M矮星II的CARMENES输入目录。使用FastCam进行高分辨率成像
CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCam
摘要：
目的：我们寻找M矮星的低质量同伴，并描述其多重性分数的目的是帮助选择最合适的CARMENES系外行星调查的目标。研究方法：我们在1.5米的卡洛斯桑切斯望远镜上用幸运的成像仪器FastCam获得了490颗M中晚期矮星的I波段高分辨率图像。对于所有检测到的二进制，我们测量的角度分离，位置角，和在I波段的星等差异。我们还计算了每一个单独的组件和估计轨道周期的质量，使用现有的震级和颜色关系的M矮星和我们自己的MJ光谱类型和质量MI的关系。为了避免样本选择中的偏差，我们构建了一个体积有限的M0.0-M5.0侏儒样本，在14 pc内完成了86%。结果：在观测的490颗恒星中，我们在76个星系中发现了80颗伴星，其中30颗是新发现的。我们观察到的样品中的多重性分数为16.7 ± 2.0%。在我们有限体积的样品中，角距为0.2 - 5.0角秒（1.4-65.6天文单位）时，它为19.5 ± 2.3%。对于M0.0-M3.5 V初级，我们的搜索对高于0.3的质量比敏感。预计物理距离小于50天文单位的双星往往质量相等。对于我们的26个系统，我们估计的轨道周期短于50年，其中10个是第一次在这里。我们测量了角间距和位置角的变化，这是由于在这些系统中的17个轨道运动。角间距小于0.2弧秒，大于5.0弧秒的双星和多星的贡献，以及从以前的搜索中确定的光谱双星，虽然不完整，但可能会增加我们的体积有限的样本中M矮星的多重性分数至少36%。
英文摘要：
Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images in the I band with the lucky imaging instrument FastCam at the 1.5 m Telescopio Carlos Sanchez for 490 mid- to late-M dwarfs. For all the detected binaries, we measured angular separations, position angles, and magnitude differences in the I band. We also calculated the masses of each individual component and estimated orbital periods, using the available magnitude and colour relations for M dwarfs and our own MJ-spectral type and mass-MI relations. To avoid biases in our sample selection, we built a volume-limited sample of M0.0-M5.0 dwarfs that is complete up to 86% within 14 pc. Results: From the 490 observed stars, we detected 80 companions in 76 systems, of which 30 are new discoveries. The multiplicity fraction in our observed sample is 16.7+-2.0% . In our volume-limited sample it is 19.5+-2.3% for angular separations of 0.2 to 5.0 arcsec (1.4-65.6 au), The distribution of the projected physical separations peaks at 2.5-7.5 au. For M0.0-M3.5 V primaries, our search is sensitive to mass ratios higher than 0.3. Binaries with projected physical separations shorter than 50 au tend to be of equal mass. For 26 of our systems, we estimated orbital periods shorter than 50 a, 10 of which are presented here for the first time. We measured variations in angular separation and position angle that are due to orbital motions in 17 of these systems. The contribution of binaries and multiples with angular separations shorter than 0.2 arcsec, longer than 5.0 arcsec, and of spectroscopic binaries identified from previous searches, although not complete, may increase the multiplicity fraction of M dwarfs in our volume-limited sample to at least 36%.
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