Model infrared spectra of passively heated proto-planetary disks surrounding intermediate-mass pre-main-sequence stars

摘要

Aims. We study theoretical spectra at mid-infrared (5-40)wavelengths of proto-planetary disks surrounding intermediate-mass pre-main-sequence stars. Observations show a wide range of spectral shapes and a rich variety in strength and shape of dust resonances. These strong variations in spectral shape reflect differences in the nature and spatial distribution of dust particles in the disk. The aim of this study is to establish what model parameters influence the mid-IRspectra of planet-forming disks. Methods. A grid of models of passively heated proto-planetary disks is used to calculate the infrared spectrum. We use hydrostatic equilibrium disk models and radiative transfer to calculate the emerging spectrum. We focus on the effects that different disk geometries (flaring, self-shadowed) and dust mineralogy have on the emerging 5-40spectrum. We adopt four scenarios for the radial and vertical distribution of crystalline silicate dust. Results. In our model, the 23.5forsterite band is more sensitive to emission from regions <30AU, while the 33.5forsterite band probes regions up to 50AU. The 23.5band strength does not depend on the degree of flaring of the disk, while the 33.5band does. Only models with a substantial abundance (>5percent) of crystalline silicates at a long distance from the star (>20-50AU) show detectable emission in the 33.5forsterite band. The carbon-dust abundance affects the strength of the dust resonances in the 10spectral region, but not in the 30region. Key words: stars: planetary systems: protoplanetary disks - stars: pre-main sequence - stars: circumstellar matter