| Apresentação/Painel: | |
| Autor: | Thais Mothé-Diniz1 |
| David Nesvorny1 | |
| Daniela Lazzaro2 | |
| Jorge Marcio Carvano2 | |
| Flavia Luzia Jasmin2 | |
| Amelia Ramirez3 | |
| Instituição: | 1OV/UFRJ - Rio de Janeiro |
| 2ON/MCT - Rio de Janeiro | |
| 3Universidad de La Serena | |
| Formato: | Painel |
| Título: | Spectroscopy of "small" and faint small-bodies with Gemini telescopes: interesting results and perspectives |
| Resumo: | Investigation of Solar System bodies such as asteroids and comets allows us to understand better the formation of the Solar System, and its further dynamical and physical evolution. Visible and near-infrared spectroscopy is a good and consolidated tool for acquiring some knowledge on how such evolutionary processes took place, through the study of the possible mineralogical features in the spectra of the small bodies, in comparison with our knowledge about minerals found on Earth and on meteorites. Silicates like pyroxene and olivine are among the most common material found in asteroids, and present very clear, broad and deep absorptions around 1.0 and/or 2.0 microns. According to the slope of the visible continuum and the characteristics of the absorptions, spectra of asteroids are classified into taxonomic classes. At the same time, according to dynamical properties, they can be grouped into "families", which are the result of the breakup of a larger body and, as so, its members are expected to share spectroscopic properties compatible with either a differentiated or a primitive parent-body. Amongst the biggest problems in solar system research is the topic of finding the asteroid spectroscopic proxies for the most common class of meteorites which fall on Earth: the Ordinary Chondrites (OC hereafter). The apparent lack of OC material among asteroids have been attributed to the space weathering effect - which is the time-dependent modification of an asteroid's reflectance spectrum, caused by effects like micrometeorite impacts or solar wind particles implantation - acting on the most common class of asteroids in the main-belt, the S-types. The smallest of the asteroids are, in its majority, results of more recent collisions, and had less time to expose their surfaces to space weathering effects. Therefore, observing objects of very small sizes (< 5 km) and families recently formed, was necessary to look for more "fresh" surfaces. In this talk the spectroscopic data obtained with the GMOS spectrographs at GEMINI South and North will be presented, and three interesting results examined. These data were obtained under the programs GS-2007A-C-6, GS-2007B-Q-7, GN-2007B-Q-67, which were awarded a total of 3 nights in classical mode, and 14 hours in queue mode. One night of the classical mode was lost due to technical problems with the instrument. Nevertheless, exciting results were achieved, and the first spectra similar to OC mineralogies were found in the Main Belt of asteroids, among extremely young asteroid families (Mothé-Diniz & Nesvorny, 2008a). Another result concerns the surface characterization of one asteroid family in the outer main belt, Tirela Family (Mothé-Diniz & Nesvorny, 2008b). Another part of the data from these programs belongs to the search for OC mineralogies among small sized-asteroids. The spectra have been analysed, and a paper is under preparation. The results will also be reported and perspectives discussed. |
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