KH 15D: A star eclipsed by a large-scale dusty vortex?

We propose that the large photometric variations of KH 15D are due to an eclipsing swarm of solid particles, trapped in a giant gaseous vortex rotating at similar to0.2 AU from the star. The efficiency of the capture-in-vortex mechanism easily explains the observed large optical depth. The weaker opacity at mid-eclipse is consistent with a size segregation and a slow concentration of the particles toward the center of the vortex. This dusty structure must extend over similar to1/3 of an orbit to account for the long eclipse duration. The estimated size of the trapped particles is found to range from 1 to 10 cm, consistent with the gray extinction of the star. The observations of KH 15D support the idea that giant vortices can grow in circumstellar disks and play a central role in planet formation.