The quasi-Hilda subgroup of ecliptic comets – an update

Konkoly Observatory, Budapest 1525, PO Box 67, Hungary e-mail: tothi@konkoly.hu

Received: 23 May 2005
Accepted: 10 November 2005

Abstract

Context. The importance of the Hilda zone is obvious in the main belt asteroid – ecliptic comet relationship. Aims. The inventory of the quasi-Hilda comet group is updated by taking into account the data bases of new discoveries performed by large survey programs. Methods. We examined the Hilda zone objects according to their Tisserand parameter with respect to Jupiter, orbital excitation parameter, as well as their distribution in the Langrangian orbital elements space. Results. We found 11 new members of the quasi-Hilda cometary subgroup of ecliptic comets, so that altogether there are now 15 known comets in the Hilda asteroid zone. In addition, we found 23 outliers of the Hilda family in the Lagrangian orbital elements space, which can be dormant or extinct comet nuclei. This proposition should be checked by both observations of the physical properties and investigation of the long-term evolution of the orbits of these objects.