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A&A 366, 1053-1060 (2001)
DOI: 10.1051/0004-6361:20000492
Updated collisional probabilities of minor body populations
A. Dell'Oro1, F. Marzari2, P. Paolicchi3 and V. Vanzani41 Dipartimento di Fisica, Università di Pisa, piazza Torricelli 2, 56127 Pisa, Italy
2 Dipartimento di Fisica, Università di Padova, Via Marzolo 8, 35131 Padova, Italy
e-mail: francesco.marzari@pd.infn.it
3 Dipartimento di Fisica, Università di Pisa, piazza Torricelli 2, 56127 Pisa, Italy
e-mail: paolo@astr15pi.difi.unipi.it
4 Dipartimento di Fisica, Università di Padova, Via Marzolo 8, 35131 Padova, Italy
e-mail: vanzani@pd.infn.it
(Received 5 June 2000 / Accepted 31 August 2000)
Abstract
The consistent increase in the discovery rate of new
asteroids and Trans Neptunian Objects (TNOs) in these last
years has urged an update of the values of
intrinsic probability of collision and impact velocity
for some minor body populations.
With the statistical method
of Dell'Oro & Paolicchi (1998), we have recomputed
the values of impact probability and velocity for Hilda asteroids,
for Trojans vs. Short Period Comets (SPC), and for TNOs.
The algorithm of Dell'Oro and Paolicchi is particularly suited for
the task since it can account for resonant
behaviour (Dell'Oro et al. 1998) and for the clustering of
the perihelion longitude of Main Belt asteroids and Hildas,
caused by the presence of a forced component in the eccentricity.
The Hilda population turns out to be well sampled
in the orbital parameter space since
no significant changes are found for the collision
frequency among Hildas, and of Hildas with Main Belt
asteroids,
although a much
larger sample of orbits has been used in our
computations (232 objects) vs. the smaller group used in
previous computation by Dahlgren (1998) (40 objects).
We also computed the
impact rate of SPCs vs. Trojans that turned out to be
an order of magnitude lower respect to the Trojans vs. Trojans
impact rate. The relative velocity is instead about 30% higher.
Using reasonable estimates of SPC and Trojan number densities,
we find that approximately 1 every 100 collisions
involving Trojans may be
with an SPC. In the case of TNOs
there is a consistent
discrepancy between our values of the collision probability
and impact speed,
and those computed by Davis &
Farinella (1997). The consistent increase in the
number of known TNOs (186 at present, only 16 at the time
of the Davis and Farinella's work) has led to a better
knowledge of their distribution
in the phase space and, consequently, to more reliable estimates
of the collisional probability and impact velocity.
Key words: minor planets -- comets -- Kuiper Belt
Offprint request: A. Dell'Oro, aldo@astr15pi.difi.unipi.it
© ESO 2001