AN EMPIRICAL CALIBRATION TO ESTIMATE COOL DWARF FUNDAMENTAL PARAMETERS FROM H-BAND SPECTRA
AN EMPIRICAL CALIBRATION TO ESTIMATE COOL DWARF FUNDAMENTAL PARAMETERS FROM H-BAND SPECTRA
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DOI：
10.1088/0004-637x/800/2/85
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发表时间：
2014-12
期刊：
影响因子：
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通讯作者：
E. Newton;D. Charbonneau;J. Irwin;A. Mann
中科院分区：
文献类型：
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作者：
E. Newton;D. Charbonneau;J. Irwin;A. Mann
干涉半径测量提供了一个直接的探针的基本参数的M矮星。然而，干涉测量法只适用于附近有限的明亮恒星样本。我们使用干涉测量半径，测辐射热光度，和有效温度开发新的经验校准的基础上，低分辨率，近红外光谱。我们发现，H-波段镁和铝的光谱特征是很好的示踪剂的恒星性质，并推导出的功能，有效温度，半径，和日志光度这些功能。我们的最佳拟合残差的标准偏差分别为73 K，0.027 R差和0.049 dex（光度误差为11%）。我们的校准从中K到中M矮星都是有效的，大致对应于3100和4800 K之间的温度。我们应用我们的H波段的关系，以M矮星为目标的MEarth过境行星调查和酷开普勒感兴趣的对象（KOIs）。我们目前的光谱测量和估计这些恒星的恒星参数。视差也可用于许多MEarth目标，使我们能够通过展示我们推断的参数和恒星绝对K星等之间的明确关系来独立验证我们的校准。我们确定对象的幅度太亮，他们的推断光度作为候选人的多个系统。我们还使用我们估计的光度来解决近红外金属丰度校准的适用性，中期和晚期M矮星。我们推断的KOIs的温度与文献中的温度非常吻合;然而，我们的恒星半径系统地大于以前的作品中提出的那些从模型等时线导出的半径。这导致行星的平均半径比使用最近的星表中的恒星属性推断的大15%。我们的研究结果证实了先前对KOI 961（开普勒-42），254（开普勒-45）和571（开普勒-186）的深入研究得出的参数，后者拥有一颗在其星星的可居住区轨道上运行的岩石行星。
Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs. However, interferometry is within reach for only a limited sample of nearby, bright stars. We use interferometrically measured radii, bolometric luminosities, and effective temperatures to develop new empirical calibrations based on low-resolution, near-infrared spectra. We find that H-band Mg and Al spectral features are good tracers of stellar properties, and derive functions that relate effective temperature, radius, and log luminosity to these features. The standard deviations in the residuals of our best fits are, respectively, 73 K, 0.027 R☉, and 0.049 dex (an 11% error on luminosity). Our calibrations are valid from mid K to mid M dwarf stars, roughly corresponding to temperatures between 3100 and 4800 K. We apply our H-band relationships to M dwarfs targeted by the MEarth transiting planet survey and to the cool Kepler Objects of Interest (KOIs). We present spectral measurements and estimated stellar parameters for these stars. Parallaxes are also available for many of the MEarth targets, allowing us to independently validate our calibrations by demonstrating a clear relationship between our inferred parameters and the stars' absolute K magnitudes. We identify objects with magnitudes that are too bright for their inferred luminosities as candidate multiple systems. We also use our estimated luminosities to address the applicability of near-infrared metallicity calibrations to mid and late M dwarfs. The temperatures we infer for the KOIs agree remarkably well with those from the literature; however, our stellar radii are systematically larger than those presented in previous works that derive radii from model isochrones. This results in a mean planet radius that is 15% larger than one would infer using the stellar properties from recent catalogs. Our results confirm the derived parameters from previous in-depth studies of KOIs 961 (Kepler-42), 254 (Kepler-45), and 571 (Kepler-186), the latter of which hosts a rocky planet orbiting in its star's habitable zone.