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.
It was connected with a significant enhancement of the hot star wind.
Simultaneously, we identified a variable optically thick warm (Teff ~ 6000 K)
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. We suggested that this connection represents a common origin
of the warm pseudophotospheres that are indicated during the active phases of
symbiotic stars.Comment: 13 pages, 9 figures, 8 tables, accepted for A&
