Discovered: A Cold, Close Neighbor of the Sun
 
April 25, 2014: NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer
Space Telescope have discovered what appears to be the coldest "brown dwarf"
known -- a dim, star-like body that  surprisingly is as frosty as Earth's
North Pole. Named "WISE J085510.83-071442.5," the brown dwarf appears to be
7.2 light-years away, earning it the title for fourth closest system to our
sun.
 
"It's very exciting to discover a new neighbor of our solar system that is so
close," said Kevin Luhman, an astronomer at Pennsylvania State University's
Center for Exoplanets and Habitable Worlds, University Park.
 
http://www.nasa.gov/sites/default/files/pia18002-full-640.gif
 
This animation shows the brown dwarf WISE J085510.83-071442.5 moving across
the sky. It was first seen in two infrared images taken six months apart in
2010 by NASA's Wide-field Infrared Survey Explorer (WISE). Two additional
images of the object were taken with NASA's Spitzer Space Telescope in 2013
and 2014. All four images were used to measure the distance to the object --
7.2 light-years -- using the parallax effect.  Movie
 
Brown dwarfs start their lives like stars, as collapsing balls of gas, but
they lack the mass to burn nuclear fuel and radiate starlight. The newfound
coldest brown dwarf is named WISE J085510.83-071442.5. It has a chilly
temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13
degrees Celsius). Previous record holders for coldest brown dwarfs, also found
by WISE and Spitzer, were about room temperature.
 
"It is remarkable that even after many decades of studying the sky, we still
do not have a complete inventory of the sun's nearest neighbors," added
Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion
Laboratory. "This exciting new result demonstrates the power of exploring the
universe using new tools, such as the infrared eyes of WISE and Spitzer."
 
WISE was able to spot the rare object because it surveyed the entire sky twice
in infrared light, observing some areas up to three times. Cool objects like
brown dwarfs can be invisible when viewed by visible-light telescopes, but
their thermal glow -- even if feeble -- stands out in infrared light. In
addition, the closer a body, the more it appears to move in images taken
months apart. Airplanes are a good example of this effect: a closer,
low-flying plane will appear to fly overhead more rapidly than a high-flying
one.
 
"This object appeared to move really fast in the WISE data," said Luhman.
"That told us it was something special."
 
After noticing the fast motion of WISE J085510.83-071442.5, Luhman spent time
analyzing additional images taken with Spitzer and the Gemini South telescope
on Cerro Pachon in Chile. Spitzer's infrared observations helped determine the
frosty temperature of the brown dwarf. Combined detections from WISE and
Spitzer, taken from different positions around the sun, revealed the object's
parallax, and thus its distance. The closest system to Earth, a trio of stars,
is Alpha Centauri, at about 4 light-years away. WISE J085510.83-071442.5 is
only a few light years farther than that.
 
http://www.nasa.gov/jpl/wise/spitzter/pia18003/#.U1qsLlfYGWc
 
This diagram pinpoints star systems closest to the sun. The year when the
distance to each system was determined is listed after the system's name. More
 
WISE J085510.83-071442.5 appears to be 3 to 10 times the mass of Jupiter. With
such a low mass, it could be a gas giant similar to Jupiter that was ejected
from its star system. But scientists estimate it is probably a brown dwarf
rather than a planet since brown dwarfs are known to be fairly common. If so,
it is one of the least massive brown dwarfs known.
 
In March of 2013, Luhman's analysis of the images from WISE uncovered a pair
of much warmer brown dwarfs at a distance of 6.5 light years, making that
system the third closest to the sun. His search for rapidly moving bodies also
demonstrated that the outer solar system probably does not contain a large,
undiscovered planet, which has been referred to as "Planet X" or "Nemesis."
 
Credits:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
 
More information:
 
For more information on NASA's WISE mission, visit: http://www.nasa.gov/wise
 
For more information on NASA's Spitzer mission, visit: http://ww
.nasa.gov/spitzer
 
The California Institute of Technology in Pasadena manages JPL for NASA.
 
 
Regards,
 
Roger

--- D'Bridge 3.99
 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)