Search for giant planets in M67 III. Excess of hot Jupiters in dense open clusters

Brucalassi, A.; Pasquini, L.; Saglia, R.; Ruiz, M. T.; Bonifacio, P.; Leão, I.; Canto Martins, B. L.; Medeiros, J. R. de; Bedin, L. R.; Biazzo, K.; Melo, C.; Lovis, C. and Randich, S. (2016): Search for giant planets in M67 III. Excess of hot Jupiters in dense open clusters. In: Astronomy & Astrophysics, Vol. 592, L1

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(-2.6)(+5.4%) for single stars and 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.

• Item Type: Journal article
• Faculties: Physics
• Subjects: 500 Science > 530 Physics
• ISSN: 1432-0746
• Language: English