Molecular Gas in the Centers of Galaxies

摘要 AST 94-17968 Turner，Jean 星际气体为星星的形成、发光的星星爆发和活动星系核提供了燃料，这些现象在星系核中最为明显。无线电和毫米波发射线观测允许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进行毫米干涉观测。星系核附近的高分辨率测量允许绘制分子气体， 单个分子云的分辨率（20秒差距）。 从这些映射的图像中，人们可以确定分子气体的质量，分子云的轨道，以及从轨道中，质量如何分布在中心区域。例如，以前的工作表明，对于许多以CO为标测的星系，在内部几百秒差距内，总质量的一半以上是分子气体。 通过多跃迁CO观测，人们可以推断云的性质，如温度和密度，并研究这些性质如何随星系中的位置而变化。最后，映射的大尺度结构的银盘在CO和氢原子21厘米线允许检查核气体和磁盘气体之间的联系。

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.