by Staff Writers
Pasadena CA (JPL) May 01, 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.
Images from the space telescopes also pinpointed the object's distance to 7.2 light-years away, earning it the title for fourth closest system to our sun. The closest system, a trio of stars, is Alpha Centauri, at about 4 light-years away.
"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. "And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."
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.
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 in March of 2013, 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, enabled the measurement of its distance through the parallax effect. This is the same principle that explains why your finger, when held out right in front of you, appears to jump from side to side when you alternate left- and right-eye views.
"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," said Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif. JPL manages and operates Spitzer. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer."
WISE J085510.83-071442.5 is estimated 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."
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|