Seminars at FGG

Asteroid-Meteorite Connections Among the Hungaria Region Asteroids: Correlations with Primitive Achondrites?

Speaker: Michael P. Lucas (Department of Earth and Planetary Sciences, University of Tennessee)

Date and time: 2014-05-09 11:30

The Hungaria region of asteroids is a poorly understood population both compositionally and dynamically. Among asteroids with semi-major axes interior to the main-belt (e.g., Hungarias, Mars-crossers, and near-Earth asteroids), only the Hungarias are located in relatively stable orbital space. Thus, these objects may represent the closest remaining reservoir of the material that accreted to form the terrestrial planets. Deciphering the mineralogy of Hungaria asteroids may place constraints on the nature of this material. We hypothesize that planetesimals in the inner part of the solar nebula (terrestrial planet region) underwent significant melting - the Hungaria region should retain this petrologically-evolved material. To test this hypothesis we have undertaken a near-infrared (NIR) spectral survey of Hungaria asteroids to characterize their compositional diversity and to forge connections with analogous meteorite groups. Thus far, we have acquired NIR spectra for a sample of 30 objects. Preliminary results indicate a compositionally diverse Hungaria background population dominated by S- and S-subtypes. Spectral band parameter analyses of 18 of these S-types show that two main meteorite groups appear to be represented, unmelted ordinary chondrites; and the partially-melted primitive achondrite meteorites acapulcoites/lodranites. Furthermore, four asteroids in or near the family zone are likely Xe-types, consistent with the largest collisional fragment 434 Hungaria. Xe-types in the Hungaria region are thought to be related to the fully-melted enstatite achondrite meteorites (aubrites). These spectral comparisons suggest that at least some objects in the Hungaria region have experienced low- to high-degrees of petrologic evolution.

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