论文标题
Nobeyama 45 m望远镜（Fugin）的森林无偏银河层面成像调查。 vii。 HI云的分子分数
FOREST unbiased Galactic plane imaging survey with the Nobeyama 45 m telescope (FUGIN). VII. molecular fraction of HI clouds
论文作者
论文摘要
在这项研究中，我们使用从四光束接收器系统获得的最新CO数据在中性原子氢（HI）云中分析了分子气体的形成，该数据在45米的望远镜（森林）无偏的银河平面成像调查上使用Nobeyama 45-m TeleScope（Fugin）和HI数据从非常大的驱动器（VLA）（VGLA）galactic（VGC）（VGC）（VGC）（VGC）（VGC）（VGC）（VGC）（VG）（VGC）（vg callactic）（vg actactic）（vg actactic）（VGC）（vg actactic）（vg calactic）（vg calactic）（vg actactic calactic（vg actactic）（vg calactic）（vg actactic）。我们将树状图算法应用于HI Data Cube以识别HI云，并通过将每个HI云中的CO线强度求和来计算HI质量和分子气体质量。基于结果，我们创建了一个5,737个目录，确定了HI云，其局部静止标准（LSR）的速度为$ v _ {\ rm lsr} \ le -20 $ 20 $ 20 $ km S $^{ - 1} $在银河系的经度和latiential range cipcy $ 20^\ le l \ le 50^l \ le 50^\ le 50^\ le 50^ / \ le 1^\ circ $。我们发现，大多数HI云都分布在16 kpc的半乳酸距离内，其中大多数位于冷中性培养基（CNM）相。此外，我们确定质量HI函数的高质量端与索引为2.3的幂律函数非常适合。尽管有两个序列的自我散热和扩散云将出现在M $ _ {\ rm tot} $ - m $ _ {{{\ rm h} _2} $图中，根据以前的工作，基于平面模型，观察数据仅显示了在这两个序列中具有较大散射的单个序列。这意味着大多数云是这两种类型的云的混合物。此外，我们建议以下分子气体形成的情况：沿着$ m _ {{\ rm h} _2} \ propto m _ {\ rm tot}^2 $沿着差异和移动两次序列的curves curves的差异，沿$ m _ {{\ rm h} _2} \ propto m _ {{\ rm h} _2} \ propto m _ {{\ rm h} _2} \ propto a {{\ rm h} _2} \ propto a {{\ rm h} _2} \ propto a的路径的进化而言：高级云的情况下。
In this study, we analyze molecular gas formation in neutral atomic hydrogen (HI) clouds using the latest CO data obtained from the four-beam receiver system on a 45-m telescope (FOREST) unbiased Galactic plane imaging survey with the Nobeyama 45-m telescope (FUGIN) and HI data taken from the Very Large Array (VLA) Galactic plane survey (VGPS). We applied a dendrogram algorithm to the HI data cube to identify HI clouds, and we calculated the HI mass and molecular gas mass by summing the CO line intensity within each HI cloud. On the basis of the results, we created a catalog of 5,737 identified HI clouds with local standard of rest (LSR) velocity of $V_{\rm LSR}\le -20$ km s$^{-1}$ in Galactic longitude and latitude ranges of $20^\circ \le l \le 50^\circ$ and $-1^\circ \le b \le 1^\circ$, respectively. We found that most of the HI clouds are distributed within a Galactocentric distance of 16 kpc, most of which are in the Cold Neutral Medium (CNM) phase. In addition, we determined that the high-mass end of the mass HI function is well fitted with the power-law function with an index of 2.3. Although two sequences of self-gravitating and diffuse clouds are expected to appear in the M$_{\rm tot}$-M$_{{\rm H}_2}$ diagram according to previous works based on a plane-parallel model, the observational data show only a single sequence with large scattering within these two sequences. This implies that most of the clouds are mixtures of these two types of clouds. Moreover, we suggest the following scenario of molecular gas formation: An HI-dominant cloud evolved with increasing H$_2$ mass along a path of $M_{{\rm H}_2} \propto M_{\rm tot}^2$ by collecting diffuse gas before reaching and moving along the curves of the two sequences.
