The Detection of SH+ in the Interstellar Medium

The N = 1 – 0, J = 1 – 1, fine structure component of sulfaniumylidene or sulfanylium, SH+, near 683 GHz has recently been detected in absorption from ground with the APEX 12 m telescope toward the evolved massive star-forming region Sagittarius B2(M):
K. M. Menten, F. Wyrowski, A. Belloche, R. Güsten, L. Dedes, and H. S. P. Müller,
Submillimeter Absorption from SH+, a New Widespread Interstellar Radical, 13CH+ and HCl
Astron. Astrophys. 525, (2011), Art. No. A77.
The absorption originates not only from the envelope of Sgr B2(M), but also from various spiral arm molecular clouds along the line of sight. The observation of the stronger J = 2 – 1 fine structure component of the same rotational transition near 526 GHz from ground is hampered by a strong terrestrial water line, but it can be observed from satellites such as Herschel. The weak 0 – 1 component near 329 GHz is affected by CO, J = 3 – 2 and by a line of 34SO2.

Shortly thereafter, SH+ was observed in emission in three fine structure components (two excited ones) with Herschel-HIFI toward W3 IRS5 in the course of a study by
A. O. Benz, S. Bruderer, E. F. van Dishoeck, et al.,
Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system
Astron. Astrophys. 521, (2010), Art. No. L35.
Note that the article actually appeared before the one mentioned above.

B. Godard, E. Falgarone, M. Gerin, D. C. Lis, M. De Luca, J. H. Black, J. R. Goicoechea, J. Cernicharo, D. A. Neufeld, K. M. Menten, and M. Emprechtinger,
reported on a
Comparative study of CH+ and SH+ absorption lines observed towards distant star-forming regions
Astron. Astrophys. 540, (2012), Art. No. A87.
The 525 GHz FS component of SH+ was observed toward 8 continuum sources with the Herschel/HIFI instrument.

Z. Nagy, F. F. S. van der Tak, V. Ossenkopf, M. Gerin, F. Le Petit, J. Le Bourlot, J. H. Black, J. R. Goicoechea, C. Joblin, M. Röllig, and E. A. Bergin,
The chemistry of ions in the Orion Bar I. – CH+, SH+, and CF+
The effect of high electron density and vibrationally excited H2 in a warm PDR surface

Astron. Astrophys. 550, (2013), Art. No. A96.
As for other hydrides, such as CH+, SH+ was observed in emission.

Contributor(s): H. S. P. Müller; 12, 2010; 07, 2014; 12, 2015.