SETI public: FW: NASA Scientist Finds World With Triple Sunsets

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>From: "NASA Jet Propulsion Laboratory" <info_at_jpl.nasa.gov>
>Reply-To: <info_at_jpl.nasa.gov>
>To: "Larry Klaes" <ljk4_at_msn.com>
>Subject: NASA Scientist Finds World With Triple Sunsets
>Date: Wed, 13 Jul 2005 12:47:54 -0700
>
>MEDIA RELATIONS OFFICE
>JET PROPULSION LABORATORY
>CALIFORNIA INSTITUTE OF TECHNOLOGY
>NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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>Whitney Clavin (818) 354-4673
>Jet Propulsion Laboratory, Pasadena, Calif.
>
>News Release: 2005-115 July 13, 2005
>
>NASA Scientist Finds World With Triple Sunsets
>
>A NASA-funded astronomer has discovered a world where the sun sets over the
>horizon,
>followed by a second sun and then a third. The new planet, called HD 188753
>Ab, is the
>first known to reside in a classic triple-star system.
>
>"The sky view from this planet would be spectacular, with an occasional
>triple sunset,"
>said Dr. Maciej Konacki (MATCH-ee Konn-ATZ-kee) of the California Institute
>of
>Technology, Pasadena, Calif., who found the planet using the Keck I
>telescope atop
>Mauna Kea mountain in Hawaii. "Before now, we had no clues about whether
>planets
>could form in such gravitationally complex systems."
>
>The finding, reported in this week's issue of Nature, suggests that planets
>are more robust
>than previously believed.
>
>"This is good news for planets," said Dr. Shri Kulkarni, who oversees
>Konacki's research
>at Caltech. "Planets may live in all sorts of interesting neighborhoods
>that, until now,
>have gone largely unexplored." Kulkarni is the interdisciplinary scientist
>for NASA's
>planned SIM PlanetQuest mission, which will search for signs of Earth-like
>worlds.
>
>Systems with multiple stars are widespread throughout the universe,
>accounting for more
>than half of all stars. Our Sun's closest star, Alpha Centauri, is a member
>of a trio.
>
>"Multiple-star systems have not been popular planet-hunting grounds," said
>Konacki.
>"They are difficult to observe and were believed to be inhospitable to
>planets."
>
>The new planet belongs to a common class of extrasolar planets called "hot
>Jupiters,"
>which are gas giants that zip closely around their parent stars. In this
>case, the planet
>whips every 3.3 days around a star that is circled every 25.7 years by a
>pirouetting pair of
>stars locked in a 156-day orbit.
>
>
>The circus-like trio of stars is a cramped bunch, fitting into the same
>amount of space as
>the distance between Saturn and our Sun. Such tight living quarters throw
>theories of hot
>Jupiter formation into question. Astronomers had thought that hot Jupiters
>formed far
>away from their parent stars, before migrating inward.
>
>"In this close-knit system, there would be no room at the outskirts of the
>parent star
>system for a planet to grow," said Konacki.
>
>Previously, astronomers had identified planets around about 20 binary stars
>and one set of
>triple stars. But the stars in those systems had a lot of space between
>them. Most
>multiple-star arrangements are crowded together and difficult to study.
>
>Konacki overcame this challenge using a modified version of the radial
>velocity, or
>"wobble," planet-hunting technique. In the traditional wobble method, a
>planet's presence
>is inferred by the gravitational tug, or wobble, it induces in its parent
>star. The strategy
>works well for single stars or far-apart binary and triple stars, but could
>not be applied to
>close-star systems because the stars' light blends together.
>
>By developing detailed models of close-star systems, Konacki was able to
>tease apart the
>tangled starlight. This allowed him to pinpoint, for the first time, the
>tug of a planet on a
>star snuggled next to other stars. Of 20 systems examined so far, HD
>188753, located 149
>light-years away, was the only one found to harbor a planet.
>
>Hot Jupiters are believed to form out of thick disks, or "doughnuts," of
>material that swirl
>around the outer fringes of young stars. The disk material clumps together
>to form a solid
>core, then pulls gas onto it. Eventually, the gas giant drifts inward. The
>discovery of a
>world under three suns contradicts this scenario. HD 188753 would have
>sported a
>truncated disk in its youth, due to the disruptive presence of its stellar
>companions. That
>leaves no room for HD 188753's planet to form, and raises a host of new
>questions.
>
>The masses of the three stars in HD 188753 system range from two-thirds to
>about the
>same mass as our Sun. The planet is slightly more massive than Jupiter.
>
>For artist's concepts and other graphics, visit
>http://planetquest.jpl.nasa.gov/ . For
>information about NASA and agency programs on the Web, visit
>http://www.nasa.gov/home/index.html .
>
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