About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 47. Chapters: 40 Eridani, AG Draconis, Black dwarf, Carbon detonation, Chandrasekhar limit, DP Leonis, Electron degeneracy pressure, Epsilon Reticuli, Feige 55, GD 356, GD 362, GD 40, GJ 1087, GJ 1221, Gliese 223.2, Gliese 293, Gliese 440, Gliese 518, Gliese 742, Gliese 86, Gliese 915, HU Aquarii, IK Pegasi, J0651, KOI-74, KOI-81, Mira B, NN Serpentis, OY Carinae, PG 1159 star, Procyon, PSR B1620-26, QS Virginis, RX J0806.3+1527, SDSS J0106-1000, Sirius, Stein 2051, Van Maanen's star, WD 0137-349, WD 0346+246, WD 0806-661, WD B1620-26, White dwarf, Zeta Capricorni, Z Chamaeleontis. Excerpt: A white dwarf, also called a degenerate dwarf, is a stellar remnant composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun, and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored thermal energy. The nearest known white dwarf is Sirius B, 8.6 light years away, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910 by Henry Norris Russell, Edward Charles Pickering, and Williamina Fleming; the name white dwarf was coined by Willem Luyten in 1922. White dwarfs are thought to be the final evolutionary state of all stars whose mass is not high enough to become a neutron star over 97% of the stars in our galaxy. After the hydrogen fusing lifetime of a main-sequence star of low or medium mass ends, it will expand to a red giant which fuses helium to carbon and oxygen in its core by the triple-alpha process. If a red giant has insufficient mass to generate the core temperatures required to fuse carbon, around 1 billion K, an inert mass of carbon and oxygen will build up at its center. After shedding its outer layers to form a planetary nebula, it will leave behind this core, which forms the remnant white dwarf. Usually, therefore, white dwarfs are composed of carbon and oxygen. If the mass of the progenitor is above 8 solar masses but below 10.5 solar masses, the core temperature suffices to fuse carbon but not neon, in which case an oxygen-neon magnesium white dwarf may be formed. Also, some helium white dwarfs appear to have been formed by mass loss in binary systems. The material in a white dwarf no longer undergoes fusion reactions, so the star has no source of energy, nor is it supported by the heat generated by fusion against gravitational collapse. It is supported only by electron degeneracy p
