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Abstract:
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Asteroid families are populations of asteroids in the Main Belt that share a common
origin, that is they are the fragments of energetic collisions between two asteroids.
Their study over the years has produced a number of important results concerning
the collisional and dynamical evolution of the Main Belt, the physical properties of
the primordial bodies of the Solar System and the physics of energetic collisions, to
name a few.
The contribution of the present thesis can be summarized into two main topics: The
first is the discovery of a new mechanism that leads to significant perturbations
on the orbits of asteroids, and consequently on the evolution of asteroid families
affected by it, and the second is the discovery of a couple of new families, each with
its own peculiarities.
The first part of this thesis was initially motivated by the irregular shape of the
(1726) Hoffmeister asteroid family. In an effort to explain this peculiarity we carried
out a thorough dynamical analysis of its past evolution and found out that none of
the mechanisms known to affect the orbits of asteroids could explain it. Investigating
further we discovered that the linear nodal secular resonance with the most massive
asteroid (1) Ceres, is the mechanism responsible for the anisotropic inclination
distribution of Hoffmeister family members.
Having established the importance of the nodal secular resonance with Ceres, we
sought to expand on the subject with the study of all linear secular resonances,
nodal and periapsidal, involving not only (1) Ceres, but (4) Vesta, the second
most massive asteroid, as well. To do so we utilized numerical integrations of test
particles across the whole Main Belt, and evaluated the impact of these resonances
on their orbits. Furthermore we identified all asteroid families crossed by one or
more of these resonances. Two of these cases, the families of (1251) Seinajoki and
(1128) Astrid were then studied in more detail, confirming the importance of the
previously ignored secular resonances with massive asteroids.
The second part details the discovery of two new asteroid families. The first one,
that of (326) Tamara family, was motivated by the unexpectedly high number of
dark asteroids in the Phocaea region, a part of the inner Main Belt which is expected
to consist mostly of bright ones. Using all available physical data we were able to
show that most of the dark asteroids therein belong to a single dynamical family,
which we then further analyzed finding that it is
264
±
43
Myrs old and that it could
have a significant contribution to the influx of small dark asteroids toward the Near
Earth region. The second discovered family, that of (633) Zelima, is a small cluster,
sub-family of the large (221) Eos family. After identifying its members, we derived
the age of the Zelima family, which turned out to be only about 3.66 Myrs. |