Investigating the Stellar Populations of M33

AST 0307863 PI：Tammy Smecker-HaneInstitution：University of加州州，IrvineDr. Smecker-Hane和她的同事们将进行第一次重大活动，以确定M33的演化，M33是一个低质量的晚期螺旋星系。与本星系群中的巨大螺旋星系（银河系和M31）不同，M33没有星系隆起，只有一个薄的盘和一个厚的盘或扁平的晕。哈勃太空望远镜的图像显示，M33的大部分球状星团比银河系和M31的球状星团要年轻6 Gyr以上。由于冷暗物质等分级星系形成模型预测低质量星系的形成晚于大质量星系，因此对M33的研究将对星系演化和结构形成理论产生强有力的约束。这些研究人员将通过获得大约1000颗恒星的光谱，高精度地确定M33不同恒星群的空间范围、运动学和化学丰度。 Smecker-Hane和她的研究生将使用Kitt Peak国家天文台4米望远镜上的马赛克相机完成M33外盘/晕的成像调查，旨在将真正的M33红巨星与前景的银河系矮星分开。 他们将使用凯克II 10米望远镜获得M33红巨星的近红外光谱，从中得出化学丰度和径向速度。将确定M33的薄盘和厚盘/晕的相对质量，并对厚盘/晕形成的理论进行约束，例如，整体崩溃与卫星合并。金属丰度分布函数可以与色星等图相结合，以打破年龄和金属丰度的简并性，并独特而准确地推导出M33的恒星形成历史。在这个项目中，两名研究生将学习复杂的数据处理和分析技术，这些技术对拥挤场测光和多缝光谱学至关重要。 六名本科生将参加这项研究：三名UCI本科生和三名NSF REU暑期学生。研究生和本科生将参加由Smecker-Hane组织的众多教育推广项目。包括在UCI天文台为公众举办的游客之夜和为K-12学生的小团体举办的图尔斯之旅。每年夏天，Smecker-Hane和一名研究生将在UCI COSMOS项目中任教，这是一个为在数学和科学方面表现出色的高中生开设的暑期项目。COSMOS班级的男女学生人数相等，约30%的少数民族学生人数不足。

AST 0307863PI: Tammy Smecker-HaneINSTITUTION: University of California, IrvineDr. Smecker-Hane and her colleagues will undertake the first major campaign to determine the evolution of M33, a low-mass, late-type, spiral galaxy. Unlike the giant spirals in the Local Group (the Milky Way and M31), M33 has no galactic bulge, only a thin disk and either a thick disk or flattened halo. Hubble Space Telescope imaging has suggested the bulk of M33's globular clusters are significantly younger, by more than 6 Gyr, than globular clusters in the Milky Way and M31. Because hierarchical galaxy formation models, such as Cold Dark Matter, predict low mass galaxies form later than massive galaxies, studies of M33 will yield powerful constraints on galaxy evolution and structure formation theories.These researchers will determine, with high precision, the spatial extent, kinematics, and chemical abundances of the distinct stellar populations of M33 by obtaining spectra of approximately 1000 stars. Smecker-Hane and her graduate students will use the Mosaic Camera on the Kitt Peak National Observatory 4-meter Telescope to complete an imaging survey of the outer disk/halo of M33 designed to separate bona fide M33 red giants from foreground Galactic dwarfs. They will use the Keck II 10-meter Telescope to obtain near-infrared spectra of M33 red giants from which they will derive chemical abundances and radial velocities. The relative masses of the thin disk and thick disk/halo of M33 will be determined and constraints will be place on theories of thick disk/halo formation, e.g., monolithic collapse verses satellite mergers. The metallicity distribution functions can be combined with color-magnitude diagrams to break the degeneracy of age and metallicity and uniquely, and accurately, derive M33's star-formation history.During this project, two graduate students will learn sophisticated data reduction and analysis techniques that are critical to crowded-field photometry and multi-slit spectroscopy. Six undergraduate students will participate in this research: three UCI undergraduates and three NSF REU summer students. The graduate and undergraduate students will participate in numerous educational outreach projects organized by Smecker-Hane. including Visitor Nights at the UCI Observatory for the general public and tours for smaller groups of K-12 students. Each summer, Smecker-Hane and a graduate student will teach in the UCI COSMOS program, a summer program for high-school students who demonstrate excellence in math and science. COSMOS classes have equal numbers of male and female students, and approximately 30% are under represented minorities.***