Author Topic: Hyperbolic Hyperbole or Interstellar Interloper? ('Oumuamua)  (Read 26737 times)

Offline nacnud

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First Object From Another Star System Found Near Earth,

« Last Edit: 12/04/2017 10:19 PM by gongora »

Offline whitelancer64

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Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #2 on: 10/26/2017 07:37 PM »
Hereís the official press release.

Small Asteroid or Comet 'Visits' from Beyond the Solar System

Quote
A small, recently discovered asteroid - or perhaps a comet - appears to have originated from outside the solar system, coming from somewhere else in our galaxy. If so, it would be the first "interstellar object" to be observed and confirmed by astronomers.
This unusual object - for now designated A/2017 U1 - is less than a quarter-mile (400 meters) in diameter and is moving remarkably fast. Astronomers are urgently working to point telescopes around the world and in space at this notable object. Once these data are obtained and analyzed, astronomers may know more about the origin and possibly the composition of the object.
A/2017 U1 was discovered Oct. 19 by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala during the course of its nightly search for Near-Earth Objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy (IfA), was first to identify the moving object and submit it to the Minor Planet Center. Weryk subsequently searched the Pan-STARRS image archive and found it was present in images taken the previous night, but was not initially identified by the moving object processing.
Weryk immediately realized this was an unusual object. "Its motion could not be explained using either a normal solar system asteroid or comet orbit," he said. Weryk contacted IfA graduate Marco Micheli, who had the same realization using his own follow-up images taken at the European Space Agency's telescope on Tenerife in the Canary Islands. But with the combined data, everything made sense. Said Weryk, "This object came from outside our solar system."
"This is the most extreme orbit I have ever seen," said Davide Farnocchia, a scientist at NASA's Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California. "It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back."
The CNEOS team plotted the object's current trajectory and even looked into its future. A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.
The object approached our solar system from almost directly "above" the ecliptic, the plane in space near where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun. On Sept. 2, the small body crossed under the ecliptic just inside of Mercury's orbit and then made its closest approach to the Sun on Sept. 9. Pulled by the Sun's gravity, the object made a hairpin turn under our solar system, passing below Earth's orbit on Oct. 14 at a distance of about 15 million miles (24 million kilometers) -- about 60 times the distance to the Moon. It has now shot back up above the plane of the planets and, travelling at 27 miles per second (44 kilometers per second) with respect to the Sun, the object is speeding toward the constellation Pegasus.
"We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What's most surprising is that we've never seen interstellar objects pass through before," said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to solar system formation.
The small body has been assigned the temporary designation A/2017 U1 by the Minor Planet Center (MPC) in Cambridge, Massachusetts, where all observations on small bodies in our solar system -- and now those just passing through -- are collected. Said MPC Director Matt Holman, "This kind of discovery demonstrates the great scientific value of continual wide-field surveys of the sky, coupled with intensive follow-up observations, to find things we wouldn't otherwise know are there."
Since this is the first object of its type ever discovered, rules for naming this type of object will need to be established by the International Astronomical Union.
"We have been waiting for this day for decades," said CNEOS Manager Paul Chodas. "It's long been theorized that such objects exist - asteroids or comets moving around between the stars and occasionally passing through our solar system - but this is the first such detection. So far, everything indicates this is likely an interstellar object, but more data would help to confirm it."
Animation of path of A2017U1

http://www.ifa.hawaii.edu/info/press-releases/interstellar/

NASA Press Release

https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system
« Last Edit: 10/26/2017 07:47 PM by Star One »

Offline zubenelgenubi

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #3 on: 10/26/2017 08:00 PM »
Pretty good article here:

http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/
Quote
What gave this object away as an interstellar visitor wasn't its very high inclination (122į) with respect to Earth's orbit, which isn't particularly rare, but more critically its extremely hyperbolic eccentricity (1.19).
<snip>
More intriguing is the fact that A/2017 U1 is coming from a spot only 6į from the solar apex, the direction that our Sun is moving (at about 20 km/s) through its interstellar neighborhood and thus, statistically, the most likely incoming direction for an interstellar visitor.
Support your local planetarium!

Offline Orbiter

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #4 on: 10/26/2017 08:04 PM »
First time a comet has been re-designated as an asteroid, too. Almost 100% certainly an interstellar object, in this case an asteroid that came from another solar system. Absolutely incredible!
Attended space missions: STS-114, STS-124, STS-128, STS-135, Atlas V "Curiosity", Delta IV Heavy NROL-15, Atlas V MUOS-2, Delta IV Heavy NROL-37, SpaceX CRS-9, SpaceX JCSAT-16, Atlas V GOES-R, SpaceX SES-11.

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #5 on: 10/26/2017 08:22 PM »
How precisely will they be able to pin down where it came from and where itís going?

Offline Orbiter

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #6 on: 10/26/2017 08:25 PM »
How precisely will they be able to pin down where it came from and where itís going?

Its location of origin in the night sky was close to the star Vega, however that does not mean that it came from the Vega system. It could have come from any of the billions of stars in the Milky Way Galaxy.
Attended space missions: STS-114, STS-124, STS-128, STS-135, Atlas V "Curiosity", Delta IV Heavy NROL-15, Atlas V MUOS-2, Delta IV Heavy NROL-37, SpaceX CRS-9, SpaceX JCSAT-16, Atlas V GOES-R, SpaceX SES-11.

Online jebbo

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #7 on: 10/26/2017 08:26 PM »
Here's the latest MPECs:
http://www.minorplanetcenter.net/mpec/K17/K17UI3.html
http://www.minorplanetcenter.net/mpec/K17/K17UI5.html

Not that many observations, but strongly hyperbolic.  However, some caution is needed; I'm waiting until next week before being sure it's interstellar.

--- Tony
« Last Edit: 10/26/2017 08:28 PM by jebbo »

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #8 on: 10/26/2017 08:27 PM »
How precisely will they be able to pin down where it came from and where itís going?

Its location of origin in the night sky was close to the star Vega, however that does not mean that it came from the Vega system. It could have come from any of the billions of stars in the Milky Way Galaxy.

Thanks. Was it travelling too fast to be captured by the Sun?

Offline hop

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #9 on: 10/26/2017 09:04 PM »
Thanks. Was it travelling too fast to be captured by the Sun?
The Sun alone doesn't capture anything. Ignoring non-gravitational forces (which should be minor in most realistic scenarios) anything arriving from interstellar space will depart at the same speed. Capture requires interactions with additional bodies.

In this case, estimates I've seen put the hyperbolic excess over 20 km/s (but take that with a grain of salt, uncertainties may be large), and it doesn't come anywhere near any of the giant planets, so it's definitely too fast to capture. It's also likely too fast for an solar system Oort cloud object perturbed by something like Planet 9 or a plausible recent stellar encounter.

Edit:
Lee Billings has a nice writeup on sciam
https://www.scientificamerican.com/article/astronomers-spot-first-ever-space-rock-from-another-star/
« Last Edit: 10/27/2017 01:42 AM by hop »

Online Zed_Noir

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #10 on: 10/27/2017 05:22 AM »
:) Not too seriously.

The object's trajectory in and out of the Solar system follows the flight path of a  covert system survey mission as describe in some of the more esoteric Sci-Fi literature.

Online jebbo

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #11 on: 10/27/2017 08:50 AM »
In this case, estimates I've seen put the hyperbolic excess over 20 km/s (but take that with a grain of salt, uncertainties may be large), and it doesn't come anywhere near any of the giant planets, so it's definitely too fast to capture. It's also likely too fast for an solar system Oort cloud object perturbed by something like Planet 9 or a plausible recent stellar encounter.

Latest analysis of the trajectory I've seen is https://projectpluto.com/temp/2017u1.htm

Incoming & outgoing Vinf ~= 26km/s

Starting to see some (low res) spectra appearing as well ...

--- Tony

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #12 on: 10/27/2017 10:43 AM »
The fact that PANSTARRS A2017/U1 appears not to have developed any kind of coma is interesting. Even if it is non-cometary in form, you would have expected there to have been at least some volatiles that would have activated during its journey through the inner solar system.
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Online jebbo

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #13 on: 10/27/2017 10:58 AM »
The fact that PANSTARRS A2017/U1 appears not to have developed any kind of coma is interesting. Even if it is non-cometary in form, you would have expected there to have been at least some volatiles that would have activated during its journey through the inner solar system.

Why? For example, I don't think you'd expect volatiles from a body ejected from inside the ice-line (e.g. by a Jupiter-analogue during a "grand tack" equivalent or inward migration to form a hot-Jupiter).

--- Tony

Offline TakeOff

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #14 on: 10/27/2017 02:10 PM »
It might've lost its volatiles billions of years ago before it was ejected from its (now long gone) binary star system of origin.

jebbo:
I think the point is that Jupiter couldn't have done it (alone) because they never get close.
« Last Edit: 10/27/2017 02:10 PM by TakeOff »

Offline cjsks

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #15 on: 10/27/2017 03:44 PM »
Makes me wonder, what would a rocky/metallic object, ~1/4 mile in diameter, entering Earth's atmosphere at 56,000+ mph look like?

Offline hop

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #16 on: 10/27/2017 04:12 PM »
Why? For example, I don't think you'd expect volatiles from a body ejected from inside the ice-line (e.g. by a Jupiter-analogue during a "grand tack" equivalent or inward migration to form a hot-Jupiter).
Agreed, the existence of volatile free interstellar asteroids does not seem at all surprising. We know a lot of rocky stuff must have been ejected by Jupiter over the history of the solar system.

OTOH, the general expectation seems to have been that we would see interstellar comets before asteroids,  because they are easier to detect, and models of our own solar system predict more icy bodies being ejected. So the fact that the first one was an asteroid may be telling us something... or it might just be a fluke ;)

A recent (but pre A/2017 U1 obviously) paper:
An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets Toni Engelhardt, Robert Jedicke, Peter Veres, Alan Fitzsimmons, Larry Denneau, Ed Beshore, Bonnie Meinke (accepted for publication in AJ)
Quote
We derived 90% confidence limits (CL) on the interstellar number density (ρCLIS) of interstellar objects (ISO; comets and asteroids) as a function of the slope of their size-frequency distribution and limiting absolute magnitude. To account for gravitational focusing, we first generated a quasi-realistic ISO population to ~750 au from the Sun and propagated it forward in time to generate a steady state population of ISOs with heliocentric distance <50 au. We then simulated the detection of the synthetic ISOs using pointing data for each image and average detection efficiencies for each of three contemporary solar system surveys --- PS1, the Mt. Lemmon Survey, and the Catalina Sky Survey. These simulations allowed us to determine the surveys' combined ISO detection efficiency under several different but realistic modes of identifying ISOs in the survey data. Some of the synthetic detected ISOs had eccentricities as small as 1.01 --- in the range of the largest eccentricities of several known comets. Our best CL of ρCLIS=1.4◊10−4 au−3 implies that the expectation that extra-solar systems form like our solar system, eject planetesimals in the same way, and then distribute them throughout the galaxy, is too simplistic, or that the SFD or behavior of ISOs as they pass through our solar system is far from expectations.

Fitzsimmons (co-author on the above) has taken spectra of A/2017 U1
https://twitter.com/FitzsimmonsAlan/status/923928561722982400
« Last Edit: 10/27/2017 04:15 PM by hop »

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #17 on: 10/27/2017 04:20 PM »
Agreed, the existence of volatile free interstellar asteroids does not seem at all surprising. We know a lot of rocky stuff must have been ejected by Jupiter over the history of the solar system.

OTOH, it the general expectation seems to have been that we would see interstellar comets before asteroids,  because they are easier to detect, and models of our own solar system predict more icy bodies being ejected. So  the fact that the first one was an asteroid may be telling us something... or it might just be a fluke ;)

True. I'm wondering what the LSST yield of similar objects will be!

Quote
A recent (but pre A/2017 U1 obviously) paper:
An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets Toni Engelhardt, Robert Jedicke, Peter Veres, Alan Fitzsimmons, Larry Denneau, Ed Beshore, Bonnie Meinke (accepted for publication in AJ)

Thanks! Hasn't seen that one. Too many papers, not enough time :)

Quote
Fitzsimmons (co-author on the above) has taken spectra of A/2017 U1
https://twitter.com/FitzsimmonsAlan/status/923928561722982400
G
Saw that ... was struck by it being red. Makes me wonder about organics (tholins) ...

--- Tony
« Last Edit: 10/27/2017 04:34 PM by jebbo »

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #18 on: 10/27/2017 04:30 PM »
Oh, and lots of people having fun calling it "Rama" ... sadly a rendezvous isn't particularly feasible

--- Tony

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #19 on: 10/27/2017 07:23 PM »
Phil Plait does make an interesting point that if you were an alien race this is exactly where you would aim something to check out our solar system without alarming any local species. Isnít there an idea that one way of exploring other star systems is to embed technology into things like asteroids?

Quote
Ö still, I canít help but wonder. I put absolutely no weight on this speculation, and would even bet heavily against it, but itís an obvious thought and I feel I have to at least mention it.

Space is vast. Even in our solar system, the outer planets are billions of kilometers away, with smaller icy objects extending for a trillion or two past that. No doubt, there is debris from other stars passing us at all kinds of distances. Most would never get within a light year, 10 trillion km.

From that distance, the inner solar system is a ridiculously small target. Mercuryís orbit is only about 115 million km across. For something coming from interstellar space, getting that close to the Sun is threading the eye of a very, very narrow needle.

Yet A/2017 U1 did just that. It passed the Sun at a distance of about 45 million kilometers. ThatísÖ weird.

Part of this is what we call a selection effect: An object like this passing out by the orbit of Jupiter would be very faint, so itís harder to discover. We only see the ones that happen to pass close to Earth. So even before this, I wouldíve wagered the first one we discover would be passing through the inner solar system as opposed to farther out.

But still, getting that close to the Sun seems unusual.

Let me be clear: I am NOT saying this is an alien spaceship. But if I were an alien race interested in exploring other systems, this is pretty much the sort of path Iíd put my probe on. Iíd aim it to pass deep within the alien solar system, check out the habitable planets, and use the starís gravity to bend the orbit to aim it at the next target.

Again, Iím quite sure this is a natural object and not an alien spaceship. Even so, itís certainly not a mundane one: Itís a freaking asteroid ejected from another star thatís been wandering the galaxy for eons and passed a few million kilometers from the Sun and Earth and is on its way back out into the void!

http://www.syfy.com/syfywire/breaking-have-astronomers-discovered-our-first-interstellar-visitor-note-not-aliens
« Last Edit: 10/27/2017 07:26 PM by Star One »

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