Solar physics is the branch of astrophysics that specialises in the study of the Sun and stars. These articles cover types of stars, the life cycle of stars, spectroscopy and observations of our Sun.
The Chandrasekhar limit is an upper bound on the mass of bodies made from electron-degenerate matter, a dense form of matter which consists of nuclei immersed in a gas of electrons.
Electron degeneracy pressure is a consequence of the Pauli exclusion principle, which states that two fermions cannot occupy the same quantum state at the same time. The force provided by this pressure sets a limit on the extent to which matter can be squeezed together without it collapsing into a neutron star or black hole.
The Hertzsprung-Russell diagram shows the relationship between different properties of stars and illustrates trends among stars. The diagram was created in 1910 by Ejnar Hertzsprung and Henry Norris Russell, and represented a huge leap forward in understanding stellar evolution, or the 'lives of stars'.
In astronomy, luminosity is the total amount of energy radiated by a star, galaxy, or another astronomical object per unit time. It is related to the brightness, which is the luminosity of an object in a given spectral region. In SI units luminosity is measured in joules per second or watts.