Alien comets

[Mchili]

I read that our Oort cloud could extend up to halfway to Proxima Centuri. Is it reasonable to assume that this star could also have its own equivalent of an Oort cloud and if so, could the two clouds merge at some point?

If true this leads to my main question. Would it be possible to have a comet that had an orbit that included both suns? At least until stellar drift upset things anyway.

I am not an astronomer and am not that proficient with orbital mechanics so apologies if these are stupid questions.

[Moontanman]

I wouldn't say it's impossible, highly improbable is a better way to put it...

[Enthalpy]

Hi Mchili, Moontanman and all,

 

some comets are expected no to belong permanently to our Solar system.

 

Though, stars pass by an other rather quickly in our vicinity, and an extremely remote comet orbit would be very slow, so orbiting two stars would be difficult.

 

Earth at 150Gm from the Sun takes 1 year per orbit, so at 2 light-years (126000 times mores, half-distance to a near star) an orbit would need 45 million years. If the star's velocity relative to our Sun is 10km/s it drifts by 1500 light-years in this time so it's no more our neighbour.

[Ophiolite]

A couple of additional points.

1. If our understanding of planetary formation is broadly correct it is likely that most stars have Oort clouds of their own.

2. It is probable that some comets are "exchanged" between planetary systems, but an orbit around both - as Moontanman noted and Enthalpy demonstrated - is highly unlikely.

3. Comets as far out as half way to Alpha Centauri are retained by only the slightest wisp of gravitational influence from the sun. Another passing star will very easily disrupt that orbit, not necessarily capturing it, but readily tearing it from solar influence.