SCATTERING AND POLARIZATION OF LIGHT BY FLUFFY DUST AGGREGATES IN THE SHELLS OF UX ORI-LIKE STARS N.A. Krivova MPI fuer Aeronomie, Katlenburg-Lindau, Germany and Astronomical Institute of St.Petersburg University, St.Petersburg, Russia V.B. Il'in Astronomical Institute of St.Petersburg University, St.Petersburg, Russia H. Kimura MPI fuer Aeronomie, Katlenburg-Lindau, Germany and I. Mann ESTEC, Noordwijk, The Netherlands ABSTRACT Monte Carlo simulations of polarized radiation transfer in the dust shells of HAeBe stars are used to model various manifistations of dust including those specific to UXORs. In contrast to previous works, a more adequate technique (DDA) is utilized to describe the optical properties of the CS dust aggregates. The emphasis is made on the effects of the fluffiness of grains. Whereas moderately porous particles give, generally, a better agreement with the observations than compact grains, highly porous aggregates contradict to most of the data. The work was partly supported by INTAS (grant 99/652).