Rapid Evolution
The above simplified model is not adequate without modification in situations when the composition changes are sufficiently rapid. The equation of hydrostatic equilibrium may need to be modified by adding a radial acceleration term if the radius of the star is changing very quickly, for example if the star is radially pulsating. Also, if the nuclear burning is not stable, or the star's core is rapidly collapsing, an entropy term must be added to the energy equation.
Read more about this topic: Stellar Structure
Famous quotes containing the words rapid and/or evolution:
“More rapid than eagles his coursers they came,
And he whistled, and shouted, and called them by name:
“Now, Dasher! now, Dancer! now, Prancer and Vixen!
On, Comet! on, Cupid! on, Donder and Blitzen!
To the top of the porch! to the top of the wall!
Now dash away! dash away! dash away all!””
—Clement Clarke Moore (1779–1863)
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)