H II区Sh2-104周围的二维分子气和正在进行的恒星形成
Two-Dimensional Molecular Gas and ongoing star formation around H II region Sh2-104
摘要：
我们对HII区Sh 2 -104进行了多波长研究。利用紫金山天文台13.7米射电望远镜获得了12 COJ =1-0和13 COJ =1-0的新图。Sh 2 -104为双环结构。半径为4.4pc的外环以12 μ m、500 μ m、12 COJ =1-0和13 COJ =1-0发射为主，而半径为2.9pc的内环以22 μ m和21 cm发射为主。我们没有检测到CO排放外环内。外环的东北部分是蓝移的，而西南部分是红移的。目前的观测结果提供了证据，围绕Sh 2 -104收集的外环是一个二维结构。从由Hi-GAL调查数据构建的柱密度图中，我们提取了21个团块。大约90%的团块将形成低质量恒星。用幂律拟合这些团块，得到M= 281 Msun（r/pc）^[1.31]。所选YSO与Sh 2 -104边缘上收集的材料相关。Sh 2 -104的动力学年龄为1.6*10^6年。将Sh 2 -104的动力学年龄与YSO时间尺度和分子环的碎裂时间进行比较，进一步证实了该区域存在收集-坍缩过程，表明大质量恒星对周围气体的正反馈.
英文摘要：
We performed a multiwavelength study towards HII region Sh2-104. New maps of 12CO J=1-0 and 13CO J=1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. Sh2-104 displays a double-ring structure. The outer ring with a radius of 4.4 pc is dominated by 12 um, 500 um, 12CO J=1-0, and 13CO J=1-0 emission, while the inner ring with a radius of 2.9 pc is dominated by 22 um and 21 cm emission. We did not detect CO emission inside the outer ring. The north-east portion of the outer ring is blueshifted, while the south-west portion is redshifted. The present observations have provided evidence that the collected outer ring around Sh2-104 is a two-dimensional structure. From the column density map constructed by the Hi-GAL survey data, we extract 21 clumps. About 90\% of all the clumps will form low-mass stars. A power-law fit to the clumps yields M=281Msun(r/pc)^1.31. The selected YSOs are associated with the collected material on the edge of Sh2-104. The derived dynamical age of Sh2-104 is 1.6*10^6 yr. Compared the Sh2-104 dynamical age with the YSOs timescale and the fragmentation time of the molecular ring, we further confirm that collect-and-collapse process operates in this region, indicating a positive feedback from a massive star for surrounding gas.
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