Discovery of the eclipse in the symbiotic binary Z Andromedae

Abstract

Our photometric observations of the symbiotic binary Z And during its recent (2000 -- 2003) active phase revealed a minimum in the U, B and V light curves (LC) at the position of the inferior conjunction of its cool component (the orbital phase 'phi' = 0). This fact and the behaviour of colour indices suggest that the minimum was due to the eclipse of the active hot object by the red giant. Physically plausible fit of the eclipse profile and a precise analysis of the spectral energy distribution (SED) in the ultraviolet continuum suggest a disk-like structure for the hot object during active phases. The present knowledge of fundamental parameters of the system limits the orbital inclination 'i' to 76 - 90 deg. The presence of the Rayleigh attenuated far-UV continuum at 'phi' around 0 during quiescent phase confirms the very high inclination of the Z And orbit.

4 pages, 3 figures, accepted for Astronomy and Astrophysics as a Letter

Cited by in corpus (9)

• Disentangling the composite continuum of symbiotic binaries I. S-type systems
• Variable Star Network: World Center for Transient Object Astronomy and Variable Stars
• A "Combination Nova" Outburst in Z Andromedae: Nuclear Shell Burning Triggered by a Disk Instability
• Structure of the hot object in the symbiotic prototype Z And during its 2000-03 active phase
• Transient jets in the symbiotic prototype Z Andromedae
• Measuring the orbital inclination of Z Andromedae from Rayleigh scattering
• The hydrogen and helium lines of the symbiotic binary Z And during its brightening at the end of 2002
• Correction of UBV photometry for emission lines
• Photometric Modulations on Intermediate Timescales in the Symbiotic Binaries