The emergence of a neutral region in the orbital plane of symbiotic binaries during their outbursts
Authors:
A. Skopal
Image & caption:
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Image caption::
Column densities of atomic hydrogen, NHobs, between the observer and the white dwarf, measured for our targets during outbursts as a function of the orbital phase φ. High values of NHobs at any position of the binary reflect the presence of a neutral region in the orbital plane, because the investigated objects are seen approximately edge-on (eclipsing systems).
Description:
Accretion of mass onto a white dwarf (WD) in a binary system can lead to explosions. During outbursts of WD in a symbiotic binary, the system brightens by several magnitudes, produces a low- and high-velocity mass-outflow, and, in some cases, ejects bipolar jets. In this study, we revealed a new striking phenomenon of these outbursts - the emergence of a neutral region in the orbital plane during the outburst. We proved its presence by determining a large amount of neutral hydrogen in the direction of the WD and around the whole binary for all suitable objects. The cause of the emergence of the neutral zone in the orbital plane is the formation of a dense disk-like structure around the WD, which subsequently blocks the ionizing radiation from the central burning WD in the orbital plane, which causes the ionized stellar wind from the giant before the outburst to become neutral during it. Our finding challenges theoretical modeling of the morphology of the stellar wind in wide binaries containing an evolved giant, specifying the evolutionary path of these systems.
Reference:
The Astronomical Journal, 165:258 (19pp), 2023 June
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