New Light on Galactic Astronomy Based on the Hipparcos Catalog

伊帕考斯任务是第一次致力于天体测量的空间实验，并于1980年被欧空局科学计划接受。这次飞行任务的主要目标是确定大约120000颗恒星的精确天体测量数据--位置、年自行和绝对三角视差，单位为1毫角秒。Hipparcos星表是对卫星获取的数据进行观测和整理的初步结果，对位置天文学、恒星演化、银河系天文学和宇宙学等各个研究领域都产生了巨大的影响。在该星表的整个样本中，对天琴座RR变星和缺乏金属的红巨星的天体测量观测一直是分配给我们研究小组的Hipparcos计划的一部分。分析星表发布前到达我们的这些恒星的数据，我们发现：(1)根据天琴座RR变星…的绝对星等校准的旧球状星团的年龄更多的证据表明，宇宙学参数的范围受到了严格的限制，以及(2)从晕到盘的形成，正如贫金属星的运动学所探测的那样，涉及到持续数十亿年的缓慢坍塌。我们还收集了许多贫金属星的光谱和光度信息，目的是在宇宙学背景下研究银河系的早期动力学演化。这主要是因为近年来，公认的金属丰度明显低于太阳的恒星数量大幅增加。关于它们的详细丰度、速度和本身运动的信息的质量和数量也是如此。利用新确定的(和/或改进的)1000多颗这样的恒星的自行，基于伊巴谷任务的结果和各种星表，包括南方自行星表，北方自行星表，天体星表，以及在STSCI获得的数字天空观测，我们已经得出了银河系厚盘和晕组分的运动学综合图。我们还发现，与大小相似但运动学上有偏差的贫金属星样本相比，我们的非运动学选择样本的观测性质也有一些有趣的差异。较少

The Hipparcos mission was the first space experiment dedicated to astrometry, and was accepted within the ESA scientific program in 1980. The primary objective of the mission was the determination of accurate astrometric data - positions, annual proper motions and absolute trigonometric parallaxes, at levels of I milliarcsec - for about 120000 stars. The Hipparcos Catalogue, the primary result of the observations and reduction of the satellite-acquired data, has provided great impacts on various research fields that include positional astronomy, stellar evolution, galactic astronomy, and cosmology.Among the whole sample in the catalogue, the astrometric observations of RR Lyrae variables and metal-deficient red giants have been parts of the Hipparcos program assigned to our research group. Analyzing the data of these stars which arrived us prior to the release of the catalogue, we have found that (1) ages of old globular clusters, calibrated from the absolute magnitudes of RR Lyrae var … More iables, put severe limits on the range of cosmological parameters, and that (2) the formation of the Galaxy from the halo to disk components, as probed by kinematics of metal-poor stars, involved the slow collapse lasting several billion years.We have also conducted the assembly of spectroscopic and photometric information for numerous metal-poor stars, for the purpose of studying early dynamical evolution of the Galaxy in the cosmological context. This is mainly because in recent years, the numbers of recognized stars with metal abundances significantly less than solar has grown enormously. So too has the quality and quantity of information available concerning their detailed abundances, velocities, and proper motions. Using newly determined (and/or refined) proper motions for over 1000 of these stars, based on results from the Hipparcos mission and various catalogs including the Southern Proper Motion catalog, the Northern Proper Motion catalog, the Astrographic Catalog, and the Digital Sky Survey obtained at STScI, we have arrived at the comprehensive view of the kinematics of the thick disk and halo components of the Galaxy. A number of interesting differences were also found between the observed properties of our non-kinematically selected sample, as compared with similar-sized, but kinematically biased samples of metal-poor stars. Less