Molecular Gas in the Centers of Galaxies

摘要AST94-17968特纳，让星际气体为恒星形成、发光恒星爆发和活动星系核提供燃料，这些现象在星系核中最为明显。射电和毫米波发射线观测可以研究星系中气体的分布和动力学。在这个项目中，将对附近星系中的一氧化碳(CO)进行毫米干涉观测。星系核附近的高分辨率测量可以在接近单个分子云(20秒)的分辨率下绘制分子气体图。从这样的映射图像中，人们可以确定分子气体的质量，分子云的轨道，以及根据轨道，质量在中心区域的分布情况。例如，之前的工作已经表明，对于许多在CO中绘制的星系来说，内部几百秒内的总质量的一半以上是分子气体。通过多跃迁CO观测，人们可以推断云的属性，如温度和密度，并研究这些属性如何随银河系中的位置变化。最后，在CO和氢原子21厘米线上绘制星系盘的大尺度结构图，可以检查核气体和盘气体之间的联系。

ABSTRACT AST 94-17968 Turner, Jean Interstellar gas provides the fuel for star formation, luminous star bursts, and active galactic nuclei, phenomena which are most apparent in galactic nuclei. Radio and millimeter wave emission line observations permit study of the distribution and dynamics of gas in galaxies. For this project, millimeter interferometric observations will be made of carbon monoxide (CO) in nearby galaxies. High resolution measurements near a galactic nucleus allow mapping the molecular gas at close to the resolution of individual molecular clouds ( 20 parsecs). From such mapped images, one can determine the mass of molecular gas, the orbits of molecular clouds, and from the orbits, how mass is distributed in the central regions. Previous work has shown, for example, that for many galaxies mapped in CO, more than half of the total mass within the inner few hundred parsecs is molecular gas. With multi-transition CO observations, one can infer cloud properties such as temperature and density and study how these properties vary with location in the galaxy. Finally, mapping the large-scale structure of the galactic disk in both CO and in the atomic hydrogen 21 cm line permits examination of the linkage between nuclear gas and disk gas.