Probing the fundamental halo properties of early-type galaxies using a new technique for wide-field stellar kinematics

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。Romanowsky博士和他的团队将测量椭圆星系外部区域的恒星运动。 欧洲的一个合作项目已经探测了这些星系的中心区域，发现了大量的内部结构，这些结构无疑是形成历史的遗迹。 Romanowsky博士将在10米凯克望远镜上使用宽视场多狭缝光谱仪，该望远镜在宽视场范围内提供高效率，将这些测量范围扩大约5倍，以更好地限制星系的组装历史。 这些测量将与已经计划用这个望远镜设置的球状星星集群的观测相结合。 研究小组将从钙的近红外吸收特征中获得恒星的化学丰度及其运动。 对5个星系的初步研究已经表明，内部区域的运动和结构可能与外部区域的运动和结构非常不同，大部分星系的质量和角动量都存在于外部区域。 一种不依赖于任何假设的星系对称性的数值技术将被用来找出引力场和恒星轨道的什么组合可以引起观察到的运动。一个早期职业科学家将被培养为博士后学者。 该小组将与K-12科学项目的在线资源Science Buddies开展合作，为网站制作河外天文学活动。 在该网站的注册用户中，38%是女孩; 8%的人认为自己是非洲裔美国人，11%是拉丁裔美国人（38%的人选择“其他”或拒绝回答）。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr. Romanowsky and his team will measure the motion of stars in the outer regions of elliptical galaxies. A European collaboration has already probed the central regions of such galaxies, finding an abundance of internal structures that are undoubtedly relics of the formation history. Dr Romanowsky will use a wide field multi-slit spectrograph on the 10-meter Keck telescope, which provides high efficiency over a wide field of view, to extend those measurements approximately 5 times further out in radius, to provide better constraints on the assembly history of the galaxy. These measurements will piggyback with observations of globular star clusters already planned with this telescope setup. The team will obtain both the chemical abundances in the stars and their motions from a near-infrared absorption feature of calcium. A pilot study of 5 galaxies has already shown that the motions and structure of the inner regions can be very different from those in the outer parts, where most of the galaxy's mass and angular momentum reside. A numerical technique that does not depend on any assumed symmetry properties of the galaxy will be used to find what combinations of the gravitational field and stellar orbits could give rise to the observed motions.An early-career scientist will be trained as a postdoctoral scholar. The team will develop their collaboration with Science Buddies, an online resource for K-12 science projects, to produce activities in extragalactic astronomy for the website. Among registered users of the site, 38% are girls; 8% identify themselves as African-American and 11% as Latino-American (38% chose 'other' or declined to respond).