A New Method for Deriving Composition of S-type Asteroids from Noisy and Incomplete Near-infrared Spectra
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Univ Arizona, Lunar & Planetary LabIssue Date
2020-03-06
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Juan A. Sanchez et al 2020 AJ 159 146Journal
ASTRONOMICAL JOURNALRights
Copyright © 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The surface composition of S-type asteroids can be determined using band parameters extracted from their near-infrared (NIR) spectra (0.7-2.50 mu m) along with spectral calibrations derived from laboratory samples. In the past, these empirical equations have been obtained by combining NIR spectra of meteorite samples with information about their composition and mineral abundance. For these equations to give accurate results, the characteristics of the laboratory spectra they are derived from should be similar to those of asteroid spectral data (i.e., similar signal-to-noise ratio (S/N) and wavelength range). Here we present new spectral calibrations that can be used to determine the mineral composition of ordinary chondrite-like S-type asteroids. Contrary to previous work, the S/N of the ordinary chondrite spectra used in this study has been decreased to recreate the S/N typically observed among asteroid spectra, allowing us to obtain more realistic results. In addition, the new equations have been derived for five wavelength ranges encompassed between 0.7 and 2.50 mu m, making it possible to determine the composition of asteroids with incomplete data. The new spectral calibrations were tested using band parameters measured from the NIR spectrum of asteroid (25143) Itokawa, and comparing the results with laboratory measurements of the returned samples. We found that the spectrally derived olivine and pyroxene chemistry, which are given by the molar contents of fayalite (Fa) and ferrosilite (Fs), are in excellent agreement with the mean values measured from the samples (Fa(28.61.1) and Fs(23.12.2)), with a maximum difference of 0.6 mol% for Fa and 1.4 mol% for Fs.ISSN
0004-6256Version
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-3881/ab723f