The Inner Rim of YSO Disks: Effects of Dust Grain Evolution

Dust-grain growth and settling are the first steps towards planet formation.An understanding of dust physics is therefore integral to a complete theory ofthe planet formation process. In this paper, we explore the possibility ofusing the dust evaporation front in YSO disks (`the inner rim') as a probe ofthe dust physics operating in circumstellar disks. The geometry of the rimdepends sensitively on the composition and spatial distribution of dust. Usingradiative transfer and hydrostatic equilibrium calculations we demonstrate thatdust growth and settling can curve the evaporation front dramatically (from acylindrical radius of about 0.5 AU in the disk mid-plane to 1.2 AU in the diskupper layers for an A0 star). We compute synthetic images and interferometricvisibilities for our representative rim models and show that the currentgeneration of near-IR long-baseline interferometers (VLTI, CHARA) can stronglyconstrain the dust properties of circumstellar disks, shedding light on therelatively poorly understood processes of grain growth, settling and turbulentmixing.Comment: 26 pages, 9 figures. Accepted for publication in Ap