Session C3 - Astrophysics and Cosmology.
FOCUS session, Monday afternoon, June 25
Building 4, Room 153,
Sputtering from grains with a size of tens of nanometers is important in a number of astrophysical scenarios [1]. Since excitations produced in a small, volatile grain by a cosmic ray ion can create `hot spots', thermal spike models have been applied to estimate the sputtering. However, these models work only over a very limited regime [2]. We use Molecular Dynamics (MD) calculations [3] to describe the energy transport and sputtering due to these `hot spots' in a grain with one quarter million particles, as a function of the energy deposited in the grain. We compare our results to the spike model as applied in [1] to the sputtering of small dust grains following the formation of a `hot spot', a model widely used in the astronomical community. We present a new model to estimate the final sputtering yield, and find that the sputtering of water could be several orders of magnitude larger than expected from previous models [1].
1-T. Hasegawa and E. Herbst, Mon. Not. R. Astron. Soc. \bf261 (1993) 83.
2-E. M. Bringa, R. E. Johnson and M. Jakas, Phys. Rev. B \bf60 (1999) 15107.
3-http://dirac.ms.virginia.edu/\~emb3t/grains/grains.html