Coolest brown dwarf discovered

Last Updated: Friday, April 9, 2010 - 16:13

Washington: Astronomers have discovered the
coolest and nearest brown dwarf to date nearly 10 light-years
from the earth.

An international team headed by Philip Lucas from the
University of Hertfordshire in UK found the brown dwarf or
failed star -- UGPSJ0722-05 -- all by itself, floating through
interstellar space.

"It was possibly formed there on its lonesome or kicked
out of its host star system by an ancient gravitational game
of stellar pinball," they said.

"This makes it the nearest brown dwarf and one of 10
nearest stellar objects to our solar system. Although its
location isn`t entirely unexpected as it is thought that the
galaxy is stuffed full of these objects, the chemical
composition of its atmosphere is a bit of a conundrum".

Lucas said, UGPSJ0722-05 appears to be the coolest ever
discovered. It could have a surface temperature as low as 400
Kelvin, even cooler than the team`s previous record of
slightly below 500 K.

How it got there may not ever be known, but its close
proximity allows astronomers to carry out detailed analysis of
the object, Discovery Channel reported.

"Brown dwarfs are too small to initiate nuclear fusion
in their cores for long periods so they`re not stars, but they
are distinct from planets too," he said.

Their interior has a convective motion of material,
ensuring it is constantly being mixed up, preventing chemicals
from settling -- chemical differentiation is a planetary
trait. Therefore, brown dwarfs are often considered to be the
"bridge" between the most massive planets -- Jupiter-like gas
giants -- and the smallest stars.

As brown dwarfs are technically "failed stars," they are
naturally very dim in visible wavelengths, but they do emit in
infrared and radiation.

PTI



First Published: Friday, April 9, 2010 - 16:13

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