Hydrogen sulfide has been detected in seven star-forming regions
very early as a very abundant molecule via its
110 101 transition in
the 2 mm region:
P. Thaddeus, M. L. Kutner, A. A. Penzias, R. W. Wilson, and K. B. Jefferts,
Interstellar Hydrogen Sulfide
Astrophys. J. 176, L73L76 (1972).
H2S was also identified in this transition toward the circumstellar envelope of OH231.8+4.2:
N. Ukita, M. Morris,
Hydrogen Sulfide in a Circumstellar Envelope
Astron Astrophys. 121, 1518 (1983);
and also in certain regions of the cold dark clouds L134N and TMC-1:
Y. C. Minh, W. M. Irvine, and L. M. Ziurys,
Detection of Interstellar Hydrogen Sulfide in Cold, Dark Clouds
Astrophys. J. 345, L63L66 (1989).
The same transition was used to identify H234S
toward certain regions in the Orion molecular cloud:
Y. C. Minh, W. M. Irvine, D. McGonagle, and L. M. Ziurys,
Observations of the H2S toward OMC-1
Astrophys. J. 360, 136141 (1990).
A weak feature near 333 GHz has been identified as the
202 111 of HDS:
G. H. Macdonald, A. G. Gibb, R. J. Habing, and T. J. Millar,
A 330360 GHz Spectral Survey of G 34.3+0.15. I. Data and Physical Analysis
Astron Astrophys. Suppl. Ser. 119, 333367 (1996).
Even D2S was recently detected toward two dense, cold
clouds Barnard 1 and NGC 1333 IRAS 4A(DCO+),
with HDS detected toward several additional sources:
C. Vastel, T. G. Phillips, C. Ceccarelli, and J. C. Pearson,
First Detection of Doubly Deuterated Hydrogen Sulfide
Astrophys. J. 593, L97L100 (2003).