IDENTIFICATION OF MAGNETITE IN B-TYPE ASTEROIDS
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)
- Department of Earth and Space Sciences, Institute for Geophysics and Planetary Physics and Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095 (United States)
Spectrally blue (B-type) asteroids are rare, with the second discovered asteroid, Pallas, being the largest and most famous example. We conducted a focused, infrared spectroscopic survey of B-type asteroids to search for water-related features in these objects. Our results show that the negative optical spectral slope of some B-type asteroids is due to the presence of a broad absorption band centered near 1.0 {mu}m. The 1 {mu}m band can be matched in position and shape using magnetite (Fe{sub 3}O{sub 4}), which is an important indicator of past aqueous alteration in the parent body. Furthermore, our observations of B-type asteroid (335) Roberta in the 3 {mu}m region reveal an absorption feature centered at 2.9 {mu}m, which is consistent with the absorption due to phyllosilicates (another hydration product) observed in CI chondrites. The new observations suggest that at least some B-type asteroids are likely to have incorporated significant amounts of water ice and to have experienced intensive aqueous alteration.
- OSTI ID:
- 21443251
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 140, Issue 3; Other Information: DOI: 10.1088/0004-6256/140/3/692; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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