The environment of V633 Cassiopeiae and V376 Cassiopeiae: Evidence for circumstellar disks

We present optical direct and polarimetric imaging, optical polarimetry, and infrared direct imaging of the Herbig Ae/Be stars V633 Cas (=LkH alpha 198) and V376 Gas. Both stars are associated with extended reflection nebulosities. V633 Cas appears as a single object associated with an extended optical nebula oriented northwest-southeast with a mean position angle of 128 degrees. This nebula, having the form of a large ''loop,'' traces the redshifted lobe of a CO outflow. Various features are present within the circumstellar medium of V633 Cas. The position of the star does not change with wavelength within the uncertainties. We suspect its linear polarization to be time variable. The polarization pattern close to V633 Cas suggests that another source, possibly the infrared source 6 '' north of V633 Gas, V633 Cas B, is the most probable candidate to drive the large-scale outflow. For V376 Gas, high-resolution images with very good seeing in R and [S II] filters show for the first time two peaks in the isophote contours, about 1 '' apart. Also, V376 Cas has the largest linear polarization observed so far in a young stellar object, approximate to 23% at a position angle of approximate to 26 degrees. This is well explained if an edge-on circumstellar disk is present. Polarization maps of V376 Cas showing a pattern of aligned vectors and two null points support this explanation. Further support comes from the detection of two intensity peaks that can be explained by the presence of a reflection nebula whose center is hidden by an optically thick disk seen edge-on. A less preferable explanation would be the presence of enhanced line emission regions due to shocks in recollimating flows. We exclude the possibility that V376 Cas is a binary star with a 1 '' separation.