Press Release

Oxygen and Carbon Found In Atmosphere of an Extrasolar Planet

By SpaceRef Editor
February 2, 2004
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Oxygen and Carbon Found In Atmosphere of an Extrasolar Planet

NASA’s Hubble Space Telescope has detected, for the first time ever, the
presence of oxygen and carbon in the atmosphere of a planet outside our
solar system.

The oxygen naturally exists and is not produced by any sort of life on
the gaseous hot world, astronomers caution. Nevertheless, it is a
promising demonstration that the chemical composition of atmospheres on
planets many light-years away can be measured. This could someday lead
to finding the atmospheric biomarkers of life on extrasolar planets.

The oxygen and carbon are bleeding off the gas-giant extrasolar planet
HD 209458b, orbiting a star lying 150 light-years from Earth. HD 209458b
is only 4.3 million miles from its Sun-like star, completing an orbit in
less than 4 days. It belongs to a class of planets called “hot
Jupiters.” Astronomers previously discovered that the upper atmosphere
is so hot it boils hydrogen off into space.

Astronomers used the Hubble Space Telescope Imaging Spectrograph to
discover a rugby-ball shaped evaporating envelope of oxygen and carbon.
Analysis of the starlight passing through the envelope shows it is being
ripped off by the extreme “hydrodynamic drag” created by its evaporating
hydrogen atmosphere.

The planet has been dubbed “Osiris” after the Egyptian god that lost
part of his body — like HD 209458b — after having been killed and cut
into pieces by his brother to prevent his return to life.

The planet HD 209458b is the first transiting planet discovered, the
first extrasolar planet known to have an atmosphere, the first
extrasolar planet observed to have an evaporating hydrogen atmosphere,
and now the first extrasolar planet found to have an atmosphere
containing oxygen and carbon.

The Hubble team led by Alfred Vidal-Madjar (Institut d’Astrophysique de
Paris, CNRS, France) is reporting this discovery in a forthcoming issue
of Astrophysical Journal Letters.

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The Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA), for
NASA, under contract with the Goddard Space Flight Center, Greenbelt,
Md. The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency (ESA).

SpaceRef staff editor.