Do any stars exist in isolation...

[60moo]

...or must they belong to a cluster or galaxy? Can we actually detect "hermit" stars? If so, is it inevitable that they will one day end up as part of a group? Is there a particular size below which a star tends to be isolated?

[Chris Peterson]

...or must they belong to a cluster or galaxy? Can we actually detect "hermit" stars? If so, is it inevitable that they will one day end up as part of a group? Is there a particular size below which a star tends to be isolated?

A star which is not gravitationally bound to a galaxy is usually called a rogue star or intergalactic star, and examples have been observed. These stars form as usual in galaxies but are ejected by gravitational interactions, either from binary systems or during galactic collisions. In a galaxy cluster, intergalactic stars may, in total, mass more than any individual galaxy.

There is probably no mass dependence on the likelihood of a star getting ejected from a galaxy.

[Ann]

Blue straggler hypervelocity star kicked out of the Milky Way!

Click to view full size image

Images: NASA/ESA/G. Bacon (STScI)

Read about it here: http://www.wired.com/wiredscience/2010/ ... fast-star/

Ann

[60moo]

Chris and Ann - thank you for your speedy replies!