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.


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