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Astron. Astrophys. 329, 1145-1151 (1998)


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Dynamical and physical properties of comet-asteroid transition objects*

M. Di Martino 1, A. Carusi 2, E. Dotto 3, M. Lazzarin 4, F. Marzari 3 and F. Migliorini 5

1 Osservatorio Astronomico di Torino, I-10025 Pino Torinese, Italy
2 IAS-CNR Area di Ricerca Tor Vergata, via Fasso del Cavaliere, I-00133 Roma, Italy
3 Università di Padova, Dipartimento di Fisica, Via Marzolo 8, I-35131 Padova, Italy
4 Università di Padova, Dipartimento di Astronomia, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy
5 Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK

Received 9 April 1997 / Accepted 8 September 1997

Abstract

In the last few years it has been pointed out that, from both physical and dynamical point of view, it is becoming more and more difficult to distinguish comets from asteroids and indeed there are some examples of small bodies first designated as comets which had, later, to be reclassified as asteroids and vice versa (Hartmann et al., 1990; McFadden, 1994). In order to investigate the evolutionary path of comets and asteroids in terms of both dynamical and physical properties, we performed spectroscopic observations of three objects discovered between 1990 and 1995 - (6042) 1990 WW2, (6144) 1994 EQ3, and 1995 QY2 - and analyzed their orbital evolution. Obtained spectra show the typical trend of low-albedo, "primitive" objects, similar to those of outer-belt asteroids and comet nuclei. The dynamical analysis shows that (6042) 1990 WW2 is on a stable orbit with a typical asteroidal behavior; (6144) 1994 EQ3 is on a Jupiter-crossing chaotic orbit and in the past could have spent some time in a Jupiter's horsehoe orbit; 1995 QY2 is a Mars crosser and librates about the 15/7 resonance with Jupiter and has a 40% chance to make a transition from asteroid to comet orbit over a timescale of about 3-5 [FORMULA] yr.

Key words: asteroids – comets

* Based on observations carried out at the European Southern Observatory (ESO), La Silla, Chile.

Send offprint requests to: M. Di Martino

© European Southern Observatory (ESO) 1998

Online publication: December 16, 1997
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