Search for giant planets in M67

A. Brucalassi; L. Pasquini; R. Saglia; M. T. Ruiz; P. Bonifacio; I. Leão; B. L. Canto Martins; J. R. de Medeiros; L. R. Bedin; K. Biazzo; C. Melo; C. Lovis; S. Randich

doi:10.1051/0004-6361/201527561

Free Access

Issue		A&A Volume 592, August 2016


Article Number		L1
Number of page(s)		6
Section		Letters
DOI		https://doi.org/10.1051/0004-6361/201527561
Published online		06 July 2016

A&A 592, L1 (2016)

III. Excess of hot Jupiters in dense open clusters^⋆

A. Brucalassi¹^,2, L. Pasquini³, R. Saglia¹^,2, M. T. Ruiz⁴, P. Bonifacio⁵, I. Leão³^,6, B. L. Canto Martins⁶, J. R. de Medeiros⁶, L. R. Bedin⁷, K. Biazzo⁸, C. Melo⁹, C. Lovis¹⁰ and S. Randich¹¹

¹ Max-Planck für extraterrestrische Physik, 85741 Garching bei München, Germany
e-mail: abrucala@mpe.mpg.de
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

Abstract

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

^⋆

Based on observations collected at the ESO 3.6 m telescope (La Silla), at the 1.93 m telescope of the Observatoire de Haute-Provence (OHP), at the Hobby Eberly Telescope (HET), at the Telescopio Nazionale Galileo (TNG, La Palma) and at the Euler Swiss Telescope.

© ESO, 2016

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Search for giant planets in M67

III. Excess of hot Jupiters in dense open clusters⋆

III. Excess of hot Jupiters in dense open clusters^⋆