Volume 592, August 2016
|Number of page(s)||6|
|Published online||06 July 2016|
Search for giant planets in M67
III. Excess of hot Jupiters in dense open clusters⋆
1 Max-Planck für extraterrestrische Physik, 85741 Garching bei München, Germany
2 University Observatory Munich, Ludwig Maximillian Universitaet, Scheinerstrasse 1, 81679 Munich, Germany
3 ESO – European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
4 Astronomy Department, Universidad de Chile, 1058 Santiago, Chile
5 GEPI, Observatoire de Paris, CNRS, Univ. Paris Diderot, Place Jules Janssen, 92190 Meudon, France
6 Universidade Federal do Rio Grande do Norte, 59300-000 Natal, Brazil
7 Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, 35141 Padova, Italy
8 Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Catania, 78 Catania, Italy
9 ESO – European Southern Observatory, 85748 Santiago, Chile
10 Observatoire de Genève, 1290 Sauverny, Switzerland
11 Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri, 20125 Firenze, Italy
Received: 14 October 2015
Accepted: 26 May 2016
Since 2008 we used high-precision radial velocity (RV) measurements obtained with different telescopes to detect signatures of massive planets around main-sequence and evolved stars of the open cluster (OC) M67. We aimed to perform a long-term study on giant planet formation in open clusters and determine how this formation depends on stellar mass and chemical composition. A new hot Jupiter (HJ) around the main-sequence star YBP401 is reported in this work. An update of the RV measurements for the two HJ host-stars YBP1194 and YBP1514 is also discussed. Our sample of 66 main-sequence and turnoff stars includes 3 HJs, which indicates a high rate of HJs in this cluster (5.6+5.4-2.6% for single stars and 4.5%+4.5-2.5% for the full sample). This rate is much higher than what has been discovered in the field, either with RV surveys or by transits. High metallicity is not a cause for the excess of HJs in M67, nor can the excess be attributed to high stellar masses. When combining this rate with the non-zero eccentricity of the orbits, our results are qualitatively consistent with a HJ formation scenario dominated by strong encounters with other stars or binary companions and subsequent planet-planet scattering, as predicted by N-body simulations.
Key words: planets and satellites: gaseous planets / techniques: radial velocities
© ESO, 2016
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