Collisional Consequences of Big Interstellar Grains

E. Grün, M. Landgraf (MPI für Kernphysik Heidelberg)

Identification by Ulysses of interstellar grains inside the planetary system provides new window for study of the local interstellar medium. Dust particles found by Ulysses and confirmed by Galileo are bigger ( tex2html_wrap_inline16 ) than the typical interstellar grains ( tex2html_wrap_inline18 ). Recently even bigger (about tex2html_wrap_inline20 ) interstellar meteors have been identified (Taylor et al., Nature, 380, 323, 1996). The goal of this analysis is the investigation of collisional effects of big interstellar grains. Interstellar dust is conventionally described by the MRN size distribution (Mathis, Rumpl and Nordsieck, ApJ, 217, 105, 1977) ranging from 5 to tex2html_wrap_inline24 in size (about tex2html_wrap_inline26 to tex2html_wrap_inline28 ). On the basis of this size distribution Jones et al. (ApJ, 469, 740, 1996) find that collisional shattering is a source of the smallest of these grains, but grains bigger than about tex2html_wrap_inline30 are rapidly depleted. In this study it is investigated whether collisions with the newly found bigger particles could provide a source for the classic interstellar grains, thereby, solving the mystery of the rapid destruction times of interstellar grains compared to the transport and injection times of grains into the diffuse interstellar medium.