Astronomy 1021 Lecture Notes - Lecture 14: Electron Degeneracy Pressure, White Dwarf, Binary Star

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Chris Racknor

Document Summary

Is the corpse of a low-mass star, supported against the crush of gravity by electron degeneracy pressure. Composiion relects the products of the stars inal fusion stage (usually mostly carbon) A typical white dwarf has the same mass as our sun, compressed into a volume the size of earth. More massive ones are smaller in size than less massive ones. A white dwarf cannot have a mass greater than1. 4 imes the mass of the sun. This is because electron speeds would reach the speed of light in a mass greater than 1. 4, and technically electrons can"t do that. A white dwarf eventually cools into a black dwarf if its alone. In a close binary system, gas from a companion star can spill toward a white dwarf, forming a swirling accreion disk around it. Accreion disks can provide a dead white dwarf with new energy.