SPECKLE MASKING OBSERVATIONS OF THE YOUNG BINARY Z-CANIS-MAJORIS

We present the first speckle masking observations of the pre-main sequ ence binary system Z CMa at optical wavelengths (narrow-band R filter and edge filter RG 610). The diffraction-limited images confirm that Z CMa is a binary with a separation of 0.100'' +/- 0.008'' at position angle 305 degrees +/- 2 degrees. The intensity ratio of the stars is 7 .2 for the narrow-band R filter and 7.7 for the RG 610 filter. The sou th-eastern component is the brighter component (i.e. the FU Ori object ), in agreement with the results of Koresko et al. (1991) based on nea r-infrared speckle data. However, our optical detection of the north-w estern component (the infrared companion) would not have been expected according to Koresko et al.'s analysis. One possible explanation coul d be scattered light. This agrees with recent polarimetric evidence fr om Whitney et al. (1993) that scattering plays a role in seeing the in frared companion. We discuss the possibility that both components of t he Z CMa system may be FU Ori objects.