May 22, 2002
(PLANETQUEST) -- Astronomers have observed in mid-infrared wavelengths the closest brown dwarf, or "failed star," to Earth. Findings on the single, free-floating brown dwarf are being presented this week at an International Astronomical Union brown dwarf symposium in Kona, Hawaii.
"This may help us understand more about brown dwarfs and giant planets in other planetary systems," said Dr. Michelle Creech-Eakman of JPL, who led the observations at the Gemini South telescope at Cerro Pachón, Chile. Between December 6 and 9, 2001, she and her colleagues from JPL and Gemini South observed the brown dwarf, which lies more than 1 million times farther from Earth than the Sun.
A brown dwarf is neither a planet nor a star. It never becomes massive or hot enough to ignite the nuclear fusion that occurs in a star, yet it lacks some characteristics of a planet. Brown dwarfs can be companions to other stars or brown dwarfs, or they can be free-floating entities. The only other brown dwarf ever observed in the mid-infrared, Gliese 229B, is part of a binary system, not a single entity, like this newest discovery. It is not known how free-floating brown dwarfs differ from those in binary systems.
"This discovery could pave the way for determining the temperature and composition of both brown dwarfs and extrasolar planets," said Dr. Glenn Orton of JPL. Only through detailed modeling and further observations will the team be able to determine what similarities may exist between these brown dwarfs and gas giants in our solar system, and perhaps in other solar systems.
Other solar systems are home to gas giant planets, presumably like our own Jupiter and Saturn, said Creech-Eakman. But these gas giants are difficult to see because they are so close to the glare of their parent stars, so scientists use more easily seen brown dwarfs as surrogates for extrasolar planets.
Because these brown dwarfs do not shine brightly like a normal star, astronomers must use advanced instruments on telescopes like Gemini South to detect them at mid-infrared wavelengths. Although this latest brown dwarf has been previously examined at other wavelengths, studying it over a wide range of wavelengths helps scientists understand basic physical properties like its temperature and the types of molecules in its atmosphere.
The team's observations were made with the Gemini South Observatory Spectrometer-Camera for the Infrared instrument, developed by the University of Florida, Gainesville.
The brown dwarf was originally discovered as part of the French Deep Near Infrared Survey of the Southern Sky. Follow-up data were taken on it as part of the southern hemisphere portion of the Two Micron All-Sky Survey.
Team member Dr. Gene Serabyn, who is also JPL project scientist for the Mid-Infrared Instrument on the Next Generation Space Telescope, said that by the mission's planned launch in 2010, even more sensitive spectroscopic observations of these objects will be possible. JPL is the U.S. partner in developing the Mid-Infrared Instrument, along with a European consortium sponsored by the European Space Agency. The Next
Generation Space Telescope is part of NASA's Origins Program, which explores the formation of galaxies, stars, planets and life.
More information on the Origins program is available at http://origins.jpl.nasa.gov/ . More information on the Gemini Observatory
is available at http://www.gemini.edu . More information on the Next Generation Space Telescope is available at http://ngst.gsfc.nasa.gov/ . More information on the Two Micron All-Sky Survey is available at http://www.ipac.caltech.edu/2mass/ .
The Next Generation Space Telescope is managed for NASA by Goddard Space
Flight Center, Greenbelt, Md. JPL is managed for NASA by the California Institute of Technology in Pasadena.
The research is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the U.S. National Science Foundation, the United Kingdom Particle Physics and Astronomy Research Council, the Canadian National Research Council, the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica, the Australian Research Council, the Argentinean Consejo Nacional de Investigaciones Cient�ficas y Técnicas, and the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnológico.
