Molecular Clouds in the Galaxy
Molecular Clouds in the Galaxy
复制标题
银河系中的分子云
DOI：
10.1007/978-94-009-3925-7_5
复制
发表时间：
1975
期刊：
影响因子：
--
通讯作者：
A. R. Rivolo
中科院分区：
文献类型：
--
作者：
P. Solomon;A. R. Rivolo
在过去的十年中，对CO分子的毫米波观测已经被证明是银河系中分子氢和恒星形成区域的最重要的探测器。氢分子（H2）没有偶极矩或射电跃迁，除了在那些被冲击加热（温度> 1000 K）产生四极振转辐射的区域外，基本上是不可观测的。在紫外线的H2吸收线的观测必然局限于非常小的消光，因此小的H2柱密度的云。由于这些原因，关于物理学、运动学、银河系分布，甚至大质量恒星形成云的存在的信息必须来自次要成分的发射线，特别是但不限于CO及其同位素变体。
Millimeter-wave observations of the CO molecule have proved, over the past decade, to be the most important probe of molecular hydrogen and star-forming regions in the Galaxy. Molecular hydrogen, H2, has no dipole moment or radio transitions and is largely unobservable except in those regions that are shock heated (to temperatures > 1000K) to produce quadrupole vibrational-rotational emission. Observations of H2absorption lines in the ultraviolet are necessarily limited to clouds with very small extinction and thus small H2column densities. For these reasons, information on the physics, kinematics, Galactic distribution, and even the existence of massive star-forming clouds must come from emission lines of minor constituents, especially, but not exclusively, CO and its isotopic variants.