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Q&A: Miscellaneous X-ray Sources
Q:
How long might a white dwarf exist before becoming a brown
dwarf?
A:
A white dwarf and a brown dwarf as astronomers
usually use these terms are 2 completely different objects. A brown
dwarf star is a "failed star" with a mass not large enough to ignite
significant nuclear burning, which means it emits very little visible
light (its mass must be less than about 80 times the mass of Jupiter,
or 0.08 of the mass of the Sun). A white dwarf star is the end state
of a star like our Sun, whose nuclear fuel supply has been exhausted.
Please see our Chandra X-ray Astronomy Field Guide to white dwarfs:
http://chandra.harvard.edu/xray_sources/white_dwarfs.html
brown dwarfs:
http://chandra.harvard.edu/xray_sources/browndwarf_fg.html
and stellar evolution:
http://chandra.harvard.edu/xray_sources/stellar_evolution.html
and also a NASA site which gives a good explanation of white dwarfs:
http://imagine.gsfc.nasa.gov/docs/science/know_l2/dwarfs.html