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Detection of water vapor in Halley's cometGaseous, neutral H2O was detected in the coma of comet Halley on 22.1 and 24.1 December 1985 Universal Time. Nine spectral lines of the nus band (2.65 micrometers) were found by means of a Fourier transform spectrometer on the NASA-Kuiper Airborne Observatory. The water production rate was about 6 x 10 to the 28th molecules per second on 22.1 December and 1.7 x 10 to the 29th molecules per second on 24.1 December UT. The numbers of spectral lines and their intensities are in accord with nonthermal-equilibrium cometary models. Rotational populations are derived from the observed spectral line intensities and excitation conditions are discussed. The ortho-para ratio was found to be 2.66 + or - 0.13, corresponding to a nuclear-spin temperature of 32 K (+5 K, -2 K), possibly indicating that the observed water vapor originated from a low-temperature ice.
Document ID
19860059115
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Mumma, M. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Weaver, H. A.
(Johns Hopkins University Baltimore, MD, United States)
Larson, H. P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Williams, M.
(Arizona, University Tucson, United States)
Davis, D. S.
(Steward Observatory Tucson, AZ, United States)
Date Acquired
August 12, 2013
Publication Date
June 20, 1986
Publication Information
Publication: Science
Volume: 232
ISSN: 0036-8075
Subject Category
Astrophysics
Accession Number
86A43853
Funding Number(s)
CONTRACT_GRANT: NAG2-206
CONTRACT_GRANT: NAG2-356
Distribution Limits
Public
Copyright
Other

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