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Professor Astronomy

Y Dwarfs? Because they're cool.

24 Aug 2011, 16:00 UTC
Y Dwarfs?  Because they're cool.
(200 words excerpt, click title or image to see full post)

Image Credit: NASA/JPL-Caltech/UCLA

That little green dot in the center of the picture above may not look like much, but it is, in fact, one of the first absolutely definitive members of a predicted type of brown dwarf, the "spectral class Y" dwarfs. It was discovered by astronomers using data from the Wide-field Infrared Survey Explorer, a satellite mission that scanned the entire sky in the infrared wavelengths of light during 2010. The star above has a temperature of about 25 degrees Celcius, or roughly 80 degrees Fahrenheit -- measurably cooler than the endless summer heat here in Texas. The discovery was announced yesterday by the WISE team, and an official journal article announcing the discovery has been accepted for publication in the Astrophysical Journal. Even cooler than the brown dwarf is the fact that this paper was headed up by a good friend of mine, Michael Cushing (now a new faculty member at the University of Toledo).

First, some quick background and definitions. Stars like the sun shine because they are giant nuclear fusion reactors, with most fusing hydrogen into helium. This process releases a lot of energy and can last for a long time - the sun's lifetime ...

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