TNOs: could some have formed elsewhere? Options

[elakdawalla]

I got a question today for Planetary Radio Q&A that I couldn't answer, being pretty ignorant about solar system formation research. Can anybody help?

We know from the metal composition of our solar system that the Sun is at least a second or third generation star. It made me wonder if it was possible that some of the comets or other KBOs that we witness might be from the Sun's predecessor star or stars. If not, could such bodies exist a bit further out? I should think it would be fantastic to be able to investigate such objects.

--Emily

[ngunn]

I saw that, and I can see why the probability of a solitary object getting captured by the sun is virtually nil, but I'm not convinced that it's true if there is a significant population of dark, loosely-bound multiple systems floating about. Nobody knows whether or not there are, and if so how common, so I don't think we're in a position to calculate odds.

[ugordan]

I saw that, and I can see why the probability of a solitary object getting captured by the sun is virtually nil, but I'm not convinced that it's true if there is a significant population of dark, loosely-bound multiple systems floating about. Nobody knows whether or not there are, and if so how common, so I don't think we're in a position to calculate odds.

Somehow, I get the feeling that this binary capture scenario only works well when there's an appreciable gravity gradient across the binary object separation distance. Alternatively, you could state this as the two-body distance being not too small compared to the large 3rd body distance. How does this apply to the KBOs and OC? These are so far away from sun, that two components in a binary system would need to be very, very separated for this capture scenario to be feasible. At tens and hundreds of AU from the sun, both objects are likely to feel effectively the same amount of gravitational pull from the sun, with the net effect being virtually no disrupting force upon the binary pair.

I agree we can't know how many binary objects there are that wander around the interstellar space, but even if there are many (not likely), furthermore ones that are very loosely bound (even less likely), IMHO the Triton-like capture mechanism would be highly improbable. I'd be interested to hear if more knowledgeable people know more about this -- Alan et. al. ?

[ngunn]

I'd be interested to hear if more knowledgeable people know more about this -- Alan et. al. ?

Me too! I was only speculating, not calculating. Relative velocity's important too. I'm guessing that for maximum disruption you would want the dark binary to be in the vicinity of the sun for about half of it's own mutual revolution period. Experts please come in! Computer simulations??