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Title: The water abundance behind interstellar shocks: results from Herschel/PACS and Spitzer/IRS observations of H{sub 2}O, CO, and H{sub 2}

We have investigated the water abundance in shock-heated molecular gas, making use of Herschel measurements of far-infrared (IR) CO and H{sub 2}O line emissions in combination with Spitzer measurements of mid-IR H{sub 2} rotational emissions. We present far-IR line spectra obtained with Herschel's Photodetector Array Camera and Spectrometer instrument in range spectroscopy mode toward two positions in the protostellar outflow NGC 2071 and one position each in the supernova remnants W28 and 3C391. These spectra provide unequivocal detections, at one or more positions, of 12 rotational lines of water, 14 rotational lines of CO, 8 rotational lines of OH (4 lambda doublets), and 7 fine-structure transitions of atoms or atomic ions. We first used a simultaneous fit to the CO line fluxes, along with H{sub 2} rotational line fluxes measured previously by Spitzer, to constrain the temperature and density distribution within the emitting gas; we then investigated the water abundances implied by the observed H{sub 2}O line fluxes. The water line fluxes are in acceptable agreement with standard theoretical models for nondissociative shocks that predict the complete vaporization of grain mantles in shocks of velocity v ∼ 25 km s{sup –1}, behind which the characteristic gas temperature is ∼1300 Kmore » and the H{sub 2}O/CO ratio is 1.2.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Department of Physics and Astronomy, Johns Hopkins University 3400 North Charles Street, Baltimore, MD 21218 (United States)
  2. LERMA, UMR 8112 du CNRS, Observatoire de Paris, École Normale Supérieure, 24 rue Lhomond, F-75005, Paris (France)
  3. Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  4. Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian Qu, 100871 Beijing (China)
  5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  6. Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio Catone (Italy)
  7. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln (Germany)
  8. Observatorio Astronómico Nacional (IGN), Alfonso XII 3, E-28014 Madrid (Spain)
  9. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22348101
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 781; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ATOMIC IONS; CARBON MONOXIDE; DENSITY; DETECTION; DISTRIBUTION; EMISSION; FAR INFRARED RADIATION; FINE STRUCTURE; HYDROGEN; INTERMEDIATE INFRARED RADIATION; MOLECULES; PERTURBED ANGULAR CORRELATION; SHOCK WAVES; SPECTRA; SPECTROSCOPY; SUPERNOVA REMNANTS; VELOCITY; WATER