Vesta: The first pyroxene band from new spectroscopic measurements |
| |
| Authors: | Lucy A McFadden Thomas B McCord Carlē Pieters |
| |
| Institution: | 1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA;2. Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA |
| |
| Abstract: | New spectral reflectance measurements of asteroid 4 Vesta were obtained using a silicon vidicon spectrometer with a resolution of 0.002–0.004 μm. The major absorption band in the near infrared has a minimum at 0.924 ± 0.004 μm with a bandwidth of 0.18 μm full width at half power (fwhp). The band represents a 30% absorption relative to peak reflectance at 0.75 μm. The absorption band has been interpreted to be due to electronic absorptions in ferrous iron in sixfold coordination in the pyroxene, pigeonite. The increased spectral resolution of these observations compared to earlier spectrophotometry enables us to refine the pyroxene composition, from the position of the Fe2+ absorption band, and arrive at a relative calcium content Ca/(Mg + Fe + Ca)] of 10–12%. The absorption band is symmetric about its center, implying the presence of little or no olivine. The existence of the 2.0-μm pyroxene band which was verified by Larson and Fink (1975) confirms the interpretation based on the 1.0-μm band. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
