Spectral properties of nine M-type asteroids

• Published in: Astronomy and astrophysics (Berlin) 2007-11, Vol.475 (2), p.747-754
• Main Authors: Birlan, M., Vernazza, P., Nedelcu, D. A.
• Format: Article
• Language: English
• Subjects: asteroids; Astronomy; Astrophysics; Earth and Planetary Astrophysics; Earth, ocean, space; Exact sciences and technology; minor planets; Physics; Sciences of the Universe
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361:20077914

Aims. We present spectroscopic results for nine M-type asteroids (325 Heidelberga, 497 Iva, 558 Carmen, 687 Tinette, 766 Moguntia, 860 Ursina, 909 Ulla, 1280 Baillauda, and 1564 Srbija) in the 0.8-2.5 μm spectral region. One visible spectrum is also presented for the asteroid 497 Iva. These asteroids were observed during several runs between 2003 and 2007, and the main goal was to investigate the NIR spectral region of M-type asteroids. Methods. The data was obtained with SpeX/IRTF in Prism mode and Dolores/TNG in LR-B mode. Spectral analysis was performed by comparing the M-type spectra and the meteorite ones ($\chi^2$ approach) and the Modified Gaussian Model. Results. With one exception, the asteroids present positive slopes of the spectra, with no absorption features, in good agreement with the spectra of metallic meteorites. The analysis of the asteroid 766 Moguntia was done by means of $\chi^2$, MGM techniques, and the Shkuratov scattering law. We conclude that the mineralogy is dominated by olivine. Its NIR spectrum is similar to those of CO/CV meteorites.