DoAr 33: a good candidate for revealing dust growth and settling in protoplanetary disks

¹ Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing, PR China
e-mail: yliu@pmo.ac.cn
² Graduate School of the Chinese Academy of Sciences, 100080 Beijing, PR China
³ Institut für Theoretische Physik und Astrophysik, Universität zu Kiel, Leibnizstr. 15, 24118 Kiel, Germany

Received: 3 April 2012
Accepted: 20 August 2012

Abstract

Aims. We aim to evaluate the evolutionary stage of the circumstellar disk around DoAr 33, a T Tauri star in the Ophiuchus molecular cloud and a promising target for follow-up observations to find signs of dust evolution in protoplanetary disks.

Methods. The currently available data on DoAr 33 comprises its spectral energy distribution from the optical to the millimeter regimes. This data set allows us to characterize the structure of a circumstellar disk using self-consistent radiative transfer models. We employed two different types of models, a well-mixed model and a settled disk model in which dust growth and settling are taken into account. Simulated annealing was used to search for an optimum parameter set.

Results. Our results suggest that the assumption of a well-mixed dust and gas phase leads to overestimation of the mid-infrared flux, whereas the (sub)millimeter emission can be predicted quite well. Observational and theoretical arguments imply that an overall decrease in mid-infrared flux can be explained by dust growth and settling towards the midplane of the disk. As expected, the settled disk model is able to satisfactorily reproduce the data points at all wavelengths. DoAr 33 is therefore a good candidate for studying dust growth and settling in protoplanetary disks, so it deserves to be investigated with future observations.