Karri Muinonen

A preliminary analysis of the orbit of the Mars Trojan asteroid (5261) Eureka

Observations and results of orbit determination of the first known Mars Trojan asteroid (5261) Eureka are presented. We have numerically calculated the evolution of the orbital elements, and have analyzed the behavior of the motion during the next 2 Myr. Strong perturbations by planets other than Mars seem to stabilize the eccentricity of the asteroid by stirring the high order resonances present in the elliptic restricted problem. As a result, the orbit appears stable at least on megayear timescales. The difference of the mean longitudes of Mars and Eureka and the semimajor axis of the asteroid form a pair of variables that essentially behave in an adiabatic manner, while the evolution of the other orbital elements is largely determined by the perturbations due to other planets.

Commission 15: Physical Study of Comets and Minor Planets: (Etude Physique Des Cometes Et Des Petites Planetes)

The report of Commission 15 was prepared primarily by the chairpersons of its two working groups: the Minor Planet Working Group and the Comet Working Group. In particular, the Minor Planet section was created by A. Cellino with a little help from E. Tedesco and the Comet section by T. Yamamoto with the assistance of D. Bockelee-Morvan, W. Huebner, A. Bhardwaj, D. Biesecker, L. Jorda, H. Kawakita, H. U. Keller, H. Kimura, A. Kouchi, and D. Prialnik. E. Tedesco was responsible for the Introduction, final editing, and merging of the two reports. Scientific activity in the field has continued to grow in the past three years, as evidenced by publication of 700 papers in the refereed literature, compared with about 400 during the previous triennium. A comprehensive overview of so large a publication list cannot be accomplished in the space at our disposal. We have therefore chosen to highlight a representative subset of these publications to provide a snapshot of the current state of the field, and, as in the last several reports, without including a comprehensive bibliography. Instead, a complete list of the references used in creating this report, assembled by searching the ADS abstract service (http://adsabs.harvard.edu/abstract−service.html) to generate a list of refereed papers published between July 2002 and June 2005, inclusive, is available in the Archive section of the Division III Physical Studies of Comets and Minor Planets web site. This site can be reached (since it does not have a permanent home) via a link from the IAU home page.