Modeling the IR spectrum of the dust shell around the [WC] star: V605 AQL

Nebulae around low mass Wolf-Rayet [WC] stars often show a strong mid and near infrared (MN-IR) emission which cannot be explained with a single grain size and an equilibrium temperature model. We investigated the effect of the grain size, radiation density, and temperature fluctuations of small dust grains on the spectral energy distribution (SED) in the infrared. A model of ISOCAM and IRAS measurements of V605 Aql (Kimeswenger et al., 1998) has been computed using a gas-dust combination model including transiently heated particles. Our calculations show that the central knot in V605 Aql (Abell 58) is too compact or just on the lower boundary that temperature fluctuations really have to be considered in model calculations for the infrared SED.