I am trying to find real physical examples of (self-gravitating) astrophysical systems that are appropriately confined and can thus be seen as in equilibrium. Modelling-wise, you can theoretically put the system in a box and get stable systems in that way. The question is: are there real examples of astrophysical systems that are actually as if they are in a box? The role of the box could be played e.g. by an external potential, a potential well or by tidal effects.
I am thinking in particular about real examples of bounded globular clusters as they look like the best candidates.
Edit (2): All globular clusters are gravitationally bound in a sense, but I am looking for self-gravitating systems that are confined in the sense that we can consider the system to behave like it is a gas confined in a box. Otherwise, the system would have (i) evaporation and (ii) for self-gravitating systems the stars would end up clumping in the centre and expelling material outside, this would make the system unstable triggering gravothermal catastrophe. Putting the system in a theoretical box solves the problem and ensures the system can stay stable, this is clear from models but I'm looking for physical examples of potentials that can do the job at a high approximation.
(I'm roughly asking what user 'uhoh' says and Anders Sandberg's reply is the kind of example I'm looking for)