Propriedades Físicas de Asteroides

Abstract

In order to contribute to a better understanding of the origin and evolution from different populations of small bodies, we did studies about some physical properties both obtained and from our observations. Initially, it was studied the rotational frequency distributions of the asteroids, from both populations Main Belt and the near-Earth regions (NEA), because it could provide evidence regarding the formation and evolution process of them. Opposed to the currently accepted, that the distributions of the biggest follow a tridimensional Maxwellian distribution, indicative of the system collisionally evolved, we find that the distribution dimensionality is more complex. In the case of smaller the distribution is consistent with dimensionality two, while to the biggers is not possible reach conclusion. The best fit to the NEAs, on the other hand, is a Maxwellian unidimensional distribution. We suggest that in the case of the biggest asteroids the bidimensionality could be associated with the formation in the protoplanetary disk, while for the NEAs, of the smaller size, your rotations are affected by YORP effect. A second study was in order a better understanding of the origin of the small basaltic asteroids found along Main Belt through the increase of the spectral properties known. Initially, we obtained spectra in the visible to 18 asteroids in the middle and out Main Belt regions, which are candidates for basaltic composition. The spectral parameters obtained look like to indicate that the asteroids from the internal region and from the Vesta family have distinct mineralogical composition than the objects from other regions. Some of these asteroids are members of the (221) Eos dynamical family, suggesting that this asteroid would be differentiated, the possibility has already been raised by other authors. In another study, we obtained spectra in the visible and in the near-infrared for six asteroids candidates to basaltic composition, or V-type, outside Vesta family and identified by colors (Y-J) e (J-Ks) from MOVIS catalog. We determined your spectral parameters and we compare with parameters of the HED meteorites, (4) Vesta and (1459) Magnya, the first basaltic asteroid in the outer Main Belt region. Most asteroids show spectral parameters similar to the HED meteorites and (4) Vesta, and only (2452) Lyot, located at the outer region, exhibit molar contents [Wo] and [Fs] lower, even from (1459) Magnya. We noted also that the values of the band area ratio change if, before the computation, we remove or not the continuum. Going on the study of the V-type asteroid population, aiming to empose bonds about your origin, we move to study the superficial properties obtained from phase curves. We began the study by an asteroid member of the Vesta family the wich because of the small size like the other basaltic objects in the Main Belt, could be to define the superficial parameters from the objects originating from (4) Vesta. These parameters would be compared to those (4) Vesta and V-type asteroids of the other Main Belt regions from literature. However, this comparison indicated to be very complex that both in the case of there are few phase curves available in the literature and the various models utilized by distinct authors. The phase curve obtained in this work to asteroid (4038) Kristina also have not completeness necessary to determine with accuracy the superficial parameters to the asteroid.