标题： HARPS对南天系外行星的搜索：XXVIII. M0矮星周围的两颗巨行星 显示英文标题

标题： The HARPS search for southern extra-solar planets: XXVIII. Two giant planets around M0 dwarfs

摘要： 围绕M型矮星的巨行星比围绕更高质量恒星的少，而行星特征与中心恒星质量之间的这种依赖关系是行星形成理论的重要观测诊断工具。 为了改进这些统计结果，我们正在使用ESO 3.6米望远镜上的HARPS光谱仪监测附近M型矮星的径向速度。 我们在这里报道在两个附近的M0型矮星Gl 676A和HIP 12961周围发现的巨行星：分别具有5木星质量和1土星质量的行星围绕它们运行。 后者是通过径向速度监测在M型矮星周围发现的最重的行星，其质量超过两倍，但其围绕早期M型矮星运行的情况大致符合行星质量与恒星质量图的上包络线。 HIP 12961（[Fe/H]=-0.07）比平均太阳邻域（[Fe/H]=-0.17）稍富含金属，而Gl 676A（[Fe/H=0.18）显著更富含金属。 因此，这两颗恒星共同加强了巨行星在更富含金属的M型矮星周围更常见的趋势，而Gl 676Ab（5木星质量）围绕富含金属的恒星运行也符合最重的行星优先在具有大冷凝物质量的盘中形成的预期。 显示英文摘要

摘要： Fewer giants planets are found around M dwarfs than around more massive stars, and this dependence of planetary characteristics on the mass of the central star is an important observational diagnostic of planetary formation theories. In part to improve on those statistics, we are monitoring the radial velocities of nearby M dwarfs with the HARPS spectrograph on the ESO 3.6 m telescope. We present here the detection of giant planets around two nearby M0 dwarfs: planets, with minimum masses of respectively 5 Jupiter masses and 1 Saturn mass, orbit around Gl 676A and HIP 12961. The latter is, by over a factor of two, the most massive planet found by radial velocity monitoring of an M dwarf, but its being found around an early M-dwarf is in approximate line with the upper envelope of the planetary vs stellar mass diagram. HIP 12961 ([Fe/H]=-0.07) is slightly more metal-rich than the average solar neighborhood ([Fe/H]=-0.17), and Gl 676A ([Fe/H=0.18) significantly so. The two stars together therefore reinforce the growing trend for giant planets being more frequent around more metal-rich M dwarfs, and the 5~Jupiter mass Gl 676Ab being found around a metal-rich star is consistent with the expectation that the most massive planets preferentially form in disks with large condensate masses.