For the past six years we have carried out a search for massive planets around main sequence and evolved stars in the open cluster ( OC ) M67 , using radial velocity ( RV ) measurements obtained with HARPS at ESO ( La Silla ) , SOPHIE at OHP and HRS at HET .
Additional RV data come from CORALIE at the Euler Swiss Telescope .
We aim to perform a long-term study on giant planet formation in open clusters and determine how it depends on stellar mass and chemical composition . We report the detection of three new extrasolar planets : two in orbit around the two G dwarfs YBP1194 and YBP1514 , and one around the evolved star S364 .
The orbital solution for YBP1194 yields a period of 6.9 days , an eccentricity of 0.24 , and a minimum mass of 0.34 M _ { \mathrm { Jup } } .
YBP1514 shows periodic RV variations of 5.1 days , a minimum mass of 0.40 M _ { \mathrm { Jup } } , and an eccentricity of 0.39 .
The best Keplerian solution for S364 yields a period of 121.7 days , an eccentricity of 0.35 and a minimum mass of 1.54 M _ { \mathrm { Jup } } .
An analysis of H \alpha core flux measurements as well as of the line bisectors spans revealed no correlation with the RV periods , indicating that the RV variations are best explained by the presence of a planetary companion .
Remarkably , YBP1194 is one of the best solar twins identified so far , and YBP1194b is the first planet found around a solar twin that belongs to a stellar cluster .
In contrast with early reports and in agreement with recent findings , our results show that massive planets around stars of open clusters are as frequent as those around field stars .