Shakhovskoy D. Structure of protoplanetary disks by the data of photo-polarimetric monitoring of Young Stellar Objects

Some results of the long-term photo-polarimetric monitoring of Young Stellar Objects (YSO) are presented. Analysis of these observations is carried out, in order to determine properties and structure of their protoplanetary disks. Parameters of scattered radiation from the disks of RR Tau and BM And can be well fitted by multiple scattering models with dust properties similar to ISM dust, "conical" shape of the disk having opening angle <30°, optical depth in the mid-plane about 1. For CQ Tau a 20-years photometric cycle is confirmed, another new cycle is found with period of about 1000 days. Variations of dust grains size on the line of sight are discovered. They correlate with 20-year photometric cycle. Results of simultaneous optical and NIR photometry of RR Tau are presented. Substantial instability of the inner edge of dust disk (near dust evaporation radius) is found. Dust evaporation temperature and the mass of dust cloud that caused unusually durable light minimum are estimated. Polarimetric observations of RZ Psc showed that dust envelope of this object of unclear evolutionary status is disk-like, seen almost edge-on. Scattered light intensity and polarization are similar to that of UX Ori type stars. The absence of IR excess indicates existance of inner dust-free lobe in the disk. Analysis of circular and linear polarization in WW Vul revealed high degree of non-spherical grains alignment in the disk. Dominating direction of alignment is short axes in the disk plane. Degree of alignment is rather variable, reflecting spatial variations of these parameter across the disk.