Quote:
Originally Posted by Gerald Sargent
When one see's increasingly high resolution images of star clusters
one has to question what keeps them apart - why does their individual
masses not result in a gravitational collapse - Gerald
|
Gerald,
I have often pondered this question myself, especially with globular clusters like Omega Centauri where the stars are close together. I think the answer is that the cluster has a rotational movement so that the stars are essentially in orbit about the cluster centre (like the planets about the Sun). Because of the distance and size of most clusters, this rotational movement is hard to detect.
However, astronomers can measure this movement. Apparently, with Omega Centauri the stars near centre orbit faster than those further out. (See Omega Centauri, Wikipedia, 3rd paragraph).
There are probably many open clusters with no apparent rotation, whose stars are weakly bound and moving through space together but don't collapse because of the larger distances between the stars.
Regards, Rob.