IfA Hosts International Brown Dwarf Symposium
Organizer Eduardo Martín addresses the
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