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

[Guest_AlexBlackwell_*]

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?

That's not your run-of-the-mill Q&A inquiry, Emily. Is this, by chance, a grad student asking?

I'm working off dim memory but I believe Jane Luu and David Jewitt did some work a few years ago on the survival of Kuiper belts over the main sequence lifetime of central stars. I believe they (or someone else) came up with estimates on the sizes of given belts and the amount of material that would survive the clearing phases of stellar evolution.

I'll try and track down a reference.

[Alan Stern]

Hi Emily,

I personally have worked on this problem and can help you out. First, comets in the KB cannot survive the red giant phase. This work was published in Nature (1990, by Stern, Shull, and Brandt). OC comets can survive this phase of stellar evolution because they are so far out.

As to the capture of interstellar comets, various dynamycists have looked at this and the capture efficiency is dismal-- <10^-12 per interloper comet. This indicates that no KB comets and only a handful of the OC comets could be captured. As to larger (KBO-sized) bodies-- forget it, the odds ar there isn't even one object that is from a passing star UNLESS the Sun was born as a double or in a cluster-- which is possible but controversial.

-Alan