ALMA High-resolution Spectral Survey of Thioformaldehyde (H2CS) Towards Massive Protoclusters

By Keith Cowing
Status Report
November 30, 2023
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ALMA High-resolution Spectral Survey of Thioformaldehyde (H2CS) Towards Massive Protoclusters
345 GHz continuum maps of I14382 overlaid with the flux contours start with 8 rms and increase with the following power-law function D = 4 × N p + 8, where D is the dynamical range of the intensity map, N is the number of contours used (15 in this case) and p = Log(Vmax/(4 × rms))/Log(N − 1) (where Vmax is the peak intensity of the continuum) is the power index. The magnitude of the noise level of the continuum map is 0.8 mJy beam−1 . The cores is labeled roughly from top to bottom and from left to right. The corresponding beam size is in the bottom left corner and the scalebar is in the bottom right corner. — astro-ph.GA

Investigating the temperature and density structures of gas in massive protoclusters is crucial for understanding the chemical properties therein.

In this study, we present observations of the continuum and thioformaldehyde (H2CS) lines at 345 GHz of 11 massive protoclusters using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope. High spatial resolution and sensitivity observations have detected 145 continuum cores from the 11 sources. H2CS line transitions are observed in 72 out of 145 cores, including line-rich cores, warm cores and cold cores.

The H2 column densities of the 72 cores are estimated from the continuum emission which are larger than the density threshold value for star formation, suggesting that H2CS can be widely distributed in star-forming cores with different physical environments. Rotation temperature and column density of H2CS are derived by use of the XCLASS software.

The results show the H2CS abundances increase as temperature rises and higher gas temperatures are usually associated with higher H2CS column densities. The abundances of H2CS are positively correlated with its column density, suggesting that the H2CS abundances are enhanced from cold cores, warm cores to line-rich cores in star forming regions.

Li Chen, Sheng-Li Qin, Tie Liu, Hong-Li Liu, Sheng-Yuan Liu, Meizhu Liu, Hongqiong Shi, Chuanshou Li, Mengyao Tang, Tianwei Zhang, Ken’ichi Tatematsu, Xiaohu Li, Fengwei Xu, Yuefang Wu, Dongting Yang

Comments: 23 pages, 7 figures, 6 tables, accepted by ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2311.17369 [astro-ph.GA] (or arXiv:2311.17369v1 [astro-ph.GA] for this version)
Submission history
From: Li Chen
[v1] Wed, 29 Nov 2023 05:44:02 UTC (2,645 KB)
Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻