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Interstellar Interlopers, Coming in from the great beyond
nprev
post Sep 25 2019, 05:53 PM
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Yeah, that exceedingly low relative velocity was really the only compelling piece of evidence to me. It does not seem unreasonable to postulate that this body had been at one time loosely (and distantly) associated with Kruger 60 and then perturbed out of the neighborhood & towards the Solar System perhaps just from other distant stellar encounters.

However, that also leaves open the possibility that Kruger 60 was not its system of genesis; might've been a semi-captured drifter there from someplace else.

In any case, fascinating. Looking forward to some good spectral data. smile.gif


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JRehling
post Sep 26 2019, 01:41 AM
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Our system is about 1/3 the age of the universe. Earlier in the age of the universe, heavy elements were nonexistent, then accumulated gradually. So the rate of production of new stars with comets should be, on balance, increasing, though star formation can ebb and flow in ways unique to any given galaxy.

The number of unknowns, though, is profound. We can say that a double system allows a dynamic for easy ejection although a large planet makes that possible as well.
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Gladstoner
post Sep 26 2019, 05:45 AM
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Borisov's path across the sky:

Attached Image


Galactic coordinates are shown.

The comet's approach from near the galactic equator in Cassiopeia:

Attached Image


These were rendered with Voyager II.
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tanjent
post Sep 26 2019, 08:39 AM
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Nice! Where would Kruger 60 be on those maps?
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ngunn
post Sep 26 2019, 09:53 AM
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Great plots Gladstoner, thanks for posting. smile.gif The first one shows nicely how the comet's path is being deflected by its solar encounter. Look for the antipodal point of its approach path, close to Beta Centauri. That's the direction it was heading before we got in the way.
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fredk
post Sep 26 2019, 02:04 PM
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QUOTE (tanjent @ Sep 26 2019, 09:39 AM) *
Where would Kruger 60 be on those maps?

About 30 degrees west of the asymptotic approach direction, very near the Galactic plane just south of the "house" of Cepheus.
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JRehling
post Sep 27 2019, 11:14 AM
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Some of you may find this site useful for tracking Borisov. I use this for observing comets. Unfortunately, Borisov is a lot dimmer than the comets I have successfully observed, but perhaps we'll get lucky and it will get much brighter in December. It is certainly a wildcard as to how it may behave when it approaches perihelion.

https://theskylive.com/c2019q4-info
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tanjent
post Oct 13 2019, 02:42 AM
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https://www.space.com/mysterious-comet-inte...er-borisov.html


This article refers to a paper by Polish researchers who seem pretty certain that Kreuger 60 is the system of origin.
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HSchirmer
post Apr 13 2020, 07:12 PM
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New Paper on how tidal effects can stretch Interstellar comets.


Image: A ‘Oumuamua-like object produced by a simulation of the tidal disruption scenario proposed by Zhang and Lin. Credit: NAOC/Y. Zhang; background: ESO/M. Kornmesser.

https://www.centauri-dreams.org/2020/04/13/...o-for-oumuamua/
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Xerxes
post Apr 14 2020, 05:58 PM
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QUOTE (HSchirmer @ Apr 13 2020, 02:12 PM) *
tidal effects can stretch Interstellar comets.


Isn't the key difficulty that the object was rotating somewhat rapidly in a stretched configuration? This requires cohesiveness in the stretched geometry that seems inconsistent with a tidally stretched rubble pile. The description here (https://www.hou.usra.edu/meetings/apophis2020/pdf/2018.pdf) indicates that they think it can melt and then freeze in an elongate configuration, but although that seems possible, there must be a very narrow window where that would occur rather than disruption or reconsolidation into a ball.

I can't seem to find the paper online, but I did find an unrelated but extremely cool thesis using the same software tool that works out the Brazil nut effect for asteroid regolith: https://www.astro.umd.edu/people/Theses/2017Ballouz.pdf
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fredk
post Apr 22 2020, 06:09 PM
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The Zhang and Lin paper was posted on the arxiv here.
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nprev
post Apr 26 2020, 06:47 AM
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I was surprised to see this considering it's now a couple of years old. Looks like a small object in a retrograde 1:1 orbital resonance with Jupiter may be of extrasolar origin, and the same may be true of some Centaurs.


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tanjent
post Apr 27 2020, 03:12 AM
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I can't find the reference via Google so I am short on details, but I recall several years ago there was a proposal for a retrograde head-on flyby of multiple asteroids in the main belt. It could not have gotten very far, but maybe a trajectory of that sort could be adapted to closely inspect this object at aphelion. I guess the power requirements would be in Juno's class though, so it would not be cheap.
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JRehling
post Apr 27 2020, 06:11 AM
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I'll offer the caveat that this is not my field in any but an amateur sense, but the publication was accepted only three days after it was received, and, per the journal's own description, a "letter" constitutes a very light form of peer review wherein speed is favored over rigor.

That's an observation from a process point of view, but from the scientific, I'm very skeptical that simulations running back >4 billion years could speak unambiguously to the origins of an object. And I would opine that this is why the work was published only on a fast track two years ago without the world flocking to this as an exceptional result in the meantime.
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stevesliva
post Apr 27 2020, 01:52 PM
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QUOTE (JRehling @ Apr 27 2020, 01:11 AM) *
That's an observation from a process point of view, but from the scientific, I'm very skeptical that simulations running back >4 billion years could speak unambiguously to the origins of an object. And I would opine that this is why the work was published only on a fast track two years ago without the world flocking to this as an exceptional result in the meantime.


I know a lot less that you, I wager, but I was thinking that this was a bit of:

1. "there are no explanations for local origin that we cannot discount (this work)"
2. ...
3. "a 1:1 retrograde orbital resonance with Jupiter."

huh.gif
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