Destruction mechanisms for interstellar dust

Abstract

Destruction rates are estimated for interstellar dust grains as a function of size and composition of the grains, and the type of region in which the grain is located. Several idealized models of the interstellar medium are considered. The destruction mechanisms examined include sputtering and grain-grain collisions in interstellar shocks, sputtering and sublimation in H II regions, photodesorption by UV, sputtering by cosmic rays, and sublimation during a supernova radiation pulse. Sublimation by the supernova radiation pulse is found to be very important for the more volatile mantle materials (binding energy U/sub o/ or =150 km s/sup -1/) shocks and grain-grain collisions in low-velocity (upsilon/sub s/< or =50 km s/sup -1/) shocks account for most refractory grain destruction. Polymerized ''HCO-material'' is almost as resistant to sputtering as refractory grains. Water icemantles may be marginally able to survive in low-density H II regions (n/sub H/< or approx. =10 cm/sup -3/), especially if the gas temperature is T< or approx. =10/sup 3.8/ K. The implicationsmore » of these destruction rates for the survival of interstellar grains are briefly discussed.« less