Despite the predictions of some philosophers, by the end of the nineteenth century, astronomy had begun to change as it incorporated the laws of physics into its discipline.  This new branch of Astronomy was called astrophysics.  All that we learned about the structure of atoms and the interactions of mass and energy could now be applied to the stars. Although there is much detail we could get into, you should at least be familiar with two laws of radiation physics, Wien’s Law, and the Stefan-Boltzmann law.
Looking for a particular star?  Find it here!
Carpe Caelum
Carpe Caelum Stellar Astronomy