Is there evidence of interstellar comets?

Question

Comets that have crossed interstellar space to arrive in our neighborhood?

How would they get free of their original system?

Answer 1

Evidence? No. The point is that if an interstellar comet was to enter our solar system, it may behave a lot like the ones from our own Oort cloud, as comets are objects that orbited far away from the sun until something tripped them into another orbit that brought them closer to the sun.

To assess the origin of a comet would require noticing something in them that does not jibe with the composition of our own solar system, which is asking a bit much at this point in time, or with an energy that is excessive (too fast, barring gravity boost described later). So far, none have been spotted that could not be explained by other effects (like the small jet boost obtained by vaporisation of the outher layer due to solar heating).

As for comets getting free of their system, it is the same mechanism that brought them on orbits passing close to the sun: perturbation. If a comet "falls" towards the sun, while being still locked inside the gravity of the solar system, it may swing by and get a gravity assisted boost from passing besides Jupiter or Saturn, and gaining enough velocity that it would totally escape from the solar system later.

The same thing could happen in another solar system that has big planets.

Answer 2

The answer might, just might, be, in the speed of winds, pass a heliosphere, of each star.

This article does not describes the passage of comets in between stars, but, answers some of it.

http://news.yahoo.com/s/space/20080702/s...

Answer 3

So, there are comets that are "way out there" in very large orbits from their parent star.  Another star passes nearby - it may still be a light year away or more.  The gravity pulls some of these outliers out of their original orbit.

When the comet comes in, you can figure out it's orbit.  If it turns out to be hyperbolic (instead of ellipsoidal) then it wasn't in orbit.  It came from somewhere else.  This happens, so interstellar comets appear to be reality.

Answer 4

Its interesting to know that galaxies pass by one another on a not infrequent basis.  Many of our own comets have enormous orbits and as a result its easy to see that a passing solar system could capture one.