In Search of Infall Motion in Molecular Clumps. III. HCO+ (1-0) and H13CO+ (1-0) Mapping Observations toward Confirmed Infall Sources
In Search of Infall Motion in Molecular Clumps. III. HCO+ (1-0) and H13CO+ (1-0) Mapping Observations toward Confirmed Infall Sources
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寻找分子团中的坠落运动。
DOI：
10.3847/1538-4357/ac22ab
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Shuling Yu
中科院分区：
文献类型：
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作者：
Yang Yang;Zhibo Jiang;Zhiwei Chen;Yiping Ao;Shuling Yu
对坍缩运动的研究有助于我们理解星星形成的初始阶段。本文利用IRAM 30米望远镜对已确认的24个落源进行了成图观测。我们用来追踪气体下落运动的线是HCO+（1-0）和H13 CO+（1-0）。所有24个排放源均显示HCO+排放，而18个排放源显示H13 CO+排放。17个源的HCO+积分强度图显示出明显的团簇结构;对于H13 CO+线，15个源显示出团簇结构。我们用RADEX辐射转移程序估算了HCO+和H13 CO+的柱密度，得到的[HCO+]/[H2]和[H13 CO +]/[HCO+]分别约为10−11-10−7和10−3-1。根据HCO+谱线轮廓的不对称性，我们区分了这些源：19个源显示蓝色不对称轮廓，其他源显示红色轮廓或对称峰轮廓。对于8个具有双峰蓝线轮廓和信噪比大于1 - 0的源，使用RATRAN模型来拟合它们的HCO+（1-0）线，并估计它们的入射参数。这些源的平均Vin为0.3-1.3 km s−1，M现in约为10−3-10−4 M yr−1，这与以往研究中中等质量或大质量星星形成的结果一致。根据迈尔斯模型估算的V in为0.1-1.6 km s−1，M tow in在10−3-10−5 M yr−1之间。此外，一些已确定的下沉源显示出其他恒星形成活动，如外流和脉泽发射。特别是对于那些双峰蓝色不对称剖面的源，大多数都有流入和流出的证据。
The study of infall motion helps us to understand the initial stages of star formation. In this paper, we use the IRAM 30 m telescope to make mapping observations of 24 infall sources confirmed in previous work. The lines we use to track gas infall motions are HCO+ (1-0) and H13CO+ (1-0). All 24 sources show HCO+ emissions, while 18 sources show H13CO+ emissions. The HCO+ integrated intensity maps of 17 sources show clear clumpy structures; for the H13CO+ line, 15 sources show clumpy structures. We estimated the column density of HCO+ and H13CO+ using the RADEX radiation transfer code, and the obtained [HCO+]/[H2] and [H13CO+]/[HCO+] of these sources are about 10−11–10−7 and 10−3–1, respectively. Based on the asymmetry of the line profile of the HCO+, we distinguish these sources: 19 sources show blue asymmetric profiles, and the other sources show red profiles or symmetric peak profiles. For eight sources that have double-peaked blue line profiles and signal-to-noise ratios greater than 10, the RATRAN model is used to fit their HCO+ (1-0) lines, and to estimate their infall parameters. The mean V in of these sources is 0.3–1.3 km s−1, and the Ṁin is about 10−3–10−4 M ⊙ yr−1, which is consistent with the results of intermediate or massive star formation in previous studies. The V in estimated from the Myers model is 0.1–1.6 km s−1, and the Ṁin is within 10−3–10−5 M ⊙ yr−1. In addition, some identified infall sources show other star-forming activities, such as outflows and maser emissions. Especially for those sources with a double-peaked blue asymmetric profile, most of them have both infall and outflow evidence.