===== Hydrogen Fluoride, HF, in Extragalactic Sources =====

The //J// = 1 – 0 transition was observed in emission with the SPIRE instrument of the //Herschel// satellite toward the ultra-luminous infrared galaxie (ULIRG) Mrk 231:\\
P. P. van der Werf, K. G. Isaak, R. Meijerink, et al.,\\
**[[https://doi.org/10.1051/0004-6361/201014682|Black Hole Accretion and Star-Formation as Drivers of Gas Excitation and Chemistry in Markarian 231]]**\\
//Astron. Astrophys.// **518**, (2010) Art. No. L42.\\
The account is sparse, but a detail of the spectrum (van der Werf, private communication) clearly shows the line well-separated from a near-by water line.

The same transition was seen with the same instrument in absorption toward the ULIRG Arp 220 by\\
N. Rangwala, P. R. Maloney, J. Glenn, et al.,\\
**[[https://doi.org/10.1088/0004-637X/743/1/94|Observations of Arp 220 Using //Herschel//-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment]]**\\
//Astrophys. J.// **743**, (2011) Art. No. 94.

R. R. Monje, T. G. Phillips, R. Peng, D. C. Lis, D. A. Neufeld, and M. Emprechtinger\\
reported on the\\
**[[https://doi.org/10.1088/2041-8205/742/2/L21|Discovery of Hydrogen Fluoride in the Cloverleaf Quasar at //z// = 2.56]]**\\
//Astrophys. J.// **743**, (2011) Art. No. 94;\\
employing the CSO. Again, the //J// = 1 – 0 transition was observed in absorption.


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Contributor(s): H. S. P. Müller; 12, 2010; 04, 2013

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