EDP Sciences
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Volume 379, Number 2, November IV 2001
Page(s) 515 - 528
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011339

A&A 379, 515-528 (2001)
DOI: 10.1051/0004-6361:20011339

The vertical structure of T Tauri accretion disks

II. Physical conditions in the disk
F. Malbet1, R. Lachaume1 and J.-L. Monin1, 2

1  Laboratoire d'Astrophysique UMR UJF-CNRS 5571, Observatoire de Grenoble, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
2  Institut Universitaire de France

(Received 18 May 2001 / Accepted 11 September 2001 )

We present a self-consistent analytical model for the computation of the physical conditions in a steady quasi-Keplerian accretion disk. The method, based on the thin disk approximation, considers the disk as concentric cylinders in which we treat the vertical transfer as in a plane-parallel medium. The formalism generalizes a work by Hubeny (1990), linking the disk temperature distribution to the local energy dissipation and leads to analytical formulae for the temperature distribution which help to understand the behaviour of the radiation propagated inside the disks. One of the main features of our new model is that it can take into account many heating sources. We apply the method first to two sources: viscous dissipation and stellar irradiation. We show that other heating sources like horizontal transfer or irradiation from the ambiant medium can also be taken into account. Using the analytical formulation in the case of a modified Shakura & Sunyaev radial distribution that allow the accretion rate to be partly self-similar in the inner region, and, for an $\alpha$ and $\beta$ prescription of the viscosity, we obtain two-dimensional maps of the temperature, pressure and density in the close environment of low mass young stars. We use these maps to derive the observational properties of the disks such as spectral energy distributions, high resolution spatial images or visibilities in order to underline their different behaviours under different input models.

Key words: accretion, accretion disk -- radiative transfer -- stars: circumstellar matter -- stars: pre-main sequence

Offprint request: F. Malbet, Fabien.Malbet@obs.ujf-grenoble.fr

© ESO 2001