Collaborative Project: Deep Astrometry and Photometry of Key Open Clusters: A New Foundation for Stellar Astrophysics

这是一项对恒星疏散星团的多管齐下的合作研究。目标是为各种天体物理问题提供有用的线索和约束，例如：(1)初始质量函数的形状及其普遍性或缺乏性；(2)恒星核心对流超调程度；(3)银河系的金属丰度梯度。该项目还将为精心挑选的疏散星团样本建立一个高质量的天文测量、光度和光谱数据数据库。这笔拨款支持这项研究的天体测量部分。将获得8个关键疏散星团的位置信息、正常运动和星团成员的确定，至少比以前的调查暗淡6个视星等（~250倍），同时保持当前正常运动精度的限制（~0.005“/年）。合作小组将进行这项调查的光度测定部分。它将为星团成员提供UBVRI的视星等和色指数，在天文测量数据库中所有的恒星，以及这8个星团和另外6个星团中较暗的恒星的内部精度达到~1%。从这些数据中，一个“现在的质量函数”将被确定为一个大范围的星团年龄、丰富度、星系位置和金属丰度。

ABSTRACTAST-9819777Platais, ImantsThis is a multi-pronged collaborative investigation of stellar open clusters. The goal is to provide useful clues and constraints on a variety of astrophysical problems such as: (1) the shape of the Initial Mass Function and its universality or lack thereof; (2) the extent of convective overshoot in stellar cores; and (3) the metallicity gradient in the Galaxy. The project will also result in a database of high quality astrometric, photometric and spectroscopic data for a carefully chosen sample of open clusters. This grant supports the astrometry portion of this investigation. Positional information, proper motions and cluster membership determinations will be acquired for 8 key open clusters to at least 6 apparent magnitudes (~250x) fainter than previous surveys, while maintaining current limits of proper motion accuracy (~0.005 "/yr). The collaborating team will conduct the photometry portion of this investigation. It will yield UBVRI apparent magnitudes and color indices for cluster members to ~1% internal precision for all stars in the astrometric database, as well as fainter stars in these 8 clusters and 6 additional clusters. From this data, a 'present day mass function' will be determined for a wide range of cluster ages, richness, galactic position and metallicity.