1994A&A...291..500B

We present the first speckle masking observations of the pre-main sequence 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±2deg. The intensity ratio of the stars is 7.2 for the narrow-band R filter and 7.7 for the RG610 filter. The south-eastern component is the brighter component (i.e. the FU Ori object), in agreement with the results of Koresko et al. (1991) based on near-infrared speckle data. However, our optical detection of the north-western component (the infrared companion) would not have been expected according to Koresko et al.'s analysis. One possible explanation could be scattered light. This agrees with recent polarimetric evidence from Whitney et al. (1993) that scattering plays a role in seeing the infrared companion. We discuss the possibility that both components of the Z CMa system may be FU Ori objects.