THE ABUNDANCE OF H{sub 2}O AND HDO IN ORION KL FROM HERSCHEL/HIFI
- Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
- Department of Physics and Astronomy and the Institute for Space Imaging Sciences, University of Calgary, Calgary, AB T2N IN4 (Canada)
Using a broadband, high spectral resolution survey toward the Orion Kleinmann-Low nebula acquired with Herschel/HIFI as part of the Herschel Observations of Extra-Ordinary Sources key program, we derive the abundances of H{sub 2}O and HDO in the different spatial/velocity components associated with this massive star-forming region: the Hot Core, Compact Ridge, and Plateau. A total of 20 transitions of H{sub 2} {sup 18}O, 14 of H{sub 2} {sup 17}O, 37 of HD{sup 16}O, 6 of HD{sup 18}O, and 6 of D{sub 2}O are used in the analysis, spanning from ground state transitions to over 1200 K in upper-state energy. Low-excitation lines are detected in multiple components, but the highest-excitation lines (E{sub u} > 500 K) are well modeled as emitting from a small ({approx}2'') clump with a high abundance of H{sub 2}O ({chi} = 6.5 Multiplication-Sign 10{sup -4} relative to H{sub 2}) and a HDO/H{sub 2}O ratio of 0.003. Using high spatial resolution (1.''5 Multiplication-Sign 1.''1) images of two transitions of HDO measured by the Atacama Large Millimeter/Submillimeter Array as part of its science verification phase, we identify this component as located near, but not directly coincident with, known continuum sources in the Hot Core region. Significant HDO/H{sub 2}O fractionation is also seen in the Compact Ridge and Plateau components. The outflowing gas, observed with both emission and absorption components, has a lower HDO/H{sub 2}O ratio than the compact components in Orion Kleinmann-Low, which we propose could be due to modification by gas-phase shock chemistry.
- OSTI ID:
- 22127053
- Journal Information:
- Astrophysical Journal, Vol. 770, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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