Post-common-envelope binaries from SDSS

Zorotovic, M.; Schreiber, M. R.; Gänsicke, B. T.; Gómez‐Morán, A. Nebot

doi:10.1051/0004-6361/200913658

Cited by 273 publications

(362 citation statements)

References 85 publications

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“…This is consistent with recent studies that show that low values of α CE seem to work best for PCEBs with M-dwarf secondaries (e.g. Zorotovic et al 2010;Toonen & Nelemans 2013;Camacho et al 2014). We also performed the KS tests for the simulated and observed systems with secondary stars in the spectral-type range M2-M3.…”

Section: Including Dcvssupporting

confidence: 88%

Detached cataclysmic variables are crossing the orbital period gap

Zorotovic¹,

Schreiber²,

Parsons³

et al. 2016

Mon. Not. R. Astron. Soc.

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A central hypothesis in the theory of cataclysmic variable (CV) evolution is the need to explain the observed lack of accreting systems in the 2-3 h orbital period range, known as the period gap. The standard model, disrupted magnetic braking (DMB), reproduces the gap by postulating that CVs transform into inconspicuous detached white dwarf (WD) plus main sequence systems, which no longer resemble CVs. However, observational evidence for this standard model is currently indirect and thus this scenario has attracted some criticism throughout the last decades. Here, we perform a simple but exceptionally strong test of the existence of detached CVs (dCVs). If the theory is correct, dCVs should produce a peak in the orbital period distribution of detached close binaries consisting of a WD and an M4-M6 secondary star. We measured six new periods which brings the sample of such binaries with known periods below 10 h to 52 systems. An increase of systems in the 2-3 h orbital period range is observed. Comparing this result with binary population models, we find that the observed peak cannot be reproduced by post-common envelope binaries (PCEBs) alone and that the existence of dCVs is needed to reproduce the observations. Also, the WD mass distribution in the gap shows evidence of two populations in this period range, i.e. PCEBs and more massive dCVs, which is not observed at longer periods. We therefore conclude that CVs are indeed crossing the gap as detached systems, which provides strong support for the DMB theory.

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Section: Including Dcvssupporting

confidence: 88%

Detached cataclysmic variables are crossing the orbital period gap

Zorotovic¹,

Schreiber²,

Parsons³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…These include for example: constraining current theories of close compact binary evolution (Davis, Kolb & Willems 2010;Zorotovic et al 2010Zorotovic et al , 2011aRebassa-Mansergas et al 2012b); demonstrating in a robust way that the majority of low-mass white dwarfs are formed in binaries (Rebassa-Mansergas et al 2011); constraining the pairing properties of main-sequence stars (Ferrario 2012); providing robust observational evidence for disrupted magnetic braking ; constraining the rotationage-activity relation of low-mass main-sequence stars (RebassaMansergas, Schreiber & Gänsicke 2013a); studying the statistical properties of the PCEB population using Monte Carlo techniques (Toonen & Nelemans 2013;Camacho et al 2014;Zorotovic et al 2014); analysing why the average mass of white dwarfs in cataclysmic variables is significantly larger than the average mass of single white dwarfs (Zorotovic, Schreiber & Gänsicke 2011b;Nelemans et al 2016;Schreiber, Zorotovic & Wijnen 2016); testing hierarchical probabilistic models used to infer properties of unseen companions to low-mass white dwarfs (Andrews, Price-Whelan & Agüeros 2014); detecting new gravitational wave verification sources (Kilic et al 2014); analysing the interior structural effects of common envelope evolution on low-mass pulsating white dwarfs (Hermes et al 2015). In addition, many eclipsing SDSS PCEBs have been identified (Nebot Gómez-Morán et al 2009;Pyrzas et al 2009Pyrzas et al , 2012Parsons et al 2013Parsons et al , 2015 which are being used to test theoretical mass-radius relations of both white dwarfs and lowmass main-sequence stars (Parsons et al 2012b,a), as well as the existence of circumbinary planets (Zorotovic & Schreiber 2013;Marsh et al 2014;Parsons et al 2014).…”

Section: The Sdss Wdms Binary Cataloguementioning

confidence: 99%

The SDSS spectroscopic catalogue of white dwarf-main-sequence binaries: new identifications from DR 9–12

Rebassa‐Mansergas

Ren

Parsons

et al. 2016

Mon. Not. R. Astron. Soc.

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We present an updated version of the spectroscopic catalogue of white dwarf-main-sequence (WDMS) binaries from the Sloan Digital Sky Survey (SDSS). We identify 938 WDMS binaries within the data releases (DR) 9-12 of SDSS plus 40 objects from DR 1-8 that we missed in our previous works, 646 of which are new. The total number of spectroscopic SDSS WDMS binaries increases to 3294. This is by far the largest and most homogeneous sample of compact binaries currently available. We use a decomposition/fitting routine to derive the stellar parameters of all systems identified here (white dwarf effective temperatures, surface gravities and masses, and secondary star spectral types). The analysis of the corresponding stellar parameter distributions shows that the SDSS WDMS binary population is seriously affected by selection effects. We also measure the Na I λλ 8183.27, 8194.81 absorption doublet and H α emission radial velocities (RV) from all SDSS WDMS binary spectra identified in this work. 98 objects are found to display RV variations, 62 of which are new. The RV data are sufficient enough to estimate the orbital periods of three close binaries.Key words: binaries: close -binaries: spectroscopic -stars: low-mass -white dwarfs. I N T RO D U C T I O NA large fraction of main-sequence stars are found in binary systems (Duquennoy & Mayor 1991;Raghavan et al. 2010;Yuan et al. 2015b). It is expected that ∼25 per cent of all main-sequence binaries are close enough to begin mass transfer interactions when the more massive star becomes a red giant or an asymptotic giant star (Willems & Kolb 2004). This has been observationally verified e.g. by Farihi, Hoard & Wachter (2010) and by Nebot . Because the mass transfer rate generally exceeds the Eddington limit, the secondary star is not able to accrete the transferred material and the system evolves through a common envelope phase. That is, the core of the giant and the main-sequence companion orbit within a common envelope formed by the outer layers of the giant star. Drag forces between the two stars and the envelope lead to the shrinkage of the orbit and therefore to the release E-mail: alberto.rebassa@upc.edu of orbital energy. The orbital energy is deposited into the envelope and is eventually used to eject it (Webbink 2008). The outcome of common envelope evolution is hence a close binary formed by the core of the giant star (which later becomes a white dwarf) and a main-sequence companion, i.e. a close white dwarf-main-sequence (WDMS) binary. These are commonly referred to as post-common envelope binaries (PCEBs). The remaining ∼75 per cent of mainsequence binaries are wide enough to avoid mass transfer interactions. In these cases the more massive stars evolve like single stars until they eventually become white dwarfs. The orbital separations of such WDMS binaries are similar to those of the main-sequence binaries from which they descend.During the last years we have mined the Sloan Digital Sky Survey (SDSS; York et al. 2000) spectroscopic data base to build up th...

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“…(1) Beuermann et al (2012b); (2) that the present-day population of PCEBs is simulated with a low value of the CE efficiency, including a fraction of the recombination energy, based on the results of Zorotovic et al (2010). A full parameter study will be presented elsewhere.…”

Section: Binary Population Simulationmentioning

confidence: 99%

“…The remaining system is a PCEB consisting of the core of the primary (a compact object) and an MS companion, in a close but detached orbit. The short duration of the CE phase ( < ∼ 10 3 yr) means that the mass of the secondary star is assumed to remain constant (Hjellming & Taam 1991), and the mass of the compact object should be equal to the mass of the core of the giant at the onset of mass transfer (for more details of CE evolution see, e.g., Iben & Livio 1993;Webbink 2008;Zorotovic et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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

Zorotovic

Schreiber

2013

A&A

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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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Post-common-envelope binaries from SDSS

Cited by 273 publications

References 85 publications

Detached cataclysmic variables are crossing the orbital period gap

Detached cataclysmic variables are crossing the orbital period gap

The SDSS spectroscopic catalogue of white dwarf-main-sequence binaries: new identifications from DR 9–12

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

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