It is, regretfully, not "jeans"; but, "Jeans" after the pioneer, J.H. Jeans, which my question is focussed to.
This concerned Jeans instability is the gravitational instability in self-gravitating large-scale fluids via which bounded structures are formed. The details of the instability and its onset threshold could be found at
J. H. Jeans, Philos. Trans. R. Soc. A 199, 1 (1902).
If this instability is understood, at least at the minimum level, the cast question is very clear and percipient, although the expected answer might not be so.