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NH3 and NH2 in the coma of Comet Brorsen-Metcalf

Tegler, Stephen C. and Burke, Luke F. and Wyckoff, Susan and Womack, Maria and Fink, Uwe and Disanti, Michael (1992) NH3 and NH2 in the coma of Comet Brorsen-Metcalf. The Astrophysical Journal, 384 (1). pp. 292-297. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1086/170872


Evidence consistent with NH3 ice in the nucleus of Comet Brorsen-Metcalf as the source of the NH2 observed in the comet coma is presented. The distribution of NH2 is symmetric and shows no evidence for jet structure at the 3-sigma significance level above background emission. An azimuthal average of the NH2 image produces an NH2 surface brightness profile for Comet Brorsen-Metcalf which yields a factor of about-10 improvement in the signal-to-noise ratio over previous 1D long-slit NH2 observations, and provides a significant constraint on the NH2 photodissociation time scale in comets. A Monte Carlo simulation of the comet coma, assuming that NH2 is the primary source of NH2, is described and compared with the observations. For an observed production rate, Q(H2O) is approximately equal to 7 x 10 exp 28 molecules/s, collisional effects on the NH3 and NH2 outflow had at most an approximately 10-percent effect on the NH2 surface brightness profile. Because Comet Brorsen-Metcalf showed no significant dust or gas production rate variability, it is argued that steady state conditions best match the comet at the time of the observations.

Item Type: Article
Publisher’s Statement: © 1992 The American Astronomical Society. Published in The Astrophysical Journal.
ID number or DOI: 10.1086/170872
Keywords: Ammonia, Brorsen-Metcalf Comet, Comet Heads, Coma, Ice, Interstellar Matter
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 22 Dec 2015 19:47
URI: http://openknowledge.nau.edu/id/eprint/1851

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