UV and X-ray monitoring of AG draconis during the 1994/1995 outbursts

Greiner, J.; Bickert, K.; Luthardt, R.; Viotti, R.; Altamore, A.; González‐Riestra, R.

doi:10.1007/bfb0102270

Cited by 23 publications

(50 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar scenarios were used to explain X-ray variability in other SSS (e.g. AG Dra, Greiner et al 1996). However, we note, that in those cases usually an anti-correlation of X-ray and optical luminosity is observed, whereas in the case of SMC 3 these two are clearly correlated.…”

Section: Discussionsupporting

confidence: 54%

TheXMM-Newtonsurvey of the Small Magellanic Cloud: a new X-ray view of the symbiotic binary SMC 3

Sturm

Haberl

Greiner

et al. 2011

A&A

Self Cite

View full text Add to dashboard Cite

Context. The XMM-Newton survey of the Small Magellanic Cloud (SMC) was performed to study the population of X-ray sources in this neighbouring galaxy. During one of the observations, the symbiotic binary SMC 3 was found at its highest X-ray luminosity as observed until now. Aims. In SMC 3 wind accretion from a giant donor star onto a white dwarf is believed to cause steady hydrogen burning on the white dwarf surface, making such systems candidates for supernova type Ia progenitors. It was suggested that the X-ray source is eclipsed every ∼4.5 years by both the companion star and its stellar wind to explain the large X-ray variability seen in ROSAT data. We use the available X-ray data to test this scenario. Methods. We present the ∼20 year X-ray light curve of SMC 3 and study the spectral evolution as seen with XMM-Newton/EPIC-pn to investigate possible scenarios which can reproduce the high X-ray variability. Results. We did not find any significant variations in the photo-electric absorption, as would be expected during eclipse ingress and egress. Instead, the X-ray spectra from different intensity levels, when modelled by black-body emission, can be better explained by variations either in normalisation (by a factor of ∼50) or in temperature (kT between 24 eV and 34 eV). The light curve shows maxima and minima with slow transitions between them. Conclusions. To explain the gradual variations in the X-ray light curve and to avoid changes in absorption by neutral gas, a predominant part of the stellar wind must be ionised by the X-ray source. Compton scattering with variable electron column density (of the order of 5 × 10 24 cm −2 ) along the line of sight could then be responsible for the intensity changes. The X-ray variability of SMC 3 could also be caused by temperature changes in the hydrogen-burning envelope of the white dwarf, an effect that could even dominate if the stellar wind density is not sufficiently high.

show abstract

Section: Discussionsupporting

confidence: 54%

TheXMM-Newtonsurvey of the Small Magellanic Cloud: a new X-ray view of the symbiotic binary SMC 3

Sturm

Haberl

Greiner

et al. 2011

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Satisfactory fits to X-ray observations, corresponding to very wide range of possible parameters, were found by many authors (e.g. Greiner et al , 1997;Asai et al , 1998;Ness et al , 2008;Sturm et al , 2011). Such the ambiguity in the inferred parameters is probably caused by fitting only a very small part of the total SSS spectrum.…”

Section: Introductionmentioning

confidence: 92%

“…Greiner et al (1997) modelled the ROSAT PSPC observations during quiescent phase between 1992 April 16 to 1993 May 12. Using the blackbody model for fixed galactic value of N H = 3.15 × 10 20 cm −2 , they obtained kT = 14.5 eV (168300 K) and L h = (9.5 ± 1.5) × 10 36 (d/2.5 kpc) 2 erg s −1 .…”

Section: Classical Symbiotic Star Ag Dramentioning

confidence: 99%

“…with a strong supersoft X-ray component, were selected to demonstrate the method on a classical symbiotic star. The first model is composed of the ROSAT PSCP observation (Greiner et al , 1997) taken on 1993 April 15 and a nearly-simultaneous ultraviolet observation with IUE from 1993 April 9. The second one includes the supersoft X-ray data made with XMM-Newton and its optical monitor (XMM-OM ) from 2005 June 11 (González-Riestra et al , 2008), the far-UV observations with FUSE taken during quiescent phase on 2004 June 24 and the IUE spectra, taken during quiescence at a similar orbital position (1979 September 25-27).…”

Section: Multiwavelength Model Sed Of Ag Dramentioning

confidence: 99%

See 1 more Smart Citation

Multiwavelength modelling the SED of supersoft X-ray sources I. The method and examples

Skopal

2015

New Astronomy

View full text Add to dashboard Cite

-New method of modelling the spectra of supersoft X-ray sources is introduced. -The method analyses the X-ray/near-IR spectral energy distribution. -The multiwavelength approach overcomes problems of modelling only the X-ray data. -More trustworthy fundamental parameters are derived. AbstractRadiation of supersoft X-ray sources (SSS) dominates both the supersof X-ray and the far-UV domain. A fraction of their radiation can be reprocessed into the thermal nebular emission, seen in the spectrum from the near-UV to longer wavelengths. In the case of symbiotic X-ray binaries (SyXBs) a strong contribution from their cool giants is indicated in the optical/near-IR. In this paper I introduce a method of multiwavelength modelling the spectral energy distribution (SED) of SSSs from the supersoft X-rays to the near-IR with the aim to determine the physical parameters of their composite spectra. The method is demonstrated on two extragalactic SSSs, the SyXB RX J0059.1-7505 (LIN 358) in the Small Magellanic Cloud (SMC), RX J0439.8-6809 in the Large Magellanic Cloud (LMC) and two Galactic SSSs, the classical nova RX J2030.5+5237 (V1974 Cyg) during its supersoft phase and the classical symbiotic star RX J1601.6+6648 (AG Dra) during its quiescent phase. The multiwavelength approach overcomes the problem of the mutual dependence between the temperature, luminosity and amount of absorption, which appears when only the X-ray data are fitted. Thus, the method provides an unambiguous solution. It was found that selection of the model (a blackbody or an atmospheric model) is not of crucial importance in fitting the global X-ray/IR SED. The multiwavelength modelling of the SED of SSSs is essential in determining their physical parameters.

show abstract

“…Our values of 150 -230 kK are comparable to those indicated in other symbiotic systems with the observed supersoft X-ray and far-UV fluxes generated by the WD's pseudophotosphere. For example, AG Dra (115-180 kK, Greiner et al 1997;Skopal et al 2009a), RR Tel (150-180 kK, González-Riestra et al 2013), and LIN 358 (250±10 kK, Skopal 2015.…”

Section: The Hot Component Temperaturementioning

confidence: 99%

New outburst of the symbiotic nova AG Pegasi after 165 yr

Skopal

Shugarov

Sekeráš

et al. 2017

A&A

View full text Add to dashboard Cite

Context. AG Peg is known as the slowest symbiotic nova, which experienced its nova-like outburst around 1850. After 165 years, during June of 2015, it erupted again showing characteristics of the Z And-type outburst. Aims. The primary objective is to determine basic characteristics, the nature and type of the 2015 outburst of AG Peg. Methods. We achieved this aim by modelling the spectral energy distribution using low-resolution spectroscopy (330-750 nm; R = 500-1000), medium-resolution spectroscopy (420-720 nm; R ∼ 11000), and U BVR C I C photometry covering the 2015 outburst with a high cadence. Optical observations were complemented with the archival HST and FUSE spectra from the preceding quiescence. Results. During the outburst, the luminosity of the hot component was in the range of 2-11×10 37 (d/0.8 kpc) 2 erg s −1 , being in correlation with the light curve (LC) profile. To generate the maximum luminosity by the hydrogen burning, the white dwarf (WD) had to accrete at ∼ 3 × 10 −7 M ⊙ yr −1 , which exceeds the stable-burning limit and thus led to blowing optically thick wind from the WD. We determined its mass-loss rate to a few ×10 −6 M ⊙ yr −1 . At the high temperature of the ionising source, 1.5 − 2.3 × 10 5 K, the wind converted a fraction of the WD's photospheric radiation into the nebular emission that dominated the optical. A one order of magnitude increase of the emission measure, from a few ×10 59 (d/0.8 kpc) 2 cm −3 during quiescence, to a few ×10 60 (d/0.8 kpc) 2 cm −3 during the outburst, caused a 2 mag brightening in the LC, which is classified as the Z And-type of the outburst. Conclusions. The very high nebular emission and the presence of a disk-like H i region encompassing the WD, as indicated by a significant broadening and high flux of the Raman-scattered O vi 6825 Å line during the outburst, is consistent with the ionisation structure of hot components in symbiotic stars during active phases.

show abstract

UV and X-ray monitoring of AG draconis during the 1994/1995 outbursts

Cited by 23 publications

References 22 publications

TheXMM-Newtonsurvey of the Small Magellanic Cloud: a new X-ray view of the symbiotic binary SMC 3

TheXMM-Newtonsurvey of the Small Magellanic Cloud: a new X-ray view of the symbiotic binary SMC 3

Multiwavelength modelling the SED of supersoft X-ray sources I. The method and examples

New outburst of the symbiotic nova AG Pegasi after 165 yr

Contact Info

Product

Resources

About