| Abstract: | Abstract— Melting and degassing of interplanetary dust particle L2005B22 at ～1200 °C was due to flash heating during atmospheric entry. Preservation of the porous particle texture supports rapid quenching from the peak heating temperature whereby olivine and pyroxene nanocrystals (3 nm-26 nm) show partial devitrification of the quenched melt at T ? 450 °C–740 °C. The implied ultrahigh cooling rates are calculated at ～105 °C/h–106 °C/h, which is consistent with quench rates inferred from the temperature-time profiles based on atmospheric entry heating models. A vesicular rim on a nonstoichiometric relic forsterite grain in this particle represents either evaporative magnesium loss during flash heating or thermally annealed ion implantation texture. |
