===== Detection of HCS+ in the ISM =====

The thioformyl cation, HCS<sup>+</sup>, has been observed in the ISM prior to the laboratory by\\
P. Thaddeus, M. Guélin, and R. A. Linke,\\
**[[https://ui.adsabs.harvard.edu/abs/1981ApJ...246L..41T|Three New 'Nonterrestrial' Molecules]]**\\
//Astrophys. J.// **246**, L41–L45 (1981).\\
The //J// = 2 – 1 transition near 85.3 GHz was detected toward the hot-core sources Orion KL, Sgr B2(OH), and DR 21 as well as toward the dense cold cloud TMC-1. In addition, the 3 – 2, 5 – 4, and 6 – 5 transitions were also detected in Orion KL.

The molecular cation was also detected in several translucent molecular clouds by\\
B. E. Turner,\\
**[[https://ui.adsabs.harvard.edu/abs/1996ApJ...461..246T|The Physics and Chemistry of Small Translucent Molecular Clouds. VI. Organo-Sulfur Species]]**\\
//Astrophys. J.// **416**, 246–264 (1996)

The 7 – 6, and 8 – 7 transitions were detected in a PDR by\\
S. Leurini, R. Rolffs, S. Thorwirth, B. Parise, P. Schilke, C. Comito, F. Wyrowski, R. Güsten, P. Bergman, K. M. Menten, and L.-Å. Nyman,\\
**[[https://doi.org/10.1051/0004-6361:20065555|APEX 1 mm Line Survey of the Orion Bar]]**\\
//Astron. Astrophys.// **454**, L47–L50 (2006)

A. Fuente, J. Cernicharo, E. Roueff, M. Gerin, J. Pety, N. Marcelino, R. Bachiller, B. Lefloch, O. Roncero, and A. Aguado,\\
studied the\\
**[[https://doi.org/10.1051/0004-6361/201628285|Ionization Fraction and the Enhanced Sulfur Chemistry in Barnard 1]]**\\
//Astron. Astrophys.// **593**, Art. No. A94 (2016).\\
They used the IRAM 30 m telescope for a molecular line survey at 3, 2, and 1.3 mm. The //J// = 3 – 2 transition of DCS<sup>+</sup> at 108.108 GHz was detected in emission. An LVG analysis suggests a D/H ratio of almost 0.1 in the region in which the DCS<sup>+</sup> emission was detected.

A. Potapov, Á. Sánchez-Monge, P. Schilke, U. U. Graf, T. Möller, and S. Schlemmer\\
reported almost at the same time on the detection of the same transition in their search for\\
**[[https://doi.org/10.1051/0004-6361/201628426|The CO–H<sub>2</sub> van der Waals complex and complex organic molecules in cold molecular clouds: A TMC-1C survey]]**\\
//Astron. Astrophys.// **594**, Art. No. A117 (2016).\\
The IRAM 30 m telescope was used once more.


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Contributor(s): H. S. P. Müller; 12, 2003; 09, 2011; 11, 2016

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