Modeling the Circumstellar Disk of $ζ$ Tauri

Abstract

We present a model for the disk of the classical Be star $ζ$ Tauri. The model consists of a Keplerian rotating disk with a power-law surface density and a vertical density distribution that follows from the balance between the thermal gas pressure and the z-component of the stellar gravitation. The opening angle of such a disk is not a fixed value but increases with the distance to the star (flared disk). We use a Monte Carlo code that solves simultaneously the thermal equilibrium, the statistical equilibrium and the hydrostatic equilibrium equations. The result is a self-consistent solution for the electron temperature, level populations and gas density distribution. It follows from this model that the only free parameter is the disk density. All other parameters (e.g. shape of the disk surface) are self-consistently calculated given the disk density. In this paper we present a successful fit for $ζ$ Tauri data using this model.