On the HU Aquarii planetary system hypothesis

Goździewski, Krzysztof; Nasıroğlu, İlham; Słowikowska, A.; Beuermann, K.; Kanbach, G.; Gauza, B.; Maciejewski, Andrzej J.; Schwarz, R.; Schwope, A. D.; Hinse, T. C.; Haghighipour, Nader; Burwitz, V.; Słonina, Mariusz; Rau, A.

doi:10.1111/j.1365-2966.2012.21341.x

Cited by 74 publications

(134 citation statements)

References 41 publications

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“…They speculate about other mechanisms being responsible for the observed variations, such as changes in the shape of the secondary star due to dynamo effect. However, in a very recent work, Goździewski et al (2012) publish almost 60 new eclipse egress times with better accuracy. Combining these with reanalyzed previous data, the authors find that a single circumbinary companion gives the best explanation for the O−C curve.…”

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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“…The question of long-term stability of such planetary systems then arises, and it may not be easy (or even impossible) to find a configuration which is compatible with observations and at the same time ensures the survival of the planetary system on secular timescales. Examples are HU Aqr (Qian et al 2011;Horner et al 2011;Goździewski et al 2012;Wittenmyer et al 2012); NN Ser Brinkworth et al 2006;Beuermann et al 2010;Hessman et al 2011;Marsh et al 2014) and HW Vir (Lee et al 2009;Beuermann et al 2012b;Horner et al 2012).…”

Section: The Cyclic Period Variationsmentioning

confidence: 99%

“…An updated version was published by Pilarčík et al (2012), who also included some post-common envelope binaries (PCEBs) with similar period variations. HU Aqr (Qian et al 2011;Goździewski et al 2012) and RR Cae (Qian et al 2012) may be added to this list.…”

Section: The Cyclic Period Variationsmentioning

confidence: 99%

Long-term photometry of the eclipsing dwarf nova V893 Scorpii

Bruch

2014

A&A

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Context. The cataclysmic variable V893 Sco is an eclipsing dwarf nova which, apart from outbursts with comparatively low amplitudes, exhibits a particularly strong variability during quiescence on timescales of days to seconds. Aims. The present study aims to update the outdated orbital ephemerides published previously, to investigate deviations from linear ephemerides, and to characterize non-random brightness variations in a range of timescales. Methods. Light curves of V893 Sco were observed on 40 nights, spanning a total time base of about 14 years. They contain 114 eclipses which were used to significantly improve the precision of the orbital period and to study long-term variations of the time of revolution. Oscillations and similar brightness variations were studied with Fourier techniques in the individual light curves. Results. The orbital period exhibits long-term variations with a cycle time of 10.2 years. They can be interpreted as a light travel time effect caused by the presence of a giant planet with approximately 9.5 Jupiter masses in a 4.5 AU orbit around V893 Sco. On some nights transient semi-periodic variations on timescales of several minutes can be seen which may be identified as quasi-periodic oscillations. However, it is difficult to distinguish whether they are caused by real physical mechanisms or if they are the effect of an accidental superposition of unrelated flickering flares. Simulations to investigate this question are presented.

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“…Horner et al (2012b)) we found that the formal parameter errors as obtained from the best-fit co-variance matrix are too optimistic. We therefore determined parameter errors from Monte Carlo bootstrap experiments (Goździewski et al 2012). For each bootstrap dataset we used the best-fit model as our initial guess and recorded the resulting parameters.…”

Section: Least-squares Fitting and Parameter Uncertaintiesmentioning

confidence: 99%

“…The proposed companions around HU Aqr have been studied in detail, and a series of studies have revealed them to be dynamically unfeasible (Horner et al 2011;Hinse et al 2012a;Wittenmyer et al 2012a;Funk et al 2011Funk et al , 2012Goździewski et al 2012). The same is true of HW Vir ) and NSVS 14256825 Hinse et al 2014).…”

Section: Introductionmentioning

confidence: 99%

On the RZ Draconis substellar circumbinary companions

Hinse

Horner

Lee

et al. 2014

A&A

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Context. Recently, using the light-travel time effect, planets and substellar companions have been proposed to orbit around binary star systems (also known as circumbinary companions) as a result of variations in timing of the observed eclipses. For the majority of these systems the proposed orbital architecture features a crossing of the orbital configurations as a result of high eccentricities for one or both of the companions. For such systems, strong mutual gravitational interactions are expected, resulting in catastrophic orbital instabilities, or collisions between the proposed components, on very short timescales. Aims. We re-examine the primary and secondary eclipse timings of the short-period and semi-detached binary RZ Draconis (RZ Dra). The proposed companions were reported to have masses of around 0.07 and 0.18 M with the inner companion on an orbit with moderate eccentricity (0.46), whose apocenter distance crosses the orbit of the outer companion. We show that the companions proposed previously follow highly unstable orbits. In an attempt to find a stable system we searched the underlying χ 2 parameter space for a best-fit model and carried out an orbit-stability study to test possible best-fit models. If the binary period changes are truly due to additional massive companions in a hierarchical configuration, they must follow stable orbits. Methods. For numerical orbital stability calculations we used well established orbit integration routines. Computations were carried out using a large-scale multi-CPU computing environment. Our data analysis of times of primary and secondary eclipse is based on the Levenberg-Marquardt least-squares minimization algorithm using the two-body Keplerian light-travel time effect model. Results. Despite the wide variety of potential models tested for the RZ Dra system in this work, we found very few models that were stable for even one million years, with the vast majority of systems tested falling apart on timescales of just hundreds of years. It seems therefore likely that the observed timing variations are not solely the result of massive, unseen companions.

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On the HU Aquarii planetary system hypothesis

Cited by 74 publications

References 41 publications

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

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

Long-term photometry of the eclipsing dwarf nova V893 Scorpii

On the RZ Draconis substellar circumbinary companions

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