SETI bioastro: Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems

From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Jul 19 2006 - 13:45:31 PDT

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    Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems

    Deepak Raghavan and Todd J. Henry

    Center for High Angular Resolution Astronomy and Department of Physics and
    Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106;
    raghavan_at_chara.gsu.edu

    Brian D. Mason

    US Naval Observatory, 3450 Massachusetts Avenue NW, Washington, DC
    20392-5420

    John P. Subasavage , Wei-Chun Jao , and Thom D. Beaulieu

    Center for High Angular Resolution Astronomy and Department of Physics and
    Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106

    and

    Nigel C. Hambly

    Institute for Astronomy, School of Physics, University of Edinburgh, Royal
    Observatory, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK

    Received 2005 November 4; accepted 2006 March 29

    ABSTRACT

    We present results of a reconnaissance for stellar companions to all 131
    radial velocity–detected candidate extrasolar planetary systems known as of
    2005 July 1. Common proper-motion companions were investigated using the
    multiepoch STScI Digitized Sky Surveys and confirmed by matching the
    trigonometric parallax distances of the primaries to companion distances
    estimated photometrically. We also attempt to confirm or refute companions
    listed in the Washington Double Star Catalog, in the Catalogs of Nearby
    Stars Series by Gliese and Jahreiß, in Hipparcos results, and in Duquennoy &
    Mayor's radial velocity survey.

    Our findings indicate that a lower limit of 30 (23%) of the 131 exoplanet
    systems have stellar companions. We report new stellar companions to HD
    38529 and HD 188015 and a new candidate companion to HD 169830. We confirm
    many previously reported stellar companions, including six stars in five
    systems, that are recognized for the first time as companions to exoplanet
    hosts. We have found evidence that 20 entries in the Washington Double Star
    Catalog are not gravitationally bound companions. At least three (HD 178911,
    16 Cyg B, and HD 219449), and possibly five (including HD 41004 and HD
    38529), of the exoplanet systems reside in triple-star systems. Three
    exoplanet systems (GJ 86, HD 41004, and Cep) have potentially close-in
    stellar companions, with planets at roughly Mercury–Mars distances from the
    host star and stellar companions at projected separations of 20 AU, similar
    to the Sun–Uranus distance. Finally, two of the exoplanet systems contain
    white dwarf companions. This comprehensive assessment of exoplanet systems
    indicates that solar systems are found in a variety of stellar multiplicity
    environments—singles, binaries, and triples—and that planets survive the
    post–main-sequence evolution of companion stars.

    Subject headings: binaries: general—planetary systems—surveys

    Online material: machine-readable tables

    http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v646n1/64035/64035.html


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