The non-radially pulsating primary of the cataclysmic variable GW Librae

Zyl, L. van; Warner, Brian D.; O’Donoghue, D.; Hellier, C.; Woudt, P. A.; Sullivan, D. J.; Pritchard, J.; Kemp, Jonathan; Patterson, Joseph; Welsh, William F.; Casares, J.; Shahbaz, T.; Hooft, F. van der; Vennes, S.

doi:10.1111/j.1365-2966.2004.07646.x

Cited by 64 publications

(73 citation statements)

References 32 publications

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“…There is little doubt that the short period variability seen in another faint CV, GW Lib (see also below), is due to nonradial g-mode pulsations of the white dwarf that dominates its optical light in quiescence (van Zyl et al 2004). Since then, similar pulsations have been discovered in about a dozen of other faint, white dwarf-dominated CVs (see, e.g., Szkody et al 2010, and references therein).…”

Section: Periodicities At 2787 and 2896 Smentioning

confidence: 89%

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

Nucita

Kuulkers

Paolis

et al. 2014

A&A

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Context. WZ Sagittae is the prototype object of a subclass of dwarf novae with rare and long (super)outbursts, in which a white dwarf primary accretes matter from a low mass companion. High-energy observations offer the possibility of a better understanding of the disk-accretion mechanism in WZ Sge-like binaries. Aims. We used archival XMM-Newton and Swift data to characterize the X-ray spectral and temporal properties of WZ Sge in quiescence. Methods. We performed a detailed timing analysis of the simultaneous X-ray and UV light curves obtained with the EPIC and OM instruments on board XMM-Newton in 2003. We employed several techniques in this study, including a correlation study between the two curves. We also performed an X-ray spectral analysis using the EPIC data and Swift/XRT data obtained in 2011.Results. We find that the X-ray intensity is clearly modulated at a period of 28.96 s, confirming previously published preliminary results. We find that the X-ray spectral shape of WZ Sge remains practically unchanged between the XMM-Newton and Swift observations. However, after correcting for interstellar absorption, the intrinsic luminosity is estimated to be L

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Section: Periodicities At 2787 and 2896 Smentioning

confidence: 89%

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

Nucita

Kuulkers

Paolis

et al. 2014

A&A

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“…As an example, if we adopt a value of 15 200 K for the effective temperature of the pulsating white dwarf component in GW Lib itself (Szkody et al 2010), a mass of about 0.84 M according to van Spaandonk et al (2010), the dominant modes with periods of 230, 370, and 650 s (van Zyl et al 2004) can easily be accounted for at the qualitative level if the donor is rather He-rich.…”

Section: Range Of Excited Modesmentioning

confidence: 99%

A connection between the instability strips of ZZ Ceti and V777 Herculis white dwarfs

Grootel

Fontaine

Brassard

et al. 2015

A&A

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Aims. We aim to determine the theoretical instability strips of white dwarfs with diverse H and He content in their atmospheres, from a solar composition to a H-depleted atmosphere. Pulsators with mixed H-He atmospheres are indeed known to exist, and these are the white dwarfs in cataclysmic accreting systems of the GW Lib type. We thus also aim to determine the range of periods of excited pulsation modes, and to qualitatively compare these to the observed periods in GW Lib white dwarf pulsators. Methods. In the first full nonadiabatic stability analysis of pulsators of this kind, we applied a time-dependent convection treatment and an energy leakage argument to compute, for cooling models of white dwarfs with various masses and envelope compositions, the location of the blue and the red edges, as well as the properties of pulsation modes. Results. We find that our derived instability strips form a true continuum in the log g-T eff plane and that their individual location depends uniquely on the assumed atmospheric composition, from the solar composition models at low effective temperatures to the H-depleted models at much higher temperatures. Taking into account our previous results from the ZZ Ceti (pure H atmosphere) and V777 Her (pure He atmosphere) white dwarf pulsators, this implies that all of these instability domains are connected via the same fundamental driving mechanism. Applying our results to the case of white dwarf pulsators of the GW Lib type, we find that our theoretical instability strips can qualitatively account for all of the known cases. The computed range of periods of excited modes also compares qualitatively very well to the observed ones. Conclusions. The GW Lib pulsators are very similar in nature to ZZ Ceti and V777 Her white dwarfs. It is the diverse chemical compositions in their atmosphere and envelope that defines their specific pulsation properties. Beyond GW Lib pulsators, white dwarfs can sometimes exhibit mixed H-He atmospheres, such as in the recently found proto-He white dwarf pulsators. Our results open the way towards quantitative asteroseismology of these various kinds of white dwarfs.

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“…Until recently, only a single CV containing a white dwarf pulsator has been discovered: GW Lib (van Zyl et al 2000(van Zyl et al , 2004. GW Lib is only partially understood, due to the lack of a proper mode identification of the observed pulsation frequencies, and more severely, due to the circumstance that the temperature of its white dwarf, T eff = 14 700 K, is actually significantly above the blue end of the ZZ Ceti instability strip (Szkody et al 2002).…”

Section: The Brightest CV White Dwarf Pulsatormentioning

confidence: 99%

HS 2331+3905: The cataclysmic variable that has it all

Araujo-Betancor¹,

Gänsicke

Hagen

et al. 2005

A&A

128

163

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Abstract. We report detailed follow-up observations of the cataclysmic variable HS 2331+3905, identified as an emissionline object in the Hamburg Quasar Survey. An orbital period of 81.08 min is unambiguously determined from the detection of eclipses in the light curves of HS 2331+3905. A second photometric period is consistently detected at P 83.38 min, ∼2.8% longer than P orb , which we tentatively relate to the presence of permanent superhumps. High time resolution photometry exhibits short-timescale variability on time scales of 5−6 min which we interpret as non-radial white dwarf pulsations, as well as a coherent signal at 1.12 min, which is likely to be the white dwarf spin period. A large-amplitude quasi-sinusoidal radial velocity modulation of the Balmer and Helium lines with a period ∼3.5 h is persistently detected throughout three seasons of time-resolved spectroscopy. However, this spectroscopic period, which is in no way related to the orbital period, is not strictly coherent but drifts in period and/or phase on time scales of a few days. Modeling the far-ultraviolet to infrared spectral energy distribution of HS 2331+3905, we determine a white dwarf temperature of T eff 10 500 K (assuming M wd = 0.6 M ), close to the ZZ Ceti instability strip of single white dwarfs. The spectral model implies a distance of d = 90 ± 15 pc, and a low value for the distance is supported by the large proper motion of the system, µ = 0.14 yr −1 . The non-detection of molecular bands and the low J, H, and K fluxes of HS 2331+3905 make this object a very likely candidate for a brown-dwarf donor.

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The non-radially pulsating primary of the cataclysmic variable GW Librae

Cited by 64 publications

References 32 publications

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

A connection between the instability strips of ZZ Ceti and V777 Herculis white dwarfs

HS 2331+3905: The cataclysmic variable that has it all

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