First spatial resolution of the stellar components
of the interacting binary CH Cyg

    CH Cyg is one of the most fascinating as well as the brightest and closest symbiotic stars. It's composed of an M7 giant and a hot companion, most likely an accreting white dwarf. The hot component shows very spectacular activity: irregular outbursts accompanied by fast, massive outflows and jets. The light curves of CH Cyg show changes with timescales ranging from minutes (flickering observed during active phases) through several hundred days (pulsations and rotation of M-giant) up to dozen of years (orbital motion of the components, activity phases).
    Diffraction-limited images for both components of CH Cyg binary system were reconstructed using visible speckle interferometry at BTA 6-m telescope (Fig.1). The orbital period 15.6 years and masses: 2.0 Msun and 0.7 Msun for red giant and white dwarf, respectively were derived from angular distance (0.042") and magnitude difference (2^m) of the components. It is shown that the collimated outflows from the system is not exactly orthogonal to the orbital plane of the binary. Subsequent monitoring program to determine precisely the astrometric binary orbit and provide better constraints on the component masses and empirical model of CH Cyg is ongoing.
Joanna Mikolajewska, Yuri Balega, Karl-Heinz Hofmann, Gerd Weigelt.
Submitted to MNRAS
(http://arxiv.org/abs/0910.5176v2)