For 10 points, name this equation derived by an Indian astrophysicist that gives the relative number of atoms in two different ionization states in a plasma.
Carl Rouse modified this equation for high densities. Rewriting this equation in terms of photon number density is used as a first approximation to derive the redshift and temperature at recombination. This equation is used to describe the dropoff in intensity of the Balmer line above 9900 Kelvin, and in calculating intensity of spectral lines this equation is combined with the Boltzmann equation. This equation is derived by finding the number of states available between two infinitesimally separated (*) momentum states in a system with local thermodynamic equilibrium and ends by finding a ratio of partition functions. This equation was notably repeatedly applied by Cecilia Payne-Gaposchkin to relate temperature to spectral class. The free electron density is found on one side of this equation, which applies in systems with a large Debye length. For 10 points, name this equation derived by an Indian astrophysicist that gives the relative number of atoms in two different ionization states in a plasma.
Carl Rouse modified this equation for high densities. Rewriting this equation in terms of photon number density is used as a first approximation to derive the redshift and temperature at recombination.
Saha ionization equation