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。罗曼诺夫斯基和他的团队将测量椭圆星系外围区域恒星的运动。一个欧洲合作组织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。罗曼诺夫斯基博士将在10米的凯克望远镜上使用宽视场多缝光谱仪，它在宽视场上提供高效率，将测量半径扩大约5倍，以更好地限制星系的组装历史。这些测量将与该望远镜已经计划好的球状星团观测一起进行。研究小组将从钙的近红外吸收特征中获得恒星中的化学丰度和它们的运动。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非常不同，而星系的大部分质量和角动量都位于外部区域。一种不依赖于任何假定的星系对称性的数值技术将被用来发现引力场和恒星轨道的什么组合可能会引起观察到的运动。一个早期的科学家将被培养成博士后学者。该团队将与科学伙伴（一个K-12科学项目的在线资源）合作，为该网站制作星系外天文学活动。在该网站的注册用户中，38%是女孩；8%的人认为自己是非裔美国人，11%的人认为自己是拉丁美洲人（38%的人选择了“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).