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Disintegration of Dust Aggregates in Interstellar Shocks and the Lifetime of Dust Grains in the ISMInterstellar grains are destroyed by shock waves moving through the ISM. In fact, the destruction of grains may be so effective that it is difficult to explain the observed abundance of dust in the ISM as a steady state between input of grains from stellar sources and destruction of grains in shocks. This is especially a problem for the larger grains. Therefore, the dust grains must be protected in some way. Jones et al. have already considered coatings and the increased post-shock drag effects for low density grains. In molecular clouds and dense clouds, coagulation of grains is an important process, and the largest interstellar grains may indeed be aggregates of smaller grains rather than homogeneous particles. This may provide a means to protect the larger grains, in that, in moderate velocity grain-grain collisions in a shock the aggregates may disintegrate rather than be vaporized. The released small particles are more resilient to shock destruction (except in fast shocks) and may reform larger grains later, recovering the observed size distribution. We have developed a model for the binding forces in grain aggregates and apply this model to the collisions between an aggregate and fast small grains. We discuss the results in the light of statistical collision probabilities and grain life times.
Document ID
20020006059
Document Type
Preprint (Draft being sent to journal)
Authors
Dominik, C. (NASA Ames Research Center Moffett Field, CA United States)
Jones, A. P. (California Univ. Berkeley, CA United States)
Tielens, A. G. G. M. (NASA Ames Research Center Moffett Field, CA United States)
Cuzzi, Jeff
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Astrophysics
Meeting Information
Shocks in AP(Manchester)
Funding Number(s)
PROJECT: RTOP 399-20-10-27
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.