CoRoT photometry and high-resolution spectroscopy of the interacting eclipsing binary AU Monocerotis

Context. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. Aims. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigate the relation between γ Doradus (γ Dor), δ Scuti (δ Sct), and hybrid stars. Methods. We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, "energy" and "efficiency", related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively. Results. We propose three main groups to describe the observed variety in pulsating A-F type stars: γ Dor, δ Sct, and hybrid stars. We assign 63% of our sample to one of the three groups, and identify the remaining part as rotationally modulated/active stars, binaries, stars of different spectral type, or stars that show no clear periodic variability. 23% of the stars (171 stars) are hybrid stars, which is a much higher fraction than what has been observed before. We characterize for the first time a large number of A-F type stars (475 stars) in terms of number of detected frequencies, frequency range, and typical pulsation amplitudes. The majority of hybrid stars show frequencies with all kinds of periodicities within the γ Dor and δ Sct range, also between 5 and 10 d −1 , which is a challenge for the current models. We find indications for the existence of δ Sct and γ Dor stars beyond the edges of the current observational instability strips. The hybrid stars occupy the entire region within the δ Sct and γ Dor instability strips and beyond. Non-variable stars seem to exist within the instability strips. The location of γ Dor and δ Sct classes in the (T eff , log g)-diagram has been extended. We investigate two newly constructed variables, "efficiency" and "energy", as a means to explore the relation between γ Dor and δ Sct stars. Conclusions. Our results suggest a revision of the current observational instability strips of δ Sct and γ Dor stars and imply an investigation of pulsation mechanisms to supplement the κ mechanism and convective blocking effect to drive hybrid pulsations. Accurate physical parameters for all stars are needed to confirm these findings.

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“…Tango et al 2006;Desmet et al 2010). Our sample consists of several binaries and eclipsing systems with (a) pulsating component(s) (see Table 4).…”

Section: Summary Discussion and Future Prospectsmentioning

confidence: 99%

TheKeplercharacterization of the variability among A- and F-type stars

Uytterhoeven

Moya

Grigahcène

et al. 2011

A&A

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“…3. Two-dimensional (2D) cross-correlation using a Fortran implementation of the TODCOR (Zucker & Mazeh 1994) called asTODCOR, developed by one of the present authors (YF) and first applied to the study of AU Mon (Desmet et al 2010). …”

Section: Radial-velocity and Orbit Determinationmentioning

confidence: 99%

Physical properties of seven binary and higher-order multiple OB systems

Mayer

Harmanec

Chini

et al. 2017

A&A

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Analyses of multi-epoch, high-resolution (R ∼ 50000) optical spectra of seven early-type systems provided various important new insights with respect to their multiplicity. For HD 93146 A, which was hitherto assumed to be SB1, lines of a secondary component could be discerned. HD 123056 turns out to be a multiple system consisting of a high-mass component A (≈ O8.5) displaying a broad He ii 5411 Å feature with variable radial velocity, and of an inner pair B (≈ B0) with double He i lines. The binary HD 164816 was revisited and some of its system parameters were improved. In particular, we determined its systemic velocity to be −7 km s −1 , which coincides with the radial velocity of the cluster NGC 6530. This fact, together with its distance, suggests the cluster membership of HD 164816. The OB system HD 318015 (V1082 Sco) belongs to the rare class of eclipsing binaries with a supergiant primary (B0.5/0.7). Our combined orbital and light-curve analysis suggests that the secondary resembles an O9.5 III star. Our results for a limited sample corroborate the findings that many O stars are actually massive multiple systems.

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“…At present, there are more than 150 DPVs discovered in the Magellanic Clouds and 11 systems (including DQ Vel) in the Milky Way (Mennickent et al 2012a). Results of multiwavelength spectroscopy and/or photometry have made it possible to study DPVs in more detail, such as AU Mon (Desmet et al 2010;Djurašević et al 2010), V393 Sco (Mennickent et al , 2012a, and LP Ara (Mennickent et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Fundamental stellar and accretion disc parameters of the eclipsing binary DQ Velorum

Barría

Mennickent

Schmidtobreick

et al. 2013

A&A

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Context. To add to the growing collection of well-studied double periodic variables (DPVs) we have carried out the first spectroscopic and photometric analysis of the eclipsing binary DQ Velorum to obtain its main physical stellar and orbital parameters. Aims. Combining spectroscopic and photometric observations that cover several orbital cycles allows us to estimate the stellar properties of the binary components and the orbital parameters. We also searched for circumstellar material around the more massive star. Methods. We separated DQ Velorum composite spectra and measured radial velocities with an iterative method for double spectroscopic binaries. We obtained the radial velocity curves and calculated the spectroscopic mass ratio. We compared our single-lined spectra with a grid of synthetic spectra and estimated the temperature of the stars. We modeled the V-band light curve with a fitting method based on the simplex algorithm, which includes an accretion disc. To constrain the main stellar parameters we fixed the mass ratio and donor temperature to the values obtained by our spectroscopic analysis. Results. We obtain a spectroscopic mass ratio q = 0.31 ± 0.03 together with donor and gainer masses M d = 2.2 ± 0.2 M , M g = 7.3 ± 0.3 M , the radii R d = 8.4 ± 0.2 R , R g = 3.6 ± 0.2 R and temperatures T d = 9400 ± 100 K, T g = 18 500 ± 500 K for the stellar components. We find that DQ Vel is a semi-detached system consisting of a B3V gainer and an A1III donor star plus an extended accretion disc around the gainer. The disc is filling 89% of the gainer Roche lobe with a temperature of 6580 ± 300 K at the outer radius. It has a concave shape that is thicker at its edge (d e = 0.6 ± 0.1 R ) than at its centre (d c = 0.3 ± 0.1 R ). We find a significant sub-orbital frequency of 0.19 d −1 in the residuals of the V-band light curve, which we interpret as a pulsation of an slowly pulsating B-type (SPB) of a gainer star. We also estimate the distance to the binary (d ∼ 3.1 kpc) using the absolute radii, apparent magnitudes, and effective temperatures of the components found in our study.

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CoRoT photometry and high-resolution spectroscopy of the interacting eclipsing binary AU Monocerotis

Cited by 36 publications

References 68 publications

TheKeplercharacterization of the variability among A- and F-type stars

TheKeplercharacterization of the variability among A- and F-type stars

Physical properties of seven binary and higher-order multiple OB systems

Fundamental stellar and accretion disc parameters of the eclipsing binary DQ Velorum

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