Stars heat up when they lose energy

[SUDOnym]

Hi There

Just came across the idea that stars heat up when they lose energy and have been thinking about why this might be... below is my best guess:

Stars heat up when they lose energy because this implies that the ions that compose the star each experience a reduction in their kinetic energy. Because of this reduction in kinetic energy, the star contracts which leads to increase in pressure at the core which leads to an increase in temperature...

I am doubtful as to whether the above explanation is even vaguely correct and would be grateful for a full and accurate explanation of the phenomenon!

 

[Astrofan]

Hi SUDOnym:

Stars are considered to be in "Hydrostatic-Equilibrium" meaning that their pressure forces balances out the gravity experienced at every point within the star.

A loss of energy naturally means a reduction of pressure since a (around solar mass main sequence) star is supported by non-relativistic gas. Reduction of pressure leads to contraction since gravity will temporally win the tug of war, this then results in the heat-up of the core which then releases more heat to balance gravity. Generally stars are never really in perfect equilibrium, but is more or less so.

Hope this answers your question