Publications of the MPIfR
Optical & Infrared
Interferometry Group
W. Barth, G. Weigelt, and H. Zinnecker
Speckle Masking Observations of the Young
Binary Z CMa
Astronomy and Astrophysics, v.291, p.500-504 (1994)
Abstract
We present the first speckle masking observations of the pre-main
sequence binary system Z canis majoris (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 sec +
or - 0.008 sec at position angle 350 deg + or - 2 deg. 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 at a. (1993) that scattering plays a
role in seeing the infrared companion. We discuss the possiblity that
both components of the Z CMa system may be FU Ori objects.
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