ASTRON 1010 Chapter Notes - Chapter 14: Electron Degeneracy Pressure, White Dwarf, Degenerate Matter
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A white dwarf is the corpse of a low-mass star, supported against the crush of gravity by electron degeneracy pressure. More specifically, the degeneracy pressure in white dwarfs arises form closely packed electrons, so we call it electron degeneracy pressure. A teaspoon of white dwarf matter would weigh several tons. Because neither electrons nor anything else can travel faster than the speed of light, no white dwarf can have a mass grater than 1. 4m, which is known as the white dwarf limit. A white dwarf cannot have a mass greater than 1. 4 times the mass of the sun. In a close binary system, gas from a companion star can spill toward a white dwarf, forming a swirling accretion disk around it. Because the process in which material falls onto another body is called accretion, this rapidly rotating disk is called an accretion disk. This thermonuclear flash causes the binary system to shine for a few glorious weeks a nova.