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Title: DEUTERATED MOLECULES IN ORION KL FROM HERSCHEL/HIFI

We present a comprehensive study of the deuterated molecules detected in the fullband HIFI survey of the Orion Kleinmann-Low nebula (Orion KL) region. Ammonia, formaldehyde, and methanol and their singly deuterated isotopologues are each detected through numerous transitions in this survey with a wide range in optical depths and excitation conditions. In conjunction with a recent study of the abundance of HDO and H{sub 2}O in Orion KL, this study yields the best constraints on deuterium fractionation in an interstellar molecular cloud to date. As previous studies have found, both the Hot Core and Compact Ridge regions within Orion KL contain significant abundances of deuterated molecules, suggesting an origin in cold grain mantles. In the Hot Core, we find that ammonia is roughly a factor of two more fractionated than water. In the Compact Ridge, meanwhile, we find similar deuterium fractionation in water, formaldehyde, and methanol, with D/H ratios of (2-8) × 10{sup –3}. The [CH{sub 2}DOH]/[CH{sub 3}OD] ratio in the Compact Ridge is found to be 1.2 ± 0.3. The Hot Core generally has lower deuterium fractionation than the Compact Ridge, suggesting a slightly warmer origin, or a greater contribution from warm gas phase chemistry.
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  2. Jet Propulsion Laboratory, Caltech, Pasadena, CA 91109 (United States)
  3. Department of Physics, Centre for Laser, Atomic, and Molecular Studies (CLAMS), University of New Brunswick, Saint John, New Brunswick E2L 4L5 (Canada)
Publication Date:
OSTI Identifier:
22270652
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; 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; AMMONIA; ASTRONOMY; ASTROPHYSICS; COSMOCHEMISTRY; DEUTERIUM; EXCITATION; FORMALDEHYDE; FRACTIONATION; HEAVY WATER; LIMITING VALUES; METHANOL; MOLECULES; NEBULAE