EDP Sciences
Free access
Volume 443, Number 3, December I 2005
Page(s) 769 - 775
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20053525

A&A 443, 769-775 (2005)
DOI: 10.1051/0004-6361:20053525

Space weathering of near-Earth and main belt silicate-rich asteroids: observations and ion irradiation experiments

S. Marchi1, R. Brunetto2, 3, S. Magrin1, M. Lazzarin1 and D. Gandolfi4

1  Dipartimento di Astronomia, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
    e-mail: [marchi;s.magrin;lazzarin]@pd.astro.it
2  Dipartimento di Fisica, Università di Lecce, via Arnesano, 73100 Lecce, Italy
    e-mail: rbrunetto@ct.astro.it
3  INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
4  Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 78, 95123 Catania, Italy
    e-mail: dgandolfi@ct.astro.it

(Received 26 May 2005 / Accepted 29 July 2005)

In this paper we report the results of a comparison between ion irradiation experiments (N+, Ar+, Ar++) on silicates, a large spectral data set of silicate-rich (S-type) asteroids, and ordinary chondrite meteorites (OCs). Ion irradiation experiments - conducted on Fe-poor olivine, Fe-poor orthopyroxene, bulk silicate-rich rocks and one OC - have been monitored by means of reflectance spectroscopy (0.3-2.5 $\mu$m). All these experiments produce reddening and darkening of reflectance spectra. The observational data consist of a set of visible and near-infrared (0.4-2.4 $\mu$m) spectra of S-type asteroids, that belong to main belt (MBAs) and near-Earth (NEOs) populations. By analyzing the spectra of OCs, MBAs, and NEOs, we find a similar mineralogy between most asteroids and meteorites, but different distributions of spectral slopes. We interpret these findings in the frame of space weathering induced by solar wind ion irradiation.

Key words: minor planets, asteroids -- meteors, meteoroids

© ESO 2005