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:
“It now appears that the negro race is, more than any other, susceptible of rapid civilization. The emancipation is observed, in the islands, to have wrought for the negro a benefit as sudden as when a thermometer is brought out of the shade into the sun. It has given him eyes and ears.”
—Ralph Waldo Emerson (1803–1882)
“The evolution of humans can not only be seen as the grand total of their wars, it is also defined by the evolution of the human mind and the development of the human consciousness.”
—Friedrich Dürrenmatt (1921–1990)