High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

We have summarized the current understanding and recently obtained findings about WZ Sge-type dwarf novae. We also reviewed the historical development of the understanding of these objects, provided the modern criteria, and reviewed the past research in relation to superhumps, early superhumps and the outburst mechanism. We regard that the presence of early superhumps (reflecting the 2:1 resonance) and long or multiple rebrightenings are the best distinguishing properties of WZ Sge-type dwarf novae. We provided the updated list of nearly 100 WZ Sge-type dwarf novae mainly based on the data obtained by the VSNET Collaboration up to Kato et al. (2015) and discussed the statistics. We could detect early superhumps with amplitude larger than 0.02 mag in 63% of the studied WZ Sge-type dwarf novae, which makes early superhumps a useful distinguishing feature for WZ Sge-type dwarf novae. Theoretical light curves of early superhumps generally appear to reproduce the existence of many low-amplitude objects, supporting the geometrical origin of early superhumps. Using the recently developed method of measuring mass ratios using developing phase of superhumps (stage A superhumps), we showed that there is a linear relation between the period variation of superhumps and the mass ratio in WZ Sge-type objects. By using this relation, we were able to draw an evolutionary picture of a large number of WZ Sge-type and identified the type of outburst to be an evolutionary sequence: type C → D → A → B → E, with some outliers for type-B objects. The duration of stage A (evolutionary phase) of superhumps is also well correlated with the estimated mass ratios. By using mass ratios from stage A superhumps and durarion of stage A, we have been able to identify best candidates for period bouncers.

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“…The object is a well-confirmed ordinary SU UMa-type dwarf nova Woudt et al 2004;Kato et al 2014a;Mason, Howell 2003).…”

Section: Ao Octmentioning

confidence: 83%

WZ Sge-type dwarf novae

Katô

2015

Publications of the Astronomical Society of Japan

161

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“…From the XMMNewton OM and MDM photometric light curves (Figures 10 and 11) orbital modulation similar to the heating light curve observed during the radio pulsar state (Woudt et al 2004;Thorstensen & Armstrong 2005) are also evident. However, the variations now appear more sinusoidal and symmetric about the peak.…”

Section: Optical/uv Variabilitymentioning

confidence: 92%

Coordinated X-Ray, Ultraviolet, Optical, and Radio Observations of the PSR J1023+0038 System in a Low-Mass X-Ray Binary State

Bogdanov

Archibald

Bassa

et al. 2015

ApJ

103

112

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The PSR J1023+0038 binary system hosts a neutron star and a low-mass, main-sequence-like star. It switches on year timescales between states as an eclipsing radio millisecond pulsar and a low-mass X-ray binary (LMXB). We present a multi-wavelength observational campaign of PSR J1023+0038 in its most recent LMXB state. Two long XMM-Newton observations reveal that the system spends ∼70% of the time in a ≈3 × 10 33 erg s −1 X-ray luminosity mode, which, as shown in Archibald et al., exhibits coherent X-ray pulsations. This emission is interspersed with frequent lower flux mode intervals with 5 10 32 ≈ × erg s −1 and sporadic flares reaching up to ≈10 34 erg s −1 , with neither mode showing significant X-ray pulsations. The switches between the three flux modes occur on timescales of order 10 s. In the UV and optical, we observe occasional intense flares coincident with those observed in X-rays. Our radio timing observations reveal no pulsations at the pulsar period during any of the three X-ray modes, presumably due to complete quenching of the radio emission mechanism by the accretion flow. Radio imaging detects highly variable, flat-spectrum continuum radiation from PSR J1023+0038, consistent with an origin in a weak jet-like outflow. Our concurrent X-ray and radio continuum data sets do not exhibit any correlated behavior. The observational evidence we present bears qualitative resemblance to the behavior predicted by some existing "propeller" and "trapped" disk accretion models although none can account for key aspects of the rich phenomenology of this system.

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“…It was discovered by Wolf on February 4, 1918. Woudt et al (2004 suggest an orbital period of P orb ∼ 4. h 3, but it was not confirmed by the observations of Rodríguez-Gil & Torres (2005).…”

Section: Gi Monmentioning

confidence: 99%

SALT observations of southern post-novae

Tomov

Swierczynski

Mikołajewski

et al. 2015

A&A

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Aims. We report on recent optical observations of the stellar and the nebular remnants of 22 southern post-novae. Methods. In this study, for each of our targets, we obtained and analysed long-slit spectra in the spectral range 3500-6600 Å and inResults. The changes in the emission lines' equivalent widths with the time since the outburst agree with earlier published results of other authors. We estimated an average value α = 2.37 for the exponent of the power law fitted to the post-novae continua. Our observations clearly show the two-component structure of the V842 Cen expanding nebulae, owing to the different velocities of the ejected matter. We discovered an expanding shell around V382 Vel with an outer diameter of about 12 .

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High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

Cited by 70 publications

References 37 publications

WZ Sge-type dwarf novae

WZ Sge-type dwarf novae

Coordinated X-Ray, Ultraviolet, Optical, and Radio Observations of the PSR J1023+0038 System in a Low-Mass X-Ray Binary State

SALT observations of southern post-novae

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