Any successful theory of stellar structure must explain the observed properties of stars. Clicking on the plot will show a full-size version. Giants and White Dwarfs must have very different internal structures from M-S stars of similar mass. Expand a star, gravitational binding gets weaker . Hydrostatic Equilibrium Gravity wants to make a star contract.
Pressure wants to make a star expand.
Pressure supports the star against Gravity. The star neither expands nor contracts. Core-Envelope Structure Outer layers press down on the inner layers. The deeper you go into a star, the greater the pressure. March 13 Copyright Richard W. Pogge, All Rights Reserved.