标题： 候选行星系统的光谱分析：55 Cnc、51 Peg、47 UMa、70 Vir 和 HD 114762 显示英文标题

标题： Spectroscopic Analyses of the Planetary System Candidates: 55 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762

摘要： 55 Cnc、51 Peg、47 UMa、70 Vir 和 HD 114762 近期被提出可能拥有行星质量的伴星。利用光谱方法我们发现，55 Cnc 和 51 Peg 是超金属富集的，47 UMa 和 70 Vir 的金属丰度接近太阳，而 HD 114762 是贫金属的。否则，以[X/Fe]表示的元素丰度模式大致与太阳相似。47 UMa 和 51 Peg 的年龄与太阳相似；70 Vir 略显年长，而 55 Cnc 和 HD 114762 至少有 10 Gyr 老。我们估算的母星 vsini 分别为：55 Cnc 1.4 km/s，51 Peg 1.8 km/s，47 UMa 2.0 km/s，70 Vir < 1 km/s，以及 HD 114762 < 1.5 km/s。使用这些数据和旋转周期及半径的估计值，对应的伴星质量分别为：> 0.6，0.51，4.6，> 20，以及 > 8.5 MJ。这些系统似乎分为三组：围绕富金属母星的小型圆形轨道上具有类似木星质量的伴星（55 Cnc 和 51 Peg），围绕较大圆形轨道的更大伴星（47 UMa），以及围绕适度贫金属母星的大偏心轨道上的远更巨大伴星（70 Vir 和 HD 114762）。我们的发现与最近提出的机制一致，即在行星系统的形成时期，气态巨行星可能会迁移到距离其母星仅数百分之一天文单位的范围内。在此过程中，巨行星与恒星之间的物质会被吸积到后者上。如果吸积的物质中氢和氦含量减少，则母星的光球成分可能会发生显著改变。 显示英文摘要

摘要： The stars 55 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762 have recently been proposed to harbor planetary mass companions. Using spectrospic methods we find that 55 Cnc and 51 Peg are super metal- rich, 47 UMa and 70 Vir have roughly solar metallicities, and HD 114762 is metal-poor. Otherwise, the abundance patterns, expressed as [X/Fe], are approximately solar. The ages of 47 UMa and 51 Peg are similar to that of the Sun; 70 Vir is slightly older, and 55 Cnc and HD 114762 are at least 10 Gyr old. Our estimates of vsini for the parent stars are 1.4, 1.8, 2.0, < 1, and < 1.5 km/s for 55 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762, respectively. Using these data and estimates for the rotation periods and radii, the corresponding masses of the companions are: > 0.6, 0.51, 4.6, > 20, and > 8.5 MJ. The systems appear to fall into three groups: roughly Jupiter mass companions with small circular orbits with metal-rich parent stars (55 Cnc and 51 Peg), larger companions with larger circular orbits (47 UMa), and much more massive companions with large eccentric orbits around moderately metal- poor parent stars (70 Vir and HD 114762). Our findings are consistent with the recently proposed mechanism whereby a gas giant migrates to within a few hundredths of an AU of its parent star during the formative epoch of the planetary system. During this process the material between the giant planet and the star is accreted onto the latter. If the accreted material is depleted in H and He, then the photospheric composition of the parent star might be altered significantly.