Compositional properties of Near-Earth Asteroids: spectroscopic comparison with Ordinary Chondrite Meteorites (original) (raw)
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Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites
Astronomy and Astrophysics Supplement Series, 1999
In the last year we have started a spectroscopic investigation of asteroids located in the region of the mainbelt between about 2.2 and 3.6 AU. The aim of this work is to study the aqueous alteration process which acted in that zone, dominated by low albedo C-type asteroids, and to compare the spectra of these hydrous objects with those of CM2 carbonaceous chondrite meteorites. In fact, the spectra of these meteorites reveal features probably due to aqueous altered materials on their surfaces. The study of the aqueous alteration process can give important information on the chemical and thermal evolution of the earliest Solar System. More that 65% of the investigated objects have revealed features suggesting the presence of hydrous materials. The comparison of the spectra of the hydrated asteroids obtained to date with those of several CM2 carbonaceous chondrite meteorites seems to indicate that aqueous altered asteroids could be the parents of CM2 meteorites. The data have been obtained during several observational runs at the Asiago Observatory with the 1.8 m telescope and at ESO-LaSilla with the 1.5 m telescope.
Spectrophotometric Studies of Near-Earth and Main-Belt Asteroids
Moscow University Physics Bulletin, 2019
The reflectance spectra of five near-Earth asteroids, one Mars crosser, and four classical asteroids of the main belt in the range 0.35-0.95 μm have been observed, calculated, and analyzed. Asteroids with a magnitude up to 17 were observed in 2013-2017 with a 2-m telescope with a CCD spectrograph with extremely low spectral resolution (R ∼ 100) of the Terskol Observatory of the Institute of Astronomy of the Russian Academy of Sciences in order to determine their taxonomic types and composition. These results show that the composition of some of the studied near-Earth asteroids is heterogeneous judging by the variations in their reflectance spectra within adjacent taxonomic classes. It is notable that some of these asteroids are binary. The physical and chemical-mineralogical interpretation of reflectance spectra is presented.
Astronomy and Astrophysics, 2010
Aims. We analyse a significantly large sample of spectroscopic data to provide a compositional characterization of the near-Earth asteroid population. We present visible and near-infrared spectra of a total of 74 near-Earth asteroids (NEAs) and Mars-crossers (MCs), covering the wavelength region from 0.5 to 2.5 μm. Using spectra of NEAs from other databases to enlarge our sample, and compiling two comparison samples of main belt asteroids (MBs) and ordinary chondrites (OCs), we analyse a total of 79 NEAs, 91 MBs, and 103 OCs. Methods. We obtained our visible and near-infrared spectra using the instruments and the telescopes located at "El Roque de los Muchachos" Observatory, in the island of La Palma (Spain). We compute several diagnostic spectral parameters from the reflectance spectra of NEAs, MBs, and OCs, that are used to infer the mineralogical composition. The distribution of the obtained values are analysed in 2 different parameter spaces. We also apply a robust statistical method based on neuronal networks to those spectral parameters, to compare the NEAs with OCs. Space weathering effects and dynamical and physical properties of NEAs and MBs are also studied. Results. Compositional differences between MBs and NEAs are inferred from the mineralogical analysis. The most remarkable results are: (1) the high olivine content of the NEAs; (2) the compositional similarity between NEAs and a small group of meteorites, the LL ordinary chondrites; and (3) that NEAs are not compositionally similar to OCs, implying that they are not the most likely parent bodies of those meteorites, as has been widely believed. To explain their apparently fresh surfaces (NEAs are on average less red than MBs), a combination of composition and size distribution (NEAs have diameters of some kilometres) should be invoked. Dynamical models applied to our sample of NEAs indicate that most of them originate in the inner part of the main belt, as expected.