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IfA Hosts International Brown Dwarf Symposium

Organizer Eduardo Martín addresses the meeting

Nearly 150 astronomers from sixteen different countries spent five days in May at the Big Island's Outrigger Waikoloa Beach Hotel discussing the latest research on brown dwarfs. The meeting was the first International Astronomical Union (IAU) Symposium dedicated exclusively to brown dwarfs.

"Holding this symposium would have been just a wild dream only 7 years ago, when no brown dwarfs had been identified yet. We have indeed seen a lot of progress in this field in a very short time, and now a dream is coming true," said Dr. Eduardo Martín, chair of the Scientific Organizing Committee, and a junior faculty member at the IfA.

Brown dwarfs are a new kind of celestial object. They have properties intermediate between those of stars and planets, and constitute a natural link between these two types of classical objects. Due to slow gravitational contraction, they emit a dim glow of light, which can only be detected with powerful telescopes, such as those located atop Mauna Kea.

The conference attendees debated current ideas about how brown dwarfs form and evolve. It is unclear whether brown dwarfs form directly from molecular clouds in a manner similar to stars, or whether they form out of circumstellar disks, in a way similar to how planets are thought to form.

Discoveries of brown dwarfs in star-forming regions, young open clusters, the solar neighborhood, and around stars and other brown dwarfs, were reported on during the meeting.

One special session, chaired by Dr. Alan Boss of the Carnegie Institution of Washington, was dedicated to delineating the boundary between brown dwarfs and giant planets. Scientists have not reached a consensus yet about what should be called a brown dwarf and what should be called a planet.

During the conference, scientists announced the discovery of a new substellar object, named SOri70, near the young star Sigma Orionis. Deep sky images and follow-up spectroscopy obtained by an international team revealed this extremely cool and dim object. The astronomers made the observations with large telescopes in Hawaii and the Canary Islands. It may be the first planet outside the solar system ever to be photographed.

However, the team will have to wait for at least two years to find out if they have taken pictures of a large, young planet or an old, brown dwarf. If the object is located at the same distance as the Sigma Orionis system (1,150 light-years from Earth), it should have an age between 1 and 8 million years and a mass close to that of Jupiter. However, the distance to the object is not known yet; and it will take the sharp imaging capabilities of the Hubble Space Telescope to determine it. There is about a 20 percent probability that SOri70 is a wandering old brown dwarf that happens to be in the direction of the Sigma Orionis, but is actually closer to Earth.

The Brown Dwarfs Symposium was hosted by the IfA in collaboration with the Subaru Telescope of the National Astronomical Observatory of Japan; the NASA Infrared Telescope Facility; the British-Canadian-Dutch Joint Astronomy Centre; and the Canada-France-Hawaii Telescope Corporation. NASA, the Hawaii Island Economic Development Board, the University of Hawaii at Hilo Conference Center, and the Hawaii Tourism Authority sponsored the conference.

From left to right: Eric Becklin (UCLA) talking about how the Stratospheric Observatory for Infrared Astronomy (SOFIA) will affect brown dwarf research; Damien Segransan (Geneva Observatory) with the youngest conference participant; and Melanie Freed (University of Arizona) in front of a poster that describes her work.

Participants from Australia, Canada, Chile, China, France, Germany, India, Israel, Italy, Japan, Russia, Spain, Switzerland,
the United Kingdom, the United States, and Venezuela came to the Big Island for IAU Symposium 211, "Brown Dwarfs."

The Brown Dwarf Symposium Web site