Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
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DOI：
10.1017/s1743921310000724
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
D. Carollo;T. Beers;M. Chiba;J. Norris;K. Freeman;Y. S. Lee
中科院分区：
文献类型：
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作者：
D. Carollo;T. Beers;M. Chiba;J. Norris;K. Freeman;Y. S. Lee
翻译后摘要的结构和运动学的公认的恒星组成部分的银河系进行了探讨，根据确定的大气参数和运动学量的32360“校准星”从斯隆数字巡天（SDSS）和它的第一个扩展，（SDSS-II），其中包括子调查SEGUE：斯隆扩展银河系的理解和探索。全空间运动的子样本16920颗恒星，探索太阳4千秒差距内的局部体积，用于推导速度椭球的内晕和外晕组成部分的银河系，以及典型的厚盘和建议的金属弱厚盘人口。这个新的校准星样本比以前分析中使用的数量增加了60%。一个最大的16920校准星的本地子样本的Likestival分析已经开发，以提取银河系的主要组成部分（厚盘，内晕，外晕），以及难以捉摸的金属弱厚盘（MWTD）的运动学信息。我们测量的厚盘，MWTD，内晕，外晕的速度椭球，表明MWTD可能是一个组件，是运动学和化学独立的典型厚盘（并限制金属丰度范围的MWTD），并推导出推断的空间密度分布的内/外晕组件。我们还提出了证据倾斜的速度椭球的恒星在我们的样本作为一个函数的高度以上的平面，在金属丰度的几个范围，并确认所观察到的金属丰度分布函数（ESTA）从内晕到外晕为主的样本的移位。
Abstract The structure and kinematics of the recognized stellar components of the Milky Way are explored, based on well-determined atmospheric parameters and kinematic quantities for 32360 “calibration stars” from the Sloan Digital Sky Survey (SDSS) and its first extension, (SDSS-II), which included the sub-survey SEGUE: Sloan Extension for Galactic Understanding and Exploration. Full space motions for a sub-sample of 16920 stars, exploring a local volume within 4 kpc of the Sun, are used to derive velocity ellipsoids for the inner- and outer-halo components of the Galaxy, as well as for the canonical thick-disk and proposed metal-weak thick-disk populations. This new sample of calibration stars represents an increase of 60% relative to the numbers used in a previous analysis. A Maximum Likelihood analysis of a local sub-sample of 16920 calibration stars has been developed in order to extract kinematic information for the major Galactic components (thick disk, inner halo, and outer halo), as well as for the elusive metal-weak thick disk (MWTD). We measure velocity ellipsoids for the thick disk, the MWTD, the inner halo, and the outer halo, demonstrate that the MWTD may be a component that is kinematically and chemically independent of the canonical thick disk (and put limits on the metallicity range of the MWTD), and derive the inferred spatial density profiles of the inner/outer halo components. We also present evidence for tilts in the velocity ellipsoids for stars in our sample as a function of height above the plane, for several ranges in metallicity, and confirm the shift of the observed metallicity distribution function (MDF) from the inner-halo to the outer-halo dominated sample.