Old Stellar Populations and Cosmology

星系中的古老恒星群将被研究并用作宇宙学探测器。从逻辑上讲，这项工作分为两个领域：研究古老的恒星群体和综合光谱本身，以及使用古老的恒星群体，特别是椭圆(E)和球状(SO)星系，作为宇宙局部哈勃膨胀中不规则性的追踪器。在后一项工作中，将扩大一个使用E星系的项目，该项目已经证明了在600-700公里S-1相对于我们周围的一个大星系球的宇宙静止框架到半径6000公里S-1处有大量运动。星系的这种运动可能会对宇宙学理论提供强大的约束，需要以各种可能的方式进行测试和探索。为此，将对N体宇宙模型进行全面分析，以此作为阐明这类哈勃流动研究中潜在陷阱的一种手段。对附近星系运动的全新和独立的估计将得到与ES星系相比较的结果。在旧恒星群区域，将继续开展一个项目，以确定E星系和球状星团中的金属度和元素丰度比。将完成G矮星和K巨星的吸收线特征与温度、丰度和表面重力之间的经验校准。这些结果将与理论合成光谱进行比较，当对恒星光谱有了令人满意的理解时，就会合成星系的综合光谱。还将分析椭圆星系的长缝光谱的径向丰度梯度，并将使用新的、高质量、高分辨率的恒星光谱来探索球状星团恒星之间的微小组成差异。

Old stellar populations in galaxies will be studied and used as cosmological probes. The work falls logically into two areas: the study of old stellar populations and integrated spectra per se and the use of old stellar populations, specifically elliptical (E) and spherical (SO) galaxies, as tracers of irregularities in the local Hubble expansion of the universe. In the latter work, a project using E galaxies that has given evidence of a bulk motion at 600-700 km s-1 with respect to the cosmic restframe of a large sphere of galaxies around us out to 6000 km s-1 in radius will be expanded. This motion of the galaxies could provide a powerful constraint on cosmological theories and needs to be tested and probed in every possible way. To this end, a comprehensive analysis of N-body universe models as a means to illuminate potential pitfalls in Hubble flow studies of this type will be carried out. Completely new and independent estimates of the motions of nearby SO galaxies will be obtained to compare with those of Es. In the area of old stellar populations, a project will be continued to determine the metallicities and element abundance ratios in E galaxies and globular clusters. An empirical calibration of absorption-line features in G dwarf and K giant stars versus temperature, abundance, and surface gravity will be completed. These results will be compared to theoretical synthetic spectra, and, when a satisfactory understanding of stellar spectra is achieved, there will be a synthesizing of integrated spectra of galaxies. Long-slit spectra of elliptical galaxies will also be analyzed for radial abundance gradients, and new, high-quality, high-resolution stellar spectra will be used to explore small composition differences among globular cluster stars.