Galactic HI in Directions of Low Total Column Density
Galactic HI in Directions of Low Total Column Density
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低总柱密度方向的银河 HI
DOI：
10.1086/164002
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
D. McCammon
中科院分区：
文献类型：
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作者：
F. J. Lockman;K. Jahoda;D. McCammon
对北方天空中已知 HI 量最小的区域进行了详细的 21 厘米研究。这些观察结果已针对杂散辐射进行了校正。主要感兴趣的区域，大约 alpha = 10(h)45(m)，delta = 57 deg 20'，最小 N(HI) 为 4.5 x 10 的 19 次方/平方厘米。在此方向上以 21' 分辨率在 4 x 3 度视场上拍摄的光谱显示最多四个 HI 线分量。其中两个，接近 0 公里/秒和 -50 公里/秒，是普遍存在的。在 -10 km/s 处也有一个狭窄的分量，这归因于覆盖了一半场的弥漫云，以及在 v -100 km/s 处的分散的 HI 斑块。低速和中速分量具有较宽的线宽，并且在整个区域中分布非常平滑，因此它们不太可能包含显着的未解析的角结构。还观察到其他八个低柱密度方向。它们的光谱通常具有多个分量，但总柱密度始终为 7 x 10 的 19 次方/平方厘米，并沿 2 度条带平滑变化。一半的方向显示出由弱漫射 HI 云产生的窄线，其中包含 0.5 至 3.0 更多» x 10 的 19 次方/平方厘米。 “ 较少的
A detailed 21 cm study of areas of that have the smallest known amount of HI in the northern sky was performed. These observations were corrected for stray radiation. The region of main interest, around alpha = 10(h)45(m), delta = 57 deg 20', has a minimium N(HI) of 4.5 x 10 to the 19th power/sq cm. Spectra taken at 21' resolution over a field 4 x 3 deg in this direction show up to four HI line components. Two, near 0 and -50 km/s, are ubiquitous. There is also a narrow component at -10 km/s attributable to a diffuse cloud covering half of the field, and scattered patches of HI at v -100 km/s. the low and intermediate velocity components have a broad line width and are so smoothly distributed across the region that it is unlikely that they contain significant unresolved angular structure. Eight other low column density directions were also observed. Their spectra typically have several components, but the total column density is always 7 x 10 to the 19th power/sq cm and changes smoothly along a 2 deg strip. Half of the directions show narrow lines arising from weak diffuse HI clouds that contain 0.5 to 3.0 more » x 10 to the 19th power/sq cm. « less