Near-infrared spectroscopy of 3:1 Kirkwood Gap asteroids III

•A mineralogical assessment of 14 asteroids was completed.•Two asteroids with L-chondrite surface assemblages were identified.•Three asteroids’ compositions are consistent with olivine-orthopyroxenitic diogenites.•Three asteroids’ compositions are consistent with harzburgitic diogenites. The researc...

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Veröffentlicht in:Icarus (New York, N.Y. 1962) N.Y. 1962), 2015-09, Vol.257, p.113-125
Hauptverfasser: Fieber-Beyer, Sherry K., Gaffey, Michael J.
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Sprache:eng
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Zusammenfassung:•A mineralogical assessment of 14 asteroids was completed.•Two asteroids with L-chondrite surface assemblages were identified.•Three asteroids’ compositions are consistent with olivine-orthopyroxenitic diogenites.•Three asteroids’ compositions are consistent with harzburgitic diogenites. The research is an integrated effort beginning with telescopic observations and extending through detailed mineralogical characterizations to provide constraints on the composition and meteorite affinities of a subset of fourteen asteroids in/near the 3:1 Kirkwood Gap. Eight asteroids were identified as having either one or two absorption features, while six were deemed featureless. The compositional analysis of Asteroids (355) Gabriella and (1447) Utra reveal Fs and Fa values which are consistent with values for the L-type ordinary chondrites (Fs19–22 and Fa22–26). The location of these two bodies with respect to each other and to the previously identified L-chondrite parent body Asteroid (1722) Goffin, suggests a small L-chondrite genetic family. These results support the model that the L-chondrites come from an asteroid family rather than from a single object. Asteroids (1368) Numidia, (1587) Kahrstadt, (1854) Skvortsov, (2497) Kulikovskij, and (5676) Voltaire were analyzed and determined to have “basaltic” silicate mineralogies similar to those of the HED (howardite–eucrite–diogenite) meteorite group. In particular, we found that the compositions of (1368), (1587) and (1854) are consistent with olivine-orthopyroxenitic diogenites, while (2497) and (5676)’s compositions are consistent with harzburgitic diogenites. The Band I and Band II absorption feature depths are much shallower than seen in diogenite spectra, typically ∼70% depth (Burbine, T.H. et al. [2000]. Forging asteroid–meteorite relationships through reflectance spectroscopy. Lunar Planet. Sci. XXXI. Abstract 1844). The nature of the weak features seen in the asteroid spectra when compared to measured band depths of in situ diogenite samples indicate an additional mechanism(s) acting to weaken the features, most likely space weathering. The aforementioned five asteroids are plausible sources for the olivine-orthopyroxenitic diogenites and harzburgitic diogenites, and very well may be fragments of Vesta. Asteroid (46) Hestia is an interesting object whose surface minerals may be consistent with a CR2 chondrite; however, the unique spectrum deserves further study in the future. Featureless Asteroids (248) Lameia
ISSN:0019-1035
1090-2643
DOI:10.1016/j.icarus.2015.04.034