GD 552: a cataclysmic variable with a brown dwarf companion?

Unda-Sanzana, E.; Marsh, T. R.; Gänsicke, B. T.; Maxted, P. F. L.; Morales-Rueda, L.; Dhillon, V. S.; Thoroughgood, T. D.; Tremou, Evangelia; Watson, C. A.; Hinojosa-Goñi, R.

doi:10.1111/j.1365-2966.2008.13458.x

Cited by 25 publications

(16 citation statements)

References 53 publications

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“… 1 Mackie (1920), 2 Thorstensen (2003), 3 Harrison et al (2004), 4 Augusteijn & Wisotzki (1997), 5 Abbott, Fleming & Pasquini (1997), 6 Gänsicke et al (2005), 7 Greenstein & Giclas (1978), 8 Unda‐Sanzana et al (2008), 9 Araujo‐Betancor et al (2005b), 10 Gänsicke et al (in preparation), 11 González (1983). …”

Section: Discussionmentioning

confidence: 99%

SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period

Gänsicke

Dillon

Southworth

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We discuss the properties of 137 cataclysmic variables (CVs) which are included in the Sloan Digital Sky Survey (SDSS) spectroscopic data base, and for which accurate orbital periods have been measured. 92 of these systems are new discoveries from SDSS and were followed‐up in more detail over the past few years. 45 systems were previously identified as CVs because of the detection of optical outbursts and/or X‐ray emission, and subsequently re‐identified from the SDSS spectroscopy. The period distribution of the SDSS CVs differs dramatically from that of all the previously known CVs, in particular it contains a significant accumulation of systems in the orbital period range 80–86 min. We identify this feature as the elusive ‘period minimum spike’ predicted by CV population models, which resolves a long‐standing discrepancy between compact binary evolution theory and observations. We show that this spike is almost entirely due to the large number of CVs with very low accretion activity identified by SDSS. The optical spectra of these systems are dominated by emission from the white dwarf photosphere, and display little or no spectroscopic signature from the donor stars, suggesting very low mass companion stars. We determine the average absolute magnitude of these low‐luminosity CVs at the period minimum to be 〈Mg〉= 11.6 ± 0.7. Comparison of the SDSS CV sample to the CVs found in the Hamburg Quasar Survey and the Palomar Green Survey suggests that the depth of SDSS is the key ingredient resulting in the discovery of a large number of intrinsically faint short‐period systems.

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Section: Discussionmentioning

confidence: 99%

SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period

Gänsicke

Dillon

Southworth

et al. 2009

Monthly Notices of the Royal Astronomical Society

Self Cite

265

338

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“…However, despite there are now more than 1400 CVs with an orbital period determination (Ritter & Kolb 2003), only a handful of period bouncer candidates have been so far identified (e.g. Patterson et al 2005b;Unda-Sanzana et al 2008;Littlefair et al 2006;Patterson 2011;Kato et al , 2016McAllister et al 2017;Neustroev et al 2017). Therefore the identification of additional period bouncers and the determination of their physical parameters is important for a direct comparison between the current models of CV evolution and observations in a region of the parameter space where very few objects are known.…”

Section: Introductionmentioning

confidence: 99%

The cataclysmic variable QZ Lib: a period bouncer

Pala

Schmidtobreick

Tappert

et al. 2018

Monthly Notices of the Royal Astronomical Society

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While highly evolved cataclysmic variables (CVs) with brown dwarf donors, often called "period bouncers", are predicted to make up 40 − 70% of the Galactic CV population, only a handful of such systems are currently known. The identification and characterization of additional period bouncers is therefore important to probe this poorly understood phase of CV evolution. We investigate the evolution of the CV QZ Lib following its 2004 super-outburst using multi-epoch spectroscopy. From time-resolved spectroscopic observations we measure the orbital period of the system, P orb = 0.06436(20) d, which, combined with the superhump period P SH = 0.064602(24) d, yields the system mass ratio, q = 0.040(9). From the analysis of the spectral energy distribution we determine the structure of the accretion disc and the white dwarf effective temperature, T eff = 10 500 ± 1500 K. We also derive an upper limit on the effective temperature of the secondary, T eff 1700 K, corresponding to a brown dwarf of T spectral type. The low temperature of the white dwarf, the small mass ratio and the fact that the donor is not dominating the near-infrared emission are all clues of a post bounce system. Although it is possible that QZ Lib could have formed as a white dwarf plus a brown dwarf binary, binary population synthesis studies clearly suggest this scenario to be less likely than a period bouncer detection and we conclude that QZ Lib is a CV that has already evolved through the period minimum.

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“…It was demonstrated that one of the systems has a very lowmass brown-dwarf companion by spectroscopic observations (Hernández Santisteban et al 2016). Unda-Sanzana et al (2008) found a CV which would have a brown-dwarf companion and a very low mass ratio. Aviles et al (2010) also detected a brown-dwarf binary with a likely small mass ratio.…”

Section: Introductionmentioning

confidence: 99%

ASASSN-16dt and ASASSN-16hg: Promising candidate period bouncers

Kimura

Isogai

Katô

et al. 2018

Publications of the Astronomical Society of Japan

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We present optical photometry of superoutbursts in 2016 of two WZ Sge-type dwarf novae (DNe), ASASSN-16dt and ASASSN-16hg. Their light curves showed a dip in brightness between the first plateau stage with no ordinary superhumps (or early superhumps) and the second plateau stage with ordinary superhumps. We find that the dip is produced by slow evolution of the 3:1 resonance tidal instability and that it would be likely observed in low mass-ratio objects. The estimated mass ratio (q ≡ M 2 /M 1 ) from the period of developing (stage A) superhumps (0.06420(3) d) was 0.036(2) in ASASSN-16dt. Additionally, its superoutburst has many properties similar to those in other low-q WZ Sge-type DNe: long-lasting stage A superhumps, small superhump amplitudes, long delay of ordinary superhump appearance, and slow decline rate in the plateau stage with superhumps. The very small mass ratio and observational characteristics suggest that this system is one of the best candidates for a period bouncer -a binary accounting for the missing population of post-period minimum cataclysmic variables. Although it is not clearly verified due to the lack of detection of stage A superhumps, ASASSN-16hg might be a possible candidate for a period bouncer on the basis of the morphology of its light curves and the small superhump amplitudes. Many outburst properties of period-bouncer candidates would originate from the small tidal effects by their secondary stars.

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GD 552: a cataclysmic variable with a brown dwarf companion?

Cited by 25 publications

References 53 publications

SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period

SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period

The cataclysmic variable QZ Lib: a period bouncer

ASASSN-16dt and ASASSN-16hg: Promising candidate period bouncers

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