Formation of a disk structure in the symbiotic binary AX Persei during its 2007-10 active phase
Authors:
A. Skopal, T.N. Tarasova, Z. Carikova, F. Castellani, G. Cherini, S. Dallaporta, A. Frigo, C. Marangoni, S. Moretti, U. Munari, G.L. Righetti, A. Siviero, S. Tomaselli, A. Vagnozzi, P. Valisa
Image & caption:
Please click on image thumbnail to get more info:
Image caption::
Sketch of the ionization structure of AX~Per during the quiescent phase (left, pole-on view) and around the hot star during the active phase (right, edge-on view). During quiescence, the solid thick line represents the H0/H+ boundary in the steady-state approximation. During activity, the neutral zone has the form of a flared disk, whose optically thick rim represents the warm pseudophotosphere (see Fig. 9 of Skopal et al. 2011 in detail).
Description:
AX Per is an eclipsing symbiotic binary. During active phases, the ionization structure in the binary changes significantly. Based on observations carried out at the observatories of AI SAS, the Asiago Astrophysical Observatory and the Crimean Astrophysical Observatory we found that AX Per entered a new active phase from 2007.5. After 19 years we measured in the light curve the eclipse of the hot star by its giant companion in the binary and determined the geometrical structure of the active component. By modeling the broad wings of the H-alpha line we revealed a strong mass-loss rate from the active star, enhanced by a factor of around 40 during the outburst. Modeling the composite optical continuum we identified the presence of a warm (~6000 K), but strong source of the radiation. The source was located at the hot star's equator and had the form of a flared disk in the direction from the central star. Its outer rim simulated 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.
Reference:
Astronomy & Astrophysics 536, art. no. 27, p. 1-13 (2011).
SK
SAS
