On the Detection of Methyl Mercaptan, CH3SH, in the ISM

Methyl mercaptan, or methanethiol, CH3SH, was detected in emission with the 7 m Bell Lab telescope toward Sagittarius B2(OH):
R. A. Linke, M. A. Frerking, and P. Thaddeus,
Interstellar methyl mercaptan
Astrophys. J. 232, L139–L142 (1979).
6 features belonging to several more J = 3 –2 and 4 –3 were observed near 75.9 and near 101 GHz. The derived rotational temperature in that source was about 9 K.

Much higher rotational temperatures (about 70 K) were derived in a 3, 2, and 1 mm line survey carried out with SEST:
E. Gibb, A. Nummelin, W. M. Irvine, D. C. B. Whittet, and P. Bergman,
Chemistry of the Organic-Rich Hot Core G327.3–0.6
Astrophys. J. 545, 309–326 (2000).

L. Majumdar, P. Gratier, T. Vidal, V. Wakelam, J.-C. Loison, K. M. Hickson, and E. Caux,
reported on the
Detection of CH3SH in protostar IRAS 16293-2422
Mon. Not. R. Astron. Soc. 458, 1859–1865 (2000).
The IRAM 30 m telescope was used to study this solar-type pair of proto-stars at 3 mm. Here, an excitation temperature of 32 ± 4 K was derived.

H. S. P. Müller, A. Belloche, L.-H. Xu, R. M. Lees, R. T. Garrod, A. Walters, J. van Wijngaarden, F. Lewen, S. Schlemmer, and K. M. Menten,
reported on
Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)
Astron. Astrophys. 587, Art. No. A92 (2016).
A line survey of Sgr B2(N) was carried out with ALMA at 3 mm. CH3SH was not only detected in its ground vibrational state, but also in its first torsionally excited state, even though the CH3OH/CH3SH ratio was only about 120. These authors derived a rotational temperature of 180 K in this source.


Contributor(s): H. S. P. Müller; 10, 2010; 07, 2016