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Mid-infrared spectral variability for compositionally similar asteroids: Implications for asteroid particle size distributions

Vernazza, P und Carry, B und Emery, J. und Hora, J.L. und Cruikshank, D. und Binzel, R.P. und Jackson, J. und Helbert, Jörn und Maturilli, Alessandro (2010) Mid-infrared spectral variability for compositionally similar asteroids: Implications for asteroid particle size distributions. Icarus: International Journal of Solar System Studies, 207 (2). Elsevier. DOI: 10.1016/j.icarus.2010.01.011

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We report an unexpected variability among mid-infrared spectra (IRTF and Spitzer data) of eight S-type asteroids for which all other remote sensing interpretations (e.g. VNIR spectroscopy, albedo) yield similar compositions. Compositional fitting making use of their mid-IR spectra only yields surprising alternative conclusions: (1) these objects are not “compositionally similar” as the inferred abundances of their main surface minerals (olivine and pyroxene) differ from one another by 35% and (2) carbonaceous chondrite and ordinary chondrite meteorites provide an equally good match to each asteroid spectrum. Following the laboratory work of Ramsey and Christensen (Ramsey, M.S., Christensen, P.R. [1998]. J. Geophys. Res. 103, 577-596), we interpret this variability to be physically caused by differences in surface particle size and/or the effect of space weathering processes. Our results suggest that the observed asteroids must be covered with very fine (<5 μm) dust that masks some major and most minor spectral features. We speculate that the compositional analysis may be improved with a spectral library containing a wide variety of well characterized spectra (e.g., olivine, orthopyroxene, feldspar, iron, etc.) obtained from very fine powders. In addition to the grain size effect, space weathering processes may contribute as well to the reduction of the spectral contrast. This can be directly tested via new laboratory irradiation experiments.

Titel:Mid-infrared spectral variability for compositionally similar asteroids: Implications for asteroid particle size distributions
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID
Carry, BObservatoire de ParisNICHT SPEZIFIZIERT
Emery, J.Department of Earth and Planetary Sciences, Knoxville, TN 37996-1410, USANICHT SPEZIFIZIERT
Hora, J.L.Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USANICHT SPEZIFIZIERT
Cruikshank, D.NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035, USANICHT SPEZIFIZIERT
Binzel, R.P.Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA 02139, USANICHT SPEZIFIZIERT
Jackson, J.Institute for Astrophysical Research, Boston University, Boston, MA 02215, USANICHT SPEZIFIZIERT
Helbert, Jörnjoern.helbert@dlr.deNICHT SPEZIFIZIERT
Maturilli, Alessandroalessandro.maturilli@dlr.deNICHT SPEZIFIZIERT
Datum:Juni 2010
Erschienen in:Icarus: International Journal of Solar System Studies
Referierte Publikation:Ja
In Open Access:Nein
In ISI Web of Science:Ja
DOI :10.1016/j.icarus.2010.01.011
Stichwörter:Asteroiden, Spektroskopie
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Raumfahrt
HGF - Programmthema:Erforschung des Weltraums
DLR - Schwerpunkt:Raumfahrt
DLR - Forschungsgebiet:R EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):R - Vorhaben Exploration des Sonnensystems
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung > Terahertz- und Infrarotsensorik
Hinterlegt von: Helbert, Dr.rer.nat. Jörn
Hinterlegt am:08 Nov 2011 10:28
Letzte Änderung:20 Mär 2013 19:44

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