KEPLER EXOPLANET CANDIDATE HOST STARS ARE PREFERENTIALLY METAL RICH
KEPLER EXOPLANET CANDIDATE HOST STARS ARE PREFERENTIALLY METAL RICH
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DOI：
10.1088/0004-637x/738/2/177
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
K. Schlaufman;G. Laughlin
中科院分区：
文献类型：
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作者：
K. Schlaufman;G. Laughlin
我们发现开普勒系外行星候选（EC）的宿主恒星优先富含金属，包括小半径EC的低质量恒星宿主。最后一次观测证实了一个初步的暗示，即低质量恒星的金属丰度与低质量和小半径系外行星的存在之间存在相关性。特别是，我们比较了开普勒EC主星的J−H-g−r色-色分布与从开普勒使命Q1和Q2期间观测到的150，000颗恒星中选择的矮星对照样本，但没有检测到行星。我们发现，在J − H = 0.30的太阳型恒星特征下，拥有巨大EC的恒星的平均g−r颜色比对照样本中恒星的平均颜色红4σ。在相同的J − H色下，拥有小半径EC的太阳型恒星的平均g−r色与对照样本中恒星的平均颜色无法区分。此外，我们发现在J − H = 0.62时，代表晚K矮星，拥有小半径EC的恒星的平均g−r颜色比对照样本中恒星的平均颜色红4σ。这些偏移不太可能是由差异变红、两个种群之间的年龄差异或对照样本中巨星的存在引起的。恒星模型表明，第一个颜色偏移是由于巨大的EC宿主种群在M* 10.1 M时[Fe/H]增加了0.2 dex，而M 67和NGC 6791的斯隆测光表明，第二个颜色偏移是由于小半径EC宿主种群在M* 10.7 M时类似的[Fe/H]增加。这些相关性是行星形成的核心吸积模型的自然结果。
We find that Kepler exoplanet candidate (EC) host stars are preferentially metal rich, including the low-mass stellar hosts of small-radius ECs. The last observation confirms a tentative hint that there is a correlation between the metallicity of low-mass stars and the presence of low-mass and small-radius exoplanets. In particular, we compare the J−H–g−r color–color distribution of Kepler EC host stars with a control sample of dwarf stars selected from the ∼150, 000 stars observed during Q1 and Q2 of the Kepler mission but with no detected planets. We find that at J − H = 0.30 characteristic of solar-type stars, the average g−r color of stars that host giant ECs is 4σ redder than the average color of the stars in the control sample. At the same J − H color, the average g−r color of solar-type stars that host small-radius ECs is indistinguishable from the average color of the stars in the control sample. In addition, we find that at J − H = 0.62 indicative of late K dwarfs, the average g−r color of stars that host small-radius ECs is 4σ redder than the average color of the stars in the control sample. These offsets are unlikely to be caused by differential reddening, age differences between the two populations, or the presence of giant stars in the control sample. Stellar models suggest that the first color offset is due to a 0.2 dex enhancement in [Fe/H] of the giant EC host population at M* ≈ 1 M☉, while Sloan photometry of M 67 and NGC 6791 suggests that the second color offset is due to a similar [Fe/H] enhancement of the small-radius EC host population at M* ≈ 0.7 M☉. These correlations are a natural consequence of the core-accretion model of planet formation.