Discovery of a 2nd Interstellar Object - C/2019 Q4 (Borisov)

[EchoLima]

It will be at its perihelion around December 7 at a distance of 2.07 AU.

[kerbiloid]

Isn't any known object on hyperbolic orbit interstellar?

[mikegarrison]

1 hour ago, kerbiloid said:

Isn't any known object on hyperbolic orbit interstellar?

Well, setting aside whether "orbit" is the right word for a hyperbolic trajectory, I guess that would be so. But what objects do you think are known to be on hyperbolic trajectories?

The Wikipedia article on this object says:

Quote

The hyperbolic excess velocity  of ≈30 km/s is an important indicator that it is interstellar as a  under 3 km/s can be explained by perturbations.

I guess the point there is that if we see an object that, as best we can tell, is on a very slightly hyperbolic trajectory, we can guess it's actually from our own stellar cloud and has just been boosted a little by interactions with other objects.

Wikipedia does say that an object named C/1980 E1 (Bowell) is on a solar escape trajectory, but it is believed to have been a formerly solar comet that was boosted by Jupiter.

Edited September 13, 2019 by mikegarrison

[kerbiloid]

47 minutes ago, mikegarrison said:

But what objects do you think are known to be on hyperbolic trajectories?

All non-periodic comets, aren't them?

[mikegarrison]

I suppose it's a matter of definitions. So-called non-periodic comets come from somewhere far away, but I think the thinking is that most of them are objects that are in the outer parts of our stellar system and just get perturbed into making a visit close by the sun. They may escape, or they may come back again so long from now that nobody will ever know it was the same object.

Part of the problem is that it's really hard to tell the difference between an orbit that is just slightly under 1.0 eccentricity and one that is just slightly over 1.0 eccentricity.

This object seems to be coming in with so much velocity that it has clearly come from outside our solar system. It has an eccentricity somewhere between 3 and 5, so it's definitely not from here.

[UmbralRaptor]

15 hours ago, kerbiloid said:

All non-periodic comets, aren't them?

Those tend to be fit with parabolas, and depending on reference frame may only have an eccentricity above 1 once you have a bunch of sig figs. For example: https://en.wikipedia.org/wiki/C/2006_P1_(McNaught)

Anyway, the 3 highest eccentricities: C/1980 E1 (Bowell) at 1.0575, 1I/ʻOumuamua at 1.19951, and C/2019 Q4 (Borisov) at... still being determined but probably above 3.

[UmbralRaptor]

Kind of a bump/update: some people determined what it would take to intercept C/2019 Q4: https://arxiv.org/abs/1909.06348

Anyone got a spare HLV?

[UmbralRaptor]

More updates:

Searching for Borisov's origins: the best guess is unlikely, so it may have been floating around for quite some time - https://arxiv.org/abs/1912.10213

Borisov may have formed from an AGB star o_O - https://arxiv.org/abs/1912.12730

[Scotius]

Oh, to get our hands on some samples from such exotic visitor