Enigmatic Recurrent Pulsational Variability of the Accreting White Dwarf Eq lyn (SDSS J074531.92+453829.6)

Mukadam, Anjum S.; Townsley, Dean M.; Szkody, Paula; Gänsicke, B. T.; Southworth, J.; Brockett, T.; Parsons, S. G.; Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Harrold, Samuel T.; Tovmassian, G.; Zharikov, S. V.; Drake, A. J.; Henden, A. A.; Rodríguez‐Gil, P.; Sion, E. M.; Zoła, S.; Szymanski, T.; Павленко, Е. П.; Aungwerojwit, A.; Qian, S.‐B.

doi:10.1088/0004-6256/146/3/54

Cited by 10 publications

(15 citation statements)

References 64 publications

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“…The long-term stability of the intermittent 27.87 s period remains the strongest argument for this to be the spin period of the white dwarf, but this leaves us without a clear understanding of the 28.96 s period. It is interesting to note that Mukadam et al (2013) found several puzzling features in the pulsational variability of another CV, EQ Lyn. In addition to possible ways to reconcile these observations with our understanding of g-mode pulsations, they considered alternatives models: r-mode pulsations and accretion disk pulsations.…”

Section: Periodicities At 2787 and 2896 Smentioning

confidence: 99%

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: 99%

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

Nucita

Kuulkers

Paolis

et al. 2014

A&A

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“…The cause of the anti-correlation is not clear. Mukadam et al (2011Mukadam et al ( , 2013, and Szkody et al (2015). Observed years are colour coded as indicated.…”

Section: Eq Lynmentioning

confidence: 98%

“…While the possibility of r modes was briefly discussed in Mukadam et al (2013), pulsations in accreting white dwarfs were generally thought as g modes similar to those in ZZ Ceti variables in the literature. As noted in § 1, however, g modes in rapidly rotating stars have characters inconsistent with observed pulsations in accreting (and hence rapidly rotating) white dwarfs.…”

Section: R-mode Fittings To Observed Pulsationsmentioning

confidence: 99%

“…After the outburst no pulsations had been observed for more than three years. Even after pulsations were detected again in 2010 February-March, pulsations disappeared time to time; pulsations seem to disappear when superhump signatures appear (Mukadam et al 2013). The superhump is caused by the precession of a fully developed elliptic accretion disk (e.g.…”

Section: Eq Lynmentioning

confidence: 99%

“…The pulsation frequencies/amplitudes are compared with r-mode visibilities for a 0.6 M WD model with log T eff = 4.187. The model parameters are chosen according to the discussion in Mukadam et al (2013).…”

Section: Eq Lynmentioning

confidence: 99%

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r-mode oscillations in accreting white dwarfs in cataclysmic variables

Saio

2019

Monthly Notices of the Royal Astronomical Society

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Some cataclysmic variables show short-period (∼200 to ∼2000 s) light variations, which are attributable to nonradial pulsations of the accreting primary white dwarf. We regard these periodic variations as r-mode (global Rossby-wave) oscillations which are presumably excited mechanically and confined into hydrogen-rich layers in the white dwarf. Often observed modulations in amplitudes and frequencies even during an observing season may be interpreted as beatings among densely distributed r-mode frequencies. Making the r-mode frequency distribution of a model to be consistent (by adjusting the rotation frequency) with the observed pulsation frequencies, we obtain the best-fit rotation rate for each case. The rotation periods thus obtained for 17 accreting white dwarfs lie between 4 and 10 minutes. Pulsation frequencies observed sometime after a dwarf-nova outburst tend to be higher than the pre-outburst values, so that the best-fit rotation rate for the post-outburst frequencies is also higher. This indicates a spin-up of the hydrogen-rich layers to occur by an enhanced accretion at the outburst. We also discuss the relation between the rotation frequencies of pulsating accreting white dwarfs and the orbital periods.

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2015

Pulsating Stars

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Enigmatic Recurrent Pulsational Variability of the Accreting White Dwarf Eq lyn (SDSS J074531.92+453829.6)

Cited by 10 publications

References 64 publications

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

XMM-NewtonandSwiftobservations of WZ Sagittae: spectral and timing analysis

r-mode oscillations in accreting white dwarfs in cataclysmic variables

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