PHOTOPHORESIS IN PROTOPLANETARY DISKS: A NUMERICAL APPROACH

Abstract. It is widely accepted that rocky planets form in the inner regions of protoplanetary disks(PPD) about 1 - 10 AU from the star. However, theoretical calculations show that when particles reachthe size for which the radial migration is the fastest they tend to be accreted very eciently by the star.This is known as the radial-drift barrier. We explore the photophoresis in the inner regions of PPD as apossible mechanism for preventing the accretion of solid bodies onto the star. Photophoresis is the thermalcreep induced by the momentum exchange of an illuminated solid particle with the surrounding gas. Recentlaboratory experiments predict that photophoresis would be able to stop the inward drift of macroscopicbodies (from 1 mm to 1 m in size). This extra force has been included in our two-uid (gas+dust) SPH codein order to study its eciency. We show that the conditions of pressure and temperature encountered inthe inner regions of PPD result in strong dynamical e ects on the dust particles due to photophoresis. Oursimulations show that there is a radial and a vertical sorting of the dust grains according to their sizes andtheir intrinsic densities. Thus, our calculations support the fact that photophoresis is a mechanism whichcan have a strong e ect on the morphology of the inner regions of PPD, ultimately a ecting the fate ofplanetesimals.Keywords: protoplanetary disk, photophoresis, hydrodynamics, planet formation