Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
The Coldest Brown Dwarf Ever Observed: Closing The Gap Between Stars And Planets
by Staff Writers
Washington DC (SPX) Apr 14, 2008


The first brown dwarfs were detected in 1995. Since then, this type of stellar object has been found to share common properties with giant planets, even though differences remain. For example, clouds of dust and aerosols, as well as large amounts of methane, were detected in their atmosphere (for the coldest ones), just as in the atmosphere of Jupiter and Saturn.

An international team of astronomers has discovered the coldest brown dwarf star ever observed. This finding, to be published in Astronomy and Astrophysics, is a new step toward filling the gap between stars and planets. An international team led by French and Canadian astronomers has just discovered the coldest brown dwarf ever observed.

Their results will soon be published in Astronomy and Astrophysics. This new finding was made possible by the performance of telescopes worldwide: Canada France Hawaii Telescope (CFHT) and Gemini North Telescope, both located in Hawaii, and the ESO/NTT located in Chile.

The brown dwarf is named CFBDS J005910.83-011401.3 (it will be called CFBDS0059 in the following). Its temperature is about 350degreesC and its mass about 15-30 times the mass of Jupiter, the largest planet of our solar system. Located about 40 light years from our solar system, it is an isolated object, meaning that it doesn't orbit another star.

Brown dwarfs are intermediate bodies between stars and giant planets (like Jupiter). The mass of brown dwarfs is usually less than 70 Jupiter masses. Because of their low mass, their central temperature is not high enough to maintain thermonuclear fusion reactions over a long time.

In contrast to a star like our Sun, which spends most of its lifetime burning hydrogen, hence keeping a constant internal temperature, a brown dwarf spends its lifetime getting colder and colder after its formation.

The first brown dwarfs were detected in 1995. Since then, this type of stellar object has been found to share common properties with giant planets, even though differences remain. For example, clouds of dust and aerosols, as well as large amounts of methane, were detected in their atmosphere (for the coldest ones), just as in the atmosphere of Jupiter and Saturn.

However, there were still two major differences. In the brown dwarf atmospheres, water is always in gaseous state, while it condenses into water ice in giant planets; and ammonia has never been detected in the brown dwarf near-infrared spectra, while it is a major component of Jupiter's atmosphere.

CFBDS0059, the newly-discovered brown dwarf, looks much more like a giant planet than the known classes of brown dwarfs, both because of its low temperature and because of the presence of ammonia.

To date, two classes of brown dwarfs have been known: the L dwarfs (temperature of 1200-2000degreesC), which have clouds of dust and aerosols in their high atmosphere; and the T dwarfs (temperature lower than 1200degreesC), which have a very different spectrum because of methane forming in their atmospheres.

Because it contains ammonia and has a much lower temperature than do L and T dwarfs, CFBDS0059 might be the prototype of a new class of brown dwarfs to be called the Y dwarfs. This new class would then become in the sequence from the hottest stars to giant planets of less than -100degreesC, by filling the gap now left in the midrange.

This discovery also has important implications in the study of extrasolar planets. The atmosphere of brown dwarfs looks very much like that of giant planets, therefore the same models are used to reproduce their physical conditions. Such modeling needs to be tested against observations.

Observing the atmospheres of extrasolar planets is indeed very hard because the light from the planets is embedded in the much stronger light from their parent stars. Because brown dwarfs are isolated bodies, they are much easier to observe. Thus, looking to brown dwarfs with a temperature close to that of the giant planets will help in testing the models of extrasolar planets' atmospheres.

.


Related Links
Astronomy and Astrophysics
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








STELLAR CHEMISTRY
Witnessing The Formation Of Distant Galaxies
London, UK (SPX) Apr 09, 2008
UK astronomers have produced the most sensitive infrared map of the distant Universe ever undertaken. Combining data over a period of three years, they have produced an image containing over 100,000 galaxies over an area four times the size of the full Moon. Some of the first results from this project will be presented by Dr Sebastien Foucaud from the University of Nottingham ... read more


STELLAR CHEMISTRY
Moondust In The Wind

NASA Sets Sights On Lunar Dust Exploration Mission

The 2008 Great Moonbuggy Race

UMaine Engineering Team To Test Inflatable Habitats For NASA Moon Mission

STELLAR CHEMISTRY
Opportunity Continues Reading The Story In The Rocks

NASA Spacecraft Fine Tunes Course For Mars Landing

NASA Spacecraft Images Mars Moon In Color And In 3D

Spirit Advances Toward Midwinter

STELLAR CHEMISTRY
New drug protects against radiation damage: study

South Korean To Star In Space Sing-Song

Russia Could Stop Tourist Flights To ISS From 2010

Boeing Patent Shuts Down AMC-14 Lunar Flyby Salvage Attempt

STELLAR CHEMISTRY
Three Rocketeers For Shenzhou

China's space development can pose military threat: Japan

Brazil To Deepen Space Cooperation With China

China Approves Second-Phase Lunar Probe Program

STELLAR CHEMISTRY
Russia to call for extending ISS use

The ESA opens a new space laboratory

First Korean astronaut docks with space station

Astronauts Relish New Asian Space Food As Expedition 17 Docks

STELLAR CHEMISTRY
Lockheed Martin Set For Launch Of ICO G1 Spacecraft

Arianespace Lauds Japan Relationship As A Partnership Of Trust

Russia To Conduct 28 Space Launches From Baikonur In 2008

Vietnam delays launch of first satellite

STELLAR CHEMISTRY
New Rocky Planet Found In Constellation Leo

New Laser Technology Could Find First Earth-like Planets

Scientists Discover 10 New Planets Outside Solar System

Googling Alien Life

STELLAR CHEMISTRY
Ball Aerospace GFO Satellite Begins Eleventh Year On Orbit

Newly Discovered Superinsulators Promise To Transform Materials Research, Electronics Design

Chemists work on bamboo fabric development

TDRS-1 Satellite Reaches 25 Years Of Age




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal 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