Eur. Phys. J. Spec. Top. (2021) 230: 495-503
https://doi.org/10.1140/epjs/s11734-021-00005-3

Review

Hundred years of the Saha equation and astrophysics

Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, 700009, Calcutta, India

^a ggphy@caluniv.ac.in

Received: 30 July 2020
Accepted: 23 December 2020
Published online: 29 March 2021

Abstract

Saha ionization equation, discovered 100 years ago, is widely acknowledged to transform astrophysics from a qualitative to a quantitative science. It helped in clarifying the confusion prevailing in the first 2 decades of the twentieth century with regard to the physical conditions present in the stellar atmospheres and the abundance of elements in stars. Saha equation continues to be useful in areas far removed from the physical conditions in stellar atmospheres for which it was developed.