these sizes are beyond reach even with adaptive optics systems and need to be explored using near-infrared interferometers.

With the first near-infrared interferometers coming on line and producing scientific data, the properties of the inner regions of the disk have been the subject of intense recent modeling efforts. Observations of the SEDs of HAeBe systems and early near-infrared interferometric observations have highlighted the possibility of the presence of an inner "puffed-up" edge [10, 21]. More recently [16] have produced a self consistent model of the inner regions of the disk. This model naturally explains the size and shape of the inner edge of the disk in terms of the stellar photospheric parameters and the properties of the dust grains. These models were used by [17] to interpret the visibilities observed with near-infrared interferometers of several disks around young stellar objects (see Fig. 4 for example).

The combination of these advanced observational and modeling techniques have allowed us to constrain the properties of dust grains on the disk midplane, in the inner regions of a small sample of HAe systems. [17] demonstrated that in almost all systems investigated, the observations are consistent with the presence of grains much larger than the interstellar grains. The analysis of the near infrared data allow us to set a minimum size of the order of ~ 1 |m for the grains that dominate the population of dust in the inner disk.

The availability of the AMBER instrument at the VLTI is expected to allow for a substantial improvement in the study of the inner disk in a large sample of intermediate mass pre-main sequence systems and possibly a number of T Tauri systems. Due to its spectroscopic capabilities, AMBER will also allow a step forward in our understanding of the gaseous component on the inner disk and the relationship between disk and jet. Some initial experiments with AMBER [19, 29] have confirmed that in HAeBe stars the Br7 emission is not associated with the magnetosphere of the central star or inner gaseous disk but with the base of the wind/jet. Moreover, the hydrogen recombination line observations have shown that the wind/jet is launched from a region of the disk similar or slightly more extended than the dusty inner disk rim (see Fig. 5 and [29]).

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