Introduction

Abstract

Compact stars—neutron stars and white dwarfs—are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of millions to billions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms—hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star may fall at the end of the luminous phase.