SETI public: Fw: Cosmic Magnifying Glass: Distant Star Reveals Planet

From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Apr 15 2004 - 10:14:30 PDT

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    From: NASA Jet Propulsion Laboratory<mailto:info_at_jpl.nasa.gov>
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    Subject: Cosmic Magnifying Glass: Distant Star Reveals Planet

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    Jane Platt (818) 354-0880
    Jet Propulsion Laboratory, Pasadena, Calif.

    Donald Savage (202) 358-1547
    NASA Headquarters, Washington, D.C.

    News Release: 2004-103 April 15, 2004

    Cosmic Magnifying Glass: Distant Star Reveals Planet

    Like Sherlock Holmes holding a magnifying glass to unveil hidden
    clues, modern day astronomers used cosmic magnifying effects to reveal
    a planet orbiting a distant star.

    This marks the first discovery of a planet around a star beyond
    Earth's solar system using gravitational microlensing. A star or
    planet can act as a cosmic lens to magnify and brighten a more distant
    star lined up behind it. The gravitational field of the foreground
    star bends and focuses light, like a glass lens bending and focusing
    starlight in a telescope. Albert Einstein predicted this effect in his
    theory of general relativity and confirmed it with our Sun.

    "The real strength of microlensing is its ability to detect low-mass
    planets," said Dr. Ian Bond of the Institute for Astronomy in
    Edinburgh, Scotland, lead author of a paper appearing in the May 10
    Astrophysical Journal Letters. The discovery was made possible through
    cooperation between two international research teams: Microlensing
    Observations in Astrophysics (Moa) and Optical Gravitational Lensing
    Experiment (Ogle). Well-equipped amateur astronomers might use this
    technique to follow up future discoveries and help confirm planets
    around other stars.

    The newly discovered star-planet system is 17,000 light years away, in
    the constellation Sagittarius. The planet, orbiting a red dwarf parent
    star, is most likely one-and-a-half times bigger than Jupiter. The
    planet and star are three times farther apart than Earth and the Sun.
    Together, they magnify a farther, background star some 24,000 light
    years away, near the Milky Way center.

    In most prior microlensing observations, scientists saw a typical
    brightening pattern, or light curve, indicating a star's gravitational
    pull was affecting light from an object behind it. The latest
    observations revealed extra spikes of brightness, indicating the
    existence of two massive objects. By analyzing the precise shape of
    the light curve, Bond and his team determined one smaller object is
    only 0.4 percent the mass of a second, larger object. They concluded
    the smaller object must be a planet orbiting its parent star.

    Dr. Bohdan Paczynski of Princeton University, Princeton, N.J., an OGLE
    team member, first proposed using gravitational microlensing to detect
    dark matter in 1986. In 1991, Paczynski and his student, Shude Mao,
    proposed using microlensing to detect extrasolar planets. Two years
    later, three groups reported the first detection of gravitational
    microlensing by stars. Earlier claims of planet discoveries with
    microlensing are not regarded as definitive, since they had too few
    observations of the apparent planetary brightness variations.

    "I'm thrilled to see the prediction come true with this first definite
    planet detection through gravitational microlensing," Paczynski said.
    He and his colleagues believe observations over the next few years may
    lead to the discovery of Neptune-sized, and even Earth-sized planets
    around distant stars.

    Microlensing can easily detect extrasolar planets, because a planet
    dramatically affects the brightness of a background star. Because the
    effect works only in rare instances, when two stars are perfectly
    aligned, millions of stars must be monitored. Recent advances in
    cameras and image analysis have made this task manageable. Such
    developments include the new large field-of-view Ogle-III camera, the
    Moa-II 1.8 meter (70.8 inch) telescope, being built, and cooperation
    between microlensing teams.

    "It's time-critical to catch stars while they are aligned, so we must
    share our data as quickly as possible," said Ogle team-leader Dr.
    Andrzej Udalski of Poland's Warsaw University Observatory. Udalski in
    Poland and Paczynski in the U.S lead the Polish/American project. It
    operates at Las Campanas Observatory in Chile, run by the Carnegie
    Institution of Washington, and includes the world's largest
    microlensing survey on the 1.3 meter (51-inch) Warsaw Telescope.

    NASA and the National Science Foundation fund the Optical
    Gravitational Lensing Experiment in the U.S. The Polish State
    Committee for Scientific Research and Foundation for Polish Science
    funds it in Poland. Microlensing Observations in Astrophysics is
    primarily a New Zealand/Japanese group, with collaborators in the
    United Kingdom and U.S. New Zealand's Marsden Fund, NASA and National
    Science Foundation, Japan's Ministry of Education, Culture, Sports,
    Science, and Technology, and the Japan Society support it for the
    Promotion of Science.

    Images and information about the latest research are available on the
    Internet at
    http://jpl.convio.net/site/R?i=jiG17Jo75kZO-3BCLCXxIg>..

    -end-


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