A NEW SAMPLE OF COOL SUBDWARFS FROM SDSS: PROPERTIES AND KINEMATICS
A NEW SAMPLE OF COOL SUBDWARFS FROM SDSS: PROPERTIES AND KINEMATICS
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DOI：
10.1088/0004-637x/794/2/145
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
A. Savcheva;A. West;J. Bochanski
中科院分区：
文献类型：
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作者：
A. Savcheva;A. West;J. Bochanski
我们给出了一个新的M亚矮星样本，它是从斯隆数字巡天第七次数据发布中汇编而来的。有了3517颗新的亚矮星，这个新的样本大大增加了光谱确认的低质量亚矮星的数量。该星表还包括905颗极矮星和534颗超矮星。我们介绍了整个星表，包括观察量和导出量，以及由共同添加的亚矮星光谱创建的模板光谱。我们给出了三个金属丰度类的颜色-颜色图和约化自行图，表明它们是从盘矮星群中分离出来的。极端矮星和超亚矮星的自身运动减弱的值更大，这是对更多动态升温的种群的预期。我们用自然运动来确定所有恒星的3D运动学。颜色-震级图显示出三个金属丰度等级的明显分离，超矮星和极端亚矮星比普通亚矮星更接近主序。所有的亚矮星都位于主星序的下方(较暗)和左侧(较蓝)。根据平均(U、V、W)速度及其色散，极端和超矮星可能属于银河晕，而普通亚矮星可能是古老的银河系(或厚)盘的一部分。利用Hα发射对亚矮星的活动进行了广泛的分析，发现了2 0 8个活跃的亚矮星。我们发现，虽然亚矮星的活度分数随着光谱级别的增加而增加，但与M矮星的行为一致，亚矮星的活度分数在最新的光谱级别上保持不变，而极端和超矮星基本上是平坦的。
We present a new sample of M subdwarfs compiled from the seventh data release of the Sloan Digital Sky Survey. With 3517 new subdwarfs, this new sample significantly increases the number of spectroscopically confirmed low-mass subdwarfs. This catalog also includes 905 extreme and 534 ultra sudwarfs. We present the entire catalog, including observed and derived quantities, and template spectra created from co-added subdwarf spectra. We show color–color and reduced proper motion diagrams of the three metallicity classes, which are shown to separate from the disk dwarf population. The extreme and ultra subdwarfs are seen at larger values of reduced proper motion, as expected for more dynamically heated populations. We determine 3D kinematics for all of the stars with proper motions. The color–magnitude diagrams show a clear separation of the three metallicity classes with the ultra and extreme subdwarfs being significantly closer to the main sequence than the ordinary subdwarfs. All subdwarfs lie below (fainter) and to the left (bluer) of the main sequence. Based on the average (U, V, W) velocities and their dispersions, the extreme and ultra subdwarfs likely belong to the Galactic halo, while the ordinary subdwarfs are likely part of the old Galactic (or thick) disk. An extensive activity analysis of subdwarfs is performed using Hα emission, and 208 active subdwarfs are found. We show that while the activity fraction of subdwarfs rises with spectral class and levels off at the latest spectral classes, consistent with the behavior of M dwarfs, the extreme and ultra subdwarfs are basically flat.