Ionization structure of hot components in symbiotic binaries during active phases

Drechsel

Тарасова

et al. 2014

A&A

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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.

Section: 2 Of Skopal 2014b)mentioning

confidence: 99%

“…This is probably a result of a decreasing mass-loss rate (see Sect. 4.4), which leads to a gradual ionization and hence flattening of the neutral disk (Cariková & Skopal 2012), which in turn leads to an enlargement of the H ii zone (see Sect. 4.3).…”

Section: Probing the Neutral Disk By The Raman-scatteringmentioning

confidence: 99%

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

Drechsel

Тарасова

et al. 2014

A&A

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“…References. 1) Cranmer & Owocki (1995); 2) Owocki et al (1996); 3) Cariková & Skopal (2012); 4) this paper. model S350 by Owocki et al (1994) as a representative Be star model: v rot = 350 km s −1 , M = 7.5 M , R pole = 4 R (at the critical velocity R max eq = 6 R ), and L = 2 310 L .…”

Section: Rapidly Rotating Be Starmentioning

confidence: 75%

“…Here we consider a typical WD in symbiotic binary with v rot = 300 km s −1 (Cariková & Skopal 2012) (5), respectively. This corresponds to the ratio R pole /R eq ∼ 0.996.…”

Section: Moderately Rotating Wdmentioning

confidence: 99%

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The applicability of the wind compression model

Cariková

2014

A&A

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Compression of the stellar winds from rapidly rotating hot stars is described by the wind compression model. However, it was also shown that rapid rotation leads to rotational distortion of the stellar surface, resulting in the appearance of non-radial forces acting against the wind compression. In this note we justify the wind compression model for moderately rotating white dwarfs and slowly rotating giants. The former could be conducive to understanding density/ionization structure of the mass outflow from symbiotic stars and novae, while the latter can represent an effective mass-transfer mode in the wide interacting binaries.

Multiwavelength modeling the SED of supersoft X-ray sources. II. RS Ophiuchi: From the explosion to the SSS phase

2015

New Astronomy

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Physical parameters of the nova RS Oph were determined from its X-ray/IR spectrum. -The model revealed the presence of a strong stellar and nebular component. -The luminosity was super-Eddington during the whole burning phase. -The high luminosity was sustained by a super-critical accretion.Abstract RS Oph is a recurrent symbiotic nova that undergoes nova-like outbursts on a time scale of 20 years. Its two last eruptions (1985 and 2006) were subject of intensive multiwavelengths observational campaign from the X-rays to the radio. This contribution aims to determine physical parameters and the ionization structure of the nova from its explosion to the first emergence of the supersoft X-rays (day 26) by using the method of multiwavelength modelling the SED. From the very beginning of the eruption, the model SED revealed the presence of both a strong stellar and nebular component of radiation in the spectrum. During the first 4 days, the nova evinced a biconical ionization structure. The ∼ 8200 K warm and 160-200 R⊙ extended pseudophotosphere encompassed the white dwarf (WD) around its equator to the latitude > 40 • . The remaining space around the WD's poles was ionized, producing a strong nebular continuum with the emission measure EM ∼ 2.3 × 10 62 cm −3 via the fast wind from the WD. The luminosity of the burning WD was highly super-Eddington for the whole investigated period. The wind mass loss at rates of 10 −4 − 10 −5 M⊙ yr −1 and the presence of jets suggest an accretion throughout a disk at a high rate, which can help to sustain the super-Eddington luminosity of the accretor for a long time.