Radial Oscillation Periods for Hamada—Salpeter Models of White Dwarfs

Abstract

Radial pulsations of white dwarfs may be responsible for the radio pulses discovered by Hewish et al. ¹, and so quantitative computations of the oscillation periods have become important to observational astronomers. The calculations of Meltzer and Thorne² are based on the Harrison-Wheeler-Wakano equation of state, which describes cold matter continuously catalysed to the composition of lowest free energy. As these authors point out, nuclear thermodynamic equilibrium is unlikely to be reached in real white dwarfs; real white dwarfs are probably better described by the Hamada-Salpeter³ models, which may be made of various elements such as helium, carbon and iron. The Hamada-Salpeter models also use an equation of state due to Salpeter⁴, which takes into account various forces between the particles of the degenerate matter.