Aldo Dell'Oro's Home Page
Research interests and activities
The study of minor bodies of our Solar System, and in particular
the asteroids, has experienced an intense development over
the last decade. Asteroids is an interdisciplinary topic that not only
concerns Astronomy, Astrophysics
and Celestial Mechanics, but also Geology, Chemistry and
Physics of Materials. Recent studies have highlighted the extreme
complexity of the physical mechanisms that underlie the formation
and evolution of these objects, leading to large changes of paradigm
in the interpretation of observational data.
Theoretical researches concerining the collisional evolution of
asteroids are conducted at the Observatory of Arcetri. The
gravitational perturbations of the planets of the Solar System
produce continuous changes, on astronomical time scales,
on the orbits of the asteroids, which in turn determine the
possibility of orbital intersections and collisions between those
bodies
In the Main Belt (the part of the Solar System between the orbits of
Mars and Jupiter in which the large majority of
asteroids reside) collisions among asteroids at velocities of the
order of 5 km/s occur for billions of years.
These collisions cause
the fragmentation of these bodies and the formation
of group of new bodies (the fragments) observed today
as dynamic groups of asteroids with orbits very similar
(Asteroid Families). The goal the research is to understand
how the overall characteristics of the population evolve, and in
particular the
size distribution and periods of rotation. To achieve this result a
deep knowledge of the statistics of
collisions and the physics of fragmentation is needed.
In recent years it has been shown that the evolution of
asteroids is dominated not only by the mutual collisions, but also by
non-gravitational dynamical effects, as the Yarkovsky effect and the
YORP effect. These mechanisms of surface heating by
of the solar radiation and the subsequent re-emission of thermal radiation,
in combination with the intrinsic rotation of asteroids,
are able to modify appreciably the orbits and rotation
of the same objects. These effects, together with the planetary
perturbations, play a crucial role in the
transfer of asteroids from the Main Belt to the region of the
inner planets, i.e. with respect to the formation of
asteroids with orbits similar to Earth's (Near Earth
Asteroids).
All these issues are studied in a single framework
that links the physics of impact and fragmentation
(investigated both in laboratory and with theoretical models) with the
dynamics of the Solar System and the physics of the interaction of
radiation with matter.
Finally, the Observatory is involved in the preparation of the Gaia
space. Although Gaia has been mainly designed for the
study of the structure of our Galaxy, it will observe about
half a million asteroids. Thanks to its enormous astrometric
precision, Gaia will provide us measurements of the orbits of asteroids
so accurate to allow to detect the effects of their
mutual gravitational perturbations, from which
the mass of a hundred asteroids will be estimated with errors of less than
30% (and for the largest ones below 10%). In addition, on the basis of
the disk-integrated photometry it will be possible to determine the period of
rotation and the direction of the axes (as well as information about
the shape)
for tens of thousands of asteroids. Gaia will contribute to the
study of minor bodies, even indirectly, after the end of
mission. Thanks to the precision in determining the orbits will be
possible to perform subsequently a large number of observations from
land of stellar occultations by asteroids, from which to obtain
direct measurements of the size of the objects. Moreover, thanks
accuracy in the determination of the positions and proper motions
of the stars near the Sun, it will be possible to carry out detailed studies
about the interaction between the interstellar environment and the
Oort cloud, with great impacts on the study of comets.
Contacts
Aldo Dell'Oro
Staff researcher
Istituto Nazionale di Astrofisica (INAF)
Osservatorio Astrofisico di Arcetri
Largo Enrico Fermi, 5
I-50125 Firenze (FI), Italy
Tel: +39 055 27 52 252
Fax: +39 055 22 00 39
E-mail: aldo.delloro@inaf.it