NIR spectral and mineralogic studies of nine Vp-type asteroids: 7 likely Vestoids and 2 likely new outer belt basaltic asteroid candidates
Abstract
Nine additional Vp-type asteroids as candidate basaltic asteroids were observed at the NASA Infrared Telescope Facility (IRTF) from January 15-19, 2015 UT, as part of a continuing NASA Planetary Astronomy Program grant to better characterize the abundance and distribution of basaltic asteroids in the main asteroid belt. The Vp-type asteroids, which are classified based on Sloan ugriz colors and the subsequent coarse visible-wavelength spectra that results, includes: (2168) Swope, (3715) Stohl, (3849) Incidentia, (5754) 1999 FR2, (10666) Feldberg, (19165) 1991 CD, (34698) 2001 OD22, and (36118) 1999 RE135. The first seven of these Vp-type asteroids either reside near (4) Vesta dynamical space or are located within the 3:1 mean-motion resonance. The latter two Vp-type asteroids are located beyond the 3:1 mean-motion resonance. NIR spectra were obtained using SpeX in prism mode (0.7 to 2.5 microns) at the parallactic angle using the 0.8 arsec slit. Seven of the Vp-type asteroids were observed on two nights while (2168) Swope was observed on three nights and (19165) 1991 CD was observed on a single night. Average near-infrared (NIR) reflectance spectra of the asteroids were analyzed using MATLAB-based (Reddy et al., 2011) and IDL-based SARA (Lindsay et al., 2013) routines to isolate absorption features and measure band centers, band areas, and band depths. Temperature corrections were applied to band centers to allow comparison with HED meteorite band parameters. Initial results indicate that all nine asteroids exhibit similar spectral band centers and Band Area Ratios (BAR) across different nights with little or no significant variation. The MATLAB and SARA analysis routines also produce similar results for all nine asteroids. All nine asteroids exhibit BAR values consistent with basaltic achondrites or exhibit larger values beyond the BAR zone as found in Gaffey et al. (1993). WISE-derived albedos for these asteroids range from 24-50%. Initial analysis indicates that the seven inner-belt Vp-type asteroids are likely Vestoids and are associated with (4) Vesta while (34698) and (36118) are new candidates for outer-belt basaltic asteroids.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #47
- Pub Date:
- November 2015
- Bibcode:
- 2015DPS....4710601H