Structure of the hot object in the symbiotic prototype Z Andromedae during its 2000–03 active phase

Skopal, A.; Vittone, A. A.; Errico, L.; Otsuka, Masaaki; Tamura, Shinichi; Wolf, M.; Elkin, V. G.

doi:10.1051/0004-6361:20052917

Cited by 31 publications

(50 citation statements)

References 40 publications

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“…In this way we justified the ionization structure of the hot components in symbiotic binaries during active phases, as we had suggested in previous papers (e.g. Skopal 2005Skopal , 2006Skopal et al 2006Skopal et al , 2011.…”

Section: Resultssupporting

confidence: 71%

Ionization structure of hot components in symbiotic binaries during active phases

Cariková

Skopal

2012

A&A

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Context. During active phases of symbiotic binaries, an optically thick medium in the form of a flared disk develops around their hot stars. During quiescent phases, this structure is not evident. Aims. We propose the formation of a flared neutral disk-like structure around the rotating white dwarf (WD) in symbiotic binaries. Methods. We applied the wind compression model and calculated the ionization boundaries in the compressed wind from the WD using the equation of photoionization equilibrium. Results. During active phases, the compression of the enhanced wind from the rotating WD can form a neutral disk-like zone at the equatorial plane, while the remainder of the sphere above/below the disk is ionized. The hydrogen column density throughout the neutral zone and the emission measure of the ionized fraction of the wind, calculated for the mass loss rate from the WD, M = 2 × 10 −6 M yr −1 with v ∞ = 2000 km s −1 , are consistent with those derived from observations. During quiescent phases, the neutral disk-like structure cannot be created because of insufficient mass loss rate. Conclusions. Formation of the neutral disk-like zone at the equatorial plane is connected with the enhanced wind from the rotating WD, observed during active phases of symbiotic binaries. This probably represents a common origin of warm pseudophotospheres, indicated in the spectrum of active symbiotic binaries with a high orbital inclination.

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Section: Resultssupporting

confidence: 71%

Ionization structure of hot components in symbiotic binaries during active phases

Cariková

Skopal

2012

A&A

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“…B.1 of Skopal et al (2006). Our model parameters, L h and T h from the quiescent and transition phases (Table 3) (Asplund et al 2004), α B (O vi) = 9.5 × 10 −12 cm 3 s −1 (Gurzadyan 1997), and τ e from Table 2, yieldn e = 2.6 × 10 10 cm −3 (R O vi ∼ 50 R ), and 1.7 × 10 11 cm −3 (R O vi ∼ 11 R ) during quiescence (2004/06/15-24) and the transition from the burst (2003/11/14-19), respectively.…”

Section: Wing Profiles and The Electron Density Around The Wdmentioning

confidence: 99%

The origin of the supersoft X-ray-optical/UV flux anticorrelation in the symbiotic binary AG Draconis

Skopal¹,

Sekeráš²,

González‐Riestra

et al. 2009

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Context. AG Draconis produces a strong supersoft X-ray emission. The X-ray and optical/UV fluxes are in strict anticorrelation throughout the active and quiescent phases. Aims. We identify the source of the X-ray emission and reveal the nature of the observed flux anticorrelation. Methods. We used X-ray and UV observations with XMM-Newton, far-UV spectroscopy from FUSE, low-and high-resolution IUE spectra, and optical/near-IR spectroscopic and/or photometric observations. We modeled the spectral energy distribution and broad wings of the O vi λ1032, λ1038 and He ii λ1640 lines by the electron-scattering during the maximum of the 2003 burst, and the subsequent transition and quiescent phase. Results. The X-ray-near-IR energy distribution at different levels of the star's brightness confirmed the observed flux anticorrelation quantitatively and showed that the optical bursts are associated to an increase in the nebular component of radiation. The profile-fitting analysis revealed a significant increase in the mean particle density around the hot star from ∼2.6 × 10 10 cm −3 during quiescent phase to ∼1.1 × 10 12 cm −3 during the burst. Conclusions. The supersoft X-ray emission is produced by the white dwarf photosphere. The X-ray and far-UV fluxes make it possible to determine its temperature unambiguously. The supersoft X-ray-optical/UV flux anticorrelation is caused by the variable wind from the hot star. The enhanced hot star wind gives rise to the optical bursts by reprocessing high-energy photons from the Lyman continuum to the optical/UV.

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“…This is a puzzle. We can only speculate that the emission regions with highly ionized elements are very small (an example is given in Appendix B of Skopal et al 2006), so that the surrounding dense layers can absorb photons of corresponding transitions. However, especially the O vi 1032 Å photons can be effectively absorbed by Rayleigh and Raman scattering.…”

Section: Probing the Neutral Disk By The Raman-scatteringmentioning

confidence: 99%

Early evolution of the extraordinary Nova Delphini 2013 (V339 Del)

Skopal

Drechsel

Тарасова

et al. 2014

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Aims. We determine the temporal evolution of the luminosity (L WD ), radius (R WD ) and effective temperature (T eff ) of the white dwarf (WD) pseudophotosphere of V339 Del from its discovery to around day 40. Another main objective was studying the ionization structure of the ejecta. Methods. These aims were achieved by modelling the optical/near-IR spectral energy distribution (SED) using low-resolution spectroscopy (3500-9200 Å), UBVR C I C and JHKLM photometry. Important insights in the physical conditions of the ejecta were gained from an analysis of the evolution of the Hα and Raman-scattered 6825 Å O vi line using medium-resolution spectroscopy (R ∼ 10 000). Results. During the fireball stage (Aug. 14. 8-19.9, 2013), T eff was in the range of 6000-12 000 K, R WD was expanding non-uniformly in time from ∼66 to ∼300 (d/3 kpc) R , and L WD was super-Eddington, but not constant. Its maximum of ∼9 × 10 38 (d/3 kpc) 2 erg s −1 occurred around Aug. 16.0, at the maximum of T eff , half a day before the visual maximum. After the fireball stage, a large emission measure of 1.0−2.0×10 62 (d/3 kpc) 2 cm −3 constrained the lower limit of L WD to be well above the super-Eddington value. The mass of the ionized region was a few ×10 −4 M , and the mass-loss rate was decreasing from ∼5.7 (Aug. 22) to ∼0.71× 10 −4 M yr −1 (Sept. 20).The evolution of the Hα line and mainly the transient emergence of the Raman-scattered O vi 1032 Å line suggested a biconical ionization structure of the ejecta with a disk-like H i region persisting around the WD until its total ionization, around day 40. On Sept. 20 (day 35), the model SED indicated a dust emission component in the spectrum. The dust was located beyond the H i zone, where it was shielded from the hard, > ∼ 10 5 K, radiation of the burning WD at that time. Conclusions. Our extensive spectroscopic observations of the classical nova V339 Del allowed us to map its evolution from the very early phase after its explosion. It is evident that the nova was not evolving according to the current theoretical prediction. The unusual non-spherically symmetric ejecta of nova V339 Del and its extreme physical conditions and evolution during and after the fireball stage represent interesting new challenges for the theoretical modelling of the nova phenomenon.

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Structure of the hot object in the symbiotic prototype Z Andromedae during its 2000–03 active phase

Cited by 31 publications

References 40 publications

Ionization structure of hot components in symbiotic binaries during active phases

Ionization structure of hot components in symbiotic binaries during active phases

The origin of the supersoft X-ray-optical/UV flux anticorrelation in the symbiotic binary AG Draconis

Early evolution of the extraordinary Nova Delphini 2013 (V339 Del)

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