Retrospective Evolution Study on the Longest-Lived Near-Sun Comets

Yu. D. Medvedev, S. R. Pavlov, A. L. Tolstoy

Transactions of IAA RAS, issue 69, 18–25 (2024)

DOI: 10.32876/ApplAstron.69.18-25

Keywords: near-Sun comets, 321P, 322P, 323P, 342P, P/1999 J6, P/2008 N4, comet dynamics, D-criteria, Kholshevnikov metrics

Abstract

The dynamic features of the orbits of the six longest-lived comets from the Marsden and Kracht families 321P, 322P, 323P, 342P, P/1999 J6, P/2008 N4 were studied. Their coordinates, velocities and transversal components of nongravitational accelerations A₂ have been improved using positional observations obtained from MPC website (2022.12.25). For most of the comets, the value of A₂ did not exceed 0.02 · 10⁻⁸ au/day². The comet P/1999 J6 was an exception, which may have resulted from its disintegration while passing its perihelion in 1999. The value of the root-meansquare error of positional observations by SOHO spacecraft in most cases reached 25 arcseconds. The equations of motion for 4 thousand years into the past were integrated and the values of D-criteria for all pairs of the orbits were obtained. Three criteria characterizing the similarity of a pair of orbits were calculated: the Southworth and Hawkins, the Drummond, and the Holshevnikov criteria. The purpose of this work is to determine the possible moments of the comets separation based on the assumption that the comets could have been parts of a single parent body in the past. As a result of the analysis, it has been suggested that a pair of comets 342P and P1999 J6 may have fragmented in 1200. Both of these comets had a close approach to Jupiter at this time. The calculations confirm the hypothesis that most near-Sun comets were formed as a result of the destruction of a protocomet.

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