HERSCHEL/HIFI OBSERVATIONS OF HYDROGEN FLUORIDE TOWARD SAGITTARIUS B2(M)
- California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125-4700 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)
- Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
- Departamento de Astrofisica, Centro de Astrobiologia (CAB), INTA-CSIC, Crta. Torrejon km 4, 28850 Torrejon de Ardoz, Madrid (Spain)
- Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
Herschel/HIFI observations have revealed the presence of widespread absorption by hydrogen fluoride (HF) J = 1-0 rotational transition, toward a number of Galactic sources. We present observations of HF J = 1-0 toward the high-mass star-forming region Sagittarius B2(M). The spectrum obtained shows a complex pattern of absorption, with numerous features covering a wide range of local standard of rest velocities (-130 to 100 km {sup -1}). An analysis of this absorption yields HF abundances relative to H{sub 2} of {approx}1.3 x 10{sup -8}, in most velocity intervals. This result is in good agreement with estimates from chemical models, which predict that HF should be the main reservoir of gas-phase fluorine under a wide variety of interstellar conditions. Interestingly, we also find velocity intervals in which the HF spectrum shows strong absorption features that are not present, or are very weak, in spectra of other molecules, such as {sup 13}CO (1-0) and CS (2-1). HF absorption reveals components of diffuse clouds with small extinction that can be studied for the first time. Another interesting observation is that water is significantly more abundant than hydrogen fluoride over a wide range of velocities toward Sagittarius B2(M), in contrast to the remarkably constant H{sub 2}O/HF abundance ratio with average value close to unity measured toward other Galactic sources.
- OSTI ID:
- 21562611
- Journal Information:
- Astrophysical Journal Letters, Vol. 734, Issue 1; Other Information: DOI: 10.1088/2041-8205/734/1/L23; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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