"Stars As Cool as the Human Body"



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Stars As Cool as the Human Body

Stars As Cool as the Human Body.

Presented by Science at NASA.

Stars are supposed to be hot stuff. But would you believe astronomers have just discovered a class of stars as cool as well as cool as you are? They're called "Y Dwarfs".

A NASA space telescope named WISE made the discovery. WISE is short for "Wide-field Infrared Survey Explorer." It's an infrared observatory whose recently concluded mission was to scan the heavens at wavelengths the human eye cannot see.

WISE recently found six incredibly cool stars less than 40 light years from Earth. One of these Y dwarfs, WISE 1828+2650, is the record holder for stellar-cool with an estimated atmospheric temperature less than 80 degrees Fahrenheit (25 degrees Celsius). WISE 1828+2650 is a room temperature star! Other Y dwarfs were about the same temperature as a human body. How can a star be so cool?

The Y's are the chilliest members of the brown dwarf family. Brown dwarfs are sometimes referred to as "failed" stars. They are more massive than planets, yet not quite massive enough to fuse atoms in their cores.

Brown dwarfs do not burn with the inner nuclear fires that keep stars like our sun shining steadily for billions of years. Without fusion to keep them going, brown dwarfs cool and fade with time, until what little light they do emit is at infrared wavelengths perfect targets for a telescope like WISE.

"WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision," says William Danchi, WISE Program Scientist at NASA Headquarters in Washington, DC.

If an astronaut could visit one of these stars, they would probably find a lonely sphere of gas that looks a lot like Jupiter only bigger.

Make that a big purple Jupiter.

Researchers suspect that molecules in the atmosphere of Y Dwarfs give the stars a purple or magenta color. No one knows for sure, though, because WISE can only see these faint stars as distant pinpricks of infrared light.

Future space travelers might consider a visiting Y Dwarfs for a closer look. At a distance of less than 40 light years, these stars are relatively nearby.

"Finding these objects so close to our sun is like discovering there's a hidden house on your block that you didn't know about," says Michael Cushing, a WISE team member at the Jet Propulsion Laboratory.

"It's thrilling to me to know we've got neighbors out there and maybe more yet to be discovered. With WISE, we may even find a brown dwarf closer to us than the closest known star, Proxima Centauri."

Now that would be pretty cool news.

For more information about stars, hot and cold, visit, science.nasa.gov

Uploaded by ScienceAtNASA on Sep 9, 2011

Visit http://science.nasa.gov for more.

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