Author Topic: Dwarf planet discovery hints at a hidden Super Earth in solar system  (Read 187989 times)

Offline Alpha_Centauri

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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.

Offline Star One

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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?

Offline Alpha_Centauri

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« Last Edit: 02/06/2019 05:28 pm by Alpha_Centauri »

Offline Star One

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Offline Alpha_Centauri

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Sure? No. But I agree with Bynaus about the logic of the latest Subaru run, and I'm not sure both Brown and Batygin would bother going if they had already found it and were just completing the survey. Mike Brown has also said previously he wouldn't wait to announce it as soon as he found it so astronomers could observe it as soon as possible. And as I said a re-evaluation of the orbital parameters is overdue.  Not impossible, but I wouldn't get your hopes up.
« Last Edit: 02/06/2019 06:08 pm by Alpha_Centauri »

Offline Bynaus

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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 heís going out there if itís a routine pre-planned visit. He hasnít 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.
« Last Edit: 02/06/2019 06:30 pm by Bynaus »
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Offline Star One

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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.
« Last Edit: 02/06/2019 06:39 pm by Star One »

Offline Alpha_Centauri

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As I suspected;

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

Offline Bynaus

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The semi-major axis is interesting for the search phase, but in the long run, I suspect the relatively low mass will be much more interesting. We don't have another 6 Earth mass body in the solar system (that we already know of), but it is in the mass range where most exoplanets known today are found. So if P9 exists and has this mass, we'd have the opportunity to study this special and abundant planet type from up close.
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Offline Alpha_Centauri

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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.

Offline Star One

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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.
« Last Edit: 02/07/2019 12:38 pm by Star One »

Offline Alpha_Centauri

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With a smaller semimajor axis aphelion is much closer to the Sun than the first estimates, putting it within touching distance of existing surveys.

Offline Star One

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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.

Offline philw1776

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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 heís going out there if itís a routine pre-planned visit. He hasnít 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!
"It'll bang right out!"

Offline Bynaus

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This one's interesting:

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).
« Last Edit: 02/11/2019 10:13 pm by Bynaus »
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Offline clongton

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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.
« Last Edit: 02/12/2019 08:34 pm by clongton »
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Offline as58

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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.

Offline Bynaus

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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.
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Offline clongton

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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.
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I started my career on the Saturn-V F-1A engine

Offline Oumuamua

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Scott Sheppard apparently found another dwarf planet in the outer solar system, at a distance of 140 AU, and with the nickname "FarFarOut", not to be confused with "FarOut" which was found in december.

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
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.

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