Introduction

This chapter deals with three possible stellar remnants: white dwarfs, neutron stars, and black holes. It relies heavily on the previous two chapters as well as on Chaps. 3, 5, and 9–12 of Vol. I. The material covered here will be needed in Chap. 6 (pulsars), Chap. 7 (binary stars), and in the study of active galactic nuclei in Vol. III.

Another closely related class of remnants, called pulsars, are known to be rotating neutron stars and will be discussed separately in Chap. 6. An entirely new class of physical phenomena arises when a compact object forms a constituent of a binary system. The role of stellar remnants in binary systems will be studied separately in Chap. 7.

Structure of White Dwarfs

It was seen in Chap. 3 that the end point of stellar evolution can lead to self-gravitating objects supported by degeneracy pressure. Such astrophysical objects are usually termed compact because, as we shall see, their sizes are significantly smaller than main-sequence stars of similar mass.