I make my stars out of spheres within Bryce and give them a sun texture and then change 5 or 6 of them to be Red Giants or white dwarves. Then I do a multi-replicate and depending onwhat I am doing in my scene set the amount to 999 then with the same selection choose to do the replicate again at 999. This will give you around 999 +5 or 6 x 999 or 998001 stars which is plenty for you local clusters for galaxies repeat the process 5 times as each time is squared.

Now let's move on to making a cluster or a galaxy!

Then once you have all of your stars you need to do the 3D disperse. You can choose to do the size as well but I find this to be a little bit of a waste of time, because if your computer as not locked up or fried by now you must not know I am joking...

 

There are some wonderful examples of how to do this above my post hehe.