We construct high signal-to-noise "template" spectra by co-adding hundreds of spectra of nearby dwarfs spanning K7 to M4, taken with Keck/HIRES as part of the California Planet Search. We identify several spectral regions in the visible (370 - 800 nm) that are sensitive to the stellar luminosity and metallicity. We use these regions to develop a spectral calibration method to measure the mass, metallicity, and distance of low-mass stars, without the requirement of geometric parallaxes. Testing our method on a sample of nearby M dwarfs we show that we can reproduce stellar masses to about 8 - 10%, metallicity to ~0.15 dex and distance to 11%. We were able to make use of HIRES spectra obtained as part of the radial velocity monitoring of the star KOI-314 to derive a new mass estimate of 0.57 +/- 0.05 Msun, a radius of 0.54 +/- 0.05 Rsun, a metallicity, [Fe/H], of -0.28 +/- 0.10 and a distance of 66.5 +/- 7.3 pc. Using HARPS archival data and combining our spectral method with constraints from transit observations, we are also able to derive the stellar properties of GJ3470, a transiting planet hosting M dwarf. We estimate a mass of 0.53 +/- 0.05 Msun, a radius of 0.50 +/- 0.05 Rsun, a metallicity, [Fe/H] = 0.12 +/- 0.12 and a distance of 29.9_{-3.4}^{+3.7} pc.
Characterizing the Cool Kepler Objects of Interest. New Effective Temperatures, Metallicities, Masses and Radii of Low-Mass Kepler Planet-Candidate Host Stars
Keck Observations in the INfrared of Taurus and $ρ$ Oph Exoplanets And Ultracool dwarfs (KOINTREAU) I: A Planetary-Mass Companion and a Disk-Obscured Stellar Companion Discovered in Taurus
Understanding magnetic activity on the surface of stars other than the Sun is important for exoplanet analyses to properly characterize an exoplanet's atmosphere and to further characterize stellar activity on a wide range of stars. Modeling stellar surface features of a variety of spectral types and rotation rates are key to understanding of the magnetic activity of these stars. Using data from Kepler, we use the starspot modeling program STarSPot (STSP) to measure the position and size of spots for KOI-340 which is an eclipsing binary consisting of a subgiant star ($\rm T_{\rm eff} = 5593 \p…
Detection of Stars within $\sim$0.8 arcseconds of Kepler Objects of Interest
我们提出了一个算法，以寻找第二个恒星的光谱与高分辨率光谱中的一个更明亮的恒星的光谱混合的微弱的光谱。我们的模型光学恒星光谱的两个输入光谱的总和，从一个巨大的图书馆的恒星在整个H-R图。从分辨率为R= 60，000的典型光谱中，我们能够在测光的V和R带通中探测到相对于主星微弱1%的伴星。我们也能够找到三重和四重系统的证据，因为任何额外的同伴都足够明亮。精确的阈值百分比取决于光谱的SNR和两颗星的属性。对于未检测到的情况，我们对任何潜在同伴的亮度进行限制。这种算法对于探测微弱的轨道伴星和角度上接近前景目标星的背景星都是有用的。光谱仪的入口狭缝的大小，0.87 x 3 arcsec（通常），设定了第二颗恒星可以被探测到的角域。我们分析了1160个加利福尼亚开普勒巡天感兴趣的天体（KOI）的光谱，以寻找次级光谱，这两个目标是提醒社区注意过境行星的两个可能的宿主恒星和光变曲线的稀释。我们报告了63个加州开普勒巡天感兴趣的天体，它们显示了二级恒星的光谱证据。
High-resolution spectroscopic surveys of the Milky Way have entered the Big Data regime and have opened avenues for solving outstanding questions in Galactic archaeology. However, exploiting their full potential is limited by complex systematics, whose characterization has not received much attention in modern spectroscopic analyses. In this work, we present a novel method to disentangle the component of spectral data space intrinsic to the stars from that due to systematics. Using functional principal component analysis on a sample of $18,933$ giant spectra from APOGEE, we find that the intri…
