Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass
Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass
复制标题
重访退役 A 恒星：更新后的巨行星出现率与恒星金属丰度和质量的函数关系
DOI：
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发表时间：
2018
影响因子：
4.9
通讯作者：
J. Johnson
中科院分区：
文献类型：
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作者：
L. Ghezzi;B. Montet;J. Johnson
对演化恒星的系外行星调查提供了越来越多的证据，证明巨行星的形成不仅取决于恒星的金属丰度（[Fe/H]），还取决于质量（）。然而，测量亚巨星和巨星的精确质量比测量它们的主序星更具挑战性，这导致了最近对恒星质量和行星出现之间相关性的真实性的担忧。为了解决这些问题，我们使用HIRES光谱对245个亚巨星样本进行光谱分析，并得出新的大气和物理参数。我们还首次以均匀的方式计算了该样品的空速。当在恒星质量的计算中考虑红化修正并对结果应用-0.12的偏移量时，次巨星的质量与它们的空间速度分布一致，与文献中的说法相反。同样，我们对它们的旋转速度的测量提供了额外的证实，即具有M的亚巨星（“退休A星”）的质量在之前的分析中并未被高估。使用这些新的结果，我们的样本演化的恒星，再加上更新的样本FGKM矮星，我们确认，巨行星的发生增加与恒星质量和金属丰度高达2.0 M <$。我们表明，形成一个巨大的行星的概率是大约一个一对一的函数的金属总量的原行星盘。这种相关性为行星形成的核心吸积机制提供了额外的支持。
Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]) but also on the mass ( ). However, measuring accurate masses for subgiants and giants is far more challenging than it is for their main-sequence counterparts, which has led to recent concerns regarding the veracity of the correlation between stellar mass and planet occurrence. In order to address these concerns, we use HIRES spectra to perform a spectroscopic analysis on a sample of 245 subgiants and derive new atmospheric and physical parameters. We also calculate the space velocities of this sample in a homogeneous manner for the first time. When reddening corrections are considered in the calculations of stellar masses and a −0.12 offset is applied to the results, the masses of the subgiants are consistent with their space velocity distributions, contrary to claims in the literature. Similarly, our measurements of their rotational velocities provide additional confirmation that the masses of subgiants with M☉ (the “retired A stars”) have not been overestimated in previous analyses. Using these new results for our sample of evolved stars, together with an updated sample of FGKM dwarfs, we confirm that giant planet occurrence increases with both stellar mass and metallicity up to 2.0 M⊙. We show that the probability of formation of a giant planet is approximately a one-to-one function of the total amount of metals in the protoplanetary disk . This correlation provides additional support for the core accretion mechanism of planet formation.