Different star types «live» and «die» in different ways based on how much matter they started with and if they were born with siblings nearby. (public.nrao.edu)
Yes, this means I literally can not advance those units any further unless I decide I want different Star Cards for them. (lightgungalaxy.com)
And even if two players play for the exact same time, they're going to get different Star Cards that may or may not benefit their character class of choice. (heavy.com)