CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS
CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS
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描述酷炫锦鲤的特征。
DOI：
10.1088/0004-637x/747/2/144
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
J. Lloyd
中科院分区：
文献类型：
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作者：
P. Muirhead;J. Johnson;K. Apps;J. Carter;T. Morton;D. Fabrycky;J. Pineda;M. Bottom;B. Rojas;E. Schlawin;K. Hamren;K. Covey;J. Crepp;K. Stassun;J. Pepper;L. Hebb;E. Kirby;A. Howard;H. Isaacson;G. Marcy;D. Levitan;T. Díaz;L. Armus;J. Lloyd
我们描述了星星KOI 961，一个M矮星，其过境信号表明开普勒使命发现了三颗短周期系外行星。我们继续比较KOI 961和巴纳德星星，一个附近的，特征很好的中M矮星。我们比较颜色，光学和近红外光谱，并发现两者之间显着的协议，这意味着类似的有效温度和金属丰度。这两颗恒星都是贫金属的，有低的投影自转速度，高的绝对径向速度，大的自行，没有静止的Hα发射-所有这些都与老M矮星相一致。我们联合收割机巴纳德星的经验测量和演化等时线的预期，估计KOI 961的质量（0.13 ± 0.05 M），半径（0.17 ± 0.04 R）和光度（2.40 × 10−3.0 ± 0.3 L）。我们计算了KOI 961的距离（38.7 ± 6.3 pc）和空间运动，像巴纳德星星一样，与银河系中的高尺度高度人口一致。我们执行一个独立的多过境适合公共开普勒光变曲线和显着修改的过境参数的三颗行星。我们计算了每个行星候选者的假阳性概率，并发现任何一个凌日信号是由于背景或分层食双星的可能性不到1%，验证了凌日的行星性质。所有三颗行星的最佳半径都小于1 R <$，KOI 961.03的大小与火星相当（RP = 0.57 ± 0.18 R <$），它们代表了迄今为止发现的一些最小的系外行星。
We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent Hα emission—all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ± 0.05 M☉), radius (0.17 ± 0.04 R☉), and luminosity (2.40 × 10−3.0 ± 0.3 L☉). We calculate KOI 961's distance (38.7 ± 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R⊕, with KOI 961.03 being Mars-sized (RP = 0.57 ± 0.18 R⊕), and they represent some of the smallest exoplanets detected to date.