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Astron. Astrophys. 336, 1056-1064 (1998)

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A study of Hilda asteroids

III. Collision velocities and collision frequencies of Hilda asteroids

M. Dahlgren

Astronomiska observatoriet, Box 515, S-75120 Uppsala, Sweden

Received 28 August 1997 / Accepted 20 April 1998


The collision velocities and collision frequencies of Hilda asteroids have been investigated numerically. The collision probabilities and collision velocities have been determined from a data base of close encounters, obtained by numerical integrations of the orbits of 909 asteroids for 55 000 years. The integration included all known main-belt, Cybele, Hilda, and Trojan objects larger than 50 km in diameter. The mean collision probability is lower for Hilda asteroids than for main-belt, Cybele and Trojan asteroids. Out of ten collisions involving a Hilda object, about seven are with main-belt objects, and the other three collisions are evenly distributed among the three outer-belt groups. The collision probabilities of individual Hilda asteroids have a strong correlation with the eccentricity of their orbits, resulting in a wide range (about a factor of six) of collision probabilities among the Hilda objects. The mean collision velocity of the Hilda asteroids is 4.6 [FORMULA], which is 0.5 [FORMULA] lower than the average for main-belt objects. The mean collision velocity of individual Hilda objects range from 3.3 to 6.0 [FORMULA].

Key words: asteroids

Send offprint requests to: M. Dahlgren
Correspondence to: Mats.Dahlgren@astro.uu.se

© European Southern Observatory (ESO) 1998

Online publication: July 27, 1998