Sulfur-bearing Molecules In Orion KL

By Keith Cowing
Press Release
October 14, 2019
Filed under
Sulfur-bearing Molecules In Orion KL
Channel maps of H2S over a velocity range of 10 to 15 km s−1 . The gray map on the background shows the ALMA-only continuum emission. The peak positions of the continuum emission are marked with green crosses. Black contours show the line emission from the ALMA-30 m combination, starting from 5% of the emission peak and increasing by a step of 5%. The red circle indicates the ring-like structure.

We present an observational study of the sulfur (S)-bearing species towards Orion KL at 1.3 mm by combining ALMA and IRAM-30m single-dish data.

At a linear resolution of ∼800 au and a velocity resolution of 1 kms−1, we have identified 79 molecular lines from 6 S-bearing species. In these S-bearing species, we found a clear dichotomy between carbon-sulfur compounds and carbon-free S-bearing species in various characteristics, e.g., line profiles, spatial morphology, and molecular abundances with respect to H2. Lines from the carbon-sulfur compounds (i.e., OCS, 13CS, H2CS) exhibit spatial distributions concentrated around the continuum peaks and extended to the south ridge. The full width at half maximum (FWHM) linewidth of these molecular lines is in the range of 2 ∼ 11 kms−1.

The molecular abundances of OCS and H2CS decrease slightly from the cold (∼68 K) to the hot (∼176 K) regions. In contrast, lines from the carbon-free S-bearing species (i.e., SO2, 34SO, H2S) are spatially more extended to the northeast of mm4, exhibiting broader FWHM linewidths (15 ∼ 26 kms−1). The molecular abundances of carbon-free S-bearing species increase by over an order of magnitude as the temperature increase from 50 K to 100 K. In particular, 34SO/34SO2 and OCS/SO2 are enhanced from the warmer regions (>100 K) to the colder regions (∼50 K). Such enhancements are consistent with the transformation of SO2 at warmer regions and the influence of shocks.

Gan Luo, Siyi Feng, Di Li, Sheng-Li Qin, Yaping Peng, Ningyu Tang, Zhiyuan Ren, Hui Shi
(Submitted on 4 Oct 2019)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:1910.01779 [astro-ph.SR] (or arXiv:1910.01779v1 [astro-ph.SR] for this version)
Submission history
From: Gan Luo
[v1] Fri, 4 Oct 2019 01:52:13 UTC (2,076 KB)
Astrobiology, Astrochemistry

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