The Edinburgh-Cape Blue Object Survey -- II. Zone 1 -- the North Galactic Cap

Kilkenny, D.; O’Donoghue, D.; Koen, C.; Stobie, R. S.; Chen, A.

doi:10.1093/mnras/287.4.867

Cited by 119 publications

(140 citation statements)

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“…QS Vir was discovered in the Edinburgh-Cape faint blue object survey of high galactic latitudes (Kilkenny et al 1997), where the eclipses revealed its binary nature. O'Donoghue et al (2003) suggest that it is a hibernating CV, which was questioned by Ribeiro et al (2010) and ruled out by Parsons et al (2011b), who confirm that it is a detached system and not a hibernating CV based on high-resolution UVES spectra.…”

Section: A2 Eclipsing Wd+ms Pcebsmentioning

confidence: 99%

Origin of apparent period variations in eclipsing post-common-envelope binaries

Zorotovic

Schreiber

2013

A&A

120

163

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Context. Apparent period variations detected in several eclipsing, close-compact binaries are frequently interpreted as being caused by circumbinary giant planets. This interpretation raises the question of the origin of the potential planets that must have either formed in the primordial circumbinary disk, together with the host binary star, and survived its evolution into a close-compact binary or formed in a post-common-envelope circumbinary disk that remained bound to the post-common-envelope binary (PCEB). Aims. Here we combine current knowledge of planet formation and the statistics of giant planets around primordial and evolved binary stars with the theory of close-compact binary star evolution aiming to derive new constraints on possible formation scenarios. Methods. We compiled a comprehensive list of observed eclipsing PCEBs, estimated the fraction of systems showing apparent period variations, reconstructed the evolutionary history of the PCEBs, and performed binary population models of PCEBs to characterize their main sequence binary progenitors. We reviewed the currently available constraints on the fraction of PCEB progenitors that host circumbinary giant planets. Results. We find that the progenitors of PCEBs are very unlikely to be frequent hosts of giant planets ( < ∼ 10 per cent), while the frequency of PCEBs with observed apparent period variations is very high (∼90 per cent). Conclusions. The variations in eclipse timings measured in eclipsing PCEBs are probably not caused by first-generation planets that survived common-envelope evolution. The remaining options for explaining the observed period variations are second-generation planet formation or perhaps variations in the shape of a magnetically active secondary star. We suggest observational tests for both options.

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Section: A2 Eclipsing Wd+ms Pcebsmentioning

confidence: 99%

Origin of apparent period variations in eclipsing post-common-envelope binaries

Zorotovic

Schreiber

2013

A&A

120

163

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“…QS Vir was discovered and later identified as an eclipsing WD binary by Kilkenny et al (1997) to be an order of magnitude too large to be caused by the Applegate mechanism; however, they are also doubtful about the plausibility of a third body in the system, while noting that it "remains the only mechanism able to produce such a large period variation". The data set available to them covered April 1992-February 2010; Almeida & Jablonski (2011) add a few more points extending it to August 2010, and argue on this basis for a system containing two circumstellar low-mass bodies.…”

Section: Qs Virmentioning

confidence: 99%

Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

Lohr

Norton

Anderson

et al. 2014

A&A

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Period or amplitude variations in eclipsing binaries may reveal the presence of additional massive bodies in the system, such as circumbinary planets. Here, we have studied twelve previously-known eclipsing post-common-envelope binaries for evidence of such light curve variations, on the basis of multi-year observations in the SuperWASP archive. The results for HW Vir provided strong evidence for period changes consistent with those measured by previous studies, and help support a two-planet model for the system. ASAS J102322−3737.0 exhibited plausible evidence for a period increase not previously suggested; while NY Vir, QS Vir and NSVS 14256825 afforded less significant support for period change, providing some confirmation to earlier claims. In other cases, period change was not convincingly observed; for AA Dor and NSVS 07826147, previous findings of constant period were confirmed. This study allows us to present hundreds of new primary eclipse timings for these systems, and further demonstrates the value of wide-field high-cadence surveys like SuperWASP for the investigation of variable stars.

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“…Nine sdBs discovered in the course of the EdinburghCape blue object survey Kilkenny et al 1997;O'Donoghue et al 2013) have been observed with the grating spectrograph and intensified Reticon Photon Counting System on the 1.9 m telescope of the SAAO (R 1300, λ = 3300−5600 Å). Spectra of five sdBs have been taken with the CAFOS spectrograph mounted at the CAHA 2.2 m telescope (R 1000, λ = 3500−5800 Å).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Hot subdwarf stars in close-up view

Geier

Heber

Edelmann

et al. 2013

A&A

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Atmospheric parameters and helium abundances of 44 bright subdwarf B stars have been determined. More than half of our sample consists of newly discovered stars from the Edinburgh Cape survey. We showed that effective temperatures and surface gravities can be derived from high resolution echelle spectra with sufficient accuracy. Systematic uncertainties have been determined by comparing the parameters derived from the high resolution data with the ones derived from medium resolution spectra. Helium abundances have been measured with high accuracy. Besides the known correlation of helium abundance with temperature, two distinct sequences in helium abundance have been confirmed. Significant isotopic shifts of helium lines due to an enrichment in 3 He have been found in the spectra of 8 subluminous B stars (sdBs). Most of these stars cluster in a small temperature range between 27 000 K and 31 000 K very similar to the known 3 He-rich main sequence B stars, which also cluster in such a small strip, but at different temperatures. Both the helium sequences and the isotopic anomaly are discussed.

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The Edinburgh-Cape Blue Object Survey -- II. Zone 1 -- the North Galactic Cap

Cited by 119 publications

References 0 publications

Origin of apparent period variations in eclipsing post-common-envelope binaries

Origin of apparent period variations in eclipsing post-common-envelope binaries

Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

Hot subdwarf stars in close-up view

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