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arXiv 1006.2850astro-ph.EPastro-ph.SR
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M矮星金属丰度的物理激发光度学标定

A Physically-Motivated Photometric Calibration of M Dwarf Metallicity

Kevin C. Schlaufman, Gregory Laughlin

摘要:

M矮星在V-K_s-M_Ks色星等图(CMD)上的位置与金属丰度有关。我们表明,以前的经验测光校准M矮金属利用这种相关性系统低估或高估金属在其范围的极端。我们从三个方面改进了以前的校准。我们利用来自Geneva-Copehnagen巡天(GCS)的F和G矮星的体积有限和运动学匹配样本来推断太阳邻域中M矮星的平均金属丰度,我们利用M矮星内部和大气的理论模型来确定金属丰度对V-K_s-M_Ks CMD中M矮星的影响,我们的最终校准完全基于具有M矮星伴星的FGK原色的高分辨率光谱学。其结果是,我们解释了一个数量级以上的校准样本的方差比以前的光度校准。我们非参数量化的观察,M矮星的主机系外行星优先在一个区域的V-K_s-M_Ks平面填充富含金属的M矮星的意义。我们发现,行星托管的M矮星分布在V-K_s-M_Ks CMD的概率p是P = 0.06 +/- 0.008场M矮星以同样的方式。有趣的是,拥有海王星和次海王星质量行星的M矮星子样本也可能优先位于由高金属丰度M矮星组成的V-K_s-M_Ks平面区域。这种偶然发生的概率是p = 0.40 +/- 0.02,这一观测结果暗示,在富含金属的M矮星周围可能更有可能发现低质量行星。在富含金属的M型矮星周围,低质量行星出现率的增加是行星形成的核心吸积模型的自然结果。(节略)

英文摘要:

The location of M dwarfs in the V-K_s--M_Ks color-magnitude diagram (CMD) has been shown to correlate with metallicity. We demonstrate that previous empirical photometric calibrations of M dwarf metallicity exploiting this correlation systematically underestimate or overestimate metallicity at the extremes of their range. We improve upon previous calibrations in three ways. We use both a volume-limited and kinematically-matched sample of F and G dwarfs from the Geneva-Copehnagen Survey (GCS) to infer the mean metallicity of M dwarfs in the Solar Neighborhood, we use theoretical models of M dwarf interiors and atmospheres to determine the effect of metallicity on M dwarfs in the V-K_s--M_Ks CMD, and we base our final calibration purely on high-resolution spectroscopy of FGK primaries with M dwarf companions. As a result, we explain an order of magnitude more of the variance in the calibration sample than previous photometric calibrations. We non-parametrically quantify the significance of the observation that M dwarfs that host exoplanets are preferentially in a region of the V-K_s--M_Ks plane populated by metal-rich M dwarfs. We find that the probability p that planet-hosting M dwarfs are distributed across the V-K_s--M_Ks CMD in the same way as field M dwarfs is p = 0.06 +/- 0.008. Interestingly, the subsample of M dwarfs that host Neptune and sub-Neptune mass planets may also be preferentially located in the region of the V-K_s--M_Ks plane populated by high-metallicity M dwarfs. The probability of this occurrence by chance is p = 0.40 +/- 0.02, and this observation hints that low-mass planets may be more likely to be found around metal-rich M dwarfs. An increased rate of low-mass planet occurrence around metal-rich M dwarfs would be a natural consequence of the core-accretion model of planet formation. (abridged)

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