Destruction mechanisms for interstellar dust.

Various dust-grain destruction mechanisms that may be important in different components of the interstellar medium (ISM) are studied. Destruction rates for grains are estimated as a function of size, composition, and type of region in which the grains are located, and the relative importance of the different mechanisms is evaluated. Grain destruction behind steady-state shock waves is examined, grain motion and sputtering in the cooling postshock gas is analyzed, and numerical results for the fractional grain mass sputtered are given for various preshock conditions, grain types and sizes, and shock speeds of 10 to 350 km/s. Grain sputtering in spherically symmetric supernova remnants is investigated as a function of supernova energy and ambient density. The results are applied to consider the destruction of grains (1) in collisions between randomly moving interstellar clouds; (2) in supernovae in a 'one-phase', a 'two-phase', and a 'three-phase' ISM; (3) by sputtering in H II regions; (4) by cosmic-ray sputtering; (5) by UV photodesorption; and (6) by sublimation of volatile mantles from grains heated in H II regions or by supernova radiation.