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首页> 外文期刊>The Astrophysical journal >FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER OBSERVATIONS OF DIFFUSE INTERSTELLAR MOLECULAR HYDROGEN
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FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER OBSERVATIONS OF DIFFUSE INTERSTELLAR MOLECULAR HYDROGEN

机译：扩散星际分子氢的远紫外光谱探索者观察

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We describe a moderate-resolution Far Ultraviolet Spectroscopic Explorer (FUSE) minisurvey of H_2 in the Milky Way and Magellanic Clouds using four hot stars and four active galactic nuclei as background sources. FUSE spectra of nearly every stellar and extragalactic source exhibit numerous absorption lines from the H_2 Lyman and Werner bands between 912 and 1120 A. One extragalactic sight line (PKS 2155-304) with low N(H I) shows no detectable H_2 and could be the "Lockman Hole of molecular gas," of importance for QSO absorption-line studies. We measure H_2 column densities in low rotational states (J = 0 and 1) to derive rotational and/or kinetic temperatures of diffuse interstellar gas. The higher J abundances can constrain models of the UV radiation fields and gas densities. In three optically thick clouds toward extragalactic sources, we find n_H ≈ 30-50 cm~(-3) and cloud thicknesses ～2-3 pc. The rotational temperatures for H_2 at high Galactic latitude, < T_(01) > = 107 ± 17 K (seven sight lines) and 120 ± 13 K (three optically thick clouds), are higher than those in the Copernicus sample composed primarily of targets in the disk. We find no evidence for great differences in the abundance or state of excitation of H_2 between sight lines in the Galaxy and those in the SMC and LMC. In the future, we will probe the distribution and physical parameters of diffuse molecular gas in the disk and halo and in the lower metallicity environs of the LMC and SMC.
机译：我们描述了银河系和麦哲伦星系中H_2的中等分辨率远紫外光谱浏览器（FUSE）小型测量，其中使用了四个热星和四个活跃的银河核作为背景源。几乎每一个恒星和银河系外源的FUSE谱图都显示了912和1120 A之间的H_2莱曼和维尔纳谱带的大量吸收线。一条低N（HI）的银河外视线（PKS 2155-304）显示没有可检测到的H_2，可能是QSO吸收线研究的重要性“分子气体的洛克曼洞”。我们在低旋转状态（J = 0和1）下测量H_2列密度，以得出弥散星际气体的旋转和/或动力学温度。较高的J丰度可以约束UV辐射场和气体密度的模型。在三个朝向银河外的光学厚云中，我们发现n_H≈30-50 cm〜（-3），云厚约2-3 pc。 H_2在高银纬度 = 107±17 K（七个视线）和120±13 K（三个光学上的厚云）下的旋转温度高于哥白尼样品中主要由目标组成的样品在磁盘中。我们没有发现证据表明银河系视线与SMC和LMC视线之间的H_2的丰度或激发状态有很大差异。将来，我们将探讨LMC和SMC在磁盘和晕圈以及较低金属性环境中扩散分子气体的分布和物理参数。

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