Coolest sub-stellar body ever found outside our solar system

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Washington, January 30 (ANI): An international team of astronomers, using the United Kingdom Infrared Telescope (UKIRT) in Hawaii, has discovered what may be the coolest sub-stellar body ever found outside our own Solar System.

This object is technically known as a brown dwarf, but what has excited astronomers is its very peculiar colors, which actually make it appear either very blue or very red, depending on which part of the spectrum is used to look at it.

The object is known as SDSS 1416+13B and is in a wide orbit around a somewhat brighter and warmer brown dwarf, SDSS 1416+13A.

"We have to be a bit careful about this one because its colors are so different than anything seen before, that we don't really understand it yet. The colors are so extreme, that this object will keep a lot of physicists busy trying to explain it," said Dr. Philip Lucas of the University of Hertfordshire's School of Physics, Astronomy and Mathematics.

SDSS 1416+13B was first noticed by Dr. Ben Burningham of the University of Hertfordshire as part of a dedicated search for cool brown dwarfs in the UKIRT Infrared Deep Sky Survey (UKIDSS).

The object appeared far bluer at near-infrared wavelengths than any brown dwarf seen before.

A near-infrared spectrum taken with the Japanese Subaru Telescope in Hawaii showed that it is a type of brown dwarf called a T dwarf, which has a lot of methane in its atmosphere.

The methane causes large gaps in the spectrum at certain wavelengths.

Dr. Burningham soon noticed that a previously observed brighter star (SDSS 1416+13A) that appears close by in the UKIDSS discovery image, was also a brown dwarf.

Team member Dr. Sandy Leggett of Gemini Observatory then used the orbiting Spitzer Space Telescope to investigate SDSS 1416+13B at longer wavelengths.

She measured its color at mid-infrared wavelengths, which are thought to be the most reliable indicator of temperature, and found that it is the reddest known brown dwarf at these wavelengths by some margin.

Comparison with theoretical models of the brown dwarf atmospheres then provided a temperature estimate of about 500 Kelvin (227 degrees Celsius).

"The fact that it is a binary companion to a warmer brown dwarf that also has an unusual spectrum is helping us to fill in some some gaps in our understanding," said Dr. Burningham.

"It seems likely that both brown dwarfs are somewhat poor in heavy elements. This would be consistent with the pair being old, which in turn implies a high gravity for both dwarfs, which can further enhance the unusual colors seen for both dwarfs," he added. (ANI)

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