Sulfur-bearing molecules in Orion KL

Abstract

We present an observational study of the sulfur (S)-bearing species towards Orion KL at 1.3 mm by combining ALMA and IRAM-30\,m single-dish data. At a linear resolution of $\sim$800 au and a velocity resolution of 1 $\mathrm{km}{\mathrm{s}}^{-1}$, 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 ${\mathrm{H}}_2$. Lines from the carbon-sulfur compounds (i.e., OCS, ${}^{13}$CS, H${}_2$CS) 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 $\sim$ 11 $\mathrm{km}{\mathrm{s}}^{-1}$. The molecular abundances of OCS and H${}_2$CS decrease slightly from the cold ($\sim$68 K) to the hot ($\sim$176 K) regions. In contrast, lines from the carbon-free S-bearing species (i.e., SO${}_2$, ${}^{34}$SO, H${}_2$S) are spatially more extended to the northeast of mm4, exhibiting broader FWHM linewidths (15 $\sim$ 26 $\mathrm{km}{\mathrm{s}}^{-1}$). 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, ${}^{34}\mathrm{SO}{/}^{34}\mathrm{S}{\mathrm{O}}_2$ and $OCS/S{\mathrm{O}}_2$ are enhanced from the warmer regions ($>$100 K) to the colder regions ($\sim$50 K). Such enhancements are consistent with the transformation of SO${}_2$ at warmer regions and the influence of shocks.

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Cited by in corpus (6)

• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C${}_2$H${}_5$CN, CH${}_3$OCHO and CH${}_3$OH lines
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): I. Detection of New Hot Corinos with ACA
• A Q-band line survey towards Orion KL using the Tianma radio telescope
• Evidence for dense gas heated by the explosion in Orion KL
• Chemical variations across the TMC-1 boundary: molecular tracers from translucent phase to dense phase
• Observational studies on S-bearing molecules in massive star forming regions