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Title: CONFIRMATION OF CIRCUMSTELLAR PHOSPHINE

Phosphine (PH{sub 3}) was tentatively identified a few years ago in the carbon star envelopes IRC +10216 and CRL 2688 from observations of an emission line at 266.9 GHz attributable to the J = 1-0 rotational transition. We report the detection of the J = 2-1 rotational transition of PH{sub 3} in IRC +10216 using the HIFI instrument on board Herschel, which definitively confirms the identification of PH{sub 3}. Radiative transfer calculations indicate that infrared pumping in excited vibrational states plays an important role in the excitation of PH{sub 3} in the envelope of IRC +10216, and that the observed lines are consistent with phosphine being formed anywhere between the star and 100 R {sub *} from the star, with an abundance of 10{sup –8} relative to H{sub 2}. The detection of PH{sub 3} challenges chemical models, none of which offer a satisfactory formation scenario. Although PH{sub 3} holds just 2% of the total available phosphorus in IRC +10216, it is, together with HCP, one of the major gas phase carriers of phosphorus in the inner circumstellar layers, suggesting that it could also be an important phosphorus species in other astronomical environments. This is the first unambiguous detection of PH{sub 3} outside the solar system,more » and is a further step toward a better understanding of the chemistry of phosphorus in space.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Instituto de Ciencia de Materiales de Madrid, CSIC, C/ Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco (Spain)
  2. Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Science Park 904, NL-1098 Amsterdam (Netherlands)
  3. LERMA, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris (France)
  4. European Space Astronomy Centre, Urb. Villafranca del Castillo, P.O. Box 50727, E-28080 Madrid (Spain)
Publication Date:
OSTI Identifier:
22365473
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 790; 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; ASTROPHYSICS; CARBON STARS; EMISSION SPECTRA; EXCITATION; GHZ RANGE; HYDROGEN; PHOSPHINES; PHOSPHORUS; RADIANT HEAT TRANSFER; SOLAR SYSTEM; SPACE; VIBRATIONAL STATES