Dr. Dejan Vinkovic
Institute for Advanced Studies, Princeton

University of Florida Astronomy Colloquium - Nov 30th, 2005

Multigrain dust - a new physics of protoplanetary disks

Planet formation is believed to occur in dense (protoplanetary) disks of gas and dust surrounding young pre-main-sequence stars. The current understanding of this process is very limited, which made protoplanetary disks a popular target for astronomical observations. But the radiative transfer interpretation of spectral and imaging data still relies on single dust grain approximations. In this presentation I will show how a more realistic description of dust as a mixture of grains (multigrain) leads to substantial corrections to the structure of inner disk regions. According to these corrections the inner disk radius is at least two times smaller than previously assumed. This makes the currently popular theory of puffed up inner disk rim incapable of explaining the observed near infrared flux. I will advocate a model of optically thin dusty halo around the inner disk as a possible explanation for the near infrared data. Reduced radius also shows that all currently known extrasolar planets are located in the zone where dust existed during the protoplanetary disk phase.