Erlebte Kinderheilkunde

Friedjung, Josef K.

doi:10.1007/978-3-642-91567-3

Cited by 17 publications

(19 citation statements)

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“…Prior to 2001 July, it had been observed to go into outburst only three times, once in 1913, once in 1946, and most recently in 1978. During the last outburst it was observed extensively with IUE (Fabian et al 1980;Friedjung 1981;Naylor 1989). The spectra at the peak of the outburst resembled those of other outbursting systems; the spectral slope was consistent with that expected from a steady state accretion disk in outburst.…”

Section: Introductionsupporting

confidence: 61%

WZ Sagittae:FUSESpectroscopy of the 2001 Outburst

Long

Froning

Gänsicke

et al. 2003

ApJ

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The short-period cataclysmic variable WZ Sge underwent its first dwarf nova outburst in 23 years in 2001 July. Here we describe 905-1187 Å spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) during the outburst and within the first few months after the outburst. The first spectrum, obtained about 7 days after the outburst began and 6.4 days past optical maximum, is dominated by a broad (50-60 Å equivalent width) feature due to O vi and can be characterized in terms of emission from a highly inclined disk modulated by the effects of a highly ionized wind. WZ Sge is fainter in later observations (starting about 45 days after optical maximum) and increasingly '' red '' in the far ultraviolet. The spectral shape increasingly resembles that expected from a metal-enriched white dwarf photosphere, although it seems likely that some disk contribution remains at least through the second FUSE observation, when the visible light curve showed the system to be undergoing a rebrightening event. The absorption lines observed on September 29 and in early November, when the visible light curve was in a fairly steady decline toward quiescence, are narrow, with widths (FWHM) of the order of 0.7-1.3 Å (200-400 km s À1 ). The most natural explanation for these spectra is that the continuum arises from a relatively massive, slowly rotating white dwarf and that the lines are created by a combination of metals in the atmosphere and absorbing material along the line of sight to the white dwarf. If the white dwarf has log g ¼ 8:5, then the white dwarf cooled from $25,000 K on September 29 to 23,000 K in early November.

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Section: Introductionsupporting

confidence: 61%

WZ Sagittae:FUSESpectroscopy of the 2001 Outburst

Long

Froning

Gänsicke

et al. 2003

ApJ

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“…For example, Friedjung (1987) showed that the energy output of nova FH Ser was well above the Eddington limit for about two months after its optical maximum. Schwarz et al (2001) demonstrated that the luminosity of the nova LMC 1991 was super-Eddington before its visual maximum and reached L WD ∼ 6 × 10 5 L .…”

Section: Evolution Of the Parameters L Wd R Wd And T Effmentioning

confidence: 99%

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

Skopal

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.

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“…(b) The temperature mass loss relation (given by Bath 1978), and (c) Relations between the observed parameters and the parameters at the base of the wind (given by Owocki & Gayley 1997). The stars are the values obtained on different days from the data of Friedjung (1987). The fact that the light curve conspicuously follows an iso‐ v ∞ contour arises because the observed v ∞ for FH Serpentis happens to vary only little, from 670 to 770 km s −1 .…”

Section: The Fundamental Structure Of Super‐eddington Winds (Sews)mentioning

confidence: 99%

“…We use the data of Friedjung (1987, also in Friedjung 1989) for the behaviour of the temperature, luminosity and velocity at infinity. These data are based on the UV measurements by Gallagher & Code (1974) and in addition include the integrated flux that falls outside the UV range observed by Gallagher & Code assuming a black body distribution 4 .…”

Section: Application Of the Sew Theorymentioning

confidence: 99%

“…Using the described method of analysis, we proceed to fit the data of Friedjung (1987), which includes T colour , L ∞ and v ∞ . Given a wind parameter 𝒲, a white dwarf mass M WD and a hydrogen mass fraction X , we solve for, at each observed point, the values of Γ 0 and W˜ that result in the observed v ∞ and Γ ∞ .…”

Section: Application Of the Sew Theorymentioning

confidence: 99%

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The theory of steady-state super-Eddington winds and its application to novae

Shaviv¹

2001

Monthly Notices of the Royal Astronomical Society

121

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We present a model for steady‐state winds of systems with super‐Eddington luminosities. These radiatively driven winds are expected to be optically thick and clumpy as they arise from an instability‐driven porous atmosphere. The model is then applied to derive the mass loss observed in bright classical novae. The main results are as follows. (i) A general relation between the mass‐loss rate and the total luminosity in super‐Eddington systems. (ii) A natural explanation of the long‐duration super‐Eddington outflows that are clearly observed in at least two cases (Novae LMC 1988 #1 and FH Serpentis). (iii) A qualitative agreement between the prediction and observations of the mass loss and temperature evolution. (iv) An agreement between the predicted average integrated mass loss of novae as a function of white dwarf mass and its observations. (v) A natural explanation for the ‘transition phase’ of novae. (vi) Agreement with η Carinae, which was used to double check the theory: the prediction for the mass shed in the star's great eruption agrees with observations to within the measurement error.

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Erlebte Kinderheilkunde

Cited by 17 publications

References 0 publications

WZ Sagittae:FUSESpectroscopy of the 2001 Outburst

WZ Sagittae:FUSESpectroscopy of the 2001 Outburst

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

The theory of steady-state super-Eddington winds and its application to novae

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