The mineralogical composition of asteroids can be constrained using visible and near-IR (VNIR) spectroscopy. The most prominent spectral features observed over this wavelength range are due to olivine and pyroxene, the two most abundant minerals in both chondritic and achondritic meteorites. The observed ratio of these two minerals is highly dependent on the amount of heating that an asteroid has undergone. The 1-micron band minimum and the band area ratio between the 2- and 1-micron bands (BAR) reveal relative abundances of olivine and/or pyroxene on an asteroid surface (Gaffey et al. 1993, Icarus 106:573). A large sample of S-, A-, V-, and R-type asteroid spectra was collected over the visible and near-IR wavelengths during the second phase of the Small Main-belt Asteroid Spectroscopic Survey (Bus and Binzel 2002, Icarus 158:106) and using the low-resolution SpeX spectrograph (Rayner et al. 2003, PASP 115:362) at NASA's Infrared Telescope Facility (IRTF). Here we present a methodology for calculating the location of the 1-micron band minimum and BAR with appropriate 1- sigma uncertainties. This method was used to characterize approximately 200 S-type asteroids throughout the main belt. We will also present the distribution of olivine / pyroxene throughout the main belt by measuring how the S-type mineralogy varies with heliocentric distance. This will provide a better understanding of both the thermal processing across the main belt and subsequent mixing of asteroids through collisional and dynamical processes.This work was conducted through a Research Experience for Undergraduates (REU) position at the University of Hawaii's Institute for Astronomy and funded by the NSF.
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007