harps_neptune_survey - Astronomy & Astrophysics...

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Unformatted text preview: Astronomy & Astrophysics manuscript no. HARPSstat c ESO 2011 September 13, 2011 The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets ? M. Mayor 1 , M. Marmier 1 , C. Lovis 1 , S. Udry 1 , D. Segransan 1 , F. Pepe 1 , W. Benz 2 , J.-L. Bertaux 3 , F. Bouchy 4 , X. Dumusque 1 , G. LoCurto 5 , C. Mordasini 6 , D. Queloz 1 , and N.C. Santos 7 , 8 1 Observatoire Astronomique de lUniversite de Gen`eve, 51 ch. des Maillettes - Sauverny, CH-1290 Versoix, Switzerland 2 Physikalisches Institut, Universitat Bern, Silderstrasse 5, CH-3012 Bern, Switzerland 3 LATMOS, CNRS / UVSQ Universite de Versailles, Saint Quentin, France 4 Observatoire de Haute-Provence, 04870 Saint-Michel lObservatoire, France 5 European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Munchen, Germany 6 Max-Planck-Institut fur Astronomie, Konigsstuhl 17, D-69117 Heidelberg, Germany 7 Centro de Astrof sica , Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 8 Departamento de F sica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Portugal Received September 2011 / Accepted 2011 ABSTRACT Aims. We report on the results of an 8-year survey carried out at the La Silla Observatory with the HARPS spectrograph to detect and characterize planets in the super-Earth and Neptune mass regime. Methods. The size of our star sample and the precision achieved with HARPS have allowed the detection of a su ffi ciently large number of low-mass planets to study the statistical properties of their orbital elements, the correlation of the host-star metallicity with the planet masses, as well as the occurrence rate of planetary systems around solar-type stars. Results. A robust estimate of the frequency of systems shows that more than 50% of solar-type stars harbor at least one planet of any mass and with period up to 100 days. Di ff erent properties are observed for the population of planets less massive than about 30 M compared to the population of gaseous giant planets. The mass distribution of Super-Earths and Neptune-mass planets (SEN) is strongly increasing between 30 and 15 M . The SEN occurence rate does not exhibit a preference for metal rich stars. Most of the SEN planets belong to multi-planetary systems. The orbital eccentricities of the SEN planets seems limited to 0.45. At the opposite, the occurence rate of gaseous giant planets is growing with the logarithm of the period, and is strongly increasing with the host-star metallicity. About 14 % of solar-type stars have a planetary companion more massive than 50 M on an orbit with a period shorter than 10 years. Orbital eccentricities of giant planets are observed up to 0.9 and beyond....
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This note was uploaded on 01/03/2012 for the course GEL 133 taught by Professor List during the Fall '10 term at Caltech.

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harps_neptune_survey - Astronomy & Astrophysics...

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