Spatial Structure of the Dusty Wind of RW Aur A

In 2011 and 2015–2018 the classical T Tauri star RW Aur A dimmed by 2– . Previously, no such dimmings had been observed in historical observations since 1895: the variability amplitude did not exceed . During these eclipses the star showed evidence of UX Ori variability: a decrease in color index and an increase in polarization. To clarify the nature of the eclipses and the high polarization associated with them, we observed the object in the visible bands by the method of differential speckle polarimetry with the 2.5-m telescope at the Caucasus Mountain Observatory of the Sternberg Astronomical Institute of the Moscow State University. The observations were carried out on October 23, 2016, at the end of a long and deep eclipse. As a simple geometric model shows, the polarized flux was reliably resolved. Using the MC3D radiative transfer simulation code, we have considered several three-dimensional dust envelope models. The two-component model that consists of a protoplanetary disk and a cone explains quantitatively the dimming and the shape of the resolved envelope. The typical size of the dust cone is 5–10 AU; this cone may be a dusty disk wind. However, our model does not reproduce the source of polarized radiation that coincides with the star and gives the bulk of the polarized flux from the object. The scattering envelope near the star unresolvable in our observations or the star itself, if its direct radiation is absorbed by aligned dust grains, can be this source.