ASTR 1P02 Lecture Notes - Lecture 8: White Dwarf, Pauli Exclusion Principle, Degenerate Matter
9 Apr 2016
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The pressure doesn"t depend on the temperature (like in normal mater/gas) but only on density (it increases with density) Chandrasekhar limit: the maximum mass of a degenerate object/body. Most white dwarfs have masses from 0. 5m to 0. 7m . Carbon and oxygen nuclei don"t obey the pauli principle: the number of nuclei in a given energy level is not limited. Electrons cannot drop into a lower energy state because of the pauli principle. Eventually all the carbon (and oxygen) nuclei will drop to the lowest energy level. The white dwarf will become a black dwarf. This happens over a very long period of ime, comparable to the age of the universe. White dwarfs have high surface temperatures of several tens of thousands of degrees. They emit a lot of high energy uv-photons. These photons excite the electrons in the atoms of the planetary nebula into higher energy states. As they drop back into lower energy states, photons are emited (luorescence).
