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Beyond Earthly Skies

An Extremely Cool White Dwarf Star

13 Oct 2013, 10:00 UTC
An Extremely Cool White Dwarf Star
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White dwarfs are dense stellar remnants that mark the final evolutionary state of intermediate-mass and low-mass stars. Right after formation, a white dwarf is very hot and will appear blue-white in colour. Since material in a white dwarf no longer undergoes fusion reactions like in a normal star, a white dwarf does not have a source of energy and will gradually cool as it radiates away its energy. As a white dwarf cools, the radiation emitted by it will shift from the hot blue-white colour of an O-type star (> 30,000 K) to the cool red colour of an M-type red dwarf star (< 4,000 K). Given sufficient time, a white dwarf will cool until it no longer emits significant heat or light, and become what is known as a black dwarf. Nonetheless, no black dwarfs are expected to exist in the present Universe because the length of time required for a white dwarf to cool to this state far exceeds the current age of the Universe.Artist’s impression of a white dwarf shown to scale with the Earth.In 1997, a white dwarf identified as WD 0346+246 was serendipitously discovered during re-examination of images taken for a survey to detect brown ...

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