Water Identified in Extrasolar Planet Atmosphere
- From: baalke@xxxxxxxxxxxxx
- Date: 10 Apr 2007 12:45:27 -0700
For Immediate Release
April 10, 2007
Contact:
Steele Wotkyns
1-928-233-3232
steele@xxxxxxxxxx
Travis Barman
(928) 233-3227
barman@xxxxxxxxxx
Water Identified in Extrasolar Planet Atmosphere
Flagstaff, Ariz. - For the first time, water has been identified in
the
atmosphere of an extrasolar planet. Through a combination of
previously published Hubble Space Telescope measurements and new
theoretical models, Lowell Observatory astronomer Travis Barman has
found strong evidence for water absorption in the atmosphere of
transiting planet HD209458b. This result was recently accepted for
publication in the Astrophysical Journal
(http://lanl.arxiv.org/abs/0704.1114).
"We now know that water vapor exists in the atmosphere of one
extrasolar planet and there is good reason to believe that other
extrasolar planets contain water vapor," said Barman.
Water vapor (or steam) has been expected to be present in the
atmospheres of nearly all of the known extrasolar planets, even those
that orbit closer to their parent star than Mercury is to our Sun.
For
the majority of extrasolar planets, their close proximity to their
parent star has made detecting water and other compounds difficult.
The identification reported here takes advantage of the fact that
HD209458b, as seen from Earth, passes directly in front of its star
every three and half days. As a planet passes in front of a star, its
atmosphere blocks a different amount of the starlight at different
wavelengths. In particular, absorption by water in the atmosphere of
a
giant planet makes the planet appear larger across a specific part of
the infrared spectrum compared to wavelengths in the visible spectrum.
An analysis of visible and infrared Hubble data carried out last year
by Harvard student Heather Knutson made possible a direct comparison
to
new theoretical models developed by Barman at Lowell Observatory. This
ultimately led to the identification of water absorption in a planet
150 light years from Earth.
"It is encouraging that theoretical predictions of water in extrasolar
planets seem to agree reasonably well with observations," said Barman.
This research was supported by NASA's Origins of Solar System program.
About Lowell Observatory
Lowell Observatory is a private, non-profit research institution
founded in 1894 by Percival Lowell. The Observatory has been the site
of many important findings including the discovery of the large
recessional velocities (red-shift) of galaxies by Vesto Slipher in
1912-1914 (a result that led ultimately to the realization the
universe
is expanding), and the discovery of Pluto by Clyde Tombaugh in 1930.
Today, Lowell's 19 astronomers use ground-based telescopes around the
world, telescopes in space, and NASA planetary spacecraft to conduct
research in diverse areas of astronomy and planetary science. Lowell
Observatory currently has four research telescopes at its Anderson
Mesa
dark sky site east of Flagstaff, Arizona, and is building a 4-meter
class research telescope, the Discovery Channel Telescope, in
partnership with Discovery Communications, Inc.
.
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