date: 2012 July 11 (Wed) 15:00-16:00
room: CPS Conference Room
speaker: Tomoko Arai (Chitec)
organizer: Hiroshi Kimura
title: Partial differentiation of asteroids inferred from meteors and meteorites
abstract: Na depletion/variation relative to the solar abundance is reported for the Geminid meteor shower, whose parent is a B(F)-type asteroid 3200 Phaethon. Since the grain size of the dust is 1-10 mm, the Na depletion/variation occurs in the mm-cm scale, which is consistent with the mineralogical observation in primitive achondrites. The Na depletion/variation is likely originated from the chemical signature of the parent asteroid, not from solar heating, because the surface temperature estimated at its perihelion is not high enough to cause Na loss. An incipient partial melting may have occurred in Phaethon, which is an active asteroid.
keywords: Asteroids, meteors, meteorites, partial melting, planetary differentiation