Imaging the Outskirts of Nearby Disk Galaxies

星系最初是如何形成的，以及它们在一生中是如何变化的，这是天体物理学中最不被理解的问题之一。许多项目都集中在解开这些谜团上。该项目依赖于星系盘的外围，以提供关于其宿主星系动态演化的线索。在银河系外围，保存了过去的吸积和演化过程的动力学特征，如径向迁移、吸积、恒星形成阈值和低水平原位恒星形成。首席研究员计划在4-10Mpc范围内获得附近盘状星系的深部、广域图像，以研究其外盘的结构、恒星群和恒星形成特性。研究人员在深度、非常低的表面亮度测量方面的经验与独特的望远镜/探测器仪器相结合，非常适合这一项目。主要的科学动机是(1)确定扩展星系盘的结构，(2)确定恒星形成在多大程度上促进了外盘的增长，(3)确定吸积如何塑造附近的星系，以及(4)确定表面光度测量和离散恒星计数在探测星系外围的能力方面的比较。在教育方面，这个项目将为初学者提供机会获得实际的研究天文台经验--作为观察者和仪器工作者。这样的培训对学生和需要受过技术培训的科学家的天文学社区来说至关重要。这位首席研究员将继续他在天文馆展览和公共宣传网站上提供成像和模拟的出色历史，他将在当地天文俱乐部和克利夫兰自然历史博物馆发表公开演讲。

Precisely how galaxies initially form and how they change throughout their lifetime are among the least understood problems in astrophysics. Many projects are centered on unraveling these mysteries. This project relies on the outskirts of galaxy disks to provide clues about the dynamical evolution of their host galaxy. In galaxy outskirts are preserved the dynamical signatures of past accretions and evolutionary processes such as radial migration, accretion, star formation thresholds, and low level in situ star formation. The principal investigator plans to obtain deep, wide-field images of nearby disk galaxies within 4--10 Mpc to study the structure, stellar populations, and star forming properties of their outer disks. The combination of the investigators' experience with deep, very low surface brightness measurements and the unique telescope/detector instrumentation are ideally suited toward this project. The primary scientific motivations are (1) to determine the structure of extended galaxy disks, (2) to determine how much star formation has contributed to the growth of outer disks, (3) to determine how accretion shaped nearby galaxies, and (4) to determine how surface photometry and discrete star counts compare in their ability to probe the outskirts of galaxies.Educationally, this project will provide opportunities for beginning students to get hands-on research observatory experience---as an observer and as an instrumentalist. Such training is critical for students and for an astronomical community that needs technically-trained scientists. The principal investigator will continue his excellent history of providing his imaging and simulations to planetarium shows and to public outreach web sites, and he will give public talks at local astronomy clubs and the Cleveland Museum of Natural History.