interesting. (Of course, there's many possible explanations - but I like the 'premature disclosure' one best! :) )
Try this instead.
https://mobile.twitter.com/plutokiller/status/906205915325513728
Judging by what happened to that tweet it looks like they do want to keep things under their hats.
Post by: Star One on 09/13/2017 07:04 pm
Quote
Safir @safirjamil
·
22h
@plutokiller As the P9 search is about to resume, is the process boring? How about vlogging it? Or live stream maybe? QnA to pass time.
Mike Brown @plutokiller
Replying to @safirjamil
a week from today.
stay tuned.
11:56 pm · 12 Sep 2017
https://mobile.twitter.com/plutokiller/status/907739846780764160
Post by: Star One on 09/17/2017 11:34 am
He actually has had this pinned to the top of his Twitter feed since July.
Quote
Mike Brown @plutokiller
Weekly PSA: no, in fact the earth is NOT going to be destroyed by [fill in crazy thing seen on internet here] next week. Thanks for asking.
6:02 pm · 21 Jul 2016
https://mobile.twitter.com/plutokiller/status/756172592348737541
Post by: meekGee on 09/17/2017 04:03 pm
Post by: Star One on 09/17/2017 07:04 pm
Would you trust a denial from the guy who killed Pluto?
Somebody recently asked him on there if he was after Mercury next!!!
Post by: meekGee on 09/18/2017 03:09 am
Would you trust a denial from the guy who killed Pluto?
Somebody recently asked him on there if he was after Mercury next!!!
Funny...
And I would respond to the idea, but I know where this would lead...
Post by: jgoldader on 09/18/2017 08:04 pm
Would you trust a denial from the guy who killed Pluto?
Somebody recently asked him on there if he was after Mercury next!!!
Funny...
And I would respond to the idea, but I know where this would lead...
Another committee... ::)
Post by: Star One on 09/21/2017 08:21 pm
Quote
We haven’t found Planet Nine yet, in case you were wondering. To date, the telescopic searches have really just begun to scratch the surface of the area that needs to be scanned, and, while clever new projects to find Planet Nine with different techniques have been proposed, most of these efforts are just getting underway. But don’t worry: the new season of Subaru searching starts tonight! With good weather, we should be able to scan a significant part of our search area. Stay tuned.
To get ready for this new season of searching for Planet Nine, we have spent most of the last year developing our understanding of the way that Planet Nine interacts with the rest of the solar system. Much of this has involved large amounts of analytic and computational work to figure out what the orbit of Planet Nine looks like and where in its orbit Planet Nine is. If we could figure that out perfectly, we could simply go out tonight and point our telescopes right at it, as was done for the discovery of Neptune in 1846. Sadly, we have less information on Planet Nine than Le Verrier did for Neptune in 1846, so we’re not able to pinpoint it just yet, but we are able to constrain what the orbit looks like and, thus, where we should look.
http://www.findplanetnine.com/2017/09/planet-nine-where-are-you-part-1.html?m=1
Post by: Star One on 09/23/2017 07:55 pm
Post by: Bynaus on 09/23/2017 07:59 pm
Post by: Star One on 09/23/2017 08:06 pm
From the Twitter feed it seems like Konstantin Batygin is with him. Not sure how long an individual session on Subaru would be, i.e., if you would have exclusive access the whole time or not.
Do you think it’s unusual for him to be out there as someone suggested?
Post by: Bynaus on 09/23/2017 08:16 pm
Post by: hop on 09/23/2017 09:16 pm
A dwarf planet class object in the 21:5 resonance with Neptune (https://arxiv.org/abs/1709.05427)
Quote
We report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.
Michele Bannister (one of the coauthors) tweeted some background
https://twitter.com/astrokiwi/status/910158216675373056
Quote
Q. Any part of the #planetnine story?
A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.
Post by: redliox on 09/24/2017 02:20 pm
A newly discovered, relatively bright, very likely dwarf planet:
A dwarf planet class object in the 21:5 resonance with Neptune (https://arxiv.org/abs/1709.05427)QuoteWe report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.
Michele Bannister (one of the coauthors) tweeted some background
https://twitter.com/astrokiwi/status/910158216675373056QuoteQ. Any part of the #planetnine story?
A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.
Impressive. The upper range of the diameter (which naturally is uncertain for now) would make it comparable to Ceres, and certainly worthy of 'dwarf' status. I doubt we'll actually find a new giant planet (gas or ice), but certainly we could find more worlds like these including perhaps those kin to Pluto and Eris' size and perhaps evidence that'd support the theory of a 5th giant that was ejected.
Post by: Star One on 09/24/2017 02:55 pm
A newly discovered, relatively bright, very likely dwarf planet:
A dwarf planet class object in the 21:5 resonance with Neptune (https://arxiv.org/abs/1709.05427)QuoteWe report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.
Michele Bannister (one of the coauthors) tweeted some background
https://twitter.com/astrokiwi/status/910158216675373056QuoteQ. Any part of the #planetnine story?
A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.
Impressive. The upper range of the diameter (which naturally is uncertain for now) would make it comparable to Ceres, and certainly worthy of 'dwarf' status. I doubt we'll actually find a new giant planet (gas or ice), but certainly we could find more worlds like these including perhaps those kin to Pluto and Eris' size and perhaps evidence that'd support the theory of a 5th giant that was ejected.
Why do you doubt we’ll find a new giant planet? I’d say the evidence at the moment is against you. It would also be nice to prove cynics wrong especially as nature time and time again has proved our pre-existing assumptions wrong in multiple fields of scientific endeavour.
I think the reason our Solar System looks the way it does is because in the way that the TNOs are controlled by Neptune or the asteroid belt is maintained by Jupiter. That the further out objects are controlled by another ice giant. Also that the Keiper belt looks the way it does is because there is true planetary sized object within it. To maintain these kind of effects requires a persistent presence and is unlikely to be explained by transitory things such as passing stars.
Post by: Bynaus on 09/24/2017 04:11 pm
If anyone would ask for reasons to doubt the existence of P9, I'd rather point to articles like this one:
https://arxiv.org/abs/1706.07447
Quote
Origin and Evolution of Short-Period Comets
D. Nesvorný et al., 2017
Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for Np(q) perihelion passages with perihelion distance q<2.5 au. The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with Np(2.5)=500 and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution (with only a slight preference for prograde orbits). In our model, the HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing Np, but the existing observational data are not good enough to constrain Np from orbital fits. Np(2.5)>1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.
EDIT: PS: And yes, I also think that we will continue to find dwarf planets in the Kuiper belt for decades to come. Every new generation of telescopes will reveal additional populations. I think its a good bet that there will be many large objects in the Oort cloud, perhaps up to Mars size or more (as this is the typical size of the planetary embryos, of which many had to be ejected early on as the gas giants formed).
Post by: Star One on 09/24/2017 05:26 pm
Since the pattern of orbital alignments (of those many "scattered disk" objects) would disappear within a few 10 Ma without P9 (i.e., if it had been ejected early on), chances are it is still out there somewhere.
If anyone would ask for reasons to doubt the existence of P9, I'd rather point to articles like this one:
https://arxiv.org/abs/1706.07447QuoteOrigin and Evolution of Short-Period Comets
D. Nesvorný et al., 2017
Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for Np(q) perihelion passages with perihelion distance q<2.5 au. The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with Np(2.5)=500 and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution (with only a slight preference for prograde orbits). In our model, the HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing Np, but the existing observational data are not good enough to constrain Np from orbital fits. Np(2.5)>1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.
EDIT: PS: And yes, I also think that we will continue to find dwarf planets in the Kuiper belt for decades to come. Every new generation of telescopes will reveal additional populations. I think its a good bet that there will be many large objects in the Oort cloud, perhaps up to Mars size or more (as this is the typical size of the planetary embryos, of which many had to be ejected early on as the gas giants formed).
The reason I think there is a larger body in there is that the whole Keiper belt is twisted out of alignment I believe and the most likely way to do that is with a body of considerable mass.
Post by: Star One on 09/25/2017 11:56 am
Quote
Mike Brown @plutokiller
Night 4 of Subaru Planet Nine search on Maunakea. We're slowly vacuuming up the sky. My blood O2 level is low, but caffeine level is peaking
https://mobile.twitter.com/plutokiller/status/912282530329407488
Post by: Ben the Space Brit on 09/25/2017 12:28 pm
Post by: Star One on 09/25/2017 08:14 pm
https://mobile.twitter.com/plutokiller/status/912284298996178944
Quote
Mike Brown @plutokiller
Curious where we were looking for Planet Nine last night? Here's the view straight down the Subaru telescope barrel. #NameThatConstellation
https://mobile.twitter.com/plutokiller/status/912391716363227137
Post by: Star One on 09/26/2017 12:43 pm
Quote
Mike Brown @plutokiller
Night 5 (of 5) of the Subaru Planet Nine search on Maunakea now underway. Another beautiful night. Tomorrow: home to play with data!
https://mobile.twitter.com/plutokiller/status/912637604402569216
Quote
Konstantin Batygin @kbatygin
Between observing runs we hiked up to lake Waiau at 13000ft. @plutokiller got so excited his head fell off. Back on now. P9 search continues
https://mobile.twitter.com/kbatygin/status/912480583002996736
Post by: Star One on 09/26/2017 08:01 pm
Quote
Mike Brown
Mike Brown @plutokiller
Telescope now shuts down for ~2 months of routine maintenance then we're back in December to resume the search. Stay tuned.
https://mobile.twitter.com/plutokiller/status/912685408722358278
I assume the environment degrades it but how often do they have do this?
Quote
Mike Brown @plutokiller
(I know 2 months is a long time, but they have to periodically remove the entire mirror from the telescope and realuminize it. Big job.)
https://mobile.twitter.com/plutokiller/status/912687846711992321
Post by: as58 on 09/26/2017 08:45 pm
I assume the environment degrades it but how often do they have do this?
I believe that the last time was in 2013 after the mirror was damaged in camera coolant leak. Recoating every few years is typical also in other major observatories. Two months does sound like quite a long stop for just recoating, so maybe they're doing some other maintenance, too.
Post by: Star One on 09/26/2017 09:43 pm
I assume the environment degrades it but how often do they have do this?
I believe that the last time was in 2013 after the mirror was damaged in camera coolant leak. Recoating every few years is typical also in other major observatories. Two months does sound like quite a long stop for just recoating, so maybe they're doing some other maintenance, too.
Thanks. I like his tweets on stuff like this as I find it’s a good springboard to learn more about a big observatory
Post by: zubenelgenubi on 09/26/2017 10:42 pm
I assume the environment degrades it but how often do they have do this?
I believe that the last time was in2013(correction: 2011) after the mirror was damaged in camera coolant leak. Recoating every few years is typical also in other major observatories. Two months does sound like quite a long stop for just recoating, so maybe they're doing some other maintenance, too.
Perhaps not...
That's carefully removing several tons? of glass from the telescope optical assembly, followed by stripping the aluminum from the figured surface, then re-coating over 50 m2 of exquisitely figured surface. The mirror would be re-coated in a vacuum chamber oven with aluminum vapor. I assume all the work is done on-site.
There's re-alignment to do after the mirror is returned to its mount.
(Drawing conclusions from general knowledge of observatory operations; could be wrong on the particulars of Subaru.)
Post by: Star One on 09/26/2017 10:45 pm
I assume the environment degrades it but how often do they have do this?
I believe that the last time was in2013(correction: 2011) after the mirror was damaged in camera coolant leak. Recoating every few years is typical also in other major observatories. Two months does sound like quite a long stop for just recoating, so maybe they're doing some other maintenance, too.
Perhaps not...
That's carefully removing several tons? of glass from the telescope optical assembly, followed by stripping the aluminum from the figured surface, then re-coating over 50 m2 of exquisitely figured surface. The mirror would be re-coated in a vacuum chamber oven with aluminum vapor. I assume all the work is done on-site.
There's re-alignment to do after the mirror is returned to its mount.
(Drawing conclusions from general knowledge of observatory operations; could be wrong on the particulars of Subaru.)
Isn’t this all going to be even more time consuming in the future with these vast multi segment telescopes?
Post by: matthewkantar on 09/26/2017 10:46 pm
Post by: zubenelgenubi on 09/27/2017 04:46 am
I assume the environment degrades it but how often do they have do this?
I believe that the last time was in2013(correction: 2011) after the mirror was damaged in camera coolant leak. Recoating every few years is typical also in other major observatories. Two months does sound like quite a long stop for just recoating, so maybe they're doing some other maintenance, too.
Perhaps not...
That's carefully removing several tons? of glass from the telescope optical assembly, followed by stripping the aluminum from the figured surface, then re-coating over 50 m2 of exquisitely figured surface. The mirror would be re-coated in a vacuum chamber oven with aluminum vapor. I assume all the work is done on-site.
There's re-alignment to do after the mirror is returned to its mount.
(Drawing conclusions from general knowledge of observatory operations; could be wrong on the particulars of Subaru.)
Isn’t this all going to be even more time consuming in the future with these vast multi segment telescopes?
Good question--I don't know the answer.
However, there may be some tasks that become easier because one is (delicately) handling smaller pieces of glass, not a single multi-ton, monolithic monster.
Post by: as58 on 09/27/2017 04:50 am
Isn’t this all going to be even more time consuming in the future with these vast multi segment telescopes?
The segments will be recoated on a rotating basis (actually a segment or two will be in recoating every day) and I believe spare segments will be swapped for the ones taken out for maintenance. It's also not a huge impact for a mirror with hundreds of segments if one or two are missing.
Post by: Star One on 09/27/2017 07:22 pm
Quote
Bart v Schuylenburg @sidebart
·
5h
What’s the chance that P9 is already in this data?
Konstantin Batygin @kbatygin
Replying to @sidebart and @plutokiller
~10-15%
https://mobile.twitter.com/kbatygin/status/913052035859193856
Post by: Star One on 09/28/2017 07:10 pm
Quote
Mike Brown @plutokiller
Replying to @Meherdust and @kbatygin
when we find it the announcement will come quickly.
https://mobile.twitter.com/plutokiller/status/913471091070218240
Post by: Star One on 10/04/2017 09:06 pm
Quote
It might be lingering bashfully on the icy outer edges of our solar system, hiding in the dark, but subtly pulling strings behind the scenes: stretching out the orbits of distant bodies, perhaps even tilting the entire solar system to one side.
If a planet is there, it's extremely distant and will stay that way (with no chance -- in case you're wondering -- of ever colliding with Earth, or bringing "days of darkness").It is a possible "Planet Nine" -- a world perhaps 10 times the mass of Earth and 20 times farther from the sun than Neptune. The signs so far are indirect, mainly its gravitational footprints, but that adds up to a compelling case nonetheless.
One of its most dedicated trackers, in fact, says it is now harder to imagine our solar system without a Planet Nine than with one.
"There are now five different lines of observational evidence pointing to the existence of Planet Nine," said Konstantin Batygin, a planetary astrophysicist at Caltech in Pasadena, California, whose team may be closing in. "If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them."
Batygin and his co-author, Caltech astronomer Mike Brown, described the first three breadcrumbs on Planet Nine's trail in a January 2016 paper, published in the Astronomical Journal. Six known objects in the distant Kuiper Belt, a region of icy bodies stretching from Neptune outward toward interstellar space, all have elliptical orbits pointing in the same direction. That would be unlikely -- and suspicious -- enough. But these orbits also are tilted the same way, about 30 degrees "downward" compared to the pancake-like plane within which the planets orbit the sun.
Breadcrumb number three: Computer simulations of the solar system with Planet Nine included show there should be more objects tilted with respect to the solar plane. In fact, the tilt would be on the order of 90 degrees, as if the plane of the solar system and these objects formed an "X" when viewed edge-on. Sure enough, Brown realized that five such objects already known to astronomers fill the bill.
Two more clues emerged after the original paper. A second article from the team, this time led by Batygin's graduate student, Elizabeth Bailey, showed that Planet Nine could have tilted the planets of our solar system during the last 4.5 billion years. This could explain a longstanding mystery: Why is the plane in which the planets orbit tilted about 6 degrees compared to the sun's equator?
"Over long periods of time, Planet Nine will make the entire solar-system plane precess or wobble, just like a top on a table," Batygin said.
The last telltale sign of Planet Nine's presence involves the solar system's contrarians: objects from the Kuiper Belt that orbit in the opposite direction from everything else in the solar system. Planet Nine's orbital influence would explain why these bodies from the distant Kuiper Belt end up "polluting" the inner Kuiper Belt.
"No other model can explain the weirdness of these high-inclination orbits," Batygin said. "It turns out that Planet Nine provides a natural avenue for their generation. These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune."
The remaining step is to find Planet Nine itself. Batygin and Brown are using the Subaru Telescope at Mauna Kea Observatory in Hawaii to try to do just that. The instrument is the "best tool" for picking out dim, extremely distant objects lost in huge swaths of sky, Batygin said.
But where did Planet Nine come from? Batygin says he spends little time ruminating on its origin -- whether it is a fugitive from our own solar system or, just maybe, a wandering rogue planet captured by the sun's gravity.
"I think Planet Nine's detection will tell us something about its origin," he said.
Other scientists offer a different possible explanation for the Planet Nine evidence cited by Batygin. A recent analysis based on a sky mapping project called the Outer Solar System Origins Survey, which discovered more than 800 new "trans-Neptunian objects," suggests that the evidence also could be consistent with a random distribution of such objects. Still, the analysis, from a team led by Cory Shankman of the University of Victoria, could not rule out Planet Nine.
If Planet Nine is found, it will be a homecoming of sorts, or at least a family reunion. Over the past 20 years, surveys of planets around other stars in our galaxy have found the most common types to be "super Earths" and their somewhat larger cousins -- bigger than Earth but smaller than Neptune.
Yet these common, garden-variety planets are conspicuously absent from our solar system. Weighing in at roughly 10 times Earth's mass, the proposed Planet Nine would make a good fit.
Planet Nine could turn out to be our missing super Earth.
https://www.jpl.nasa.gov/news/news.php?release=2017-259&rn=news.xml&rst=6964
Post by: CuddlyRocket on 10/06/2017 05:49 am
Dynamical Evolution Induced by Planet Nine (https://arxiv.org/abs/1710.01804) (arXiv)
Quote
The observational census of trans-Neptunian objects with semi-major axes greater than ~250 AU exhibits unexpected orbital structure that is most readily attributed to gravitational perturbations induced by a yet-undetected, massive planet. Although the capacity of this planet to (i) reproduce the observed clustering of distant orbits in physical space, (ii) facilitate dynamical detachment of their perihelia from Neptune, and (iii) excite a population of long-period centaurs to extreme inclinations is well established through numerical experiments, a coherent theoretical description of the dynamical mechanisms responsible for these effects remains elusive. In this work, we characterize the dynamical processes at play, from semi-analytic grounds. We begin by considering a purely secular model of orbital evolution induced by Planet Nine, and show that it is at odds with the ensuing stability of distant objects. Instead, the long-term survival of the clustered population of long-period KBOs is enabled by a web of mean-motion resonances driven by Planet Nine. Then, by taking a compact-form approach to perturbation theory, we show that it is the secular dynamics embedded within these resonances that regulates the orbital confinement and perihelion detachment of distant Kuiper belt objects. Finally, we demonstrate that the onset of large-amplitude oscillations of orbital inclinations is accomplished through capture of low-inclination objects into a high-order secular resonance and identify the specific harmonic that drives the evolution. In light of the developed qualitative understanding of the governing dynamics, we offer an updated interpretation of the current observational dataset within the broader theoretical framework of the Planet Nine hypothesis.
It's a bit heavy on the Maths, to say the least! Basically, they provide a better theoretical underpinning of the P9 hypothesis to show that it can explain the known population of more distant KBOs etc. But it still needs to be found!
Post by: Ben the Space Brit on 10/06/2017 09:33 am
What I'm saying is that, if they fail to turn up Sol-IX, it may yet turn out that there is a system-wide dynamic interaction at work here (that could be several GY old and of which we are witnessing only a tiny part) that explains these effects without an extra major body in the system.
Post by: Star One on 10/06/2017 09:43 am
It's worth remembering that the math for 'Planet-X' was considered solid back at the turn of the 20th Century; that's why Percival Lowell funded the sky survey that ultimately turned up Pluto. However, it eventually turned out that there was some weird gravitational resonance affecting Neptune that made the calculations worthless and the 'need' for Planet-X went away.
What I'm saying is that, if they fail to turn up Sol-IX, it may yet turn out that there is a system-wide dynamic interaction at work here (that could be several GY old and of which we are witnessing only a tiny part) that explains these effects without an extra major body in the system.
I think your theory is pretty unlikely as the likelihood of such interaction is vanishingly small, generally to maintain such effects needs a continuous influence and that’s more likely to a planet than any other explanation.
Anyway it’s a bit of a non-comparison comparing the two being as the mathematical modelling of the solar system has advanced hugely in almost a hundred years.
Post by: Bynaus on 10/06/2017 09:49 am
It's worth remembering that the math for 'Planet-X' was considered solid back at the turn of the 20th Century; that's why Percival Lowell funded the sky survey that ultimately turned up Pluto. However, it eventually turned out that there was some weird gravitational resonance affecting Neptune that made the calculations worthless and the 'need' for Planet-X went away.
What I'm saying is that, if they fail to turn up Sol-IX, it may yet turn out that there is a system-wide dynamic interaction at work here (that could be several GY old and of which we are witnessing only a tiny part) that explains these effects without an extra major body in the system.
Not all gravitational interactions are equal, and the arguments which supported a Planet X are different from the ones which are in support of Planet Nine (except that the relevant force in both cases is gravity).
In the case of Planet X, it was not a strange resonance, but a too high inferred mass of Neptune (http://adsabs.harvard.edu/cgi-bin/bib_query?1993AJ....105.2000S) which led the researchers astray.
In the case of P9, it is a set of four or five different observations of small solar system object populations which each would be difficult to explain without a Planet Nine. The only way that P9 could not be real is if biases and bad luck would conspire to give a false impression of the distribution of the orbital elements of these objects. I don't think a resonance of some sort could do this.
Post by: CuddlyRocket on 10/11/2017 05:40 am
Post by: Star One on 10/14/2017 08:37 pm
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Konstantin Batygin @kbatygin
Replying to @S3anizl3
We're still in data-analysis mode. The direction were were looking roughly overlaps Taurus and Orion.
https://mobile.twitter.com/kbatygin/status/917469057095393281
Post by: clongton on 10/16/2017 02:03 pm
One of the great pending discoveries in genetic engineering will be to give professionals the ability to subsist only on strong coffee instead of oxygen and any nutrients.
Tea, Ben - Tea. Without tea there is no civilization :)
Post by: MickQ on 10/17/2017 11:58 am
One of the great pending discoveries in genetic engineering will be to give professionals the ability to subsist only on strong coffee instead of oxygen and any nutrients.
Tea, Ben - Tea. Without tea there is no civilization :)
What is going on here ??? An American pushing tea on an Englishman ??? I think P9 is exerting more than a gravitational influence :o
Post by: meekGee on 10/17/2017 03:21 pm
Indeed, in ESA's words, "a previously unobserved phenomena"...One of the great pending discoveries in genetic engineering will be to give professionals the ability to subsist only on strong coffee instead of oxygen and any nutrients.
Tea, Ben - Tea. Without tea there is no civilization :)
What is going on here ??? An American pushing tea on an Englishman ??? I think P9 is exerting more than a gravitational influence :o
Post by: Bynaus on 10/18/2017 08:39 am
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Evaluating the Dynamical Stability of Outer Solar System Objects in the Presence of Planet Nine
Juliette C. Becker, Fred C. Adams, Tali Khain, Stephanie J. Hamilton, and David Gerdes
We evaluate the dynamical stability of a selection of outer solar system objects in the presence of the proposed new solar system member Planet Nine. We use a Monte Carlo suite of numerical N-body integrations to construct a variety of orbital elements of the new planet and evaluate the dynamical stability of eight trans-Neptunian objects (TNOs) in the presence of Planet Nine. These simulations show that some combinations of orbital elements (a, e) result in Planet Nine acting as a stabilizing influence on the TNOs, which can otherwise be destabilized by interactions with Neptune. These simulations also suggest that some TNOs transition between several different mean-motion resonances during their lifetimes while still retaining approximate apsidal antialignment with Planet Nine. This behavior suggests that remaining in one particular orbit is not a requirement for orbital stability. As one product of our simulations, we present an a posteriori probability distribution for the semimajor axis and eccentricity of the proposed Planet Nine based on TNO stability. This result thus provides additional evidence that supports the existence of this proposed planet. We also predict that TNOs can be grouped into multiple populations of objects that interact with Planet Nine in different ways: one population may contain objects like Sedna and 2012 VP113, which do not migrate significantly in semimajor axis in the presence of Planet Nine and tend to stay in the same resonance; another population may contain objects like 2007 TG422 and 2013 RF98, which may both migrate and transition between different resonances.
PDF link: http://iopscience.iop.org/article/10.3847/1538-3881/aa7aa2/pdf
Post by: Star One on 10/19/2017 05:53 pm
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From that set of simulations, we found out that there are preferred versions of Planet Nine that make the TNO stay stable for longer, so it basically increases the probability that our solar system exists the way it does," Becker said. "Through these computer simulations, we were able to determine which realization of Planet Nine creates our solar system—the whole caveat here being, if Planet Nine is real."
The group, which includes U-M physics professors David Gerdes and Fred Adams as well as graduate student Stephanie Hamilton and undergraduate Tali Khain, also examined the resonance of these TNOs with Planet Nine. An orbital resonance occurs when objects in a system periodically exert gravitational forces upon each other that cause the objects to line up in a pattern.
In this case, the researchers found that occasionally, Neptune will bump a TNO out of its orbital resonance, but instead of sending that TNO skittering into the sun, out of the solar system or into another planet, something catches that TNO and confines it into a different resonance.
"The ultimate goal would be to directly see Planet Nine—to take a telescope, point it at the sky, and see reflected light from the sun bouncing off of Planet Nine," Becker said. "Since we haven't yet been able to find it, despite many people looking, we're stuck with these kinds of indirect methods."
http://ns.umich.edu/new/releases/25168-in-search-of-the-ninth-planet
Post by: missinglink on 10/24/2017 07:18 am
The Super-Earth that Came Home for DinnerI thought this was due to observational bias? By which I mean, super earths closely orbiting their stars will be found preferentially because the deviations from expected behavior they cause in the stars are more easily detected from where we are.Quote. . . Over the past 20 years, surveys of planets around other stars in our galaxy have found the most common types to be "super Earths" and their somewhat larger cousins -- bigger than Earth but smaller than Neptune.
https://www.jpl.nasa.gov/news/news.php?release=2017-259&rn=news.xml&rst=6964
Post by: Bynaus on 10/24/2017 07:48 am
The Super-Earth that Came Home for DinnerI thought this was due to observational bias? By which I mean, super earths closely orbiting their stars will be found preferentially because the deviations from expected behavior they cause in the stars are more easily detected from where we are.Quote. . . Over the past 20 years, surveys of planets around other stars in our galaxy have found the most common types to be "super Earths" and their somewhat larger cousins -- bigger than Earth but smaller than Neptune.
https://www.jpl.nasa.gov/news/news.php?release=2017-259&rn=news.xml&rst=6964
There is an observational bias, for sure. In particular, we can assume that there are many small planets which we cannot detect today. Still, the frequency of planets in size between Earth and Neptune (not known from the solar system, perhaps with the exception of P9) is surprisingly high, and higher than would have been predicted from planet formation models (which essentially assumed that early-formed planets would grow rapidly to become gas giants, while late-formed planets would not find any gas and stay rocky - Uranus and Neptun were then considered strange borderline cases - well, it turns out, they are more typical planets than all the other worlds of the solar system which we could detect with Kepler).
Post by: Ben the Space Brit on 10/24/2017 01:47 pm
Post by: Star One on 10/26/2017 08:23 pm
https://mobile.twitter.com/cosmos4u/status/923280935025610753
Post by: Star One on 11/27/2017 07:06 pm
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Mike Brown
@plutokiller
Replying to @Alex997tt
most of the searching is really writing software that does the searching. and testing it. and fixing bugs. and running it and finding more bugs. repeat.
https://mobile.twitter.com/plutokiller/status/934893302536478720
Post by: Star One on 12/06/2017 08:20 pm
Planet Nine! An Update from Konstantin Batygin
Post by: Star One on 12/08/2017 05:14 pm
https://www.theatlantic.com/science/archive/2017/12/planet-nine-or-planet-nein/547907/
Post by: KelvinZero on 12/09/2017 03:49 pm
I guess for this super earth it would be absurdly larger? Has there been any discussion of how this could affect the sort of moon system it could have?
Post by: CuddlyRocket on 12/10/2017 02:03 am
I guess for this super earth [its Hill sphere] would be absurdly larger? Has there been any discussion of how this could affect the sort of moon system it could have?
According to Wikipedia the radius of a planet's Hill sphere is approximately a x (1-e) x cube root of m/3M, where a is the semi-major axis, e the orbital eccentricity, m the planet mass and M the mass of the Sun. For Planet Nine, a is approx 25 times that of Neptune; 1-e approximately 0.4 times and the cube root of m approximately 0.8 times. This gives a Hill radius approximately eight times that of Neptune (930 million kilometers - 6.2 AU! - versus 116 million kilometers).
As for the effect on any moon system, it would mean that a much more expansive moon system would be possible (Neptune's furthest moon (Neso) is at 50 million kilometers). However, it would seem likely that any initial moons would have been lost in the process of Planet Nine attaining its present orbit and the chances of it meeting, let alone capturing, any objects would be very low!
Post by: Star One on 12/14/2017 07:58 pm
https://www.newscientist.com/article/mg23631561-300-planet-x-we-are-closing-in-on-the-solar-systems-new-occupant/
Post by: hop on 12/15/2017 01:49 am
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The recent 'Planet Nine' hypothesis has led to many observational and archival searches for this giant planet proposed to orbit the Sun at hundreds of astronomical units. While trans-Neptunian object searches are typically conducted in the optical, models suggest Planet Nine could be self-luminous and potentially bright enough at ~3-5 microns to be detected by the Wide-field Infrared Survey Explorer (WISE). We have previously demonstrated a Planet Nine search methodology based on time-resolved WISE coadds, allowing us to detect moving objects much fainter than would be possible using single-frame extractions. In the present work, we extend our 3.4 micron (W1) search to cover more than three quarters of the sky and incorporate four years of WISE observations spanning a seven year time period. This represents the deepest and widest-area WISE search for Planet Nine to date. We characterize the spatial variation of our survey's sensitivity and rule out the presence of Planet Nine in the parameter space searched at W1 < 16.7 in high Galactic latitude regions (90% completeness).Needless to say, the title would be different if they found it. However, the detectability of P9 at WISE wavelengths is quite model dependent, so this certainly doesn't rule it out either.
Post by: jgoldader on 12/15/2017 10:33 am
A 3pi Search for Planet Nine at 3.4 microns with WISE and NEOWISE (http://) A. M. Meisner, B. C. Bromley, S. J. Kenyon, T. E. Anderson
Just read it, looks like a good paper. They seem to have done an impressive job. As you noted, hop, the expected IR flux is highly model dependent. That said, they seem to have thoroughly searched a large and interesting part of the parameter space and come up empty.
Post by: sanman on 12/15/2017 10:57 am
Post by: Alpha_Centauri on 12/15/2017 11:28 am
Post by: Star One on 12/15/2017 11:50 am
It should be pointed out that even if it is possible for P9 to show up in WISE, dependant on its atmospheric chemistry, this search is still only sensitive to the closer regions of P9s orbit. Realistically if it does exist it is likely near aphelion and so beyond our reach. Aaron Meisner's work on the new astrometrically corrected coadds is awesome though.
Mike Brown has repeatedly said this so it was unlikely this search would turn up anything. He’s even made reference to the fact, I believe, that WISE data would be unlikely to show it because it’s likely at the furtherest part of its orbit.
Post by: Alpha_Centauri on 12/15/2017 12:12 pm
Post by: jebbo on 12/15/2017 12:14 pm
Sometimes I think there should be a Journal of Null Results :-)
--- Tony
Post by: KelvinZero on 12/15/2017 12:18 pm
So once Planet 9 is found, how long might it take a spacecraft to reach it from Earth?Of course hugely dependent on what technology, what mass.. but just to begin with some numbers.
https://en.wikipedia.org/wiki/Planet_Nine
Implies orbit varies from 200 - 1200 AU.
https://en.wikipedia.org/wiki/Voyager_1
Has been flying for about 40 years, and has travelled 141 AU (as of Nov 22, 2017)
Im sure we can do a lot better, but I don't know what to point at as state of the art right now and if we were going to send a probe I guess it would be with technology that is best discussed in the advanced topics section.
https://en.wikipedia.org/wiki/Breakthrough_Starshot discusses 15-20% of light speed.
A lightyear is about 63,000 AU, and 20% would be more than 13,000AU / year. .. so around a month if it is at its furthest point, 1200AU?
(That would certainly be a fun little project for exploring our solar system)
Pls check my numbers yourself. I could easily have messed up.
Post by: hop on 12/15/2017 06:03 pm
Mike Brown has repeatedly said this so it was unlikely this search would turn up anything. He’s even made reference to the fact, I believe, that WISE data would be unlikely to show it because it’s likely at the furtherest part of its orbit.Context matters for these kinds of statements. "standard WISE data products go to mag X, equilibrium blackbody in at 600 AU would be Y temperature" gives a rather different impression than what was discussed in the paper. Meisner's coadds go significantly deeper than the basic WISE data products, and under some models P9 is significantly brighter at these wavelengths than a first order estimate would suggest. Again, this doesn't mean P9 ruled out, but the work being discussed did have potential to discover plausible flavors of P9 over much of the proposed orbit.
They also note there's more to be done with WISE data:
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Our methodology should be readily applicable to the WISE W2 channel. Typically, (W1−W2) ~ 0.8 corresponds
to equal signal-to-noise in W1 and W2, meaning that we should expect sensitivity to Planet Nine at W2 < 15.9. This survey limit would render the most W2-luminous model of Fortney et al. (2016) detectable at distances of up to ~1,700 AU. One operational advantage of searching in W2 rather than W1 is that W2 has a factor of ~2 fewer background sources relative to W1. A disadvantage is that scattered moonlight, one of the dominant time-dependent artifacts affecting WISE data, is more pronounced in W2 than in W1 Whereas our survey has omitted some regions, we note that the ongoing Kuchner et al. (2017) search is examining the entire sky in both W1 and W2, based on the time-resolved coadds of Meisner et al. (2017a).
Because the Kuchner et al. (2017) search employs deep W2 coadds, it can also serve as a fainter extension of the Luhman (2014) search for a roughly Jovian mass companion to the Sun.
WISE continues to collect additional data in W1 and W2, so that there will eventually be at least one additional year
of NEOWISER exposures in both bands relative to those currently available.
Post by: Star One on 12/15/2017 07:01 pm
Post by: Alpha_Centauri on 12/15/2017 07:37 pm
Found plenty of probably "nearby" cold brown dwarfs though. Sorry, no P9 yet.
Post by: Star One on 01/22/2018 08:12 pm
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Mike Brown
@plutokiller
·
21 Jan
As of yesterday(!) we now have statistically rigorous calculations of best fit orbit and mass of P9 and, critically, uncertainties on all of these parameters. Along with that comes a rigorous calculation of a probability that that is no P9: 0.01%
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Mike Brown
@plutokiller
·
21 Jan
So this is all great news for the search. The less great news? The area that we need to search remains pretty big. It will still take some time. We're back to the telescope in a couple of weeks, and will keep at it until it's found.
Quote
Mike Brown
@plutokiller
·
21 Jan
(papers with all of the details coming soon[ish] to an arXiv near you)
https://mobile.twitter.com/plutokiller/status/955099713308475392
Post by: TakeOff on 01/24/2018 05:57 pm
Post by: hop on 01/24/2018 07:01 pm
Wasn't planet Nine dismissed after precision measurements of the Solar System's barycenter recently? Using pulsars and Cassini's location of Saturn to within 100 meters or so. A massive planet out there would've been noticed.Nope. If there were a really convincing negative conclusion, people wouldn't still be using lots of precious telescope time to look for it.
There was some back and forth over the Cassini results some time ago, but nothing close to definitive.
Post by: Alpha_Centauri on 01/24/2018 07:07 pm
Post by: Star One on 01/24/2018 09:07 pm
Wasn't planet Nine dismissed after precision measurements of the Solar System's barycenter recently? Using pulsars and Cassini's location of Saturn to within 100 meters or so. A massive planet out there would've been noticed.Nope. If there were a really convincing negative conclusion, people wouldn't still be using lots of precious telescope time to look for it.
There was some back and forth over the Cassini results some time ago, but nothing close to definitive.
Considering how much telescope time Brown appears to have been clocking up in the last few months with more to come soon it sounds at least as far as he’s concerned that he’s not buying their conclusions.
Post by: Star One on 02/10/2018 08:27 pm
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Mike Brown
@plutokiller
Night 2 on Mauna Kea and it is still clear and beautiful with the Magellanic Clouds just peeking over the southern horizons and the Milky Way blazing overhead. But, sadly, the high winds are turning the stars into pancakes in my images. I like pancakes. But not this many pancakes
https://mobile.twitter.com/plutokiller/status/962204876875821056
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Mike Brown
@plutokiller
One more night like tonight and my hopes for finding Planet Nine this season fade to zero. But I guess it is time start working up my optimism for next winter.
https://mobile.twitter.com/plutokiller/status/962205325775454208
Post by: Ben the Space Brit on 02/12/2018 04:19 pm
I didn’t know high winds could smear out images like this for a professional scope.
It makes sense that extremely high sustained movement of the atmosphere would have optical effects that would be difficult to filter out without impacting on the accuracy of data on extremely faint near-point sources.
Post by: jgoldader on 02/13/2018 12:39 am
I didn’t know high winds could smear out images like this for a professional scope.
I wish I'd held onto some of the stuff we got back in the day so I could show you. Wind shake produced smeared stars, like a whole bunch of hyphens (or sometimes slashes, even shaped like an upper-case L on occasion), and when the seeing was going really bad, your image went from the hoped-for near diffraction-limited sharpness to horrible blobs 5+ arc-seconds wide, with the PSF never looking the same twice. You'd wonder if you weren't looking through clouds, because if you spread faint starlight over enough pixels, you can't really see the stars.
Post by: as58 on 02/13/2018 04:46 am
I didn’t know high winds could smear out images like this for a professional scope.
I'm not sure which instrument Brown is using, but it's very likely something without adaptive optics. AO only works well over a small field of view (thought it's improving with multi-conjugate systems), so survey telescopes don't have them.
And even when using an instrument with AO, seeing still matters. There's limits to what AO can do, so the best data is obtained in good seeing conditions.
Post by: Star One on 02/13/2018 05:54 am
I didn’t know high winds could smear out images like this for a professional scope.
I'm not sure which instrument Brown is using, but it's very likely something without adaptive optics. AO only works well over a small field of view (thought it's improving with multi-conjugate systems), so survey telescopes don't have them.
And even when using an instrument with AO, seeing still matters. There's limits to what AO can do, so the best data is obtained in good seeing conditions.
He’s using the Subaru Telescope out in Hawaii.
Post by: mikelepage on 02/13/2018 06:40 am
I guess for this super earth [its Hill sphere] would be absurdly larger? Has there been any discussion of how this could affect the sort of moon system it could have?
According to Wikipedia the radius of a planet's Hill sphere is approximately a x (1-e) x cube root of m/3M, where a is the semi-major axis, e the orbital eccentricity, m the planet mass and M the mass of the Sun. For Planet Nine, a is approx 25 times that of Neptune; 1-e approximately 0.4 times and the cube root of m approximately 0.8 times. This gives a Hill radius approximately eight times that of Neptune (930 million kilometers - 6.2 AU! - versus 116 million kilometers).
As for the effect on any moon system, it would mean that a much more expansive moon system would be possible (Neptune's furthest moon (Neso) is at 50 million kilometers). However, it would seem likely that any initial moons would have been lost in the process of Planet Nine attaining its present orbit and the chances of it meeting, let alone capturing, any objects would be very low!
Shoemaker-Levy 9 was shredded through a previous interaction with Jupiter before it finally crashed. I wonder if it's not a bit premature to say any initial moons would definitely have been "lost" by the ejection event.
Hard to say with any certainty until we find it, but perhaps any such moons could have been kept (although tidally disrupted) through the event that ejected planet nine. Perhaps we'll find an extensive ring system, or (my fanciful hope) a large liquid water "ocean moon" in an orbit conducive to tidal heating.
Post by: Star One on 03/22/2018 04:56 pm
Looking for Planet Nine, Astronomers Gaze into the Abyss
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Two years on, the search for our solar system’s missing world is as frenzied as ever—and the putative planet is running out of places to hide
https://www.scientificamerican.com/article/looking-for-planet-nine-astronomers-gaze-into-the-abyss/#
Post by: hop on 04/23/2018 07:11 am
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Two planetary mass objects in the far outer Solar System --- collectively referred to here as Planet X --- have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18,000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the "wide-fast-deep" survey) of the southern sky beginning in 2022, and is therefore an important tool to search for these hypothesized planets. Here we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the wide-fast-deep survey plus additional coverage) we estimate that LSST will confidently detect or rule out the existence of Planet X in 61\% of the entire sky. At orbital distances up to ∼75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a non-detection of Planet X in LSST data.
Post by: Star One on 04/23/2018 10:57 am
Post by: Bynaus on 04/23/2018 12:21 pm
They talk about two planets at first but only mention one in the abstract, so are they talking about planet 9 which is beyond the Kuiper belt or 10 which is supposed to be within the Kuiper belt?
This is about detectability of transneptunian planets with LSST in general - so they are talking about both.
Note that both planets - the 5-20 Earth-Masses Batygin & Brown "Planet Nine" and the Mars-to-Super-Earth-mass "Kuiper-belt-tilter" from Volk & Malhotra - are beyond the Kuiper belt. The latter is supposed to be at a distance of 60-100 AU (the Kuiper belt extends to roughly 55 AU).
EDIT: Both can be found with LSST if they are in the region surveyed by the telescope. The Kuiper-belt tilter is likly easier to find, as it moves faster and is brighter. If Planet Nine is currently near aphelion, it can still be detected in principle but the region of the sky where it would be in that case is not surveyed by LSST at sufficient quality.
Post by: Star One on 04/23/2018 03:43 pm
They talk about two planets at first but only mention one in the abstract, so are they talking about planet 9 which is beyond the Kuiper belt or 10 which is supposed to be within the Kuiper belt?
This is about detectability of transneptunian planets with LSST in general - so they are talking about both.
Note that both planets - the 5-20 Earth-Masses Batygin & Brown "Planet Nine" and the Mars-to-Super-Earth-mass "Kuiper-belt-tilter" from Volk & Malhotra - are beyond the Kuiper belt. The latter is supposed to be at a distance of 60-100 AU (the Kuiper belt extends to roughly 55 AU).
EDIT: Both can be found with LSST if they are in the region surveyed by the telescope. The Kuiper-belt tilter is likly easier to find, as it moves faster and is brighter. If Planet Nine is currently near aphelion, it can still be detected in principle but the region of the sky where it would be in that case is not surveyed by LSST at sufficient quality.
Thank you. The reason I thought the nominal tenth planet was actually in the Kuiper belt was basing that on the fact I have previously heard Alan Stern talk about a object like Mars in size within the belt.
Post by: Bynaus on 04/23/2018 06:02 pm
They talk about two planets at first but only mention one in the abstract, so are they talking about planet 9 which is beyond the Kuiper belt or 10 which is supposed to be within the Kuiper belt?
This is about detectability of transneptunian planets with LSST in general - so they are talking about both.
Note that both planets - the 5-20 Earth-Masses Batygin & Brown "Planet Nine" and the Mars-to-Super-Earth-mass "Kuiper-belt-tilter" from Volk & Malhotra - are beyond the Kuiper belt. The latter is supposed to be at a distance of 60-100 AU (the Kuiper belt extends to roughly 55 AU).
EDIT: Both can be found with LSST if they are in the region surveyed by the telescope. The Kuiper-belt tilter is likly easier to find, as it moves faster and is brighter. If Planet Nine is currently near aphelion, it can still be detected in principle but the region of the sky where it would be in that case is not surveyed by LSST at sufficient quality.
Thank you. The reason I thought the nominal tenth planet was actually in the Kuiper belt was basing that on the fact I have previously heard Alan Stern talk about a object like Mars in size within the belt.
Well, to be perfectly correct, of course the scattered disk objects are usually considered to be members of the Kuiper belt too, and they are found beyond 55 AU. The Volk-Malhotra object ("tilter") would definetly be in the scattered disk. On the other hand, that's beyond the cold classical disk, which ends at about 55 AU.
So from that perspective, its not wrong when Alan Stern says it would be in the Kuiper belt. But its not part of that transneptunian disk of coplanar, icy objects one typically pictures as the "Kuiper belt".
Post by: Star One on 05/09/2018 08:00 pm
Planet Nine makes some KBOs go wild
http://www.findplanetnine.com/2018/05/planet-nine-makes-some-kbos-go-wild.html?m=1
Here’s the related paper.
https://arxiv.org/pdf/1804.11281.pdf
Post by: Alpha_Centauri on 05/10/2018 10:24 pm
https://twitter.com/dAArkEnergy/status/994539491070181376
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Today @theDESurvey announced the discovery of a trans-Neptunian object with one of the most remarkable orbits ever seen. 2015 BP519 has a=449 au, e=0.92, and an inclination of 54 degrees. There's nothing else like it. Preview from our paper that will appear on arXiv later today:
https://twitter.com/kbatygin/status/994627384409145344
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#PlanetNine induced orbital evolution at its finest
Post by: Star One on 05/11/2018 07:17 am
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Replying to @dAArkEnergy and @theDESurvey
#2015BP519 has an amazingly inclined orbit, and heading north with perihelion in 2058 at 35AU. It may be large enough (~400–700 km) to qualify as a dwarf planet!
(link: http://web.gps.caltech.edu/~mbrown/dps.html) web.gps.caltech.edu/~mbrown/dps.ht…
Likely: Anything icy larger than 500 km is highly likely to be round.
Post by: Archibald on 05/11/2018 09:03 am
Post by: Bynaus on 05/11/2018 10:48 am
Post by: 192 on 05/11/2018 03:35 pm
So what is general consensus as of today ? I've heard of a Mars- or Earth size planet, and a Neptune-size planet farther away. Also, there might be a lot of pluto-sized planet.
Planet Nine is hypothesised to be between 5 and 15 Earth Masses. If you're interested in more detail I'd suggest checking out http://www.findplanetnine.com/.
If you're interested in Dwarf Planets in the outer Solar System, http://web.gps.caltech.edu/~mbrown/dps.html#table has a nice table of the known dwarf planets and most likely candidates discovered so far.
Post by: Star One on 05/16/2018 08:09 pm
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Astronomers argue that there’s an undiscovered giant planet far beyond the orbit of Neptune. A newly discovered rocky body has added evidence to the circumstantial case for it.
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What’s more, Batygin and Brown also predicted that over time, Planet Nine’s gravity would push these Kuiper belt objects out of their current plane and into ever-higher orbital inclinations. Although astronomers have already spotted a bizarre population of worlds that orbit the sun perpendicularly to the plane of the solar system, they had never caught an object transitioning between the two populations. “There’s no real way to put something on an orbit like that — except that it’s exactly what we predicted from Planet Nine,” Brown said. Batygin notes that the new object fits so perfectly with their model that it almost looks like one of the data points in their simulations. “A good theory reproduces data — but a great theory predicts new data,” he said.
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“There is no other reasonable way to populate the Kuiper belt with such highly inclined bodies,” Batygin said. “I think the case for the existence of Planet Nine is now genuinely excellent.”
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Other astronomers aren’t so certain — in part because the early solar system remains a mystery. Scientists suspect that the sun was born within a cluster of stars, meaning that the early planets might have had many close encounters with other stars that sent them on paths that seem impossible today. And even once the stars dispersed, the early solar system likely contained tens of thousands of dwarf planets that could have provided the gravitational nudges needed to push 2015 BP519, as the new object is called, into such an odd orbit. “To me, Planet Nine is one of a number of ways that the solar system could have unfolded,” said Michele Bannister, an astronomer at Queen’s University Belfast who was not involved in the study. “It’s a potential idea.” But at the moment it is just that — an idea.
https://www.quantamagazine.org/a-new-worlds-extraordinary-orbit-points-to-planet-nine-20180515/
Post by: jebbo on 05/17/2018 06:19 am
--- Tony
Post by: Star One on 05/17/2018 06:34 am
There's been some discussion on twitter that the orbit of 2015 BP519 is explicable using Neptune alone ...
--- Tony
It’s more accurate to state that’s it is hard but not impossible for Neptune to have created this object alone, but it is towards the ‘edge’ of Neptune’s influence.
Post by: hop on 05/17/2018 05:08 pm
It’s more accurate to state that’s it is hard but not impossible for Neptune to have created this object alone, but it is towards the ‘edge’ of Neptune’s influence.The paper looked at Neptune's current orbit, but doesn't examine migration in the early solar system. They do mention it as a possible alternative (along with stellar encounters), but don't analyze the probabilities:
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Although it is unclear how an object with a semi-major axis as high as that of 2015 BP519 would be generated in this process, we cannot exclude the idea that 2015 BP519's currently observed orbital inclination may come from a period of violent instability in the early history of the solar system.This is totally reasonable, one paper can't cover everything. However, it does leave significant room for non-P9 explanations. Some of the twitter discussion (https://twitter.com/astrokiwi/status/996867082196267008) suggests previous simulations of migration do put things in this kind of orbit.
Post by: Star One on 05/17/2018 07:22 pm
It’s more accurate to state that’s it is hard but not impossible for Neptune to have created this object alone, but it is towards the ‘edge’ of Neptune’s influence.The paper looked at Neptune's current orbit, but doesn't examine migration in the early solar system. They do mention it as a possible alternative (along with stellar encounters), but don't analyze the probabilities:QuoteAlthough it is unclear how an object with a semi-major axis as high as that of 2015 BP519 would be generated in this process, we cannot exclude the idea that 2015 BP519's currently observed orbital inclination may come from a period of violent instability in the early history of the solar system.This is totally reasonable, one paper can't cover everything. However, it does leave significant room for non-P9 explanations. Some of the twitter discussion (https://twitter.com/astrokiwi/status/996867082196267008) suggests previous simulations of migration do put things in this kind of orbit.
Some of the Twitter discussions I saw around this topic would have been more constructive if certain participants hadn’t worn their pro & anti P9 biases so clearly on their sleeves.
Isn’t it just better to say the origin of this object at the present time is ambiguous.
Post by: Star One on 06/01/2018 05:52 pm
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Two planetary mass objects in the far outer Solar System --- collectively referred to here as Planet X --- have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18,000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the "wide-fast-deep" survey) of the southern sky beginning in 2022, and is therefore an important tool to search for these hypothesized planets. Here we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the wide-fast-deep survey plus additional coverage) we estimate that LSST will confidently detect or rule out the existence of Planet X in 61\% of the entire sky. At orbital distances up to ∼75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a non-detection of Planet X in LSST data.
https://arxiv.org/abs/1804.07713
Post by: hop on 06/01/2018 08:17 pm
On the detectability of Planet X with LSSTPreviously posted and discussed up-thread https://forum.nasaspaceflight.com/index.php?topic=34329.msg1813564#msg1813564
Not complaining, just pointing back to earlier discussion. These papers tend to come around once when they are first posted and hit the media after they are published.
Post by: Torbjorn Larsson, OM on 06/01/2018 09:48 pm
It’s more accurate to state that’s it is hard but not impossible for Neptune to have created this object alone, but it is towards the ‘edge’ of Neptune’s influence.The paper looked at Neptune's current orbit, but doesn't examine migration in the early solar system. They do mention it as a possible alternative (along with stellar encounters), but don't analyze the probabilities:QuoteAlthough it is unclear how an object with a semi-major axis as high as that of 2015 BP519 would be generated in this process, we cannot exclude the idea that 2015 BP519's currently observed orbital inclination may come from a period of violent instability in the early history of the solar system.This is totally reasonable, one paper can't cover everything. However, it does leave significant room for non-P9 explanations. Some of the twitter discussion (https://twitter.com/astrokiwi/status/996867082196267008) suggests previous simulations of migration do put things in this kind of orbit.
Some of the Twitter discussions I saw around this topic would have been more constructive if certain participants hadn’t worn their pro & anti P9 biases so clearly on their sleeves.
Isn’t it just better to say the origin of this object at the present time is ambiguous.
I think people can have constructive discussions despite being biased, as long as the bias is based on the available evidence. (But of course I am biased to think that.)
There is not much of an ambiguity theory wise. If P9 has migrated during "a period of violent instability in the early history of the solar system", which is likely, that event is passed when 2015 BP519 is constrained by P9. So you lose a lot of predictions in one swoop, making P9 the preferred model in some likelihood ratio test. (That should be quantified to be valid and not argumentative of course, but it looks iffy of you aren't a modeler and have lots of time on your hand.)
Speaking of predictions, the excitement does not come from adding an ad hoc hypothesis to the rest, but as I understand it Batygin has pressed that it is the first unexpected prediction that passed a test ('not only a good theory, but a great theory').
Post by: Star One on 06/02/2018 07:03 am
On the detectability of Planet X with LSSTPreviously posted and discussed up-thread https://forum.nasaspaceflight.com/index.php?topic=34329.msg1813564#msg1813564
Not complaining, just pointing back to earlier discussion. These papers tend to come around once when they are first posted and hit the media after they are published.
Apologies I didn’t notice the date on the paper.
Post by: Star One on 06/12/2018 08:03 pm
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Bumper car-like interactions at the edges of our solar system—and not a mysterious ninth planet—may explain the the dynamics of strange bodies called “detached objects,” according to a new study.
CU Boulder Assistant Professor Ann-Marie Madigan and a team of researchers have offered up a new theory for the existence of planetary oddities like Sedna—an icy minor planet that circles the sun at a distance of nearly 8 billion miles. Scientists have struggled to explain why Sedna and a handful of other bodies at that distance look separated from the rest of the solar system.
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The findings may provide clues around another phenomenon: the extinction of the dinosaurs. As space debris interacts in the outer solar system, the orbits of these objects tighten and widen in a repeating cycle. This cycle could wind up shooting comets toward the inner solar system—including in the direction of Earth—on a predictable timescale.
“While we’re not able to say that this pattern killed the dinosaurs,” Fleisig said, “it’s tantalizing.”
https://www.colorado.edu/today/2018/06/04/collective-gravity
Post by: Star One on 08/03/2018 08:11 pm
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New Planet Nine paper just submitted to a scientific journal. When do you get to see it? First, it goes to a scientific editor who sends it out for peer review. Finding someone to do timely peer review the month of August is never easy, but with luck we might get review ...
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back in a month. We then respond to reviewers comments and, depending on how critical the comments were, it might go back to the reviewers. So best case is that maybe it is accepted for publication mid-September. Worst is, I don't know, December? It can be a long process ...
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but, with luck, it will lead to a paper even better than the one originally submitted.
Sometimes people post papers before they have been through review, but, in most cases, I prefer to wait until after review. But then it will be posted for all to see....
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I'll give the teaser though: the paper is super cool. It helps us both confirm that Planet Nine is almost certainly out there, and it helps us to pinpoint the orbital path of Planet Nine, so we will know where to look this fall. Stay tuned!
https://mobile.twitter.com/plutokiller/status/1024323434107437056
Post by: CuddlyRocket on 08/07/2018 07:03 am
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(Abstract)
The hypothesis of an additional planet in the outer Solar System has gained new support as a result of the confinement noted in the angular orbital elements of distant trans-Neptunian objects. Orbital parameters proposed for the external perturber suggest semimajor axes between 500 and 1000 au, perihelion distances between 200 and 400 au for masses between 10 and 20 M⊕. In this paper we study the possibility that lower perihelion distances for the additional planet can lead to angular confinements as observed in the population of objects with semimajor axes greater than 250 au and perihelion distances higher than 40 au. We performed numerical integrations of a set of particles subjected to the influence of the known planets and the putative perturber during the age of the Solar System and compared our outputs with the observed population through a statistical analysis. Our investigations showed that lower perihelion distances from the outer planet usually lead to more substantial confinements than higher ones, while retaining the Classical Kuiper Belt as well as the ratio of the number of detached with perihelion distances higher than 42 au to scattering objects in the range of semimajor axes from 100 au to 200 au.
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(Conclusions)
... we concluded that planets with perihelion distances as small as 90 au should not be discarded in principle. They produce better confinements while preserving the Classical Kuiper Belt and the ratio between the number of detached to scattering objects in the region 100 au < a < 200 au.
Post by: Star One on 08/14/2018 06:22 am
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We report the discovery and dynamical analysis of 2015 BP519, an extreme Trans-Neptunian Object detected detected by the Dark Energy Survey at a heliocentric distance of 55 AU and absolute magnitude Hr= 4.3. The current orbit, determined from a 1110-day observational arc, has semi-major axis a≈ 450 AU, eccentricity e≈ 0.92 and inclination i≈ 54 degrees. With these orbital elements, 2015 BP519 is the most extreme TNO discovered to date, as quantified by the reduced Kozai action, which is is a conserved quantity at fixed semi-major axis a for axisymmetric perturbations. We discuss the orbital stability and evolution of this object in the context of the known Solar System, and find that 2015 BP519 displays rich dynamical behavior, including rapid diffusion in semi-major axis and more constrained variations in eccentricity and inclination. We also consider the long term orbital stability and evolutionary behavior within the context of the Planet Nine Hypothesis, and find that BP519 adds to the circumstantial evidence for the existence of this proposed new member of the Solar System, as it would represent the first member of the population of high-i, ϖ-shepherded TNOs.
https://arxiv.org/abs/1805.05355
Post by: Bynaus on 08/29/2018 11:02 am
https://www.preposterousuniverse.com/podcast/2018/08/27/episode-11-mike-brown-on-killing-pluto-and-replacing-it-with-planet-9/
1) They now have a very good estimate for the orbit - but they don't know where along the orbit it is
2) Semimajor axis is about 500 AU, with significant eccentricity and inclination
3) The mass is about 7+-2 Earth masses
4) After accounting for all biases, he estimates that the probability of a chance alignment of the nodes of the far-flung Kuiper belt objects is about 0.1%. Which makes him 99.9% confident that P9 exists.
The new mass estimate is excitingly low... P9 might really be the first "exoplanet" (a representative of the most abundantly found type of exoplanet so far: a super-Earth/sub-Neptune), right at our door-step!
Go hear it - its quite an interesting interview anyway!
Post by: Alpha_Centauri on 08/30/2018 07:40 am
I’m tentative about equivalences between outer planets in our solar system and sub-Neptunes formed largely in-situ on tight orbits wind-sculpted by their star. For a start at 7 earth masses you have to think this thing must have got chucked out very early, it’s evolutionary history is likely quite different and that may be reflected in its composition. Less a gassy rockball and more a slightly rocky gasball.
Post by: Bynaus on 08/30/2018 08:03 am
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Less a gassy rockball and more a slightly rocky gasball.
Don't you mean the other way around? The rocky core would contribute a major portion of the total mass, with a lot of volatiles on top and only a little bit of H + He, as the planet didn't have much time to accrete these elements from the disk.
Post by: Alpha_Centauri on 08/30/2018 11:21 am
7 Earth masses, according to Mike Brown, fits very well with the suggested mass of the ejected "fifth gas giant".
Indeed but my point was the mass is sensitive to the ejection time, too late and the embryonic ice giant would have rapidly grown more massive than this.
QuoteLess a gassy rockball and more a slightly rocky gasball.
Don't you mean the other way around? The rocky core would contribute a major portion of the total mass, with a lot of volatiles on top and only a little bit of H + He, as the planet didn't have much time to accrete these elements from the disk.
That's the whole difference between core accretion and disk instability. Presumably as an embryonic ice giant this object formed through disk instability. Disk instability, unlike core accretion, accretes significant fractions of gas as well as dust right from the start in a short space of time. While it's true that the rocky mass is critical to the runaway formation of the real Gas Giants of Jupiter and Saturn its effect when talking about Neptunes is more modest.
So both a very young Planet Nine and an extrasolar sub-Neptune form with not insignificant gas fractions. However the sub-Neptunes have their H2/He envelopes wind-sculpted away and will be significantly rockier than their outer solar system equivalents, even if they began life larger.
Post by: Bynaus on 08/30/2018 11:35 am
7 Earth masses, according to Mike Brown, fits very well with the suggested mass of the ejected "fifth gas giant".
Indeed but my point was the mass is sensitive to the ejection time, too late and the embryonic ice giant would have rapidly grown more massive than this.
Perhaps, although Uranus and Neptune didn't grow much larger than this although they remained in that disk. Its probably just a question of reaching runnaway mass while the gas is still there. Jupiter and Saturn suceeded, but the ice giants didn't.
QuoteLess a gassy rockball and more a slightly rocky gasball.
Don't you mean the other way around? The rocky core would contribute a major portion of the total mass, with a lot of volatiles on top and only a little bit of H + He, as the planet didn't have much time to accrete these elements from the disk.
That's the whole difference between core accretion and disk instability. Presumably as an embryonic ice giant this object formed through disk instability. Disk instability, unlike core accretion, accretes significant fractions of gas as well as dust right from the start in a short space of time. While it's true that the rocky mass is critical to the runaway formation of the real Gas Giants of Jupiter and Saturn its effect when talking about Neptunes is more modest.
So both a very young Planet Nine and an extrasolar sub-Neptune form with not insignificant gas fractions. However the sub-Neptunes have their H2/He envelopes wind-sculpted away and will be significantly rockier than their outer solar system equivalents, even if they began life larger.
Uranus, Neptune and P9 have the typical sizes of the planetary embryos expected to form in the outer disk by accretion. Also, they only contain little He + H (10-15%), also in accordance with the expectation from accretion.
The same is likely true for most Neptunians among the exoplanets, just that they migrated inward instead of outward. Atmospheric loss from Neptunians doesn't really start until you hit them with 400 solar constants or so.
I think disk instability has to take place further out from the host star, and also produces higher planet masses (on the order of a Jupiter mass) with stellar metallicities.
Post by: Star One on 08/30/2018 11:35 am
Post by: Bynaus on 08/30/2018 11:43 am
Brown says in the interview about its ejection that it would have occurred when the Sun was still in its stellar nursery. With assumingly the gravitational influences of the other stars stopping it wondering off.
Not so much keeping it from wandering off but raising its orbit (perihelion) enough so it doesn't dive back into the gas giant region anymore. Without that, it would revisit the position where it got its last "kick" over and over again (or until a new kick or a collision happened).
Post by: Star One on 09/03/2018 04:32 pm
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At the moment of the observation, the “Planet Nine” might hide in the light pollution of the Milky Way, could find itself in the shine of a bright star, or, even worse, it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years.
https://advocator.ca/science/planet-nine-might-be-invisible-hiding-beyond-neptune-scientists-think/5244
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Michael Brown from the California Institute of Technology has said he thinks “Planet Nine” will eventually be found, but it will take significantly stronger telescopes and planet finding technology than currently exist.
http://www.foxnews.com/science/2018/09/03/planet-nine-may-exist-but-it-might-be-hiding-behind-neptune.html
Here’s a better article on the hunt for Planet Nine.
https://www.washingtonpost.com/amphtml/national/health-science/is-there-a-mysterious-planet-nine-lurking-in-our-solar-system-beyond-neptune/2018/08/31/1957c8ca-a495-11e8-8fac-12e98c13528d_story.html
Post by: KelvinZero on 09/04/2018 03:00 am
Bit depressing this news about the hunt for planet nine.Oh well. At least we know there are plenty of objects out there so there won't be decades of looking and finding nothing but nothing, regardless.QuoteAt the moment of the observation, the “Planet Nine” might hide in the light pollution of the Milky Way, could find itself in the shine of a bright star, or, even worse, it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years.
https://advocator.ca/science/planet-nine-might-be-invisible-hiding-beyond-neptune-scientists-think/5244
I didn't really understand the line "it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years."
The way it is worded makes it sound like a fundamental optics constraint rather than something that could be solved with telescopes that may only be 'mere' decades away. Just poor wording?
Post by: Star One on 09/04/2018 06:44 am
Bit depressing this news about the hunt for planet nine.Oh well. At least we know there are plenty of objects out there so there won't be decades of looking and finding nothing but nothing, regardless.QuoteAt the moment of the observation, the “Planet Nine” might hide in the light pollution of the Milky Way, could find itself in the shine of a bright star, or, even worse, it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years.
https://advocator.ca/science/planet-nine-might-be-invisible-hiding-beyond-neptune-scientists-think/5244
I didn't really understand the line "it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years."
The way it is worded makes it sound like a fundamental optics constraint rather than something that could be solved with telescopes that may only be 'mere' decades away. Just poor wording?
The Washington Post article is better written though I don’t think it addresses the thinking behind that particular quote.
Post by: Star One on 09/04/2018 08:58 pm
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Mike Brown
@plutokiller
Uh, no. OK, so I'm eternally optimist and think we'll find Planet Nine this year, on my most pessimistic days I fear that it might take a decade.
https://twitter.com/plutokiller/status/1036810171043930113
Was intrigued by this exchange with Mike Brown.
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Do you think it’s a good idea if NASA, JAXA, ESA starts a study to define what type of spacecraft and instruments to prepare before planet 9 is found? Would a modernized version of New Horizons function that far away? Or are preparations already on the way?
https://twitter.com/sidebart/status/1037002155843117056
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there are ideas already floating around!
https://twitter.com/plutokiller/status/1037023067384426496
Post by: CuddlyRocket on 09/05/2018 10:59 pm
I didn't really understand the line "it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years."
The way it is worded makes it sound like a fundamental optics constraint rather than something that could be solved with telescopes that may only be 'mere' decades away. Just poor wording?
Poor thinking, I suspect - they just failed to consider the effect of bigger and better telescopes!
Post by: KelvinZero on 09/06/2018 04:49 am
Poor thinking, I suspect - they just failed to consider the effect of bigger and better telescopes!Yeah I think Star One was right, the washington post article was more clear. From memory it mentioned a different currently existing approach that can already do better, so it was really just saying certain current approaches will not work if the planet is in a certain part of the orbit. The "thousand years" really just says that waiting is not a practical option to fix this.
Post by: Star One on 09/06/2018 08:02 am
Poor thinking, I suspect - they just failed to consider the effect of bigger and better telescopes!Yeah I think Star One was right, the washington post article was more clear. From memory it mentioned a different currently existing approach that can already do better, so it was really just saying certain current approaches will not work if the planet is in a certain part of the orbit. The "thousand years" really just says that waiting is not a practical option to fix this.
It seemed to me those other articles were picking and choosing what they posted about the story in order to give them a dramatic headline.
Post by: Star One on 09/10/2018 08:10 pm
https://twitter.com/kbatygin/status/1038948193172512768
https://arxiv.org/pdf/1809.02594.pdf
Post by: Bynaus on 09/10/2018 08:15 pm
Post by: Star One on 09/10/2018 08:23 pm
Yes but given its rather negative conclusion I don't think its the one Mike Brown hinted about earlier (the one in review)...
No I don’t think we can expect that until December at the earliest from what he’s said in the past.
Post by: jbenton on 09/11/2018 04:12 am
1) Do Trujillo & Sheppard not have Twitter, or other means of outreach? It seems as if most of the updates have come from Brown and Batygin. I was under the understanding that they were both looking for it.
2) What sort of super-WISE could discover or rule out a body 5-10 Earth masses out to 1,000 AU? 10,000? WISE has a primary mirror of 40cm in diameter. The proposed NEOCam would have a primary of 50cm and would observe at most of the same wavelengths as WISE (though it would also have a longer focal length, I think, and be at L1 rather than L2, and not be an all-sky survey. Two different 'scopes for two different missions. But I was thinking something with the same field of view as WISE, but a larger mirror, similar instruments) What about if it had a 1m mirror?
3) Would the Whipple Space Telescope - if it existed - be at all useful for the search?
https://en.wikipedia.org/wiki/Whipple_(spacecraft)
Post by: as58 on 09/11/2018 03:19 pm
Just read through this thread and I have three questions:
2) What sort of super-WISE could discover or rule out a body 5-10 Earth masses out to 1,000 AU? 10,000? WISE has a primary mirror of 40cm in diameter. The proposed NEOCam would have a primary of 50cm and would observe at most of the same wavelengths as WISE (though it would also have a longer focal length, I think, and be at L1 rather than L2, and not be an all-sky survey. Two different 'scopes for two different missions. But I was thinking something with the same field of view as WISE, but a larger mirror, similar instruments) What about if it had a 1m mirror?
AFAIK IR emission drops very quickly when you move to smaller mass planets. Luhman (and others) were able to get good limits for Jupiter-sized planets in the outer Solar System, but I doubt IR surveys could provide very useful constraints for sub-10 M_Earth planets compared to what current and near-term optical telescopes can do.
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3) Would the Whipple Space Telescope - if it existed - be at all useful for the search?
https://en.wikipedia.org/wiki/Whipple_(spacecraft)
That mission looks like something that could provide statistics about the population of Kuiper belt objects, but not that useful for finding a particular object.
Post by: CuddlyRocket on 09/12/2018 10:23 pm
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One idea is to look for the heat glow [Planet 9] should emit directly. Luhman essentially ruled out the existence of anything bigger and warmer than a gas giant with a 2014 analysis of infrared data, but physicists expect a smaller, colder Planet Nine to shine in the millimeter part of the spectrum. Stars are dim here, so there’s less risk of Brown’s nightmare scenario. Best of all, direct emissions, unlike reflected light, have to make only a one-way trip.
Current millimeter telescopes in Antarctica and Chile could detect Planet Nine today should it stray across their search field, according to Gilbert Holder, a cosmologist at the University of Illinois. Yet those instruments are busy mapping the cosmic microwave background (CMB), so they’re not necessarily pointed in the right direction at the right times. Holder is waiting for the Next Generation CMB Experiment, which his preliminary calculations estimate could pick up a planet as small as Earth at 1,000 AU. “There would be nowhere for Planet Nine to hide once this thing was turned on,” he said.
Post by: Star One on 09/14/2018 05:50 pm
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77
Of course this is what Mike Brown’s paper will be addressing.
Post by: leovinus on 09/14/2018 11:36 pm
From Why Can't We Find Planet Nine? (https://www.quantamagazine.org/why-cant-we-find-planet-nine-20180703/) (quantamagazine.com)QuoteOne idea is to look for the heat glow [Planet 9] should emit directly. Luhman essentially ruled out the existence of anything bigger and warmer than a gas giant with a 2014 analysis of infrared data, but physicists expect a smaller, colder Planet Nine to shine in the millimeter part of the spectrum. Stars are dim here, so there’s less risk of Brown’s nightmare scenario. Best of all, direct emissions, unlike reflected light, have to make only a one-way trip.
Current millimeter telescopes in Antarctica and Chile could detect Planet Nine today should it stray across their search field, according to Gilbert Holder, a cosmologist at the University of Illinois. Yet those instruments are busy mapping the cosmic microwave background (CMB), so they’re not necessarily pointed in the right direction at the right times. Holder is waiting for the Next Generation CMB Experiment, which his preliminary calculations estimate could pick up a planet as small as Earth at 1,000 AU. “There would be nowhere for Planet Nine to hide once this thing was turned on,” he said.
Instead of looking for the object directly, could we use JWST going to L2 1.5 million km from Earth for a parallax detection in the same search field? Or is a baseline of 1.5 million km, ~1% of an AU, too small for an object at 1000AU?
Post by: Alpha_Centauri on 09/15/2018 06:46 am
Post by: CuddlyRocket on 09/15/2018 07:38 pm
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77
Of course this is what Mike Brown’s paper will be addressing.
Dr Siegel doesn't present any evidence that 'most scientists think Planet Nine doesn't exist'. He has the OSSOS paper casting doubt on the hypothesis - itself disputed by Mike Brown - but that's far from 'most scientists'! He himself says that the "OSSOS study doesn't rule out Planet Nine, but it does cast doubt on the idea that the Solar System needs one. Unless a deeper, better survey indicates otherwise, or Planet Nine serendipitously turns up, the default position should be its non-existence." 'Default position' sounds a bit of a weak argument!
Post by: Star One on 09/16/2018 08:56 am
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77
Of course this is what Mike Brown’s paper will be addressing.
Dr Siegel doesn't present any evidence that 'most scientists think Planet Nine doesn't exist'. He has the OSSOS paper casting doubt on the hypothesis - itself disputed by Mike Brown - but that's far from 'most scientists'! He himself says that the "OSSOS study doesn't rule out Planet Nine, but it does cast doubt on the idea that the Solar System needs one. Unless a deeper, better survey indicates otherwise, or Planet Nine serendipitously turns up, the default position should be its non-existence." 'Default position' sounds a bit of a weak argument!
The other thing that struck me about it is why write an article as if this was a new paper when in fact as it says in the article itself it was published in 2017. He also fails to make clear in my view that Mike Brown has and is addressing this issue.
Post by: as58 on 09/16/2018 12:20 pm
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77
Of course this is what Mike Brown’s paper will be addressing.
Dr Siegel doesn't present any evidence that 'most scientists think Planet Nine doesn't exist'. He has the OSSOS paper casting doubt on the hypothesis - itself disputed by Mike Brown - but that's far from 'most scientists'! He himself says that the "OSSOS study doesn't rule out Planet Nine, but it does cast doubt on the idea that the Solar System needs one. Unless a deeper, better survey indicates otherwise, or Planet Nine serendipitously turns up, the default position should be its non-existence." 'Default position' sounds a bit of a weak argument!
I'm sure that most scientists have no opinion whatsoever on whether Planet Nine exists. Many scientists (even astronomers) have not even heard about it.
Post by: clongton on 09/16/2018 07:53 pm
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77 (https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77)
Of course this is what Mike Brown’s paper will be addressing.
Star One, the paper leads off with the statement "most scientists disagree..." and then the "scientists" are never identified.
What scientists? How many? What disciplines? I hate statements like this. It's no better than "we have it from an anonymous source". Statements like this are worthless and I find it very hard to give credence to anything which leads off like this. It's little more than click-bait. Because of that I rarely bother to read any paper that starts off like this because I am already prejudiced against it.
Post by: Star One on 09/16/2018 08:45 pm
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77 (https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77)
Of course this is what Mike Brown’s paper will be addressing.
Star One, the paper leads off with the statement "most scientists disagree..." and then the "scientists" are never identified.
What scientists? How many? What disciplines? I hate statements like this. It's no better than "we have it from an anonymous source". Statements like this are worthless and I find it very hard to give credence to anything which leads off like this. It's little more than click-bait. Because of that I rarely bother to read any paper that starts off like this because I am already prejudiced against it.
But it is reporting a genuine scientific paper.
Post by: clongton on 09/16/2018 10:36 pm
This Is Why Most Scientists Think Planet Nine Doesn't Exist
https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77 (https://www.forbes.com/sites/startswithabang/2018/09/14/this-is-why-scientists-think-planet-nine-doesnt-exist/#2c326c4f6e77)
Of course this is what Mike Brown’s paper will be addressing.
Star One, the paper leads off with the statement "most scientists disagree..." and then the "scientists" are never identified.
What scientists? How many? What disciplines? I hate statements like this. It's no better than "we have it from an anonymous source". Statements like this are worthless and I find it very hard to give credence to anything which leads off like this. It's little more than click-bait. Because of that I rarely bother to read any paper that starts off like this because I am already prejudiced against it.
But it is reporting a genuine scientific paper.
OSSOS is a study that began in 2013 and ended in 2017. It spent 5 years surveying the sky to find TNOs. But it was not looking for P9. It did find 8 objects that, after the fact, are identified as potentially providing evidence for or against P9. What it boils down to is one man's opinion that because (1) we have not found P9 and (2) the few objects that OSSOS did find (while not looking for P9) that could "potentially" provide evidence for or against P9, did not comply with what would be expected if P9 were influencing them. However all that actually says is that P9 isn't influencing THEM. Why? Why isn't it obvious? It is to him. It's because P9 doesn't exist of course! At least in this single man's mind. And he is not "most scientists".
What this paper is, is a well written expression of what this single individual theorizes may be true - his theory - and he offers the reasons he holds to that. That's fine. But this is still just a single man's opinion, *not* "most scientists". And remind me how many single person's opinions have been demonstrated to be incorrect over time when the unexpected was actually found?
I don't say this to denigrate this man; I have no reason to do that. I respect what he does and the obvious dedication with which he does it. His paper is interesting but it does not offer any compelling evidence that P9 does not in fact exist, which is what he is trying to say. Obviously his evidence has convinced him, but there are just as many on the other side of the question who are equally passionate with their opposite position. ISTM that the jury is still out and probably will be for considerable time. There has not been enough time nor instruments dedicated to testing Mr. Brown's hypothesis. That HAS to happen. So for now, stack this paper up with all the others written by equally dedicated scientists on this subject; some for and some against. One day we'll know which stack ultimately represented the actual facts.
But again, when a paper begins with "most scientists agree/disagree", I know intuitively that it's one person's or perhaps a small group's opinion on a subject, not a definitive statement, without regard to the passion and work involved in the presented theory. And that certainly proved to be the case with this well-written paper.
Post by: KelvinZero on 09/16/2018 11:24 pm
Something I often quote is the estimated 200 Kuiper belt dwarf planets.. and perhaps 10,000 beyond. Is there any estimate of the rate that we will be finding new objects at, and is any new hardware going to come online and dramatically up this rate?
I really want this planet to exist, but I am trying to be sort of philosophical and "big picture" about it. :)
All this other stuff is very interesting and even if we don't look for it, evidence for this planet should either diminish or grow dramatically as we proceed.
Post by: Star One on 09/17/2018 08:18 am
The general point seems to be a good one. My takeaway is that we really want some unbiased way to detect more objects.. (and biases don't just come from people, they also come from seasons etc.)
Something I often quote is the estimated 200 Kuiper belt dwarf planets.. and perhaps 10,000 beyond. Is there any estimate of the rate that we will be finding new objects at, and is any new hardware going to come online and dramatically up this rate?
I really want this planet to exist, but I am trying to be sort of philosophical and "big picture" about it. :)
All this other stuff is very interesting and even if we don't look for it, evidence for this planet should either diminish or grow dramatically as we proceed.
Well there was some speculation not so long ago that there is a Mars sized object in the Kuiper belt, even Alan Stern seems to think this is possible. Of course then we get into is it a planet debate again. I’d say if there is an object that big then it must be a planet, but I’d of thought the IAU definition would say not as it wouldn’t have cleared its orbit surely?
https://gizmodo.com/a-mysterious-mars-sized-object-could-be-hiding-at-the-e-1796343294
Post by: Bynaus on 09/17/2018 08:29 am
The general point seems to be a good one. My takeaway is that we really want some unbiased way to detect more objects.. (and biases don't just come from people, they also come from seasons etc.)
Something I often quote is the estimated 200 Kuiper belt dwarf planets.. and perhaps 10,000 beyond. Is there any estimate of the rate that we will be finding new objects at, and is any new hardware going to come online and dramatically up this rate?
I really want this planet to exist, but I am trying to be sort of philosophical and "big picture" about it. :)
All this other stuff is very interesting and even if we don't look for it, evidence for this planet should either diminish or grow dramatically as we proceed.
The "Kuiper cliff" at 55 AU seams to be real, and we should have found all "Plutos" within 55 AU, so we won't find any more very large classical KBOs. But the scattered disk (smoothly transitioning into the Oort cloud?) might be very large, and might contain many large objects. Its just very difficult to make any discovery rate predictions because we don't know the orbital distribution of these objects out there, nor their size-frequency distribution, nor their albedo distributions.
One far day, we should send a few space telescopes of the Hubble/Spitzer class on New Horizons-like trajectories. That at least would break the D^4 dependency (and turn it into a D^~2 dependency).
Post by: Star One on 09/17/2018 09:07 am
The general point seems to be a good one. My takeaway is that we really want some unbiased way to detect more objects.. (and biases don't just come from people, they also come from seasons etc.)
Something I often quote is the estimated 200 Kuiper belt dwarf planets.. and perhaps 10,000 beyond. Is there any estimate of the rate that we will be finding new objects at, and is any new hardware going to come online and dramatically up this rate?
I really want this planet to exist, but I am trying to be sort of philosophical and "big picture" about it. :)
All this other stuff is very interesting and even if we don't look for it, evidence for this planet should either diminish or grow dramatically as we proceed.
The "Kuiper cliff" at 55 AU seams to be real, and we should have found all "Plutos" within 55 AU, so we won't find any more very large classical KBOs. But the scattered disk (smoothly transitioning into the Oort cloud?) might be very large, and might contain many large objects. Its just very difficult to make any discovery rate predictions because we don't know the orbital distribution of these objects out there, nor their size-frequency distribution, nor their albedo distributions.
One far day, we should send a few space telescopes of the Hubble/Spitzer class on New Horizons-like trajectories. That at least would break the D^4 dependency (and turn it into a D^~2 dependency).
That article actually mentions this but then adds a caveat that no survey is exhaustive given technological limitations and therefore something larger at 50AU could exist.
Post by: Bynaus on 09/17/2018 09:39 am
Adding here that with "Hubble/Spitzer" class I only refer to the size if the telescope, not its technology. Such a "traveling telescope" should of course have a wide angle camera system to search for additional objects.
Post by: Star One on 09/19/2018 07:53 pm
He believes he can find it even if it is aligned with the Galaxy disc.
Would this just be by mathematical analysis of prior data?
Quote
I was outside before sunrise this morning and realized that Orion -- and thus the Planet Nine search region -- was overhead. As that region of the sky moves toward the middle of the night it'll be time to head to the telescope once again.
https://twitter.com/plutokiller/status/1042091336738799617
Quote
Our latest analysis (which I finished this morning!) shrinks the Planet Nine search area by about a factor of 2, saving us a lot of time at the telescope. Now we just need the weather to cooperate and the volcanoes to not restart. Fingers are all crossed.
https://twitter.com/plutokiller/status/1042092274807496705
Quote
that's actually a super important question. we have a paper coming out addressing that very question soon which shows that it is highly improbably that they are random. stay tuned
https://twitter.com/plutokiller/status/1042412316459843584
If he does find it would other telescopes would be capable of verifying what must be a very difficult target?
Post by: CuddlyRocket on 09/20/2018 11:03 am
If he does find it would other telescopes would be capable of verifying what must be a very difficult target?
Yes. There are quite a few telescopes with greater resolving power, albeit over a small field of view. They're not well-suited to a wide-area search, but are better suited to characterise the orbit etc once they know where to look. The plan is to use the nearby Keck telescopes (no doubt the Hubble will look at it at some point). One thing they'll hope to detect is a moon, which will enable them to determine the mass.
Post by: Bynaus on 09/20/2018 11:15 am
If he does find it would other telescopes would be capable of verifying what must be a very difficult target?
Yes. There are quite a few telescopes with greater resolving power, albeit over a small field of view. They're not well-suited to a wide-area search, but are better suited to characterise the orbit etc once they know where to look. The plan is to use the nearby Keck telescopes (no doubt the Hubble will look at it at some point). One thing they'll hope to detect is a moon, which will enable them to determine the mass.
If we use the 1:5000 "rule" for the mass of a moon system, and about 7 Earth masses for the planet, we'd end up with a total system mass of about 10% of the mass of Luna. If that is concentrated in a single object with a density of 2 g/cc, we get a diameter of 2000 km, so about the size of Pluto. At 500 AU, it will be almost 80'000 times (12 magnitudes) fainter than Pluto at perihelion. That's about 25th magnitude, not impossible, but difficult. Of course, the mass of the satellite system might be distributed over many smaller bodies...
Post by: Star One on 09/28/2018 07:56 pm
Quote
Closely held irregular satellite like, say, the Galilean satellites of Jupiter, would be safe during an ejection. We really hope for moons around Planet Nine, as that would allow us to quickly and accurately measure the mass of the planet.
https://twitter.com/plutokiller/status/1045345996463529985
Post by: Bynaus on 09/28/2018 08:03 pm
New Tweet from Mike Brown.QuoteClosely held irregular satellite like, say, the Galilean satellites of Jupiter, would be safe during an ejection. We really hope for moons around Planet Nine, as that would allow us to quickly and accurately measure the mass of the planet.
https://twitter.com/plutokiller/status/1045345996463529985
Somewhat relevant recent arxiv preprint: https://arxiv.org/abs/1809.05639
Quote
Survivability of Moon Systems Around Ejected Gas Giants
We examine the effects that planetary encounters have on the moon systems of ejected gas giant planets. We conduct a suite of numerical simulations of planetary systems containing three Jupiter-mass planets (with the innermost planet at 3 AU) up to the point where a planet is ejected from the system. The ejected planet has an initial system of 100 test-particle moons. We determine the survival probability of moons at different distances from their host planet, measure the final distribution of orbital elements, examine the stability of resonant configurations, and characterize the properties of moons that are stripped from the planets. We find that moons are likely to survive in orbits with semi-major axes out beyond 200 planetary radii (0.1 AU in our case). The orbital inclinations and eccentricities of the surviving moons are broadly distributed and include nearly hyperbolic orbits and retrograde orbits. We find that a large fraction of moons in two-body and three-body mean-motion resonances also survive planetary ejection with the resonance intact. The moon-planet interactions, especially in the presence of mean-motion resonance, can keep the interior of the moons molten for billions of years via tidal flexing, as is seen in the moons of the gas giant planets in the solar system. Given the possibility that life may exist in the subsurface ocean of the Galilean satellite Europa, these results have implications for life on the moons of rogue planets---planets that drift through the galaxy with no host star.
While they simulated Jupiter mass planets, ejected to interstellar space, I think the results are applicable, in a sufficiently broad sense, to Planet Nine too. So as Brown says, you expect at least some inner moons to survive. Also, their orbits might have been mingled by the encounter, in different orientations, eccentric, etc.
Post by: Mongo62 on 10/02/2018 02:58 am
Inner Oort Cloud objects have perihelia beyond the Kuiper Belt with semi-major axes less than a few thousand au. They are beyond the strong gravitational influences of the known planets yet are tightly bound to the Sun such that outside forces minimally affect them. Here we report the discovery of the third known Inner Oort Cloud object after Sedna and 2012 VP113, called 2015 TG387. 2015 TG387 has a perihelion of 65 +-1 au with a semi-major axis of 1190 +-70 au. The longitude of perihelion angle for 2015 TG387 is between that of Sedna and 2012 VP113, and thus similar to the main group of clustered extreme trans-Neptunian objects (ETNOs), which may be shepherded into similar orbital angles by an unknown massive distant planet, called Planet X or Planet 9. 2015 TG387's orbit is stable over the age of the solar system from the known planets and Galactic tide. When including simulated stellar encounters to our Sun over 4 Gyrs, 2015 TG387's orbit is still mostly stable, but its dynamical evolution depends on the stellar encounter scenarios used. Surprisingly, when including a massive Planet X beyond a few hundred au on an eccentric orbit that is anti-aligned in longitude of perihelion with most of the known ETNOs, we find 2015 TG387 is typically stable for Planet X orbits that render the other ETNOs stable as well. In fact, 2015 TG387's longitude of perihelion librates about 180 degrees from Planet X's longitude of perihelion in most stable simulations, keeping 2015 TG387 anti-aligned with Planet X over the age of the solar system. We find a power law slope near 3 for the semi-major axis distribution of Inner Oort Cloud objects (IOCs), meaning there are many more high than low semi-major axis IOCs. There are about 2 million IOCs larger than 40 km, giving a mass of 10^22 kg. The IOCs inclination distribution is similar to the scattered disk, with an average inclination of 19 degs.
Post by: Star One on 10/02/2018 03:45 pm
Quote
Konstantin Batygin, assistant professor of planetary science at Caltech, who has worked on theoretical simulations of the hypothetical Planet Nine, described the latest observations as a “great discovery indeed”.
“Despite centuries of surveys, our understanding of the solar system remains incomplete,” he said. “This certainly adds to the growing ledger of … objects that show Planet Nine’s influence.”
https://www.theguardian.com/science/2018/oct/02/dwarf-planet-the-goblin-discovery-planet-nine-oort-cloud
Quote
Batygin was also excited. “I’m running code as we speak that evaluates how the inferred orbit and mass of [the hypothetical planet] are affected by this new object,” he said, when I contacted him the day before the discovery was announced.
https://www.theatlantic.com/amp/article/571831/
Also this.
Quote
The datafiles of the Minor Planet Center contain several additional objects with similar orbits. So you can include them in the modeling.
https://twitter.com/SVanaverbek/status/1047026830660788225
Post by: Star One on 10/03/2018 08:29 pm
Quote
The journey of a scientific paper, part 2. We submitted the paper back at the end of July, and just got back the reviews. A bit slow, but, you know, August happened. So now we read the peer review and decide what we think.
https://twitter.com/plutokiller/status/1047515040893435904
Quote
This review is typical: parts of the paper just need some clarifying, which is pretty easy, but there is at least one important question a reviewer asks that I can't answer without some extra analysis. it's a good question and I hadn't clearly focused on.
https://twitter.com/plutokiller/status/1047515829435125760
Quote
So, with luck, it'll be just a couple of days of analysis, a rewrite and back to review. Then we start all over again, but I think this round will quickly come to conclusion. So maybe November? Always a little hard to guess.
https://twitter.com/plutokiller/status/1047516275298066432
Post by: Chris Bergin on 10/04/2018 06:48 pm
https://www.nasaspaceflight.com/2018/10/new-dwarf-planet-goblin-solar-system-discovered/
Post by: Bynaus on 10/04/2018 07:50 pm
Justin Davenport's reviewed the latest paper on this:
https://www.nasaspaceflight.com/2018/10/new-dwarf-planet-goblin-solar-system-discovered/
Good article! Don't want to nitpick, but here's a few things I noticeD: Typo in the first sentence "dwarf planet 2015" instead of "2015 TG387".
Also, its worth noting that despite being called a dwarf planet by the authors and the press release, it isn't on the IAU's official list of dwarf planets (which only includes five worlds so far), nor is it clear that it should be, as its size is only known very approximately (say, within a factor of two), and the nominal diameter given (300 km) falls into the transition region where bodies start to fall into hydrostatic equilibrium, the nr. 1 requirement to be classified a dwarf planet (apart from orbiting the sun). So it might turn out to be too small to be in hydrostatic equilibrium.
Finally, the inner Oort cloud isn't really a "part of the sky", as its all around us, rather a region in the outer solar system.
Post by: CuddlyRocket on 10/04/2018 08:10 pm
Also, its worth noting that despite being called a dwarf planet by the authors and the press release, it isn't on the IAU's official list of dwarf planets (which only includes five worlds so far), nor is it clear that it should be, as its size is only known very approximately (say, within a factor of two), and the nominal diameter given (300 km) falls into the transition region where bodies start to fall into hydrostatic equilibrium, the nr. 1 requirement to be classified a dwarf planet (apart from orbiting the sun). So it might turn out to be too small to be in hydrostatic equilibrium.
'Dwarf planet' is sexier; more likely to attract press attention or otherwise favourable publicity! They're obviously aware of the requirement as they say "it's believed to be spherical", though I'm not sure on what basis. By the time anyone disproves this no-one will care they got it wrong; but equally, it will be a long time before it gets on the IAU list!
Post by: Bynaus on 10/04/2018 08:13 pm
Also, its worth noting that despite being called a dwarf planet by the authors and the press release, it isn't on the IAU's official list of dwarf planets (which only includes five worlds so far), nor is it clear that it should be, as its size is only known very approximately (say, within a factor of two), and the nominal diameter given (300 km) falls into the transition region where bodies start to fall into hydrostatic equilibrium, the nr. 1 requirement to be classified a dwarf planet (apart from orbiting the sun). So it might turn out to be too small to be in hydrostatic equilibrium.
'Dwarf planet' is sexier; more likely to attract press attention or otherwise favourable publicity! They're obviously aware of the requirement as they say "it's believed to be spherical", though I'm not sure on what basis. By the time anyone disproves this no-one will care they got it wrong; but equally, it will be a long time before it gets on the IAU list!
Its probably a good bet that by the time this object would make it to that list, the list will no longer be in use. :)
But yeah, I agree, its much sexier to talk about a dwarf planet, whether thats justified or not. Why focus on the signal if you can instead amplify the noise! ::)
Post by: Star One on 10/05/2018 08:55 pm
https://www.scientificamerican.com/article/orbital-forensics-hint-at-suns-long-lost-planet/
Post by: Torbjorn Larsson, OM on 10/08/2018 08:40 pm
Justin Davenport's reviewed the latest paper on this:
https://www.nasaspaceflight.com/2018/10/new-dwarf-planet-goblin-solar-system-discovered/
Good article!
Really good! It reminded me - which follows this non-systematically - that the original data sets are rather unbiased. While OSSOS' data, which was weakening significance when included, was excluded by Brown because OSSOS effectively punished themselves out (saw that they had observer bias). So I am much more happy by the recent new aligned objects.
I have not had time to read the whole thread but I saw a discussion on Planet Nine formation and migration. There are some fresh advances, one on which Batygin commented, namely revisiting the problem that the distribution of protoplanetary disk observed masses show they do not yet add up to the planet distribution masses [ http://dx.doi.org/10.1051/0004-6361/201834076 ]. Two mechanisms could be acting, one is pebble formation/disk instabilities and rapid planet formation, the other is environmental (cloud) mass flows and so absence of gravitational freedom, both of which could inform on P9 size vs migration end mechanism. The other advance is that Bill Bottke (and Levison et cetera) has been forced by data on Trojan binaries to suggest that Jupiter-Saturn migration happened within 100 Myrs* [ https://www.nature.com/articles/s41550-018-0564-3 ].
*) Coincidentally, the latest combined genomic and fossil evidence agrees that *if* a late bombardment spike happened anyway - and besides the iffy lunar basin data other lunar data disagree AFAIK - life did not seem to notice. The most likely emergence date is within 40 Myrs after Moon formation, which also adds up to within 100 Myrs. Mind that phylogenies tend to push roots as far back as they can go, but these are newly developed and comprehensive statistical methods and done by some of the best groups, still pushing a much later emergence prior way back. ["Integrated genomic and fossil evidence illuminates life’s early evolution and eukaryote origin", Nature Ecology and Evolution, Betts et al.] YMMV, but it adds to a suggestion of an early P9 migration.
EDITS: 1. Due to accidental posting before finishing 1st draft. 2. 2nd draft. 3. 3d draft.
Post by: Star One on 10/09/2018 05:54 am
My pet theory is that these simulations fail to introduce the occasional binary star floating by. Without it, you are left simulating large planets that disturb orbits and continue to look for things that are not there. But +1 if anyone finds another planet 10x Earth's size/mass.
https://www.popularmechanics.com/space/solar-system/a19574767/passing-star-nudged-solar-system-70000-years-ago-may-have-sent-comets-flying-in/
Brown has addressed this factor and it has dismissed as it would only be a transitory effect.
Post by: Star One on 12/08/2018 10:02 am
https://twitter.com/plutokiller/status/1071254311005413376
Post by: Star One on 12/10/2018 10:38 pm
Quote
Final night (of 7!) at the
@SubaruTelescope
. Once again a spectacular looking one. I haven't had 7 nights of good data in a row since, uh, uh, uh, uh, uh, uh, ever? My feeling is that *if* we are going to find Planet Nine with Subaru these are the data in which we will find it.
https://twitter.com/plutokiller/status/1071978898458464256
Quote
This week's data covers something like the ~85% confidence region of where we think Planet Nine is (except for the region of the Milky Way galaxy, which we'll talk about later).
https://twitter.com/plutokiller/status/1071979337442717701
Quote
If P9 is in the region we have surveyed, I'd say we have a 90-95% chance of detecting it. 5-10% of the time it might be too close to a star and we miss it. But we are trying hard to prevent that problem by looking on multiple nights.
https://twitter.com/plutokiller/status/1071979658856386560
Quote
My biggest fear, though, is the Milky Way galaxy. There are SO MANY stars that we tend to avoid even looking there. But our predicted region goes through the Milky Way. So we are going to have to deal. We're testing a little of that this week,
https://twitter.com/plutokiller/status/1071980020594237440
Quote
but we will be back in February to really beat hard on the Milky Way. Perhaps by using some more sophisticated image analysis techniques we'll be able to pick out P9 in a sea of star. (perhaps we won't have to because we found it already!)
https://twitter.com/plutokiller/status/1071980277570752513
Quote
What happens if we don't find it? Overall, if our predictions are right, I'd say we are 80% certain of success. 80% is smaller than I like, but filling in that last 20% would take many many many more nights on the telescope. So perhaps if we don't find it we were just unlucky.
https://twitter.com/plutokiller/status/1071980641896419328
Quote
What if we're just wrong, though? I have few doubts that something like the predicted P9 exists (see new paper coming out in January for the 99.8% confidence level statistics....), but there is always the chance that we are missing something in predicting where it should be.
https://twitter.com/plutokiller/status/1071980986114629632
Quote
Last week
@kbatygin
and I spent a lot of time discussing what could possibly go wrong with the predictions. We have some new ideas to try, though we are not convinced they'll change anything. IT SHOULD BE WHERE WE SAY. ahem.
https://twitter.com/plutokiller/status/1071981428466900992
Quote
So that's where we stand. With the absurdly good data from this week we have a serious shot. It's just going to now take some time to sort through it all (for example: I didn't expect to get so much data; need new disks drives.....). Stay tuned!
https://twitter.com/plutokiller/status/1071981721594122240
Post by: Star One on 01/21/2019 06:44 am
Quote
The strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
Post by: clongton on 01/21/2019 09:59 am
Mystery Orbits In Outermost Reaches Of Solar System Not Caused By 'Planet Nine' (https://scienmag.com/mystery-orbits-in-outermost-reaches-of-solar-system-not-caused-by-planet-nine/)QuoteThe strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
"Researchers"? More like naysayers. The authors are a PHD student researcher and his former Professor - *not* astronomers. The referenced article does not identify any other "astronomers" that hold to this theory. It also clearly states that to achieve the same effect as the theorized planet 9, the combined mass of TNOs would need to be more than 10x Earth mass while at the same time admitting that the current scientific consensus is that the existing combined mass of such objects is estimated at 1/10th Earth mass.
It would be a decent working theory if it weren't for that *massive* mass discrepancy and the statement in the article that "astronomers" are saying this, when clearly they are not. These 2 academics set out, on their own, to create a theory that would explain the effect of planet 9, but without planet 9. THEY developed this model, not "astronomers".
Provide us with the names of some accredited and known astronomers who hold to this theory, who can also explain the mass discrepancy, and perhaps some reasonable credibility can be assigned to this. Lacking that there is none.
Post by: Star One on 01/21/2019 11:40 am
Mystery Orbits In Outermost Reaches Of Solar System Not Caused By 'Planet Nine' (https://scienmag.com/mystery-orbits-in-outermost-reaches-of-solar-system-not-caused-by-planet-nine/)QuoteThe strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
"Researchers"? More like naysayers. The authors are a PHD student researcher and his former Professor - *not* astronomers. The referenced article does not identify any other "astronomers" that hold to this theory. It also clearly states that to achieve the same effect as the theorized planet 9, the combined mass of TNOs would need to be more than 10x Earth mass while at the same time admitting that the current scientific consensus is that the existing combined mass of such objects is estimated at 1/10th Earth mass.
It would be a decent working theory if it weren't for that *massive* mass discrepancy and the statement in the article that "astronomers" are saying this, when clearly they are not. These 2 academics set out, on their own, to create a theory that would explain the effect of planet 9, but without planet 9. THEY developed this model, not "astronomers".
Provide us with the names of some accredited and known astronomers who hold to this theory, who can also explain the mass discrepancy, and perhaps some reasonable credibility can be assigned to this. Lacking that there is none.
It does say in that article and I do remember this that others had put forward a similar theory. Wish I could remember the details now but it was sometime ago.
Post by: Bynaus on 01/21/2019 11:47 am
Mystery Orbits In Outermost Reaches Of Solar System Not Caused By 'Planet Nine' (https://scienmag.com/mystery-orbits-in-outermost-reaches-of-solar-system-not-caused-by-planet-nine/)QuoteThe strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
"Researchers"? More like naysayers. The authors are a PHD student researcher and his former Professor - *not* astronomers. The referenced article does not identify any other "astronomers" that hold to this theory. It also clearly states that to achieve the same effect as the theorized planet 9, the combined mass of TNOs would need to be more than 10x Earth mass while at the same time admitting that the current scientific consensus is that the existing combined mass of such objects is estimated at 1/10th Earth mass.
It would be a decent working theory if it weren't for that *massive* mass discrepancy and the statement in the article that "astronomers" are saying this, when clearly they are not. These 2 academics set out, on their own, to create a theory that would explain the effect of planet 9, but without planet 9. THEY developed this model, not "astronomers".
Provide us with the names of some accredited and known astronomers who hold to this theory, who can also explain the mass discrepancy, and perhaps some reasonable credibility can be assigned to this. Lacking that there is none.
It does say in that article and I do remember this that others had put forward a similar theory. Wish I could remember the details now but it was sometime ago.
See e.g. here: https://www.nature.com/articles/d41586-018-05345-0
Post by: clongton on 01/21/2019 02:28 pm
Mystery Orbits In Outermost Reaches Of Solar System Not Caused By 'Planet Nine' (https://scienmag.com/mystery-orbits-in-outermost-reaches-of-solar-system-not-caused-by-planet-nine/)QuoteThe strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
"Researchers"? More like naysayers. The authors are a PHD student researcher and his former Professor - *not* astronomers. The referenced article does not identify any other "astronomers" that hold to this theory. It also clearly states that to achieve the same effect as the theorized planet 9, the combined mass of TNOs would need to be more than 10x Earth mass while at the same time admitting that the current scientific consensus is that the existing combined mass of such objects is estimated at 1/10th Earth mass.
It would be a decent working theory if it weren't for that *massive* mass discrepancy and the statement in the article that "astronomers" are saying this, when clearly they are not. These 2 academics set out, on their own, to create a theory that would explain the effect of planet 9, but without planet 9. THEY developed this model, not "astronomers".
Provide us with the names of some accredited and known astronomers who hold to this theory, who can also explain the mass discrepancy, and perhaps some reasonable credibility can be assigned to this. Lacking that there is none.
It does say in that article and I do remember this that others had put forward a similar theory. Wish I could remember the details now but it was sometime ago.
See e.g. here: https://www.nature.com/articles/d41586-018-05345-0 (https://www.nature.com/articles/d41586-018-05345-0)
Thanks for that but it still does not address the massive mass discrepancy. The scientific consensus is still that the combined mass of all the TNOs is 1/10th Earth mass. That's an order of magnitude too little.
Post by: Bynaus on 01/21/2019 02:41 pm
Mystery Orbits In Outermost Reaches Of Solar System Not Caused By 'Planet Nine' (https://scienmag.com/mystery-orbits-in-outermost-reaches-of-solar-system-not-caused-by-planet-nine/)QuoteThe strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.
"Researchers"? More like naysayers. The authors are a PHD student researcher and his former Professor - *not* astronomers. The referenced article does not identify any other "astronomers" that hold to this theory. It also clearly states that to achieve the same effect as the theorized planet 9, the combined mass of TNOs would need to be more than 10x Earth mass while at the same time admitting that the current scientific consensus is that the existing combined mass of such objects is estimated at 1/10th Earth mass.
It would be a decent working theory if it weren't for that *massive* mass discrepancy and the statement in the article that "astronomers" are saying this, when clearly they are not. These 2 academics set out, on their own, to create a theory that would explain the effect of planet 9, but without planet 9. THEY developed this model, not "astronomers".
Provide us with the names of some accredited and known astronomers who hold to this theory, who can also explain the mass discrepancy, and perhaps some reasonable credibility can be assigned to this. Lacking that there is none.
It does say in that article and I do remember this that others had put forward a similar theory. Wish I could remember the details now but it was sometime ago.
See e.g. here: https://www.nature.com/articles/d41586-018-05345-0 (https://www.nature.com/articles/d41586-018-05345-0)
Thanks for that but it still does not address the massive mass discrepancy. The scientific consensus is still that the combined mass of all the TNOs is 1/10th Earth mass. That's an order of magnitude too little.
Even two orders of magnitude. Well, the mass of the Kuiper belt is estimated to be 0.1 Earth masses (~1 Mars mass) based on the objects we see or infer (we don't see them all, but we take the largest ones and extrapolate using typical size-frequency distributions to the smaller ones - most of the mass is in the big objects anyway).
Beyond the Kuiper belt, we can't say much, we know too few objects to do solid statistics. But some estimates for the mass of the scattered disk exceed 0.1 Earth masses in total, so in fact it could well be more massive than the "actual" Kuiper belt! Mass estimates for the Oort cloud are often in the several Earth masses region... So could there be some kind of inner Oort cloud with 10 Earth masses? Can't really say no to that right now - and if it is so, it might well explain the orbits of the bodies that were allegedly affected by P9, at least, the new paper claims that. Personally, to me this seems like a less elegant idea than P9, and P9 is testable, whereas this new idea is difficult to test right now.
Post by: Alpha_Centauri on 01/21/2019 02:41 pm
Yes this is not a new idea, the trouble is there's not any shred of empirical evidence that such a massive eccentric disk exists.
Edit: Btw, here's the paper being referenced,
https://arxiv.org/pdf/1804.06859.pdf
Post by: Stan-1967 on 01/21/2019 02:47 pm
https://www.colorado.edu/aps/ann-marie-madigan
She & her research team have been pursuing these theories since at lest 2016. The modeling of the physics is computationaly intensive, & gates deeper work ( she says). She has some decent talks up on Youtube where she presents her side.
Post by: clongton on 01/21/2019 04:09 pm
Sensationalist reporting really damages people's understanding of science. [snip]
Thanks Alpha. You expressed my sentiments far better than I did.
By no means am I discounting the possibility of the shepherding being accounted for by a massive TNO/Ort Cloud disk. What I am saying is, exactly as you expressed, articles like that do more damage than good for the scientific community. When a researcher proposes something they need to (1) present some solid empirical data that actually supports their theory and (2) acknowledge all known shortcomings of their theory and provide at least some genuinely reasonable arguments adjudicating the shortcomings. The referenced article did acknowledge the massive mass shortcoming but not as a shortcoming - and - separated the required mass vs. the scientifically accepted mass by several paragraphs, a shortcoming that the casual reader would thus have totally missed.
Post by: Star One on 01/21/2019 04:09 pm
Sensationalist reporting really damages people's understanding of science. Time and time again you get these articles that radically overstate the studies they quote. The paper itself explicitly says it is not evidence ruling out Planet 9.
Yes this is not a new idea, the trouble is there's not any shred of empirical evidence that such a massive eccentric disk exists.
Edit: Btw, here's the paper being referenced,
https://arxiv.org/pdf/1804.06859.pdf
To be fair it does actually mention that in the article itself.
Sensationalist reporting really damages people's understanding of science. [snip]
Thanks Alpha. You expressed my sentiments far better than I did.
By no means am I discounting the possibility of the shepherding being accounted for by a massive TNO/Ort Cloud disk. What I am saying is, exactly as you expressed, articles like that do more damage than good for the scientific community. When a researcher proposes something they need to (1) present some solid empirical data that actually supports their theory and (2) acknowledge all known shortcomings of their theory and provide at least some genuinely reasonable arguments adjudicating the shortcomings. The referenced article did acknowledge the massive mass shortcoming but not as a shortcoming - and - separated the required mass vs. the scientifically accepted mass by several paragraphs, a shortcoming that the casual reader would thus have totally missed.
Why would they have missed it. It’s hardly hidden and do at least credit the average reader with some intelligence to be able to associate ideas a few paragraphs apart. You seem to be veering dangerously close to attacking the article because you appear to have some general axe to grind against scientific reporting, rather than constraining yourself to a specific criticism.
Post by: Comga on 01/21/2019 04:16 pm
Justin Davenport's reviewed the latest paper on this:
https://www.nasaspaceflight.com/2018/10/new-dwarf-planet-goblin-solar-system-discovered/
Good article! Don't want to nitpick, but here's a few things I noticed: Typo in the first sentence "dwarf planet 2015" instead of "2015 TG387".
Also, its worth noting that despite being called a dwarf planet by the authors and the press release, it isn't on the IAU's official list of dwarf planets (which only includes five worlds so far), nor is it clear that it should be, as its size is only known very approximately (say, within a factor of two), and the nominal diameter given (300 km) falls into the transition region where bodies start to fall into hydrostatic equilibrium, the nr. 1 requirement to be classified a dwarf planet (apart from orbiting the sun). So it might turn out to be too small to be in hydrostatic equilibrium.
Finally, the inner Oort cloud isn't really a "part of the sky", as its all around us, rather a region in the outer solar system.
Sorry to chime in late, but a pet peeve: 300 km should not be converted to 186 miles. (and not because Imperial units are so archaic.) 200 miles is a better representation. It's within the error bars and better represents the accuracy of the estimate.
Post by: Star One on 01/21/2019 04:21 pm
Justin Davenport's reviewed the latest paper on this:
https://www.nasaspaceflight.com/2018/10/new-dwarf-planet-goblin-solar-system-discovered/
Good article! Don't want to nitpick, but here's a few things I noticed: Typo in the first sentence "dwarf planet 2015" instead of "2015 TG387".
Also, its worth noting that despite being called a dwarf planet by the authors and the press release, it isn't on the IAU's official list of dwarf planets (which only includes five worlds so far), nor is it clear that it should be, as its size is only known very approximately (say, within a factor of two), and the nominal diameter given (300 km) falls into the transition region where bodies start to fall into hydrostatic equilibrium, the nr. 1 requirement to be classified a dwarf planet (apart from orbiting the sun). So it might turn out to be too small to be in hydrostatic equilibrium.
Finally, the inner Oort cloud isn't really a "part of the sky", as its all around us, rather a region in the outer solar system.
Sorry to chime in late, but a pet peeve: 300 km should not be converted to 186 miles. (and not because Imperial units are so archaic.) 200 miles is a better representation. It's within the error bars and better represents the accuracy of the estimate.
We are trying to get rid of imperial measurement in most of the world not encourage it.
Post by: JH on 01/21/2019 05:16 pm
We are trying to get rid of imperial measurement in most of the world not encourage it.
He was not promoting the use of imperial units, he was saying that if you are going to give a converted estimate (because, as much as many people go into conniptions at the prospect, hundreds of millions of people think in miles) you should not give a false sense of the accuracy by giving an exact conversion. The diameter is only known to be roughly 300 km, therefore it is more correct to say 200 miles, rather than 186 miles.
Post by: Alpha_Centauri on 01/21/2019 05:17 pm
I despair when I see articles posted on the latest about Planet Nine and you get a whole host of "but I thought Planet 9 was disproved months ago?" comments from folks. This constant back and forth over the "facts" generates mistrust of scientists and science itself.Sensationalist reporting really damages people's understanding of science. [snip]
Thanks Alpha. You expressed my sentiments far better than I did.
By no means am I discounting the possibility of the shepherding being accounted for by a massive TNO/Ort Cloud disk. What I am saying is, exactly as you expressed, articles like that do more damage than good for the scientific community. When a researcher proposes something they need to (1) present some solid empirical data that actually supports their theory and (2) acknowledge all known shortcomings of their theory and provide at least some genuinely reasonable arguments adjudicating the shortcomings. The referenced article did acknowledge the massive mass shortcoming but not as a shortcoming - and - separated the required mass vs. the scientifically accepted mass by several paragraphs, a shortcoming that the casual reader would thus have totally missed.
I can't exactly blame them for being confused, headlines like this article's are irresponsible. Even if the article does (somewhat) clarify the situation further down the page the damage has already been done.
Yes to be clear I'm not arguing in favour or against either idea (just that the disk idea is no more compelling, and not without issues), the real problem is the way journalists inject fake drama into the whole thing and distort what the scientific consensus on the topic is.
Post by: vjkane on 01/21/2019 07:24 pm
Yes to be clear I'm not arguing in favour or against either idea (just that the disk idea is no more compelling, and not without issues), the real problem is the way journalists inject fake drama into the whole thing and distort what the scientific consensus on the topic is.Models are only representation of known or possible relationships between data. They are all wrong to some degree or other. In this case, the data are sparse and have multiple possible explanations and therefore modeled relationships. That causes scientists to propose multiple, competing explanations. Eventually, one model (or type of model) tends to be accepted by the community. In this case, that could come from finding another large planet, no discovery of a planet for a long time (although you can't prove a negative, just convince most knowledgeable folks that it is highly unlikely), or someone comes up with a model that fits the data much better than any current attempt.
So the back and forth is to be expected.
Post by: faramund on 01/21/2019 09:20 pm
Sensationalist reporting really damages people's understanding of science. [snip]
Thanks Alpha. You expressed my sentiments far better than I did.
By no means am I discounting the possibility of the shepherding being accounted for by a massive TNO/Ort Cloud disk. What I am saying is, exactly as you expressed, articles like that do more damage than good for the scientific community. When a researcher proposes something they need to (1) present some solid empirical data that actually supports their theory and (2) acknowledge all known shortcomings of their theory and provide at least some genuinely reasonable arguments adjudicating the shortcomings. The referenced article did acknowledge the massive mass shortcoming but not as a shortcoming - and - separated the required mass vs. the scientifically accepted mass by several paragraphs, a shortcoming that the casual reader would thus have totally missed.
I strongly disagree that (1) is needed. Large amounts of science is built on hypothesis, i.e. a theory that might be correct. This frequently happens, and then later science tries to find stronger evidence either for or against that theory. Its not uncommon in science for there to be multiple conflicting theories that attempt to explain some situation/effect. Some of those theories will be considered stronger, because they have more evidence, and some weaker, maybe being not much stronger than a thought bubble. I'm completely happy with this, and really, I can't imagine any functional alternative.
Post by: Alpha_Centauri on 01/21/2019 09:46 pm
I'm not talking about how science works, i'm talking about how it is communicated.Yes to be clear I'm not arguing in favour or against either idea (just that the disk idea is no more compelling, and not without issues), the real problem is the way journalists inject fake drama into the whole thing and distort what the scientific consensus on the topic is.Models are only representation of known or possible relationships between data. They are all wrong to some degree or other. In this case, the data are sparse and have multiple possible explanations and therefore modeled relationships. That causes scientists to propose multiple, competing explanations. Eventually, one model (or type of model) tends to be accepted by the community. In this case, that could come from finding another large planet, no discovery of a planet for a long time (although you can't prove a negative, just convince most knowledgeable folks that it is highly unlikely), or someone comes up with a model that fits the data much better than any current attempt.
So the back and forth is to be expected.
When I speak of back and forth I mean sensationalist headlines of "model disproves X", when it does nothing of the sort, then almost equally certain statements when a counter-study comes along saying "new model proves X". Eventually people just give up and come to the conclusion scientists haven't a clue.
Post by: whitelancer64 on 01/21/2019 10:08 pm
What's really lacking is the media reports. Clickbait headlines that don't convey what the science actually shows.
Post by: Star One on 01/21/2019 10:32 pm
I'm not talking about how science works, i'm talking about how it is communicated.Yes to be clear I'm not arguing in favour or against either idea (just that the disk idea is no more compelling, and not without issues), the real problem is the way journalists inject fake drama into the whole thing and distort what the scientific consensus on the topic is.Models are only representation of known or possible relationships between data. They are all wrong to some degree or other. In this case, the data are sparse and have multiple possible explanations and therefore modeled relationships. That causes scientists to propose multiple, competing explanations. Eventually, one model (or type of model) tends to be accepted by the community. In this case, that could come from finding another large planet, no discovery of a planet for a long time (although you can't prove a negative, just convince most knowledgeable folks that it is highly unlikely), or someone comes up with a model that fits the data much better than any current attempt.
So the back and forth is to be expected.
When I speak of back and forth I mean sensationalist headlines of "model disproves X", when it does nothing of the sort, then almost equally certain statements when a counter-study comes along saying "new model proves X". Eventually people just give up and come to the conclusion scientists haven't a clue.
Are you going to continue to take this thread off topic with your anti-media crusade you seem to be on at the moment?
Post by: Alpha_Centauri on 01/21/2019 10:38 pm
Anyway, speaking of the devil here's Brown and Batygin's new "new model proves X" paper.
http://web.gps.caltech.edu/~mbrown/papers/ps/clustering.pdf
Quote
ORBITAL CLUSTERING IN THE DISTANT SOLAR SYSTEM
The most distant Kuiper belt objects appear to be clustered in longitude of perihelion and in
orbital pole position. To date, the only two suggestions for the cause of these apparent clusterings
have been either the effects of observational bias or the existence of the distant giant planet in an
eccentric inclined orbit known as Planet Nine. To determine if observational bias can be the cause of
these apparent clusterings, we develop a rigorous method of quantifying the observational biases in
the observations of longitude of perihelion and orbital pole position. From this now more complete
understanding of the biases we calculate that the probability that these distant Kuiper belt objects
would be clustered as strongly as observed in both longitude of perihelion and in orbital pole position
is only 0.2%. While explanations other than Planet Nine may someday be found, the statistical
significance of this clustering is now difficult to discount.
Post by: Star One on 01/21/2019 11:21 pm
Talking about how the Planet 9 debate is being presented is hardly off topic, if you don't like it don't read it and stick to shitposting about aliens.
Anyway, speaking of the devil here's Brown and Batygin's new "new model proves X" paper.
http://web.gps.caltech.edu/~mbrown/papers/ps/clustering.pdfQuoteORBITAL CLUSTERING IN THE DISTANT SOLAR SYSTEM
The most distant Kuiper belt objects appear to be clustered in longitude of perihelion and in
orbital pole position. To date, the only two suggestions for the cause of these apparent clusterings
have been either the effects of observational bias or the existence of the distant giant planet in an
eccentric inclined orbit known as Planet Nine. To determine if observational bias can be the cause of
these apparent clusterings, we develop a rigorous method of quantifying the observational biases in
the observations of longitude of perihelion and orbital pole position. From this now more complete
understanding of the biases we calculate that the probability that these distant Kuiper belt objects
would be clustered as strongly as observed in both longitude of perihelion and in orbital pole position
is only 0.2%. While explanations other than Planet Nine may someday be found, the statistical
significance of this clustering is now difficult to discount.
I think this new article by Jason Wright about SETI & how it’s treated by some scientists rather neatly answers your childish comment about my supposed posting about aliens. And for want going off topic myself is sufficient a response.
https://www.centauri-dreams.org/2019/01/21/oumuamua-seti-and-the-media/
Post by: LouScheffer on 01/22/2019 02:20 am
It would be a decent working theory if it weren't for that *massive* mass discrepancy ...
It's not obvious to me that there is a mass discrepancy. The 'Planet 9' folks are positing a 10 Earth mass planet. So in both case there are 10 Earth masses of material in the Kuiper belt. In one case it's combined into a planet; in the other it has remained small objects in a disc. And if the P9 folks can barely see a 10 Earth mass planet, why could there not be 100 x 0.1 Earth mass planetoids, or 1000 x 0.01 Earth mass planetoids?
I'm not saying I believe in the disk theory, just that the mass discrepancy is not as strong a hypothesis-killer as it might seem, since the best alternative (P9) also has the same total mass in the Kuiper belt.
Post by: libra on 01/22/2019 06:55 am
100 miles = 160 km
200 miles = 320 km
Post by: Bynaus on 01/22/2019 06:59 am
https://mobile.twitter.com/plutokiller/status/1087495838379651072
Post by: Alpha_Centauri on 01/22/2019 06:28 pm
It would be a decent working theory if it weren't for that *massive* mass discrepancy ...
It's not obvious to me that there is a mass discrepancy. The 'Planet 9' folks are positing a 10 Earth mass planet. So in both case there are 10 Earth masses of material in the Kuiper belt. In one case it's combined into a planet; in the other it has remained small objects in a disc. And if the P9 folks can barely see a 10 Earth mass planet, why could there not be 100 x 0.1 Earth mass planetoids, or 1000 x 0.01 Earth mass planetoids?
I'm not saying I believe in the disk theory, just that the mass discrepancy is not as strong a hypothesis-killer as it might seem, since the best alternative (P9) also has the same total mass in the Kuiper belt.
The point is if such a disk existed then the lowest-perihelion and largest members would likely have been found already, and the effect they would have on TNO population statistics would imply a large missing mass. However empirical studies of TNOs shows no evidence of a great reservoir of undiscovered objects, hence the mass discrepancy. Sure there may be some reason why we haven't seen it, but as things stand it is an issue that does make the disk idea less convincing.
It's easier to hide a 10 Mearth point source than a 10 Mearth disk.
Post by: Star One on 01/22/2019 08:40 pm
Is Planet Nine just a ring of icy bodies? (http://www.findplanetnine.com/2019/01/is-planet-nine-just-ring-of-icy-bodies.html?m=1)
Quote
Finally, however, after three years, a new hypothesis has been proposed which can at least explain the alignments without Planet Nine. The basic trick is to take Planet Nine and split it up into a massive ring of bodies on an eccentric inclined orbit like that of Planet Nine’s. Because Planet Nine’s long distance gravitational effects are mostly caused by the long term average position of Planet Nine (which is basically an inclined eccentric ring!) this ring has more or less the same effects that Planet Nine has. (For the aficionados out there, read this as "Planet Nine's interactions are predominantly secular rather than resonant.")
I am happy that there is finally an alternative explanation, even if that alternative is only Planet-Nine-ground-up-into-a-ring.
Post by: tappa on 02/06/2019 02:53 pm
If there is any verified news please point me to it. Thanks
Post by: Star One on 02/06/2019 03:06 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
Can I ask where you saw this as I cannot see anything on either of their Twitter threads?
Was it this? And I wonder if he was meant to say anything.
https://twitter.com/astrosumo/status/1093033743252508673
Post by: Bynaus on 02/06/2019 04:00 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
As I understand it, the data reduction on their fall run is not done yet. With the new run, they are just covering additional "territory" (areas of the sky where P9 could be). If they had found something they wanted to confirm, they would not go back to Subaru, but use a telescope with a more narrow field of view and better resolution / sensitivity. Subaru is great for looking simultaneously at large areas of the sky, which is what you want to do if you are searching for an object like P9.
Post by: Star One on 02/06/2019 04:23 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
As I understand it, the data reduction on their fall run is not done yet. With the new run, they are just covering additional "territory" (areas of the sky where P9 could be). If they had found something they wanted to confirm, they would not go back to Subaru, but use a telescope with a more narrow field of view and better resolution / sensitivity. Subaru is great for looking simultaneously at large areas of the sky, which is what you want to do if you are searching for an object like P9.
The only problem with that idea is Mr Brown usually announces that on his Twitter thread when he’s going out there if it’s a routine pre-planned visit. He hasn’t done so this time.
Post by: tappa on 02/06/2019 04:48 pm
Yes
Was it this? And I wonder if he was meant to say anything.
https://twitter.com/astrosumo/status/1093033743252508673
Post by: Alpha_Centauri on 02/06/2019 04:49 pm
Post by: Star One on 02/06/2019 05:18 pm
There will be a paper out next week, though before anyone gets excited I seem to remember them saying some time ago they were working on a paper on refinements to P9's orbital parameters. I don't think it's a discovery paper.
Hasn’t that one already been published, it’s the one a small number of posts up thread?
Post by: Alpha_Centauri on 02/06/2019 05:21 pm
https://mobile.twitter.com/plutokiller/status/1092781179504185344
https://mobile.twitter.com/kbatygin/status/1092882186619969536
Post by: Star One on 02/06/2019 05:59 pm
No, there's another as yet unpublished one coming;
https://mobile.twitter.com/plutokiller/status/1092781179504185344
https://mobile.twitter.com/kbatygin/status/1092882186619969536
Thanks. Are we sure that’s not a discovery paper reading those links?
Post by: Alpha_Centauri on 02/06/2019 06:07 pm
Post by: Bynaus on 02/06/2019 06:29 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
As I understand it, the data reduction on their fall run is not done yet. With the new run, they are just covering additional "territory" (areas of the sky where P9 could be). If they had found something they wanted to confirm, they would not go back to Subaru, but use a telescope with a more narrow field of view and better resolution / sensitivity. Subaru is great for looking simultaneously at large areas of the sky, which is what you want to do if you are searching for an object like P9.
The only problem with that idea is Mr Brown usually announces that on his Twitter thread when he’s going out there if it’s a routine pre-planned visit. He hasn’t done so this time.
It wasn't news to me that they would go back in February. I have read this before, either on this twitter feed or perhaps in that longform interview/story from a few weeks ago...
EDIT: found it: https://longreads.com/2019/01/22/the-hunt-for-planet-nine/
Search for "February" on the page.
Post by: Star One on 02/06/2019 06:38 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
As I understand it, the data reduction on their fall run is not done yet. With the new run, they are just covering additional "territory" (areas of the sky where P9 could be). If they had found something they wanted to confirm, they would not go back to Subaru, but use a telescope with a more narrow field of view and better resolution / sensitivity. Subaru is great for looking simultaneously at large areas of the sky, which is what you want to do if you are searching for an object like P9.
The only problem with that idea is Mr Brown usually announces that on his Twitter thread when he’s going out there if it’s a routine pre-planned visit. He hasn’t done so this time.
It wasn't news to me that they would go back in February. I have read this before, either on this twitter feed or perhaps in that longform interview/story from a few weeks ago...
EDIT: found it: https://longreads.com/2019/01/22/the-hunt-for-planet-nine/
Search for "February" on the page.
And so the wait goes on.
But I will wait to see if Brown says anything on his Twitter thread.
Post by: Alpha_Centauri on 02/07/2019 06:51 am
https://mobile.twitter.com/plutokiller/status/1093189343219310592
The parameters have changed somewhat, which is interesting from a point of view of trying to find it, particularly the lower semi-major axis,
https://mobile.twitter.com/plutokiller/status/1071386572585496576
Post by: Bynaus on 02/07/2019 07:36 am
Post by: Alpha_Centauri on 02/07/2019 09:44 am
Post by: Star One on 02/07/2019 12:37 pm
It actually kind of worries me, since it makes it more likely it should have been found by now. I'm going to have another look at the WISE imagery when the new catalogue comes out.
Brown has said previously he believes P9 is currently sitting at its furthest point in its orbit. Plus WISE wasn’t infallible.
Post by: Alpha_Centauri on 02/07/2019 12:49 pm
Post by: Star One on 02/07/2019 01:39 pm
With a smaller semimajor axis aphelion is much closer to the Sun than the first estimates, putting it within touching distance of existing surveys.
I hope they address that concern.
Post by: philw1776 on 02/11/2019 04:40 pm
Just read on twitter that Mike Brown & Konstantin Batygin are going back to Subaru for further observations. What could this mean? Since they were at Subaru in December, does it mean that they found something & they are going back to confirm? There has been total radio silence on planet 9 from both Mike & Konstantin.
If there is any verified news please point me to it. Thanks
As I understand it, the data reduction on their fall run is not done yet. With the new run, they are just covering additional "territory" (areas of the sky where P9 could be). If they had found something they wanted to confirm, they would not go back to Subaru, but use a telescope with a more narrow field of view and better resolution / sensitivity. Subaru is great for looking simultaneously at large areas of the sky, which is what you want to do if you are searching for an object like P9.
The only problem with that idea is Mr Brown usually announces that on his Twitter thread when he’s going out there if it’s a routine pre-planned visit. He hasn’t done so this time.
He announced the Feb plan to return months ago. Going to observe in the dreaded, crowded Milky Way. It was even posted here in this thread.
https://twitter.com/plutokiller/status/1071980277570752513
Bottom Line: Nothing new. Part of the plan. Good Luck!
Post by: Bynaus on 02/11/2019 10:05 pm
https://mobile.twitter.com/plutokiller/status/1093938173053362176
So if it takes 5000 years for a revolution around the sun, it would put its semi-major axis at 300 AU. That's... remarkably close! But ok, if its smaller than originally thought, it will be less bright. Going from 15 Earth masses to 6 Earth masses might reduce its radius from Neptune-like (~4 Earth radii) to super-Earth-like (~1.5-2 Earth radii), which could mean a reduction in brightness on the order of a factor 4 to 7. On the other hand, the brightness varies as the fourth power of distance. A reduction in the semi-major-axis by ~50% is just enough to compensate (i.e., an object of ~1.5-2 Earth radii at 300 AU has about the same brightness as an object of ~4 Earth radii at 450 AU).
Post by: clongton on 02/12/2019 08:12 pm
So if it takes 5000 years for a revolution around the sun, it would put its semi-major axis at 300 AU. That's... remarkably close!
Just a curiosity question Bynaus.
That sounds like you're assuming that the sun is at the center of Planet 9's elliptical orbit. Have you considered that the sun may not be at the center? For example, say the elliptical orbit is one of high eccentricity. Is it possible that the sun could instead be at a focal point, like in the attached diagram, instead of at the center of the ellipse? That could add some interesting dynamics to the "shepherding" of some of the commets and TNOs, especially with an inclination of ~20 degrees. The semi-major axis could still be between 300 and 500 AU but the perihelion could actually be somewhere inside the zone where the 8 known planets are. If so that might create theories regarding Pluto's very odd orbit, inside and outside Neptune's orbit, Uranus' odd rotation angle and Venus' clockwise rotation. A large body passing thru the planetary zone once every few thousands of years would surely cause major disruptions to any planet that was close enough to its path, such as these.
Like I said, just a curiosity question.
Post by: as58 on 02/12/2019 08:20 pm
So if it takes 5000 years for a revolution around the sun, it would put its semi-major axis at 300 AU. That's... remarkably close!
Just a curiosity question Bynaus.
That sounds like you're assuming that the sun is at the center of the ellipse. Have you considered that the sun may not be at the center? For example, say the elliptical orbit is one of high eccentricity. Is it possible that the sun could instead be at a focal point, like in the attached diagram, instead of at the center of the ellipse? That could add some interesting dynamics to the "shepherding" of some of the commets and TNOs, especially with an inclination of ~20 degrees. The semi-major axis could still be between 300 and 500 AU but the perihelion could actually be somewhere inside the zone where the 8 known planets are.
Like I said, just a curiosity question.
Sun has to be at the focus and the orbital period follow directly from Kepler's third law, so I'm not sure what you mean.
Post by: Bynaus on 02/13/2019 04:41 am
Post by: clongton on 02/13/2019 04:05 pm
As as58 said, the sun is always at a focus. Unless the eccentricity of P9 is >0.9, it won't cross paths with the other 8 (for a = 300 AU). And it won't, because that would be a dynamically unstable orbit which would have been destroyed many billion years ago.
Thank you.
Post by: Oumuamua on 02/22/2019 10:22 am
I've only been able to find one article so far:
https://www.sciencemag.org/news/2019/02/astronomers-discover-solar-system-s-most-distant-object-nicknamed-farfarout (https://www.sciencemag.org/news/2019/02/astronomers-discover-solar-system-s-most-distant-object-nicknamed-farfarout)
The object was apparently discovered this week, and thus appears to still lack a proper designation, and has not been published yet.
Unless they can recover it in existing images it will likely take a few years before they know if it is compatible with current models for planet 9.
Post by: Star One on 02/25/2019 04:05 pm
https://www.sciencealert.com/astronomers-have-discovered-an-even-farther-outer-object-than-dwarf-planet-farout
Post by: Star One on 02/26/2019 08:34 pm
Quote
What’s going on in the Kuiper Belt? Objects orbit differently than expected. Why? Is it a planet? Nah. Wait. Yes! “OMG, there’s a planet out there! ... If you believe the data, there has to be a planet out there.” Does it stand up to scrutiny? Time will tell. -
@plutokiller
https://twitter.com/ClemsonResearch/status/1098698452245102594
Quote
The local media report ... Hopefully video of the event shows up online so all of us can watch.
https://twitter.com/WordsmithFL/status/1099628665153953792
Quote
This WEDNESDAY, 2/27,
@TWIScience
wil be LIVE @ 8 p.m. PT, with a LIVE interview with
@kbatygin
and
@plutokiller
, THE PLANET 9 GUYS!! (link: http://twis.org/live) twis.org/live OR (link: http://facebook.com/ThisWeekinScience) facebook.com/ThisWeekinScie….
https://twitter.com/TWIScience/status/1100145962176135168
https://youtu.be/gG58idb6HuA
Post by: Alpha_Centauri on 02/27/2019 02:00 am
https://twitter.com/kbatygin/status/1100574606312656897
https://arxiv.org/pdf/1902.10103.pdf
Post by: Star One on 02/27/2019 06:50 am
Quote
First, an exec summary of the paper: we did thousands of new P9 simulations, and realized that P9 is smaller (m~5Mearth), closer (a~400-500AU), more circular (e~0.2) and visually brighter (V~23) than we originally thought. Pic:
@jtuttlekeane
Now, let’s dig into the details a bit.
https://twitter.com/kbatygin/status/1100574608355250176
Post by: clongton on 02/27/2019 12:58 pm
Post by: Crispy on 02/27/2019 01:02 pm
Post by: Bynaus on 02/27/2019 01:03 pm
Post by: clongton on 02/27/2019 01:07 pm
... and that the orbit cannot be so eccentric that it crosses the orbits of the other planets.
And yet
Post by: Bynaus on 02/27/2019 01:11 pm
Post by: Star One on 02/27/2019 03:08 pm
http://www.findplanetnine.com/2019/02/progress.html?m=1
http://www.findplanetnine.com/2019/02/stories.html?m=1
http://www.findplanetnine.com/2019/02/version-2x.html?m=1
Quote
The smaller distance from the sun more than makes up for the diminished surface area. Indeed, if we make naive baseline assumptions about P9’s albedo and adopt the interpolated exoplanet mass-radius relation to estimate P9’s size, Planet Nine turns out to be about one magnitude brighter than we previously thought. Annoyingly, though, the aphelion is very close to (in?) the galactic plane, where confusion due to background stars can readily impede detection. Still, unless we are unlucky and P9 is unexpectedly small and/or dark, it should be within the reach of LSST and comparable telescopes like Subaru. The good news is that in the case of Planet Nine hypothesis, time truly will tell.
Post by: Orbiter on 02/27/2019 03:10 pm
... and that the orbit cannot be so eccentric that it crosses the orbits of the other planets.
And yet Mercury crosses the orbit of Neptune.
Uh... do you mean Pluto?
Post by: Alpha_Centauri on 02/27/2019 04:35 pm
All those orbits look exactly like the one that I was trying (obviously unsuccessfully) to describe as a highly eccentric orbit. My suggestion was that Planet X may be following such an orbit instead of the roughly circular one we are used to thinking of when we speak of the planets. I was told that I was crazy that no such orbit was possible for a planet and yet there they are. Now I notice that in the paper linked above that just such an orbit has a good possibility of being the path of Planet X.The eccentric orbits in that diagram don't cross Neptune's orbit either, or indeed get anywhere near it, though even if they did the point is they have negligible mass to have any effect.
Planet 9 (as Brown and Batygin described) was always thought to be on a moderately eccentric orbit, in fact the latest paper cuts the eccentricity by over half. But that's a different question to whether its perihelion would be low enough to be anywhere near the present 8, or indeed cross orbits, which is what people were disputing. Clearly if a 5 Earth mass object got anywhere near the known planets its effect would be so obvious we wouldn't be having this discussion.
Post by: clongton on 02/27/2019 07:00 pm
You mean Pluto. Apart from Pluto not being a planet ;) this is a very special resonant arrangement. Such a thing cannot be accomplished for P9 given the high mass of P9 and the very high period ratio with Neptune.
Yes I meant Pluto. Thanks for the correction. :) I fixed my post.
Up until recently the "planet" Pluto crossed the orbit of the planet Neptune.
So I guess the best way to prove that planets don't cross the orbits of other planets is to take the one example where one does that and declare that it's not a planet? lol, problem solved ;) :)
Alpha_Centauri I agree that there would be noticable disruptions if such a crossing did occur. But the orbital period of such a planet would be so long, perhaps 3-4 thousand years that there's no reliable record of the last time that may have happened, especially if it traversed nowhere near us. We really haven't been around to record stuff all that long after all. There's lots of stuff that happened in ages past that we will never have a clue about.
Bynas the solar system's a really big place, with far, FAR more space than mass and I honestly don't understand why what I suggest cannot occur. Even a 5em planet could traverse that vast open space and not cause much of a ripple if it wasn't near any planets at the time. If you don't mind, would you explain it to us? Much appreciated. Thanks
Post by: Bynaus on 02/27/2019 07:13 pm
Why is there no reason why it should be on a resonant orbit? Because it was likely ejected from the giant planet region. The chance that this ejection happened to be into a resonant orbit is extremely unlikely, even more so because Uranus and Neptune likely migrated outwards afterward. For Pluto and Neptune, the reason why they are in resonance is because Neptune migrated, "piling up" the small objects in its own resonances in the process. P9 is much too far away for the same process to happen.
Finally, just look at that new paper - Batying & Co. just showed that the P9 explanation works best if the eccentricity is low (at least, lower than proposed originally - 0.2-0.5 is still quite eccentric compared to the other planets, except Mercury perhaps - but 0.2-0.5 is still not enough to cross the orbit of Neptune; at a = 400 AU, it would need an eccentricity of >0.93 to do that!). You just don't get what we see out there by having a high eccentricity P9.
EDIT: @clongton: in your first post above, do you realize most of the orbits on the illustration are for small bodies? Only the yellow ellipse is showing the proposed orbit of P9. Small bodies can of course cross the orbits of the planets, as they have very small masses compared to the latter and are thus continually removed from their unstable orbits. One example (a little more close to home) are the Centaurs.
Post by: clongton on 02/27/2019 10:51 pm
Ok. I've been over that paper a couple of times now and I'll confess to coming away each time with a mild headache. I'll keep going back until it is clearer to me. That will likely take 5 or 6 times thru it, but I'll get there. Now, you said:
Quote
Why is there no reason why it should be on a resonant orbit? Because it was likely ejected from the giant planet region. The chance that this ejection happened to be into a resonant orbit is extremely unlikely, even more so because Uranus and Neptune likely migrated outwards afterward.
You also said:
Quote
At 400 AU, the orbital period is 8000 years. That means, if the planet crosses the orbit of Neptune, it has done so over half a million times since the beginning of the solar system.
You're making an assumption (also made by many prominent professionals) that P9 formed in situ within the solar system and migrated outward, and has been with us from the beginning. But the paper's authors provided 2 other plausible reasons for why P9 is likely where it is, including that it is not an original member of the solar system and did not form from Sol's planetary disk cloud. I refer you to Section 7, Formation Scenarios, page 63 and Figure 26, located on page 65 of the paper. It is referencing that P9 could also have formed around its own host star, which then had a close encounter with Sol sometime in the past and P9 was stolen from its host star by Sol as the star went by with P9 closer to Sol than its own star. IF P9 entered our system this way, or even if it was a rogue planet that Sol captured, it would not have been a member of our system from the beginning and therefore may not have orbited Sol anywhere near as many times as if it formed in situ within our system and would not have the history of planetary interactions you're assuming to be likely. It's a new paper (26 February 2019) and therefore the capture of P9 from space seems to remain a recognized possibility by the team that is trying to locate it. So I'm trying to understand what P9's orbit may have been or may now be like if either of the other 2 scenarios prove fruitful. ISTM that if P9 is a capture that the orbit would surely be highly eccentric for a very long time (.6 to .9 for example), and may have, early in its history with our solar system, traversed the orbits of 1 or more of our own planets until it settles into some stable orbital path closer to .15 to .2 for example. That process could still be ongoing and make P9's orbit difficult to nail down if any of the researchers are tying themselves to only 1 of the 3 presented possibilities of how P9 came to be. For all we know, P9's orbit could even potentially be retrograde; we really just don't know yet. But a lot of outer solar objects are retrograde and that would make more sense if P9 were as well. I'm just thinking out loud here.
Post by: Torbjorn Larsson, OM on 02/28/2019 12:13 am
The most interesting paper is the updated likelihood model with the 0.2 % likelihood for random null, and the obviously as per above the detail update in the review paper. 8)
Isn’t this tweet a bit worrying as far as it not being observed so far, where he talks about it being visually brighter under the new model.
It is AFAIU still so excentric orbit that the prior likelihood is for the planet being at aphelion. They are uncertain that Subaru will catch it and notes that LSST should be able to. At least given the new mass superEarth ice giant albedo and barely at that.
You're making an assumption (also made by many prominent professionals) that P9 formed in situ within the solar system and migrated outward, and has been with us from the beginning. But the paper's authors provided 2 other plausible reasons for why P9 is likely where it is, including that it is not an original member of the solar system and did not form from Sol's planetary disk cloud.
How can likelihoods in the percents (IIRC; as formation over billions of years, in an unseen debris field) or per milles (caught my eye; capture in the natal cluster) be plausible compared to the more than 5 % and possibly 15 % pathway of a scatter? (I don't think it can be truly said to "migrate" outside the 35ish au primordial disk.) C.f. how Mercury resonance vs tidal lock has been claimed to be something like 30 % likelihood. It seems to me they mentioned the two alternatives to be thorough but also to implicitly dismiss them.
Also, planets are not only quantitatively tied to dominating their neighborhood at the end of accretion, they are also robust phenomena - mature system planets show similar clearing. In oither words since Ceres is not an astronomical planet (but an astrophysical differentiated one), Pluto is not one. This is an old and void battlefield. ::)
EDIT: "Ice dwarf"!? -> Ice giant.
Post by: whitelancer64 on 02/28/2019 12:24 am
So if it takes 5000 years for a revolution around the sun, it would put its semi-major axis at 300 AU. That's... remarkably close!
Just a curiosity question Bynaus.
That sounds like you're assuming that the sun is at the center of Planet 9's elliptical orbit. Have you considered that the sun may not be at the center? For example, say the elliptical orbit is one of high eccentricity. Is it possible that the sun could instead be at a focal point, like in the attached diagram, instead of at the center of the ellipse? That could add some interesting dynamics to the "shepherding" of some of the commets and TNOs, especially with an inclination of ~20 degrees. The semi-major axis could still be between 300 and 500 AU but the perihelion could actually be somewhere inside the zone where the 8 known planets are. If so that might create theories regarding Pluto's very odd orbit, inside and outside Neptune's orbit, Uranus' odd rotation angle and Venus' clockwise rotation. A large body passing thru the planetary zone once every few thousands of years would surely cause major disruptions to any planet that was close enough to its path, such as these.
Like I said, just a curiosity question.
Emphasis mine.
All those orbits look exactly like the one that I was trying (obviously unsuccessfully) to describe as a highly eccentric orbit. My suggestion was that Planet X may be following such an orbit instead of the roughly circular one we are used to thinking of when we speak of the planets. I was told that I was crazy that no such orbit was possible for a planet and yet there they are. Now I notice that in the paper linked above that just such an orbit has a good possibility of being the path of Planet X.
Nobody said you were crazy, but I do think you may have badly stated what was in your head.
The Sun is ALWAYS at one of the foci of an elliptical orbit - this is the First of Kepler's Laws of Planetary Motion.
Also, orbits are almost always elliptical to some degree, it would be extraordinarily rare for one to be perfectly circular. Given any gravitational perturbation it would be nudged away from circular. For example, the most circular orbit of any planet is Venus, and even so it varies by 2 million km from perihelion to aphelion.
Post by: Bynaus on 02/28/2019 05:52 am
Quote from: clongton
Ok. I've been over that paper a couple of times now and I'll confess to coming away each time with a mild headache. I'll keep going back until it is clearer to me. That will likely take 5 or 6 times thru it, but I'll get there.
Kudos for that! I really prefer to discuss with people who go through the effort of actually reading the paper in question and trying to get to its core message! I read it through yesterday too, although I have to admit that most of the math stuff is beyond me (Hamiltonians etc.).
Quote
You're making an assumption (also made by many prominent professionals) that P9 formed in situ within the solar system and migrated outward, and has been with us from the beginning.
Note that "in situ" means "in place", if we say "P9 formed in situ" (which is one of the possibilities the authors give in the paper), we mean, out there, right on the orbit where it is now. The second scenario is the one you are alluding to, formation within the giant planet region (the solar system extends much beyond P9s present-day orbit) and then ejection.
If it did indeed form in situ, there is still no reason why it should be on a resonant orbit that would shield it from encounters with Neptune or other planets. And if it was captured from another star, same thing.
Quote
It is referencing that P9 could also have formed around its own host star, which then had a close encounter with Sol sometime in the past and P9 was stolen from its host star by Sol as the star went by with P9 closer to Sol than its own star. IF P9 entered our system this way, or even if it was a rogue planet that Sol captured, it would not have been a member of our system from the beginning and therefore may not have orbited Sol anywhere near as many times as if it formed in situ within our system and would not have the history of planetary interactions you're assuming to be likely.
Actually, they also show that capture from another star is only likely if this happened within the sun's birth cluster, where stellar distances are much smaller than later on. That cluster disperses within a few million years to a few 10 million years, so yes, if P9 was captured from another star, it has likely been there for essentially the whole history of the solar system.
Quote
ISTM that if P9 is a capture that the orbit would surely be highly eccentric for a very long time (.6 to .9 for example), and may have, early in its history with our solar system, traversed the orbits of 1 or more of our own planets until it settles into some stable orbital path closer to .15 to .2 for example.
If P9 was ejected from the giant planet region, then its orbit must have been very eccentric early on, on the order of what you suggest (see p. 66, second paragraph). But then the orbit was sculpted by the galactic tide and (perhaps) stellar encounters, which led to the perihelion being lifted out of the giant planet region to the place where it is today. If that hadn't happened, P9 would have collided with Jupiter or another of the giant planets at some point early on, and we wouldn't see its effects on the small body populations today.
If it was captured from a passing star, a high eccentricity, including crossing into the giant planet region, is not a necessity, but such an orbit would be subject to the same forces from galactic tides and stellar encounters, acting toward partial circularization of the orbit and rising of the perihelion (btw, this is how the objects in the Oort cloud got there: they were ejected and on initially very eccentric orbits, but then their orbits got circularized by the galactic tides). And since capture from another star must have happened (if it happened) early on, these forces have been at work for essentially the same amount of time compared to the scenario where it was ejected from the giant planet region.
Quote
For all we know, P9's orbit could even potentially be retrograde; we really just don't know yet. But a lot of outer solar objects are retrograde and that would make more sense if P9 were as well. I'm just thinking out loud here.
I don't think it could be on a retrograde orbit. These newer works are able to exclude a mass > 10 Earth masses for it, and a large swath of the theoretically available parameter space (high inclinations, high eccentricities, large masses, etc.). Over the last few years, they have clearly been narrowing down on the actual orbit. And that orbit is neither retrograde nor very eccentric. And it certainly doesn't cross into the giant planet region.
Post by: Star One on 02/28/2019 06:47 am
Post by: Bynaus on 02/28/2019 07:05 am
If P9 was captured from another star in the Sun’s stellar nursery which I believe is a strong likelihood under the capture scenario. Wouldn’t its time in orbit still be so long that it would be little different to if it formed in the planetary disc with the Sun.
Exactly.
Post by: clongton on 02/28/2019 02:38 pm
If P9 was ejected from the giant planet region, then its orbit must have been very eccentric early on, on the order of what you suggest (see p. 66, second paragraph). But then the orbit was sculpted by the galactic tide and (perhaps) stellar encounters, which led to the perihelion being lifted out of the giant planet region to the place where it is today. If that hadn't happened, P9 would have collided with Jupiter or another of the giant planets at some point early on, and we wouldn't see its effects on the small body populations today.
And since capture from another star must have happened (if it happened) early on, these forces have been at work for essentially the same amount of time compared to the scenario where it was ejected from the giant planet region.
Thanks for that Bynaus. Yea, I definitely misused "in situ" there. Caffeine deprivation. In situ formation of P9 is imo the least likely of the 3 formation theories, mostly because, as the paper points out in stark detail, there is simply insufficient material from the planetary disc much beyond 30AU to form such a planet. The material is just not there and in all probability it never was. ~30 AU seems to just be a mathematical brick wall for planetary formation - for OUR solar system. In addition it just does not compute for me that P9 could be so far out of the ecliptic if it was an in situ formed planet. So for me, in situ formation is effectively dismissed. So we're left with formation deeper in the solar system followed by ejection, or either capture of a stripped-away planet from a passing star or capture of a rogue planet that got too close. In either case the paper seems to bear out the initially highly elliptical orbit for P9 I postulated, which has circularized, most likely by galactic tides and stellar interactions.
I tend to (very lightly) come down on the side of capture of an extrasolar planet over ejection of a native planet, but only because of how far it is off the ecliptic. Short of a massive collision of some kind (with maybe the asteroid belt being the leftovers?) I don't see how normal migration or ejection from the inner system could produce such an inclination. Other than that single nit I consider both options equally likely.
As for capture being early in solar system history, while that may be correct, I don't think there's enough data available to actually say that. I think you're assuming that the passing star formed more or less at the same time as Sol, because you're assuming it formed from the same planetary cloud as Sol. Please please correct me if I'm wrong. While that is certainly a distinct possibility, that limits the time period to somewhere around 4-4.5 billion years. Yet we know the galaxy is ~10 billion years old, 2-1/2 times older than our solar system, and that there are rogue planets around that could have come from anywhere, from anyplace in that timespan. P9 could have come from anywhere in that kind of timespan. I'd prefer to leave that part open for now, until we have eyes on P9 and can make some definitive analysis.
Got thru the paper another time and yes, each reading does clear up things a little more. But one surely does need to take their time when reading and let things sink in before moving on. And yea, the math is excruciating. :)
Post by: Bynaus on 02/28/2019 03:36 pm
But for capture vs ejection, the latter is much more likely to lead to the observed orbit of P9. The inclination of the solar system relative to a passing star can have any value - half of the captured planets will be on retrograde orbits! So the chance of one ending up within 20° of the ecliptic (and prograde!) is quite low. On the other hand, this is quite likely for ejection. It is possible to have an inclination change through an encounter, think of how Saturn ejected Voyager 1 out of the ecliptic, or how Ulysses got ejected from the ecliptic by Jupiter. This is why astronomers consider the ejection scenario as much more likely than capture.
Edit: regarding rogue planets, you can't capture a rogue planet on its own, you need to have a binary partner to the rogue that can take away the excess momentum. See the Fig. in the paper you copied, which shows the captured planet orbiting another star at first. And most of the sun's very close encounters with other stars happened during the time in the birth cluster. So chances favor that time for the capture of P9, if thats where it is from originally.
The bonus of the ejection model is that having 5 giant planets makes the models of the time of giant planet migration work even better.
Post by: Star One on 02/28/2019 04:11 pm
Agree with you on in situ being not very likely. But then, there are stars with disks that extend for 100s of AU, and some of them contain planets in very far out (like HR 8799)...
But for capture vs ejection, the latter is much more likely to lead to the observed orbit of P9. The inclination of the solar system relative to a passing star can have any value - half of the captured planets will be on retrograde orbits! So the chance of one ending up within 20° of the ecliptic (and prograde!) is quite low. On the other hand, this is quite likely for ejection. It is possible to have an inclination change through an encounter, think of how Saturn ejected Voyager 1 out of the ecliptic, or how Ulysses got ejected from the ecliptic by Jupiter. This is why astronomers consider the ejection scenario as much more likely than capture.
Edit: regarding rogue planets, you can't capture a rogue planet on its own, you need to have a binary partner to the rogue that can take away the excess momentum. See the Fig. in the paper you copied, which shows the captured planet orbiting another star at first. And most of the sun's very close encounters with other stars happened during the time in the birth cluster. So chances favor that time for the capture of P9, if thats where it is from originally.
The bonus of the ejection model is that having 5 giant planets makes the models of the time of giant planet migration work even better.
Brown has always favoured the capture theory mostly in terms of the planet being captured from another star in the Sun’s stellar nursery as I mentioned above.
Post by: Bynaus on 02/28/2019 05:24 pm
Post by: Star One on 02/28/2019 05:52 pm
Just to be clear, I think Brown favors the ejection scenario overall. But within the capture scenario, he favors capture within the birth cluster.
Yes you’re quite correct. Apologies I should have been clearer in my post above.
Post by: clongton on 02/28/2019 06:03 pm
Agree with you on in situ being not very likely. But then, there are stars with disks that extend for 100s of AU, and some of them contain planets in very far out (like HR 8799)...
That's correct and I should have been clearer. I was speaking in terms of our solar system only. I corrected my post to clarify that. I don't always express myself well (which can get me into trouble) so I thank you for your patience with me.
Post by: Star One on 03/27/2019 04:22 pm
Something Other Than Planet Nine Could Be Hiding in The Outer Solar System (https://www.sciencealert.com/something-other-than-planet-nine-could-be-hiding-in-the-outer-solar-system)
Post by: ugordan on 03/27/2019 04:38 pm
This apparently is an updated version of an article that originally appeared in January but has now been reposted.
Something Other Than Planet Nine Could Be Hiding in The Outer Solar System (https://www.sciencealert.com/something-other-than-planet-nine-could-be-hiding-in-the-outer-solar-system)
Somehow, I find the alternative explanation of an eccentric ring of many smaller bodies (all placed on the same average orbit somehow?) instead of one single, massive body as unlikely. Mike Brown has the same reasoning: http://www.findplanetnine.com/2019/01/is-planet-nine-just-ring-of-icy-bodies.html
It's (much?) easier to postulate a single object being ejected into a weird, elliptical orbit, than a bunch of smaller masses which are ejected and spread around that same kind of orbit, to provide the same average gravitational influence as the hypothesized Planet 9. Unless one can show that this orbit is somehow "special" and preferred after getting tossed around by the massive planets we already know about, which I don't see how one can do.
Post by: Phil Stooke on 03/27/2019 06:41 pm
Post by: Bynaus on 03/27/2019 08:06 pm
I suppose one possibility would be that the event which ejected the single object into that orbit also tidally disrupted it, resulting in a swarm of objects in similar orbits which over time spread along the orbit to create that 'ring'. I'm not advocating for that explanation, just suggesting that it might not be so hard to account for a ring after all.
1) Its going to be difficult to tidally disrupt a gas giant... (only another gas giant could do it, relatively low mass ratio means extremely close pass of the disruptee is necessary, plus all the mass that could form fragments is concentrated in a high density core, the gas itself does not form fragments, so you need a larger gas giant which makes the above problems worse, etc.)
2) Its going to be next to impossible to rise the perihelion of so many small fragments and funnel them all back into a neat ring at a certain inclination (as opposed to near-spherical cloud like the Oort cloud - but you don't get the P9-like-effect from such a cloud!).
Unless you have some simulation to back up such a claim (or a publication where the author did this), its usually best to leave this kind of judgment ("might not be so hard") to the experts. Not taking a piss here, just trying to keep the quality of the discussion high.
Post by: ugordan on 03/27/2019 08:59 pm
I suppose one possibility would be that the event which ejected the single object into that orbit also tidally disrupted it, resulting in a swarm of objects in similar orbits which over time spread along the orbit to create that 'ring'. I'm not advocating for that explanation, just suggesting that it might not be so hard to account for a ring after all.
I guess that's possible, but it still leaves the question of how those fragments got stabilized in an orbit that's far enough from any of the gas/icy giants at perihelion. Not that the P9 hypothesis has a good answer to that either. If it was some 3rd body interaction like a passing star or brown dwarf, I think that would still more easily explain the single massive body being perturbed than a long train of tidally-disrupted fragments in roughly similar orbits as their closest approach to that body would vary by hundreds of years and so their resulting orbits would be more dispersed from the original fragment train. Unless the 3rd body perturbation happened quite soon after the original body being disrupted and ejected from the "inner" solar system, which seems like it would have been an amazing coincidence.
Post by: KelvinZero on 03/28/2019 12:51 am
What about something half way between the two: some sort of cloud or clump of dwarf planets possibly still in the process of forming a planet?
Edit: if it is one world, how about Mongo.. and if a collection of worlds, or it has moons, we could start with Arboria, Ardentia, Aerie, Aquaria, and Frigia :)
https://en.wikipedia.org/wiki/Mongo_(fictional_planet)
Post by: Star One on 06/09/2019 11:24 am
Quote
It's now been a year since the Zwicky Transient Facility has been operating at Palomar Observatory. So it is time to answer the question everyone should have been (but no one was? maybe?) asking. Is Planet Nine in the public ZTF archive already?
https://twitter.com/plutokiller/status/1137076882170568704
Post by: Star One on 09/29/2019 07:44 pm
Jakub Scholtz, James Unwin
(Submitted on 24 Sep 2019)
We highlight that the anomalous orbits of Trans-Neptunian Objects (TNOs) and an excess in microlensing events in the 5-year OGLE dataset can be simultaneously explained by a new population of astrophysical bodies with mass several times that of Earth (M⊕). We take these objects to be primordial black holes (PBHs) and point out the orbits of TNOs would be altered if one of these PBHs was captured by the Solar System, inline with the Planet 9 hypothesis. Capture of a free floating planet is a leading explanation for the origin of Planet 9 and we show that the probability of capturing a PBH instead is comparable. The observational constraints on a PBH in the outer Solar System significantly differ from the case of a new ninth planet. This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH.
https://arxiv.org/abs/1909.11090
Mike Browns response to the above:
https://twitter.com/plutokiller/status/1177247326319964163
Post by: KelvinZero on 09/30/2019 06:08 am
That link gives some arguments that MACHOs are not a good candidate to explain dark matter, though I guess that is not the claim here.
The 9th planet being a black hole would imply about 1 in 10 planets in the universe being some sort of object like that. I guess it cannot be formed by any currently accepted stellar event. It would have to come from the beginning of the universe or similar. It is a pretty huge leap.. Still I think it is exciting that the universe still has room for surprises. I actually had a thread a while ago with wild speculation and wishful thinking of what the most useful object could still exist out there, not currently absolutely ruled out by observation, that could act as a gateway to slingshot us around the galaxy. (eg exploiting Oberth effect around a black hole or similar) .. also there is that "halo drive" idea that came out since.
Post by: Star One on 09/30/2019 06:27 am
That sounds a bit like the MACHO idea. https://en.wikipedia.org/wiki/Massive_compact_halo_object
That link gives some arguments that MACHOs are not a good candidate to explain dark matter, though I guess that is not the claim here.
The 9th planet being a black hole would imply about 1 in 10 planets in the universe being some sort of object like that. I guess it cannot be formed by any currently accepted stellar event. It would have to come from the beginning of the universe or similar. It is a pretty huge leap.. Still I think it is exciting that the universe still has room for surprises. I actually had a thread a while ago with wild speculation and wishful thinking of what the most useful object could still exist out there, not currently absolutely ruled out by observation, that could act as a gateway to slingshot us around the galaxy. (eg exploiting Oberth effect around a black hole or similar) .. also there is that "halo drive" idea that came out since.
When I was reading through the Twitter thread started by Mike Brown one of the posters stated it is now not possible for the universe to form such BHs, hence the name.
Could Spektre RG spot this?
Post by: Star One on 10/31/2019 10:12 pm
https://www.youtube.com/watch?v=ZLSiFl0FfWw
Post by: Star One on 03/06/2020 08:51 pm
https://www.youtube.com/watch?v=xrTYhWcfH2o
Post by: Star One on 06/28/2020 10:18 pm
https://youtu.be/PcrVKacgif0
Post by: Star One on 06/29/2020 06:44 am
Post by: Alpha_Centauri on 06/29/2020 08:55 am
https://arxiv.org/abs/1901.07115
https://arxiv.org/abs/1902.10103
I don't know why the videomaker discusses the Nesvorny paper since it is not relevant to the Planet Nine hypothesis. I doesn't state what he is claiming about being able to explain the eTNOs with Neptune, it's a prosaic work on solar system evolution.
https://arxiv.org/abs/1807.06647
It always pays to be suspicious of random Youtube channels pronouncing on science.
That said there has been a recent paper which demonstrates you don't need Planet Nine to explain the DES sample, though this sample is too small to rule it out with much confidence.
https://arxiv.org/abs/2003.08901
Here's a few writeups that mention it.
https://www.discovermagazine.com/the-sciences/139-minor-planets-found-in-our-solar-system
https://futurism.com/new-research-no-planet-nine-after-all
https://www.theguardian.com/science/2020/jun/28/beyond-pluto-the-hunt-for-our-solar-system-new-ninth-planet
Post by: ugordan on 06/29/2020 09:42 am
Regarding the paper mentioned above I’ve not seen Mike Brown or anyone counter it which is interesting.
Konstantin Batygin has, in fact, covered in a twitter thread:
https://twitter.com/kbatygin/status/1266902054632488960
Post by: Star One on 06/29/2020 03:27 pm
Post by: Star One on 07/11/2020 08:20 am
Quote
Harvard astronomers Avi Loeb and Amir Siraj have proposed a new strategy for detecting a grapefruit-sized black hole in the outer solar system, in a paper that has been accepted for publication in The Astrophysical Journal Letters. Using the Vera C. Rubin Observatory, still under construction in Chile, astronomers could indirectly detect this object by observing it do what black holes do best: gobble up stuff.
https://gizmodo.com/astronomers-have-a-plan-to-detect-a-possible-black-hole-1844338053
Here’s the related paper:
https://arxiv.org/pdf/2005.12280.pdf
Post by: Star One on 08/24/2020 08:48 am
Quote
A new theory published today in the Astrophysical Journal Letters by scientists from Harvard University suggests that the sun may once have had a binary companion of similar mass. If confirmed, the presence of an early stellar companion increases the likelihood that the Oort cloud was formed as observed and that Planet Nine was captured rather than formed within the solar system.
https://phys.org/news/2020-08-sun-life-binary-companion.html#!
Here’s the related paper:
https://arxiv.org/abs/2007.10339
Is it possible that when the stars in the sun’s stellar nursery scattered out into the universe that this ‘disconnected’ binary companion still travelled in the same direction as the Sun?
Post by: Alpha_Centauri on 08/24/2020 01:07 pm
https://www.zooniverse.org/projects/fulsdavid/catalina-outer-solar-system-survey
Not the deepest search, but good for high inclination where the largest objects tend to be. If you're lucky you might find a large eTNO that could point the way to Planet Nine.
Post by: Bynaus on 08/24/2020 05:45 pm
QuoteA new theory published today in the Astrophysical Journal Letters by scientists from Harvard University suggests that the sun may once have had a binary companion of similar mass. If confirmed, the presence of an early stellar companion increases the likelihood that the Oort cloud was formed as observed and that Planet Nine was captured rather than formed within the solar system.
https://phys.org/news/2020-08-sun-life-binary-companion.html#!
Here’s the related paper:
https://arxiv.org/abs/2007.10339
Is it possible that when the stars in the sun’s stellar nursery scattered out into the universe that this ‘disconnected’ binary companion still travelled in the same direction as the Sun?
Yes, they would likely have travelled in the same direction, more or less, unless they were separated by a very close encounter (~on the order of their separation) with a similar mass star, in which case, the former companion could have taken any direction.
Note however that the companion would have been ejected at ~sqrt(2) * its orbital velocity, with the orbital velocity at a few 100 AU being on the order of <1 km/s. At 1 km/s, one travels roughly one parsec per Megayear, so after 4.5 Gigayears, around 20 orbits around the center of the galaxy, countless close encounters of both the sun and the former companion star with other stars, that former companion could be nearly anywhere.
Post by: Star One on 08/24/2020 08:17 pm
Thanks for that. Is it correct that the Sun is unusual in that star’s of the Sun’s type are usually found in binary pairs normally with a lower mass companion.QuoteA new theory published today in the Astrophysical Journal Letters by scientists from Harvard University suggests that the sun may once have had a binary companion of similar mass. If confirmed, the presence of an early stellar companion increases the likelihood that the Oort cloud was formed as observed and that Planet Nine was captured rather than formed within the solar system.
https://phys.org/news/2020-08-sun-life-binary-companion.html#!
Here’s the related paper:
https://arxiv.org/abs/2007.10339
Is it possible that when the stars in the sun’s stellar nursery scattered out into the universe that this ‘disconnected’ binary companion still travelled in the same direction as the Sun?
Yes, they would likely have travelled in the same direction, more or less, unless they were separated by a very close encounter (~on the order of their separation) with a similar mass star, in which case, the former companion could have taken any direction.
Note however that the companion would have been ejected at ~sqrt(2) * its orbital velocity, with the orbital velocity at a few 100 AU being on the order of <1 km/s. At 1 km/s, one travels roughly one parsec per Megayear, so after 4.5 Gigayears, around 20 orbits around the center of the galaxy, countless close encounters of both the sun and the former companion star with other stars, that former companion could be nearly anywhere.
Post by: Bynaus on 08/24/2020 09:01 pm
Thanks for that. Is it correct that the Sun is unusual in that star’s of the Sun’s type are usually found in binary pairs normally with a lower mass companion.QuoteA new theory published today in the Astrophysical Journal Letters by scientists from Harvard University suggests that the sun may once have had a binary companion of similar mass. If confirmed, the presence of an early stellar companion increases the likelihood that the Oort cloud was formed as observed and that Planet Nine was captured rather than formed within the solar system.
https://phys.org/news/2020-08-sun-life-binary-companion.html#!
Here’s the related paper:
https://arxiv.org/abs/2007.10339
Is it possible that when the stars in the sun’s stellar nursery scattered out into the universe that this ‘disconnected’ binary companion still travelled in the same direction as the Sun?
Yes, they would likely have travelled in the same direction, more or less, unless they were separated by a very close encounter (~on the order of their separation) with a similar mass star, in which case, the former companion could have taken any direction.
Note however that the companion would have been ejected at ~sqrt(2) * its orbital velocity, with the orbital velocity at a few 100 AU being on the order of <1 km/s. At 1 km/s, one travels roughly one parsec per Megayear, so after 4.5 Gigayears, around 20 orbits around the center of the galaxy, countless close encounters of both the sun and the former companion star with other stars, that former companion could be nearly anywhere.
Yes, in general, the higher the mass of the star, the higher the fraction of binaries. On the other hand, not all binaries are forever - if they are very loosly bound, like the sun and its former companion (if it existed - we don't know), or if its a multiple system which eventually becomes dynamically unstable, they might be disrupted at a later point in their life. I seem to remember that the odds of a star like Alpha Centauri (A+B) keeping distant Proxima over its age of ca. 5 Gigayears are just about even.
Post by: Star One on 10/01/2020 08:50 pm
https://youtu.be/SwRmHrsNyFU
Post by: Star One on 11/12/2020 03:15 pm
Quote
The search for Planet Nine — a hypothesized ninth planet in our solar system — may come down to pinpointing the faintest orbital trails in an incredibly dark corner of space.
That’s exactly what Yale astronomers Malena Rice and Gregory Laughlin are attempting with a technique that scoops up scattered light from thousands of space telescope images and identifies orbital pathways for previously undetected objects.
https://news.yale.edu/2020/10/27/lighting-path-planet-nine
Post by: Star One on 02/16/2021 10:15 am
No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects
The apparent clustering in longitude of perihelion ϖ and ascending node Ω of extreme trans-Neptunian objects (ETNOs) has been attributed to the gravitational effects of an unseen 5-10 Earth-mass planet in the outer solar system. To investigate how selection bias may contribute to this clustering, we consider 14 ETNOs discovered by the Dark Energy Survey, the Outer Solar System Origins Survey, and the survey of Sheppard and Trujillo. Using each survey's published pointing history, depth, and TNO tracking selections, we calculate the joint probability that these objects are consistent with an underlying parent population with uniform distributions in ϖ and Ω. We find that the mean scaled longitude of perihelion and orbital poles of the detected ETNOs are consistent with a uniform population at a level between 17% and 94%, and thus conclude that this sample provides no evidence for angular clustering.
https://arxiv.org/abs/2102.05601
https://www.cnet.com/news/any-evidence-for-planet-nine-is-gone-scientists-dispute-probability-of-mystery-planet/
Post by: Bynaus on 02/16/2021 12:04 pm
In other words: continue the search for P9!
Post by: edzieba on 02/16/2021 12:58 pm
Post by: Star One on 02/16/2021 01:13 pm
Using just 14 objects to try and extrapolate the distribution and sampling bias of all TNOs seems like a "this really could have waited for Vera Rubin first catalogue" task.I’d say that statement could be applied to both sides of the discussion especially if you factor in the large new ground based telescopes due to come online in the next decade.
Post by: clongton on 02/16/2021 02:01 pm
Post by: Star One on 02/16/2021 03:49 pm
Only 14 objects? In all that vast space? That's like scooping up a 4-liter jar of seawater next to an Exon Mobile oil tanker dock and using that to establish the likelihood that there might be fish somewhere in the ocean.Well didn’t Brown and Batygin do something very similar in their original paper proposing Planet Nine.
Anyway here is the start of Mr Batygin’s Twitter thread on the matter.
https://mobile.twitter.com/kbatygin/status/1360381088216936451
He expands further in this thread.
https://mobile.twitter.com/kbatygin/status/1360390787653980161
Post by: Bynaus on 02/16/2021 07:01 pm
http://findplanetnine.blogspot.com/2021/02/is-planet-nine-finally-dead.html?m=1
In short: adding objects from a strongly biased survey done in the direction of the clustering (by pure chance) actually reduces the overall statistical confidence in the clustering.
Post by: leovinus on 02/16/2021 07:27 pm
And Mike Browns even more detailed answer...
http://findplanetnine.blogspot.com/2021/02/is-planet-nine-finally-dead.html?m=1
In short: adding objects from a strongly biased survey done in the direction of the clustering (by pure chance) actually reduces the overall statistical confidence in the clustering.
Thanks for the link. Well worth reading in full actually.
Post by: Dizzy_RHESSI on 02/16/2021 10:58 pm
Konstantin Batygin brought up an interesting observation in reaction to this paper (in a twitter feed): only the orbits of objects which are dynamically detached from Neptune show clustering. Those which interact dynamically with Neptune show no clustering.
This claim is discussed in the paper.
"We also address the fact that the clustering by a putative Planet X/Planet 9 should be more robust in the sample of ETNOs with q >40 au, since these objects avoid strong perturbations by Neptune. If we restrict our ETNOs to these 8 objects, Pjoint increases to 94%. Finally, we analyze the subset of objects which are either stable or metastable in the presence of the putative Planet X/Planet 9 (Batygin et al. 2019): 2015 TG387, 2013 SY99, 2015 RX245, 2014 SR349,2012 VP113, 2013 RA109, and 2013 FT28. For this subset Pjoint= 82%."
And Mike Browns even more detailed answer...
http://findplanetnine.blogspot.com/2021/02/is-planet-nine-finally-dead.html?m=1
In short: adding objects from a strongly biased survey done in the direction of the clustering (by pure chance) actually reduces the overall statistical confidence in the clustering.
The whole point of the Napier et al. paper is about assessing the selection function of the three different surveys. As long as the bias of a dataset is accounted for it should not decrease the significance. The paper comes to a very different conclusion on why there is a discrepancy with previous work.
"Our result differs drastically from the corresponding value in BB19 of 0.2%. Closer inspection sheds some light on the apparent discrepancy. If we examine only the overlapping set of ETNOs used this work and in BB19 (2015 BP519, 2013 RF98, 2013 SY99, 2015RX245, 2015 GT50, 2015 KG163, 2013 FT28, 2014 SR349, and 2014 FE72),Pjoint drops to <0.005. This indicates an expected issue: small number statistics are sensitive to fluctuations. For example, when BB19 performed their analysis a small but important set of the ETNOs had not yet been reported to the MPC. As a concrete demonstration of the importance of the omission of a few ETNOs from BB19, consider DES. Of the five ETNOs discovered by the DES wide survey, BB19 included only 2015 BP519. From Figure 4 it is clear that this object lands in an extremely low-probability region. This drives down Pjoint, and thus gives a satisfactory answer as to why the result of this work differs so significantly from that of BB19."
Brown's comment about uncertainties is also rather odd. Napier et al. don't use any kind of clustering statistic, they're just comparing the observed positions of TNOs to their simulated selection functions. You get a probability which encapsulates their uncertainties. Brown and Batygin (2019) did exactly the same thing with much less detailed modelling, they also didn't publish uncertainties on the result (which is just a probability).
Post by: Star One on 02/17/2021 06:18 am
That’s what I don’t understand about this aren’t Brown and Batygin doing exactly the same thing in their original paper?Konstantin Batygin brought up an interesting observation in reaction to this paper (in a twitter feed): only the orbits of objects which are dynamically detached from Neptune show clustering. Those which interact dynamically with Neptune show no clustering.
This claim is discussed in the paper.
"We also address the fact that the clustering by a putative Planet X/Planet 9 should be more robust in the sample of ETNOs with q >40 au, since these objects avoid strong perturbations by Neptune. If we restrict our ETNOs to these 8 objects, Pjoint increases to 94%. Finally, we analyze the subset of objects which are either stable or metastable in the presence of the putative Planet X/Planet 9 (Batygin et al. 2019): 2015 TG387, 2013 SY99, 2015 RX245, 2014 SR349,2012 VP113, 2013 RA109, and 2013 FT28. For this subset Pjoint= 82%."And Mike Browns even more detailed answer...
http://findplanetnine.blogspot.com/2021/02/is-planet-nine-finally-dead.html?m=1
In short: adding objects from a strongly biased survey done in the direction of the clustering (by pure chance) actually reduces the overall statistical confidence in the clustering.
The whole point of the Napier et al. paper is about assessing the selection function of the three different surveys. As long as the bias of a dataset is accounted for it should not decrease the significance. The paper comes to a very different conclusion on why there is a discrepancy with previous work.
"Our result differs drastically from the corresponding value in BB19 of 0.2%. Closer inspection sheds some light on the apparent discrepancy. If we examine only the overlapping set of ETNOs used this work and in BB19 (2015 BP519, 2013 RF98, 2013 SY99, 2015RX245, 2015 GT50, 2015 KG163, 2013 FT28, 2014 SR349, and 2014 FE72),Pjoint drops to <0.005. This indicates an expected issue: small number statistics are sensitive to fluctuations. For example, when BB19 performed their analysis a small but important set of the ETNOs had not yet been reported to the MPC. As a concrete demonstration of the importance of the omission of a few ETNOs from BB19, consider DES. Of the five ETNOs discovered by the DES wide survey, BB19 included only 2015 BP519. From Figure 4 it is clear that this object lands in an extremely low-probability region. This drives down Pjoint, and thus gives a satisfactory answer as to why the result of this work differs so significantly from that of BB19."
Brown's comment about uncertainties is also rather odd. Napier et al. don't use any kind of clustering statistic, they're just comparing the observed positions of TNOs to their simulated selection functions. You get a probability which encapsulates their uncertainties. Brown and Batygin (2019) did exactly the same thing with much less detailed modelling, they also didn't publish uncertainties on the result (which is just a probability).
Post by: Orbiter on 02/17/2021 07:34 pm
Post by: clongton on 02/18/2021 12:01 pm
https://twitter.com/plutokiller/status/1361754940121640962 (https://twitter.com/plutokiller/status/1361754940121640962)
Thank you Mike. I knew that sounded fishy. I agree. When papers are published they should also publish their uncertainties. To do anything else betrays, in my opinion, a decision to publish only things that support their preconceived conclusions, ignoring what does not. That is NOT good science. Good science automatically allows one to develop theories and opinions, but does not allow one to hide data points that might call those theories into question.
I don't have a dog in this hunt, so I'm good with whatever the ultimate true outcome is - whatever that is. But I do have an intense interest. And the last thing I want is for someone to tell me what I'm supposed to think by obscuring some of the data.
Post by: Blackstar on 02/18/2021 01:35 pm
Post by: Lee Jay on 02/18/2021 01:47 pm
But isn't this somewhat besides the point? Brown made the claim five years ago. It's up to him to prove it.
I don't agree with that. Proof for general relativity is still being collected long after Einstein's death. It's perfectly valid and acceptable for others to prove or disprove Brown's hypothesis.
Science doesn't care where the data comes from, just that it's repeatable.
Post by: Blackstar on 02/18/2021 04:13 pm
But isn't this somewhat besides the point? Brown made the claim five years ago. It's up to him to prove it.
I don't agree with that. Proof for general relativity is still being collected long after Einstein's death. It's perfectly valid and acceptable for others to prove or disprove Brown's hypothesis.
Science doesn't care where the data comes from, just that it's repeatable.
I'm not saying that it's "not valid." I'm saying that he made the claim that there's another (big) planet out there. That got a lot of attention. And we're still waiting for him to find that planet.
Post by: Alpha_Centauri on 02/18/2021 05:43 pm
But isn't this somewhat besides the point? Brown made the claim five years ago. It's up to him to prove it.
I don't agree with that. Proof for general relativity is still being collected long after Einstein's death. It's perfectly valid and acceptable for others to prove or disprove Brown's hypothesis.
Science doesn't care where the data comes from, just that it's repeatable.
I'm not saying that it's "not valid." I'm saying that he made the claim that there's another (big) planet out there. That got a lot of attention. And we're still waiting for him to find that planet.
That's....not really how it works. You could probably count the number of times a major scientific hypothesis has been proven by the person who proposed it on your hands.
Indeed the whole point of publishing such a theory is that you do not have the means at your disposal to prove it, or you would have done so and got to keep all the glory for yourself.
Now unless Brown can pull a new large survey telescope out of his ass it's not really likely he'll find it alone. Publishing the hypothesis makes it more likely people will develop the instruments to find it (or not).
Post by: baldusi on 02/18/2021 05:52 pm
But isn't this somewhat besides the point? Brown made the claim five years ago. It's up to him to prove it.
I don't agree with that. Proof for general relativity is still being collected long after Einstein's death. It's perfectly valid and acceptable for others to prove or disprove Brown's hypothesis.
Science doesn't care where the data comes from, just that it's repeatable.
I'm not saying that it's "not valid." I'm saying that he made the claim that there's another (big) planet out there. That got a lot of attention. And we're still waiting for him to find that planet.
He made an excellent point in every way. If his blog data is correctly processed, it is true that widening the data set might, under certain circumstances increase the error bands enough. Specially if you have such a sparse data set so full of observation bias.
The blog and analysis has two points:
1) The bias is only shown for objects that are not affected by Nepturn's orbit (i.e. periapsis >> 35AU). Adding objects with lower periapsis does eliminate the bias (but doesn't makes sense)
2) Adding many objects from different observation campaigns that focused on other areas might increase the variance so much to not being able to refute the null-hypothesis.
Besides, you know quite well that if such an object exists, it probably is transiting around the galactic center, from our POV, and thus almost impossible to detect. I'm not saying that really hard to prove/disprove theories should not be taken with a lot of salt. But Everything I've read about his hypothesis and his proof are quite solid and well argued.
Frankly, I would love to have a mission that surveys for asteroids and Planet 9 (if that is even possible).
Post by: Coastal Ron on 02/18/2021 06:24 pm
I'm not saying that it's "not valid." I'm saying that he made the claim that there's another (big) planet out there. That got a lot of attention. And we're still waiting for him to find that planet.
He made an excellent point in every way....
Besides, you know quite well that if such an object exists, it probably is transiting around the galactic center, from our POV, and thus almost impossible to detect. I'm not saying that really hard to prove/disprove theories should not be taken with a lot of salt. But Everything I've read about his hypothesis and his proof are quite solid and well argued.
Nevertheless, it is still an unsubstantiated theory, and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
I read something the other day that said the mass that was out there could also be a small black hole, so lots of theories about what could be causing the effects we see, but until we have FACTS they are just theories.
Post by: Bynaus on 02/18/2021 06:32 pm
Certainly, when the Vera Rubin telescope comes online, we will know.
Post by: Star One on 02/18/2021 06:40 pm
They are on it, though (Brown & Batygin). Both observationally, theoretically, methodically... I don't think anyone else world-wide is as passionate about finding P9 as these two. And there is only so many nights they can request on Subaru for this, next to all the *other* intersting stuff that telescope is used for! Give them a break.Would that be as effective at detecting a primordial Black Hole if it turns out to be that instead of a planet?
Certainly, when the Vera Rubin telescope comes online, we will know.
Post by: Bynaus on 02/18/2021 06:43 pm
They are on it, though (Brown & Batygin). Both observationally, theoretically, methodically... I don't think anyone else world-wide is as passionate about finding P9 as these two. And there is only so many nights they can request on Subaru for this, next to all the *other* intersting stuff that telescope is used for! Give them a break.Would that be as effective at detecting a primordial Black Hole if it turns out to be that instead of a planet?
Certainly, when the Vera Rubin telescope comes online, we will know.
No chance. But in that case, it could find more objects with aligned orbits, though. Or exclude the whole aligned-orbits thing.
Post by: Lee Jay on 02/18/2021 06:46 pm
Nevertheless, it is still an unsubstantiated theory,
It's a hypothesis, not a theory.
Quote
and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
Post by: CuddlyRocket on 02/18/2021 07:47 pm
... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
Post by: Star One on 02/18/2021 08:12 pm
Huh I don’t think that’s right. If that was true there would be no practical applications of science. For example unless we knew certain things to a high degree of certainty we wouldn’t now be rolling out a vaccine program against COVID-19. You can’t build important things like this unless you’ve got some certainties.... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
Post by: Lee Jay on 02/18/2021 08:14 pm
... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
I mostly agree, but it's also possible to collect data that supports a hypothesis, as well as data that would disprove it. For example, a direct observation of planet 9 would tend to support the hypothesis that planet 9 exists.
Post by: Lee Jay on 02/18/2021 08:17 pm
Huh I don’t think that’s right. If that was true there would be no practical applications of science. For example unless we knew certain things to a high degree of certainty we wouldn’t now be rolling out a vaccine program against COVID-19. You can’t build important things like this unless you’ve got some certainties.... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
You can have certainties in math. In science, everything is provisional, meaning nothing is certain. It's all a matter of degree, and some things are more certain than others, but nothing is entirely certain.
Post by: mandrewa on 02/18/2021 09:06 pm
https://twitter.com/plutokiller/status/1361754940121640962 (https://twitter.com/plutokiller/status/1361754940121640962)
Thank you Mike. I knew that sounded fishy. I agree. When papers are published they should also publish their uncertainties. To do anything else betrays, in my opinion, a decision to publish only things that support their preconceived conclusions, ignoring what does not. That is NOT good science. Good science automatically allows one to develop theories and opinions, but does not allow one to hide data points that might call those theories into question.
I don't have a dog in this hunt, so I'm good with whatever the ultimate true outcome is - whatever that is. But I do have an intense interest. And the last thing I want is for someone to tell me what I'm supposed to think by obscuring some of the data.
Mike Brown is polite and restrained but I will try to explain the issue more briefly and bluntly. The "No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects" paper is nonsense because what its authors did is take low-quality data, throw it into the mix, and then because of the low-quality data that they just added, which because it is so uncertain can't possible test the hypothesis anyway, decreases the significance of the overall set of data, so that now it can be asserted that the new data set has error bars so wide that it could be consistent with no clustering!
This is just crazy and backwards reasoning. In no way does it test the hypothesis that there is orbital clustering in Trans-Neptunian objects.
Now ironically the low-quality data that was added is completely consistent with orbital clustering and the existence of a Planet 9 since it shows the same clustering and in the same place. But that is besides the point. The significance of throwing in this low-quality data is that it increases the error bars and makes any analysis more doubtful. It's like trying to look at something through a telescope and deliberately throwing dirt on your lens before you do it.
Post by: Alpha_Centauri on 02/18/2021 09:26 pm
Post by: Blackstar on 02/18/2021 09:29 pm
... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
Yeah yeah, sure. Look, Brown was on my panel for the last planetary science decadal survey, so I'm not some ignorant science rube, I am rather familiar with this. He's a great scientist. But he also made some really bold statements when he published his paper five years ago. I'm too lazy to go look them up, but he was rather cocky about how sure he was that he was right and something would be found relatively quickly.
You can talk about the scientific method (or process), but there's also the public relations aspect of this, and the guy making the bold statements doesn't get to just walk away and wait for everybody else to prove that he's wrong as if this is a totally logical, unemotional process. This is analogous to the Venus phosphine announcement last year where it looks like some people published a paper, but made some rather bold claims that are now being called into question. Yeah, that's the way that science works, but there's more to it than just publishing papers and collecting data, there's the way it is presented and the personalities behind it.
Post by: Lee Jay on 02/18/2021 09:48 pm
The simple truth is this is a case of "more (good) data required".
That's the fundamental rule of science, isn't it?
Post by: Star One on 02/19/2021 08:57 am
Oh of course. I just meant you needed pretty good certainties otherwise you could never apply them.Huh I don’t think that’s right. If that was true there would be no practical applications of science. For example unless we knew certain things to a high degree of certainty we wouldn’t now be rolling out a vaccine program against COVID-19. You can’t build important things like this unless you’ve got some certainties.... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
You can have certainties in math. In science, everything is provisional, meaning nothing is certain. It's all a matter of degree, and some things are more certain than others, but nothing is entirely certain.
Post by: Star One on 02/19/2021 09:00 am
Talking about the human aspect of science his long running spat with Alan Stern doesn’t do either of them any favours.... and the burden of proof is with the person making the unsubstantiated theory to show that it has the ability to be the only answer to the question.
No. There's no "burden of proof". People interested in this topic are all welcome to collect data and do analysis that could support or disprove the hypothesis. If enough data is collected - by anyone - and validated by repeated observations by others, the hypothesis will be elevated to a fact (data point - planet 9 exists) or theory (explanation for existing data - why planet 9 exists and why it's where it is, for example).
People get this wrong about science all the time. It's not about proving hypotheses. It's about disproving them. And when a hypothesis is disproven, someone has to come up with a new hypothesis. Hypotheses that have not been disproven after a long time and many attempts tend to be 'promoted' to a theory, but even then a single observation can disprove the entire thing.
So, it's not Brown and Batygin's job to prove their hypothesis. It's everyone else's job to try and disprove it.
Yeah yeah, sure. Look, Brown was on my panel for the last planetary science decadal survey, so I'm not some ignorant science rube, I am rather familiar with this. He's a great scientist. But he also made some really bold statements when he published his paper five years ago. I'm too lazy to go look them up, but he was rather cocky about how sure he was that he was right and something would be found relatively quickly.
You can talk about the scientific method (or process), but there's also the public relations aspect of this, and the guy making the bold statements doesn't get to just walk away and wait for everybody else to prove that he's wrong as if this is a totally logical, unemotional process. This is analogous to the Venus phosphine announcement last year where it looks like some people published a paper, but made some rather bold claims that are now being called into question. Yeah, that's the way that science works, but there's more to it than just publishing papers and collecting data, there's the way it is presented and the personalities behind it.
Post by: Dizzy_RHESSI on 02/19/2021 03:47 pm
Mike Brown is polite and restrained but I will try to explain the issue more briefly and bluntly. The "No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects" paper is nonsense because what its authors did is take low-quality data, throw it into the mix, and then because of the low-quality data that they just added, which because it is so uncertain can't possible test the hypothesis anyway, decreases the significance of the overall set of data, so that now it can be asserted that the new data set has error bars so wide that it could be consistent with no clustering!
That is absolutely false. Napier et al. quote the significance of the 3 different surveys separately and combined, so it cannot just be the DES data. All three surveys are consistent with no clustering in their analysis. I would refrain from branding anything as "nonsense" if you haven't read it.
Now ironically the low-quality data that was added is completely consistent with orbital clustering and the existence of a Planet 9 since it shows the same clustering and in the same place.
Brown's plot in his tweet makes no allowance for selection biases. There's a reason both papers didn't do clustering by eye. If you look at Fig 4 of the Napier paper you will see that the simulated selection functions are strongly biased towards q=p=0. Of course ETNOs will cluster in the middle, otherwise they aren't detected. The real question is whether or not there is excess clustering above what one would expect purely by selection.
When papers are published they should also publish their uncertainties.
Which uncertainties are you talking about? They published the posterior distributions and their list of objects, which Brown and Batygin (2019) did not.
Post by: mandrewa on 02/19/2021 08:22 pm
Mike Brown is polite and restrained but I will try to explain the issue more briefly and bluntly. The "No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects" paper is nonsense because what its authors did is take low-quality data, throw it into the mix, and then because of the low-quality data that they just added, which because it is so uncertain can't possible test the hypothesis anyway, decreases the significance of the overall set of data, so that now it can be asserted that the new data set has error bars so wide that it could be consistent with no clustering!
That is absolutely false. Napier et al. quote the significance of the 3 different surveys separately and combined, so it cannot just be the DES data. All three surveys are consistent with no clustering in their analysis. I would refrain from branding anything as "nonsense" if you haven't read it.Now ironically the low-quality data that was added is completely consistent with orbital clustering and the existence of a Planet 9 since it shows the same clustering and in the same place.
Brown's plot in his tweet makes no allowance for selection biases. There's a reason both papers didn't do clustering by eye. If you look at Fig 4 of the Napier paper you will see that the simulated selection functions are strongly biased towards q=p=0. Of course ETNOs will cluster in the middle, otherwise they aren't detected. The real question is whether or not there is excess clustering above what one would expect purely by selection.
Dizzy, thank you for your response. And I mean that sincerely, even if it proves that I am embarrassingly wrong. You are right. I have not read the paper. I am a passerby and I have not spent months of my life thinking about the problem. But from reading Mike Brown's response to this paper and spending some minutes thinking about it I think I see what the issue is. Or at least part of the issue.
The problem is that for all of the data sets there is a difference in the effort or the attention directed at the search for objects in different regions of the extreme trans-Neptunian. Now because there hasn't been an equal effort in all sectors there is going to be a natural imbalance in objects detected even if the complete set of extreme trans-Newtonian objects, including those not yet discovered, are evenly distributed.
Now ideally it is possible to take into account both the objects discovered and the different levels of attention that have been directed at the sectors of extreme trans-Neptunian space and calculate whether a perceived clustering is an artifact of the attention paid or whether it is real. I have no idea how to do this myself, but I have not the slightest doubt that there could be a dispute about how this is to be done.
Now I have read Mike Brown's response, and I think channeled it -- except in blunter language -- and you have read the paper and you understood it, and who knows, maybe even you are one of the authors. So I have a few questions that might clarify a few things.
First off I noticed that Mike Brown, in his response, excluded one of the objects that was included the There-Is-No-Planet-9 paper. Quote, "there is one additional object that Napier et al. include that was never reported to the Minor Planet Center; we restrict our analysis to objects whose detection history we can track."
How important is that one object, mathematically speaking? Is it possible that this one object, whose existence is clearly disputed, is responsible for half or more of the difference in apparent clustering between the two analyses?
Second, Mike Brown said, "Interestingly, when Napier et al. looked only at the objects which are identical between their analysis and our analysis, they see clustering at the 99.5% significance level in excellent agreement with our original analysis, so we all agree that those 2019 results appear on firm ground."
Now Brown and Batygin's paper claimed 99.8% significance for the same 14 objects. So if Brown's statement is true this seems like confirmation that the mathematical methods the two papers use are in pretty good agreement.
Do you disagree with Brown's assertion?
Third, the seven new objects detected by the DES survey are all concentrated in the same general area because that is the only area that the DES survey looked at. It seems intuitively obvious to me that when the question is -- Is there clustering? -- that including data like this will (a) either falsely give the impression that there is clustering or (b) increase the level of uncertainty on whatever it all means because it is going to be really hard to mathematically compensate for surveying in only one region.
And isn't that the essence of the problem? Or am I missing something?
Post by: Dizzy_RHESSI on 02/19/2021 11:44 pm
The problem is that for all of the data sets there is a difference in the effort or the attention directed at the search for objects in different regions of the extreme trans-Neptunian. Now because there hasn't been an equal effort in all sectors there is going to be a natural imbalance in objects detected even if the complete set of extreme trans-Newtonian objects, including those not yet discovered, are evenly distributed.
Yes, and this is the point of simulating the selection function by building up the survey with a list of telescope exposures.
Now I have read Mike Brown's response, and I think channeled it -- except in blunter language -- and you have read the paper and you understood it, and who knows, maybe even you are one of the authors. So I have a few questions that might clarify a few things.
As I have said, Brown's comment doesn't make much sense, we can see that in the probability per survey. You might call it blunt but another word for it is ignorant, I don't mean that as an insult or a general statement but you hadn't read the paper you called "nonsense". It's best not to make pointed accusations if you're not sure. And no I am not a co-author, I simply looked at the papers before making any strong claims.
First off I noticed that Mike Brown, in his response, excluded one of the objects that was included the There-Is-No-Planet-9 paper. Quote, "there is one additional object that Napier et al. include that was never reported to the Minor Planet Center; we restrict our analysis to objects whose detection history we can track."
How important is that one object, mathematically speaking? Is it possible that this one object, whose existence is clearly disputed, is responsible for half or more of the difference in apparent clustering between the two analyses?
I'm assuming Brown is talking about uo5m93 which is from the OSSOS survey, in which case the answer is no. Brown and Batygin 2019 agrees that OSSOS showed no evidence of clustering. And as I said before the Napier et al. paper showed the surveys independently, one object wouldn't affect all the results.
Napier et al. suggest that one object is actually behind the BB16 result, and it may just be small number statistics. 2015 BP519 is the only DES object used by BB16 and it's an extreme outlier, as shown in Brown's figure. Napier et al. show that the significance decreases sharply (lower evidence) if this one object is dropped. Brown and Batygin (2019) unfortunately did not test the robustness of their result to show it wasn't just driven by a single outlier. That is a point for Brown and Batygin to respond to, sadly Brown hasn't addressed this.
Second, Mike Brown said, "Interestingly, when Napier et al. looked only at the objects which are identical between their analysis and our analysis, they see clustering at the 99.5% significance level in excellent agreement with our original analysis, so we all agree that those 2019 results appear on firm ground."
Now Brown and Batygin's paper claimed 99.8% significance for the same 14 objects. So if Brown's statement is true this seems like confirmation that the mathematical methods the two papers use are in pretty good agreement. Do you disagree with Brown's assertion?
It's not the same 14 objects, only 9 are common between the two papers. Note the intersection includes the anomalous object (2015 BP519). A key point of the Napier et al. paper is that the sample was constructed to be independent from the Batygin and Brown (2016) paper which made the original claim about Planet 9 with just 6 objects. Results should be replicable with independent samples if they are robust. If both papers are robust then the result of Brown and Batygin (2019) is, at best, much less significant than claimed.
Third, the seven new objects detected by the DES survey are all concentrated in the same general area because that is the only area that the DES survey looked at. It seems intuitively obvious to me that when the question is -- Is there clustering? -- that including data like this will (a) either falsely give the impression that there is clustering or (b) increase the level of uncertainty on whatever it all means because it is going to be really hard to mathematically compensate for surveying in only one region.
Brown and Batygin (2019) used one object from DES, the outlier. If you really believe DES is unworkable then that paper is also biased.
Post by: clongton on 02/20/2021 03:19 pm
Which uncertainties are you talking about? They published the posterior distributions and their list of objects, which Brown and Batygin (2019) did not.
From Mike Brown's Twitter published 2021-02-16
Quote
But there is a solution. That solution? Publish your uncertainties.
Napier et al. get it right, in the end:
Ah ha! Sadly, they don't check for consistency with the previously measured clustering, or they would see that, indeed, the ETNOs were already known to be clustered precisely where DES has looked.
I think this solves the mystery of how adding in objects which appear quite clustered makes the significance of your clustering appear to go away.
I think that the right conclusion is that the highly-biased DES data is consistent with the previous measurements of clustering, but that the bias from DES is strong enough that we should probably not be surprised by this. In the end, the previously measured clustering from our 2019 paper is still valid (and has actual uncertainties published), and the conclusions of that paper remain. The clustering of distant Kuiper belt objects is highly significant. It's hard to imagine a process other than Planet Nine that could make these patterns. The search continues.
Post by: Dizzy_RHESSI on 02/21/2021 06:27 pm
Which uncertainties are you talking about? They published the posterior distributions and their list of objects, which Brown and Batygin (2019) did not.
From Mike Brown's Twitter published 2021-02-16QuoteBut there is a solution. That solution? Publish your uncertainties.
Napier et al. get it right, in the end:
Ah ha! Sadly, they don't check for consistency with the previously measured clustering, or they would see that, indeed, the ETNOs were already known to be clustered precisely where DES has looked.
I think this solves the mystery of how adding in objects which appear quite clustered makes the significance of your clustering appear to go away.
I think that the right conclusion is that the highly-biased DES data is consistent with the previous measurements of clustering, but that the bias from DES is strong enough that we should probably not be surprised by this. In the end, the previously measured clustering from our 2019 paper is still valid (and has actual uncertainties published), and the conclusions of that paper remain. The clustering of distant Kuiper belt objects is highly significant. It's hard to imagine a process other than Planet Nine that could make these patterns. The search continues.
I'm aware of Brown's comments, but Napier et al. used this same method Brown and Batygin (2019) who also didn't calculate "uncertainties" on their result. The result is a significance of deviation, it doesn't come with any formal uncertainly. There's no uncertainties missing from their result. Brown seems to be demanding that they quote some upper limit, which would only be possible if they adopted one specific model of the clustering. Even if Napier et al. did this, it would be incomparable to Brown and Batygin's result because they never did this to begin with. Brown's seem either nonsensical or hypocritical, but he's not actually specific about which uncertainties are he things are missing.
Post by: Star One on 04/14/2021 08:17 am
Quote
(1/8) New P9 stuff: Injection of Inner Oort Cloud Objects Into the Distant Kuiper Belt by Planet Nine, published in ApJL, on #arxiv tonight: https://arxiv.org/pdf/2104.05799.pdf…
Writeup: http://findplanetnine.blogspot.com/2021/04/the-inner-oort-cloud-connection.html…
Thread below…
https://mobile.twitter.com/kbatygin/status/1382165869271285762
Article:
http://findplanetnine.blogspot.com/2021/04/the-inner-oort-cloud-connection.html?m=1
Paper:
https://arxiv.org/pdf/2104.05799.pdf
Post by: Star One on 04/14/2021 10:10 am
Post by: Bynaus on 04/14/2021 11:16 am
In other words Planet nine if it exists is having even more of an impact on the outer solar system than first suspected when the theory for its existence was put forward.
Or rather, a different one than assumed when the P9 hypothesis was first presented. Constraints on orbit (eccentricity, semi-major-axis) and mass were originally computed under the assumption that all scattered (&aligned) objects come from the Kuiper belt. Factoring in that some might come from the "inner Oort cloud", populated when the sun was still in its birth cluster, these constraints work out a bit differently now, but how exactly depends on how many of these far-out TNOs are really from the Kuiper belt vs. the inner Oort cloud. "More data needed".
Post by: Star One on 04/14/2021 12:54 pm
Would it be possible to differentiate the two populations in the Kuiper belt using current observational technology through their chemical composition. And related to that would it be possible to constrain the proportion of the Kuiper belt that originated from the ‘inner Oort Cloud’.In other words Planet nine if it exists is having even more of an impact on the outer solar system than first suspected when the theory for its existence was put forward.
Or rather, a different one than assumed when the P9 hypothesis was first presented. Constraints on orbit (eccentricity, semi-major-axis) and mass were originally computed under the assumption that all scattered (&aligned) objects come from the Kuiper belt. Factoring in that some might come from the "inner Oort cloud", populated when the sun was still in its birth cluster, these constraints work out a bit differently now, but how exactly depends on how many of these far-out TNOs are really from the Kuiper belt vs. the inner Oort cloud. "More data needed".
Post by: Bynaus on 04/14/2021 06:10 pm
Would it be possible to differentiate the two populations in the Kuiper belt using current observational technology through their chemical composition. And related to that would it be possible to constrain the proportion of the Kuiper belt that originated from the ‘inner Oort Cloud’.In other words Planet nine if it exists is having even more of an impact on the outer solar system than first suspected when the theory for its existence was put forward.
Or rather, a different one than assumed when the P9 hypothesis was first presented. Constraints on orbit (eccentricity, semi-major-axis) and mass were originally computed under the assumption that all scattered (&aligned) objects come from the Kuiper belt. Factoring in that some might come from the "inner Oort cloud", populated when the sun was still in its birth cluster, these constraints work out a bit differently now, but how exactly depends on how many of these far-out TNOs are really from the Kuiper belt vs. the inner Oort cloud. "More data needed".
I am sure there are already plenty of expert minds thinking in that direction at this very moment. To my knowledge, there is no way to tell them apart from here, today. Too far to sample, and perhaps not characteristically different enough to discern by observations alone (although I think that's probably still TBD). There might be slight differences, since "inner Oort cloud" objects would have formed closer in, in the giant planet zone, whereas KBOs from the "classical" Kuiper belt came from further out, so they would have formed in zones where other molecular species were present in gaseous / solid form, etc.
Post by: Star One on 04/16/2021 08:45 am
https://youtu.be/39y6Oqo6p18
Post by: Star One on 09/04/2021 07:18 am
Planet 9 may be closer and easier to find than thought—if it exists
Quote
A new study's "treasure map" suggests that a planet several times more massive than Earth could be hiding in our solar system, camouflaged by the bright strip of stars that make up the Milky Way.
https://www.nationalgeographic.com/science/article/planet-9-may-be-closer-and-easier-to-find-than-thought-if-it-exists
Here’s the new paper:
https://arxiv.org/pdf/2108.09868.pdf
Post by: leovinus on 09/04/2021 03:39 pm
First time we’ve had an update in this planet nine business in what feels like ages. Though I can see it’s actually not that long. I am sure I’ve heard Brown talking about it hiding in the bright strip of the Milky Way before.
Planet 9 may be closer and easier to find than thought—if it existsQuoteA new study's "treasure map" suggests that a planet several times more massive than Earth could be hiding in our solar system, camouflaged by the bright strip of stars that make up the Milky Way.
https://www.nationalgeographic.com/science/article/planet-9-may-be-closer-and-easier-to-find-than-thought-if-it-exists
Here’s the new paper:
https://arxiv.org/pdf/2108.09868.pdf
Thank you. The Arxiv article makes for interesting reading. In particular, the discussion of "observational bias" addresses comments from other authors and articles in the last 2 years or so. Previous articles on this topic were followed by many comments of peers, other authors, and more analysis, so love to see where the new article and analysis takes us.
Post by: Star One on 09/05/2021 09:37 am
It does raise the question of what else is hidden in the same way because of the Milky Way.First time we’ve had an update in this planet nine business in what feels like ages. Though I can see it’s actually not that long. I am sure I’ve heard Brown talking about it hiding in the bright strip of the Milky Way before.
Planet 9 may be closer and easier to find than thought—if it existsQuoteA new study's "treasure map" suggests that a planet several times more massive than Earth could be hiding in our solar system, camouflaged by the bright strip of stars that make up the Milky Way.
https://www.nationalgeographic.com/science/article/planet-9-may-be-closer-and-easier-to-find-than-thought-if-it-exists
Here’s the new paper:
https://arxiv.org/pdf/2108.09868.pdf
Thank you. The Arxiv article makes for interesting reading. In particular, the discussion of "observational bias" addresses comments from other authors and articles in the last 2 years or so. Previous articles on this topic were followed by many comments of peers, other authors, and more analysis, so love to see where the new article and analysis takes us.
Post by: Dinamobolso on 11/02/2021 06:44 am
Quote
Recent estimates of the characteristics of Planet Nine have suggested that it could be closer than originally assumed. Such a Planet Nine would also be brighter than originally assumed, suggesting the possibility that it has already been observed in wide-field moderate-depth surveys. We search for Planet Nine in the Zwicky Transient Facility public archive and find no candidates. Using known asteroids to calculate the magnitude limit of the survey, we find that we should have detected Planet Nine throughout most of the northern portion of its predicted orbit -- including within the galactic plane -- to a 95% detection efficiency of approximately V=20.5. To aid in understanding detection limits for this and future analyses, we present a full-sky synthetic Planet Nine population drawn from a statistical sampling of predicted Planet Nine orbits. We use this reference population to estimate that this survey rules out 56% of predicted Planet Nine phase space, and we demonstrate how future analyses can use the same synthetic population to continue to constrain the amount of parameter space effectively searched for Planet Nine.
NEW Article:
http://findplanetnine.blogspot.com/2021/10/the-hunt-is-on.html?m=1 (http://findplanetnine.blogspot.com/2021/10/the-hunt-is-on.html?m=1)
NEW Papper:
https://arxiv.org/abs/2110.13117 (https://arxiv.org/abs/2110.13117)
Post by: clongton on 11/02/2021 01:19 pm
1. Do all the studies assume a circular solar orbit, not unlike the other 8 planets, or are allowances being made in the search for the possibility that Planet Nine may be in a highly eccentric solar orbit?
2. Do all the studies assume that Planet Nine is in the Earth-sun ecliptic or are allowances being made in the search for the possibility that Planet Nine may be in a non ecliptic solar orbit?
Just wondering if all the bases are covered.
Post by: Lee Jay on 11/02/2021 03:06 pm
I have 2 questions:
1. Do all the studies assume a circular solar orbit, not unlike the other 8 planets, or are allowances being made in the search for the possibility that Planet Nine may be in a highly eccentric solar orbit?
2. Do all the studies assume that Planet Nine is in the Earth-sun ecliptic or are allowances being made in the search for the possibility that Planet Nine may be in a non ecliptic solar orbit?
Just wondering if all the bases are covered.
No and yes and No and yes.
Post by: Star One on 11/02/2021 04:47 pm
https://twitter.com/plutokiller/status/1452842758767403009
And his response to being asked the chances of finding it by 2025:
https://twitter.com/plutokiller/status/1452845827127271424
Post by: Dinamobolso on 11/10/2021 06:55 am
Post by: deadman1204 on 11/10/2021 03:27 pm
This is more about him laying claim to a first detection "just in case" its real.
Post by: Star One on 11/10/2021 06:37 pm
A search for Planet 9 in the IRAS data
I have carried out a search for Planet 9 in the IRAS data. At the distance range proposed for Planet 9, the signature would be a 60 micron unidentified IRAS point source with an associated nearby source from the IRAS Reject File of sources which received only a single hours-confirmed (HCON) detection. The confirmed source should be detected on the first two HCON passes, but not on the third, while the single HCON should be detected only on the third HCON. I have examined the unidentified sources in three IRAS 60micron catalogues: some can be identified with 2MASS galaxies, Galactic sources or as cirrus. The remaining unidentified sources have been examined with the IRSA Scanpi tool to check for the signature missing HCONs, and for association with IRAS Reject File single HCONs. No matches of interest survive.
For a lower mass planet (< 5 earth masses) in the distance range 200-400 AU, we expect a pair or triplet of single HCONs with separations 2-35 arcmin. Several hundred candidate associations are found and have been examined with Scanpi. A single candidate for Planet 9 survives which satisfies the requirements for detected and non-detected HCON passes. A fitted orbit suggest a distance of 225+-15 AU and a mass of 3-5 earth masses. Dynamical simulations are needed to explore whether the candidate is consistent with existing planet ephemerides. If so, a search in an annulus of radius 2.5-4 deg centred on the 1983 position at visible and near infrared wavelengths would be worthwhile.
https://arxiv.org/abs/2111.03831
Post by: Star One on 11/11/2021 10:40 am
https://youtu.be/VQqOo2Kfzbs
Post by: Star One on 11/11/2021 10:48 am
Quote
His data suggest the new world would be three to five times more massive than the Earth, and orbiting the Sun at about 225 times the distance of our own planet.
Michael Rowan-Robinson, Emeritus professor of astrophysics at Imperial College London, and a former President of the Royal Astronomical Society, found his candidate for a new world in historic observations made by an early space telescope.
The Infrared Astronomical Satellite (IRAS) was launched in 1983 as the first orbiting observatory to look at the entire night sky in the infrared region of the spectrum, which lies just beyond the rainbow of visible light.
Over ten months, the mission observed more than a quarter of a million infrared sources in the sky, by detecting their heat against the cold sky background.
Quote
In a research paper describing his search for Planet 9, the professor admits that the observations are not of high quality and were made in a region of sky full of filaments of galactic gas known as cirrus because of their cloud-like nature.
He also concedes that a more recent comprehensive survey of the night sky by Pan-STARRS telescopes in Hawaii have failed to record the object, suggesting it is not real.
Quote
Planetary scientist Professor Mike Brown, who rejoices under the Twitter handle @plutokiller, and has been making his own search for another planet, tweeted: “The candidate is on an orbit utterly inconsistent with our predictions for Planet Nine, and would not be capable of gravitationally perturbing the distant Solar System in the ways that we have suggested. But, of course, that doesn’t mean it isn’t real!
“It just means that it would be a serendipitous discovery of something while searching for Planet Nine. Pluto happened the same way. Tombaugh was searching for Lowell’s Planet X (which didn’t exist) and accidentally found Pluto. Pluto was not the predicted Planet X.”
https://www.skymania.com/wp/professor-finds-possible-ninth-planet-in-our-solar-system/
Post by: Dinamobolso on 11/11/2021 11:24 pm
Or is your planet 9 still possible?
Pd: Sorry for my English.
Post by: Star One on 11/12/2021 07:00 am
Bad news for Mike Brown n Batygin?This planet, if it is a planet, could not cause the changes in the orbits of objects in the outer solar system that they base their hypothesis on.
Or is your planet 9 still possible?
Pd: Sorry for my English.
Post by: baldusi on 11/12/2021 01:59 pm
Mike Brown stated in a tweet that it would not be the planet and does not rules out his. But, if it is indeed a planet, his Planet IX would then be Planet X. Which would be kinda funny. In fact, Pluto was discovered looking for an non existing planet.Bad news for Mike Brown n Batygin?This planet, if it is a planet, could not cause the changes in the orbits of objects in the outer solar system that they base their hypothesis on.
Or is your planet 9 still possible?
Pd: Sorry for my English.
Post by: deadman1204 on 11/12/2021 02:11 pm
Kinda makes you wonder how many could be out there.
Post by: Dinamobolso on 11/12/2021 03:53 pm
Bad news for Mike Brown n Batygin?This planet, if it is a planet, could not cause the changes in the orbits of objects in the outer solar system that they base their hypothesis on.
Or is your planet 9 still possible?
Pd: Sorry for my English.
But doesn't it affect you in any way?
They have the same perihelion
Post by: Dinamobolso on 11/12/2021 03:59 pm
I've heard there is recent talk about a 10th mars size planet out there.
Kinda makes you wonder how many could be out there.
The influence of the sun is 100,000 AU.
Is much to discover.
There is the other theory, that a small terrestrial planet was expelled from the inner solar system.
Post by: Star One on 11/12/2021 08:36 pm
I've heard there is recent talk about a 10th mars size planet out there.That’s been speculated for some little time as the reason for the ‘Kuiper Cliff’.
Kinda makes you wonder how many could be out there.
Post by: Dinamobolso on 11/13/2021 02:27 am
https://twitter.com/plutokiller/status/1459359063922208774?t=q3f2zTp64Wf7_5JjSYLd_g&s=19
Post by: Star One on 11/25/2021 08:28 pm
https://youtu.be/U8p0baDb24Q
He confirms that if it does exist this planetary candidate it would possibly be a super Earth.
Post by: jbenton on 08/01/2023 04:43 pm
https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size (https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size)
In ancient Greek mythology, Aeolus was the Keeper of the Winds (making it a quite fitting name for a sophisticated weather satellite). I don't know of any stories of him in mythology outside of the Odyssey.
In the Odyssey, when "long-suffering" Odysseus ends up on the shores of Aeolus' island home of Aeolia, he agrees to give Odysseus a magical bag of winds. He guarantees that - if used properly - it will direct the ship's sails all the way back to Odysseus' island home of Ithaca. Unfortunately, soon after Odysseus is finally in view of Ithaca, his once faithful, now rebellious crew conclude that Odysseus is hiding something from them within the bag (perhaps gold) and so they eagerly open it wide, pushing them all the way back to Aeolia.
I thought it would be fitting here, since the giant planet (if it exists) appears to be pushing several other objects around, kind of like a bunch of things being "scattered to the Four Winds" in the idiom.
Just skimming through this thread, I noticed AegeanBlue already brought up this name as a possibility. I can't remember if I read this before, but - in all probability - AegeanBlue thought of all this long before I did. Based on what AB said, it seems to me that there would be a case that it would be a fitting name for the next Major Planet discovered even without any connection to wind:
In terms of naming, Aeolus is a major god and does not seem to have an asteroid named after him. It could be a name
Aeolus is not taken and he is a relatively major god. The 12 Olympian gods have already been named, if we go to the second generation gods a.k.a Titans they are all satellites of Saturn, the first generation gods are Uranus and Earth (also transliterated as Gaia). Going forward from the classical to the Hellenistic there were syncratic gods like Sarapis and Hermanubis, worship of abstract notions like Fortune (=Tyche), imported Gods like Astarte or Mithras on top of the worship of deified monarchs. Augustus allowed himself to be worshiped by the Hellenistic cities as a god, so long Rome was also worshiped along with him.
...
There are also some other neat ideas for naming this object (if it exists) on this thread.
Post by: Phil Stooke on 08/03/2023 07:34 am
Post by: jebbo on 08/03/2023 04:28 pm
I'll ask around and see if I can quantify this better.
--- Tony
Post by: leovinus on 08/03/2023 05:07 pm
https://arxiv.org/search/?query=%22Planet+nine%22&searchtype=all&abstracts=show&order=-announced_date_first&size=50
and Mike Brown and Konstantin Batygin papers on the subject seem to be from last year
Limits on the Detection of Planet Nine in the Dark Energy Survey
https://resolver.caltech.edu/CaltechAUTHORS:20220512-620314000
A Search for Planet Nine using the Zwicky Transient Facility Public Archive
https://resolver.caltech.edu/CaltechAUTHORS:20211130-215738362
Let's be patient :)
Post by: deadman1204 on 08/04/2023 12:59 am
The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.Wouldn't a planet 10 exert less influence than that?
I'll ask around and see if I can quantify this better.
--- Tony
Post by: Robotbeat on 08/04/2023 01:30 am
No. The "Planet 9" (remember, the guy who killed Pluto is the same guy who thinks there's a bigger Planet 9 out there) is supposed to be like 460AU and 6.3 times the mass of the Earth. That would put the barycenter of the solar system about 32000km offset from where it is now.The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.Wouldn't a planet 10 exert less influence than that?
I'll ask around and see if I can quantify this better.
--- Tony
So...
Post by: Lee Jay on 08/04/2023 03:43 am
No. The "Planet 9" (remember, the guy who killed Pluto is the same guy who thinks there's a bigger Planet 9 out there) is supposed to be like 460AU and 6.3 times the mass of the Earth. That would put the barycenter of the solar system about 32000km offset from where it is now.The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.Wouldn't a planet 10 exert less influence than that?
I'll ask around and see if I can quantify this better.
--- Tony
So...
So...it could be a ring of material rather than a planet. Remember, the original analysis had no way to distinguish between them.
Post by: Star One on 08/04/2023 08:32 am
So in other words there is no ninth planet. And Alan Stern gets the last laugh over Mike Brown then.No. The "Planet 9" (remember, the guy who killed Pluto is the same guy who thinks there's a bigger Planet 9 out there) is supposed to be like 460AU and 6.3 times the mass of the Earth. That would put the barycenter of the solar system about 32000km offset from where it is now.The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.Wouldn't a planet 10 exert less influence than that?
I'll ask around and see if I can quantify this better.
--- Tony
So...
Post by: joncz on 08/04/2023 12:15 pm
The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.
https://www.youtube.com/shorts/QQofqq8eW1g
Post by: sebk on 08/04/2023 02:06 pm
No. The "Planet 9" (remember, the guy who killed Pluto is the same guy who thinks there's a bigger Planet 9 out there) is supposed to be like 460AU and 6.3 times the mass of the Earth. That would put the barycenter of the solar system about 32000km offset from where it is now.The odds of a big planet X have dropped recently due to the pulsar timing discovery of a gravitational wave background. This meant knowing the position of the Solar System barycentre to within a few 100 metres, and this puts very strong constraints on the mass of any additional planet.Wouldn't a planet 10 exert less influence than that?
I'll ask around and see if I can quantify this better.
--- Tony
So...
But such far away plane takes thousands of years. So the question is how much the barycenter would shift during the pulsar timing observation.