Publisher's Synopsis
Astrophysicists distinguish between three different types of compact stars. These are white dwarfs, neutron stars, and black holes. Most compact stars are the endpoints of stellar evolution and are thus often referred to as stellar remnants, the form of the remnant depending primarily on the mass of the star when it formed. These objects are all small in volume for their mass, giving them a very high density. The former contain matter in one of the densest forms found in the Universe which, together with the unprecedented progress in observational astronomy, make such stars superb astrophysical laboratories for a broad range of most striking physical phenomena. These range from nuclear processes on the stellar surface to processes in electron degenerate matter at subnuclear densities to boson condensates and the existence of new states of baryonic matter--like color superconducting quark matter--at supernuclear densities. More than that, according to the strange matter hypothesis strange quark matter could be more stable than nuclear matter, in which case neutron stars should be largely composed of pure quark matter possibly enveloped in thin nuclear crusts. Another remarkable implication of the hypothesis is the possible existence of a new class of white dwarfs. Thermonuclear fusion drives stars through many stages of combustion; the hot center of the stars allows hydrogen to fuse into helium. Once the core has burned all available hydrogen it will contract until another source of support becomes available. As the core contracts and heats, transforming gravitational energy into kinetic (or thermal) energy, the burning of the helium ashes begins. For stars to burn heavier elements, higher temperatures are necessary to overcome the increasing Coulomb repulsion and allow fusion through quantum-mechanical tunneling. This book explores the diverse forms that such compact stars can possibly take, as constrained by the laws of nature: the general principles of relativity and quantum mechanics, the properties of nuclear matter deduced from nuclei, and the asymptotic freedom of quarks at high density. It reviews general relativity, essential aspects of nuclear and particle physics, and general features of white dwarfs, neutron stars and black holes; the discovery of pulsars and associated phenomena, and the strange-matter hypothesis.
