Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst^*

¹ Institute of Astronomy and Isaac Newton Institute of Chile Bulgarian Branch, National Astronomical Observatory Rozhen, PO Box 136, 4700 Smolyan, Bulgaria
² Sternberg Astronomical Institute, Moscow University, Universitetski pr. 13, 119899 Moscow, Russia

Corresponding author: N. Tomov, rozhen@mbox.digsys.bg

Received: 25 July 2002
Accepted: 14 January 2003

Abstract

Broad-band UBVJHKLM data have been obtained at the time of the quiescent orbital photometric maximum of the classical symbiotic binary system Z And  and at some epochs of its 2000–2002 active phase. The data of the active phase are related to the time of the optical maximum and after it when the star was returning to quiescence. Broad-band quiescent RI photometry from the literature was also used to obtain the parameters of the cool component of this binary. All of these data suggest that the hot compact component has undergone a major expansion and the emission measure of the circumbinary nebula has also increased. Some mechanisms for interpretation of the outburst are reviewed.