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Comet P/Encke's nongravitational forceA nearly direct measurement of the nongravitational force on a cometary nucleus is presented. IUE spectra of comet P/Encke show significant Greenstein effects even when centered on the nucleus. These imply net heliocentric components of outflow of 1.6 and 0.3 km/s for the OH radicals before and after perihelion near r = 0.8 AU. This implies a large asymmetry in the radial nongravitational acceleration (A1) about perihelion, which must be taken into account in order to derive the mass of the nucleus. The asymmetry is consistent with Sekanina's (1988) latest model for the Encke nucleus, but the measurements suggest an outflow velocity near 2 km/s, significantly greater than generally accepted values. A tentative value for the mass of the Encke nucleus is proposed, although improved modeling of the nongravitational acceleration is required to obtain a definitive value.
Document ID
19880060309
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
A'Hearn, Michael F.
(Maryland, University College Park, United States)
Schleicher, David G.
(Lowell Observatory Flagstaff, AZ, United States)
Date Acquired
August 13, 2013
Publication Date
August 1, 1988
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 331
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
88A47536
Funding Number(s)
CONTRACT_GRANT: NAG5-252
Distribution Limits
Public
Copyright
Other

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