Electron optical depths and temperatures of symbiotic nebulae from Thomson scattering

Abstract

Symbiotic binaries are comprised of nebulae, whose densest portions have electron concentrations of 1E+8 - 1E+12 cm-3 and extend to a few AU. They are optically thick enough to cause a measurable effect of the scattering of photons on free electrons. In this paper we introduce modelling the extended wings of strong emission lines by the electron scattering with the aim to determine the electron optical depth, tau(e) and temperature, T(e), of symbiotic nebulae. We applied our profile-fitting analysis to the broad wings of the OVI 1032, 1038 A doublet and HeII 1640 A emission line, measured in the spectra of symbiotic stars AG Dra, Z And and V1016 Cyg. Synthetic profiles fit well the observed wings. By this way we determined tau(e) and T(e) of the layer of electrons, throughout which the line photons are transferred. During quiescent phases, the mean tau(e) = 0.056 +/- 0.006 and T(e) = 19 200 +/- 2 300 K, while during active phases, mean quantities of both parameters increased to tau(e) = 0.64 +/- 0.11 and T(e) = 32 300 +/- 2 000 K. During quiescent phases, the faint electron-scattering wings are caused mainly by free electrons from/around the accretion disk and the ionized wind from the hot star with the total column density, N(e) <~ 1E+23 cm-2. During active phases, the large values of tau(e) are caused by a supplement of free electrons into the binary environment as a result of the enhanced wind from the hot star, which increases N(e) to ~1E+24 cm-2.

9 pages, 5 figures, 2 tables. Accepted for publication in MNRAS

References in corpus (2)

• Broad H-alpha wings from the optically thin stellar wind of the hot components in symbiotic binaries
• Structure of the hot object in the symbiotic prototype Z And during its 2000-03 active phase

Cited by in corpus (9)

• A pilot search for mm-wavelength recombination lines from emerging ionized winds in pre-planetary nebulae candidates
• Impact of Resonance, Raman, and Thomson Scattering on Hydrogen Line Formation in Little Red Dots
• Symbiotic stars in X-rays II: faint sources detected with XMM-Newton and Chandra
• Broad Wings around H$\alpha$ and H$\beta$ in the Two S-Type Symbiotic Stars Z Andromedae and AG Draconis
• Mass-loss rate by the Mira in the symbiotic binary V1016 Cygni from Raman scattering
• Multiwavelength modelling the SED of supersoft X-ray sources III. RS Ophiuchi: The supersoft X-ray phase and beyond
• Wind asymmetry imprint in the UV light curves of the symbiotic binary SY Mus
• Multiwavelength modeling the SED of Luminous Supersoft X-ray Sources in Large Magellanic Cloud and Small Magellanic Cloud
• LIN 358: A symbiotic binary accreting above the steady hydrogen fusion limit