Discovery and Photometry of Low Metallicity and Horizontal Branch Stars in the Galactic Halo

比尔斯博士将完成对我们银河系南北半球的客观棱镜调查，然后跟踪选定的金属丰度极低的恒星和处于进化轨道水平分支的恒星。候选者的最终数据库应该包括大约16000颗铁含量相对较低的恒星，大约25000颗水平分支星将被确定。我们银河系的光晕包含了整个银河系中不到1%的发光恒星。然而，光晕对于揭示恒星演化的关键问题、星系形成和演化的过程，以及限制整个星系中物质的分布，都是至关重要的。要了解光晕，首先必须找到它并描述它的特征。理想情况下，完整的光晕中大约10亿颗发光恒星的光谱和光度信息将使观测者能够绘制出一幅不受采样偏差影响的光晕图。如果做不到这一点，人们只能尽量减少为使问题易于处理而必须强加的任何选择标准的影响。从最广泛的意义上说，比尔斯博士调查的目的是发现一些物体，最终使我们对银河系的光晕有一个更全面的了解。

Dr. Beers will complete an objective prism survey of the northern and southern hemispheres of our Galaxy and then follow up on selected stars which have extremely low metal abundances and stars on the horizontal branch of their evolutionary track. The final database of candidates should include about 16,000 stars with relatively low abundances of iron, and about 25,000 horizontal branch stars will be identified. The halo of our Galaxy contains less than 1 percent of the luminous stars in the entire Galaxy. Yet the halo is fundamental for revealing crucial issues of stellar evolution, the processes of galaxy formation and evolution, and for constraining the distribution of matter throughout the Galaxy. To understand the halo, one must first find it and characterize it. Ideally, complete spectroscopic and photometric information for the approximately one billion luminous stars which populate the halo would allow the observer to draw a picture of the halo which is untainted by sampling bias. Short of this, one can only attempt to minimize the effects of any selection criteria which must be imposed to make the problem tractable. In its broadest sense, the purpose of Dr. Beers' survey is to discover the objects which will, eventually, allow for a much more complete understanding of the halo of our Galaxy.