Authors:

Andrea Isella, Osservatorio Astrofisico di Arcetri (Firenze) & Dipartimento di Fisica, Università degli Studi di Milano

Antonella Natta, Osservatorio Astrofisico di Arcetri (Firenze)

Abstract:

We propose an hydrostatic, axisymmetric, radiative equilibrium model for the inner rim of passive irradiated dusty disks. The model follows the two layer description of Chiang and Goldreich (1997) but it accounts for the vaporization of dust grains in the inner disk. Since the dust vaporization temperature varies with the gas density, as proposed by Pollack at al. in 1994, the resulting inner rim has a curved surface and is puffed up in comparison with a standard fleared disk model. We propose that the effect of the rim surface bending can solve the problem of the vanishing flux of a vertical rim at face-on inclination (Dullemond, Dominik and Natta, 1997): the resulting inner rim emits in fact almost isotropically under all inclination angles. The inner radius of the rim is located at the vaporization radius of the grains in the midplane directly heated by the unattenuated stellar radiation. Using astronomical silicates, we find that this radius decreases with increasing grain dimensions and that the resulting range is consistent with the interferometric observations of Monnier and Millan-Gabet (2002). We compute SED and synthetic immages at near-infrared wavelengths of the inner rim for different inclination angles. We also derive visibility curves to compare with the new interferometric data from VLTI-AMBER.