General theory of Relativity

9

Astrophysics

9.1 INTRODUCTION

As a brief introduction to astrophysics, we consider the model of a star in hydrostatic equilibrium. The polytropes are a family of equations of state for a gas in hydrostatic equilibrium and in these equations, the pressure is given as a power law in density. The polytropes serve as simple model of a star, such as the Eddington Standard model. The lane–Emden equation, which describes the polytropes, is derived and solved analytically. Furthermore, we derive the Chandrashekhar mass limit for the formation of a black hole.

Lastly, we discuss how the Pauli Exclusion and Heisenberg Uncertainty principles govern the formation of white dwarfs, neutron stars, and black holes. It is believed that black holes form at the ...