Volume 527, March 2011
|Number of page(s)||10|
|Section||Interstellar and circumstellar matter|
|Published online||08 February 2011|
Shocks in dense clouds
III. Dust processing and feedback effects in C-type shocks
Institut d’Astrophysique Spatiale (IAS), Bâtiment 121, Université Paris-Sud
11 and CNRS,
Received: 21 October 2010
Accepted: 29 December 2010
Aims. We study the impact of grain-grain collisions in C-type shocks propagating in dense clouds (nH ≥ 104 cm-3) on the evolution of the dust size distribution, the shock dynamics and the release of chemical species into the gas phase such as SiO.
Methods. Our shock code for transverse C-type shocks is extended to self-consistently couple the charge, dynamics and evolution of the size distributions of silicate and carbon grains with the shock dynamics. Dust processes included are sputtering in gas-grain collisions, vaporisation and shattering in grain-grain collisions.
Results. Grain shattering and its feedback onto the dynamics of C-type shocks is found to be only significant at densities higher than ~105 cm-3. Numerous small grains are produced in the shock through the fragmentation of large grains. C shocks are therefore shorter and warmer when shattering is included. Vaporisation is more efficient than sputtering at destroying grain cores. In particular, vaporisation destroys dust at low shock velocities where sputtering is inefficient (20−25 km s-1). Unlike sputtering, vaporisation produces SiO early in the shock, which may affect the SiO emission line profiles. All these effects are found to be negligible below a density of ~104 cm-3.
Key words: shock waves / magnetohydrodynamics (MHD) / dust, extinction / ISM: clouds / ISM: jets and outflows / ISM: kinematics and dynamics
© ESO, 2011
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