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F. Marzari (Universita' di Padova), H. Scholl (Observatoire de Nice), P. Tricarico (Washington State University)
The three asteroids (5261) Eureka, 1998 VF31 and 2001 DH47 are L5 Trojans of Mars while 1999 UJ7 librates in the L4 region. Two of them, (5261) Eureka and 1998 VF31, appear to be km-sized highly differentiated bodies according to spectroscopic and photometric observations of Rivkin et al. (2003). They are presumably fragments of larger parent bodies. Applying Laskar's frequency map analysis we have investigated the stability of the Trojan region finding that all four bodies reside in the most stable region. These regions have a dynamical half-lifetime of the order of the age of the solar system according to our numerical integrations over timescales of a few Gyrs. The most stable regions are weakly chaotic due to secular frequencies in the planetary system. Clouds of clones loose about half of their members over the age of the solar system. The Yarkovsky effect does not increase the number of escapers. Capture of small asteroids migrating towards Mars due to the Yarkovsky effect is not possible according to our results. The four observed Mars Trojans may have resided in the Trojan region since a very early phase of the planetary evolution. They may be some of the oldest small asteroids in the terrestrial planet region.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.