Dust around Herbig Ae/Be stars: modelling of observational data

Herbig Ae/Be (HAeBe) stars, young stars surrounded by dust shells, are believed to be precursors of β Pic-like stars, and the dust around them is thought to be a possible source material for the formation of planets. A group of the HAeBe stars (UX Ori, WW Vul, etc.) shows large brightness variations. The dust in the vicinity of these stars is responsible not only for their excess emission in the infrared, anomalous extinction in the ultraviolet and visual, and specific spatial distributions of the intensity and polarization, but also for the “blueing” effect in the colour-magnitude diagrams and the intrinsic polarization increase observed in deep minima. In contrast to the previous studies, we take advantage of a simultaneous modelling of all the observational data mentioned. Monte-Carlo simulations of polarized radiation transfer in the shells with a spheroidal density distribution have been performed for different dust grain models. The results are compared with observations of a typical HAeBe star WW Vul. Some effects related to a possible porosity of the circumstellar grains are considered.