2011A&A...536A..27S

AX Per is an eclipsing symbiotic binary. During active phases, deep narrow minima are observed in its light curve, and the ionization structure in the binary changes significantly. From ∼2007.5, AX Per entered a new active phase. We aim to derive the ionization structure in the binary and its changes during the recent active phase. We used optical high- and low-resolution spectroscopy and UBVR_CI_C photometry. We modeled the SED in the optical and broad wings of the Hα line profile during the 2007-10 higher level of the AX Per activity. After 10 orbital cycles (∼18.6 years), we again measured the eclipse of the hot component by its giant companion in the light curve. We derived a radius of 27±2R_☉ for the eclipsed object and 115±2R_☉ for the eclipsing cool giant. The new active phase was connected with a significant enhancement of the hot star wind. From quiescence to activity, the mass-loss rate increased from ∼9x10^–8 to ∼3x10^–6M_☉/yr, respectively. The wind causes the emission of the He⁺⁺ zone, located in the vicinity of the hot star, and also is the reason for the fraction of the [OIII] zone at farther distances. Simultaneously, we identified a variable optically thick warm (T_eff∼6000K) source that contributes markedly to the composite spectrum. The source was located at the hot star's equator and has the form of a flared disk, whose outer rim simulates the warm photosphere. The formation of the neutral disk-like zone around the accretor during the active phase was connected with its enhanced wind. It is probable that this connection represents a common origin of the warm pseudophotospheres that are indicated during the active phases of symbiotic stars.