Studying Infall in Infrared Dark Clouds with Multiple HCO+ Transitions
| Autor: | Xie, Jinjin, Wu, Jingwen, Fuller, Gary A., Peretto, Nicolas, Ren, Zhiyuan, Chen, Longfei, Yan, Yaoting, Li, Guodong, Duan, Yan, Xia, Jifeng, Wang, Yongxiong, Li, Di |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Res. Astron. Astrophys. 21: 208 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/1674-4527/21/8/208 |
| Popis: | We investigate the infall properties in a sample of 11 infrared dark clouds (IRDCs) showing blue-asymmetry signatures in HCO$^{+}$ J=1--0 line profiles. We used JCMT to conduct mapping observations in HCO$^{+}$ J=4--3 as well as single-pointing observations in HCO$^{+}$ J =3--2, towards 23 clumps in these IRDCs. We applied the HILL model to fit these observations and derived infall velocities in the range of 0.5-2.7 km s$^{-1}$, with a median value of 1.0 km s$^{-1}$, and obtained mass accretion rates of 0.5-14$\times$10$^{-3}$ Msun yr$^{-1}$. These values are comparable to those found in massive star forming clumps in later evolutionary stages. These IRDC clumps are more likely to form star clusters. HCO$^{+}$ J =3--2 and HCO$^{+}$ J =1--0 were shown to trace infall signatures well in these IRDCs with comparable inferred properties. HCO$^{+}$ J=4--3, on the other hand, exhibits infall signatures only in a few very massive clumps, due to smaller opacties. No obvious correlation for these clumps was found between infall velocity and the NH3/CCS ratio. Comment: 22 pages, 14 figures, accepted by RAA |
| Databáze: | arXiv |
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