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]

Indeed, and I like your multiple disc idea too. Would the multiple discs have to be contemporaneous or could new ones be acquired some time later than the one from which the major planets formed, say by the system passing slowly through a dense molecular cloud? These may sound like unlikely freak events, but we know that some galaxies go through fits of star formation, possibly triggered by galactic collisions. We don't know much about the history of our galaxy or how many others it has swallowed. There could have been times when the solar system had nowhere safe to hide. Just look at M82!

[Guest_Richard Trigaux_*]

Indeed, and I like your multiple disc idea too. Would the multiple discs have to be contemporaneous or could new ones be acquired some time later than the one from which the major planets formed, say by the system passing slowly through a dense molecular cloud? These may sound like unlikely freak events, but we know that some galaxies go through fits of star formation, possibly triggered by galactic collisions. We don't know much about the history of our galaxy or how many others it has swallowed. There could have been times when the solar system had nowhere safe to hide. Just look at M82!

Why not, a star already having a disk can get another load of matter, eventually not in the same plane. But mandatorily there will be interactions between the two disks, which will more or less collapse into one.

But if there are already planets, it is very likely that they will direct further flows of matter, and will forbid the formation of new planets where there is already a Titus-Bode series.