The evolution of the inner regions of protoplanetary disks: a statistical study

We perform a statistical study to test the evolution of the inner regions of protoplanetary disks. We compare synthetic SEDs with near and mid-IR photometric data obtained for disk-bearing stars in stellar clusters of different ages.We use a modified version of the D'Alessio models, which include a parametrized approach for the curvature of the inner wall. We define a disk color excess (DCE) from observed IR colors and use the models to reproduce observed distributions of these DCEs, in the IRAC and MIPS 24 bands. We find that the decrease in the DCEs with the age is related to the degree of dust settling in the disk as well as the height of the inner wall. Our study shows that disks settle in very short timescales and at 5 Myr most of the disks have settled. We also find that at 1-3Myr, most of the disks have wall heights of 3.8H. At 5-10 Myr the wall heights are of the order of 0.5 H. This suggests that 5 Myr is a crucial stage where the disks reach a very advanced evolutionary stage. This is the first statistical study looking for trends of evolution, using observational constrains that include several stellar clusters with near and mid-IR data , in an age interval from 1-10My