Variation of Nongravitational Parameters for Comet Encke as a Result of its Decay
M. G. Ishmukhametova1,2, E. D. Kondrat'eva1, V. S. Usanin1,2
1Kazan State University, Kazan, Russia
2Engelhard Astronomical Observatory, Zelenodolsky region, Russia
Abstract:
An assumption is made that variations of nongravitational parameters of comet Encke in Marsden's model are caused by its secular decay. To account for decrease of nongravitational parame-ters three variants of physical processes are proposed: 1) deposition of a substantial nonvolatile mass not impeding the sublimation; 2) generation of a little-massive mantle shrinking the effective area linearly; 3) generation of a little-massive mantle shrinking the area exponentially. The corresponding equations are derived. The adequa-cy of the first two models over more than 150 years is shown.
Key words:
Very Long Baseline Interferometry (VLBI), Near Earth Objects (NEOs), comet Encke, variations of nongravitational parameters, Marsden's model, secular decay, deposition of a substantial nonvolatile mass, to imped the sublimation, a little-massive mantle, to shrink the effective area linearly, to shrink the area exponentially, adequacy of models.