http://arxiv.org/abs/1409.3618
We investigate the relationship among the angular orbital elements — the longitude of the ascending node, Omega, the inclination, i, and the argument of perihelion, omega — of dwarf sungrazing comets of the Kreutz system, whose catalogued orbits were derived using a parabolic gravitational approximation. While in a plot of omega against Omega the major and dwarf sungrazers follow a similar law, in a plot of i against Omega they behave differently. The major sungrazers fit a curve of invariable (reference) apsidal orientation, whereas the dwarf comets lie along a curve that makes with it 15 deg. While the perihelion longitude of dwarf sungrazers is statistically constant, the perihelion latitude increases systematically with Omega. A perturbation analysis indicates that this is due to an acceleration normal to the orbit plane. The culprit is neglect of an erosion-driven acceleration in the motions of the dwarf sungrazers, as illustrated by computing, for several test SOHO/STEREO sungrazers, orbital solutions with the nongravitational terms incorporated in the equations of motion, while forcing the reference apsidal line. We proceed in three steps. In the first step we apply Marsden et al.’s standard Style II formalism and solve for the normal acceleration. In the second step we relax the constraint on the nongravitational law. And in the third step we in addition relax the constraint on the other two acceleration components. The resulting nongravitational accelerations on the dwarf sungrazers exceed the highest values among the catalogued comets in nearly parabolic orbits by up to 3 orders of magnitude, topping in extreme cases the Sun’s gravitational acceleration (sic!). Application of a basic mass-loss model suggests that the nuclei of dwarf sungrazers fragment copiously and their dimensions shrink rapidly, implying the objects’ imminent decay a fraction of a day before perihelion.
Z. Sekanina and R. Kracht
Mon, 15 Sep 14
28/47
Comments: 17 pages, 7 figures, 7 tables; submitted to The Astrophysical Journal
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