A multisite photometric study of two unusual β Cep stars: the magnetic V2052 Oph and the massive rapid rotator V986 Oph

Handler, G.; Shobbrook, R. R.; Uytterhoeven, K.; Briquet, Maryline; Neiner, C.; Tshenye, T.; Ngwato, B.; Winckel, H. Van; Guggenberger, E.; Raskin, Gert; Rodríguez‐López, C.; Mazumdar, A.; Barban, C.; Lorenz, D.; Vandenbussche, B.; Şahìn, T.; Medupe, R.; Aerts, C.

doi:10.1111/j.1365-2966.2012.21414.x

Cited by 28 publications

(36 citation statements)

References 56 publications

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“…Heynderickx et al 1994;Dupret et al 2003). Recent applications of this technique to derive the modes of individual stars include, for example, Aerts & Kolenberg (2005), Tremblay et al (2006), Daszyńska-Daszkiewicz (2008), Handler et al (2012).…”

Section: Multiband Variability Propertiesmentioning

confidence: 99%

Stellar variability in open clusters

Mowlavï¹,

Barblan²,

Saesen³

et al. 2013

A&A

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Aims. We analyze the population of periodic variable stars in the open cluster NGC 3766 based on a 7-year multiband monitoring campaign conducted on the 1.2 m Swiss Euler telescope at La Silla, Chili. Methods. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the millimagnitude (mmag) level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. Results. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of δ Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7 d, with amplitudes between 1 and 4 mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. The properties of this new group of variable stars are summarized and arguments set forth in favor of a pulsation origin of the variability, with g-modes sustained by stellar rotation. Potential members of this new class of low-amplitude periodic (most probably pulsating) A and late-B variables in the literature are discussed. We additionally identify 16 eclipsing binary, 13 SPB, 14 δ Sct, and 12 γ Dor candidates, as well as 72 fainter periodic variables. All are new discoveries. Conclusions. We encourage searching for this new class of variables in other young open clusters, especially in those hosting a rich population of Be stars.

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Section: Multiband Variability Propertiesmentioning

confidence: 99%

Stellar variability in open clusters

Mowlavï¹,

Barblan²,

Saesen³

et al. 2013

A&A

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“…An overview of the currently known magnetic early-type pulsators is given in Buysschaert et al (2016). So far, only V2052 Oph (Neiner et al 2012a;Handler et al 2012;Briquet et al 2012) and β Cep (Shibahashi & Aerts 2000;Henrichs et al 2013) have been studied in detail using magnetoasteroseismology. Respectively three and five pulsation modes have been detected for these two magnetic pulsators.…”

Section: The Effect Of Magnetism In Early-type Starsmentioning

confidence: 99%

Magnetic characterization of the SPB/β Cep hybrid pulsator HD 43317

Buysschaert

Neiner

Briquet

et al. 2017

A&A

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Large-scale magnetic fields at the surface of massive stars do not only influence the outer-most layers of the star, but also have consequences for the deep interior, only observationally accessible through asteroseismology. We performed a detailed characterization of the dipolar magnetic field at the surface of the B3.5V star HD 43317, a SPB/β Cep hybrid pulsator, by studying the rotationally modulated magnetic field of archival and new Narval spectropolarimetry. Additionally, we employed a grid-based approach to compare the Zeeman signatures with model profiles. By studying the rotational modulation of the He lines in both the Narval and HARPS spectroscopy caused by co-rotating surface abundance inhomogeneities, we updated the rotation period to 0.897673 ± 0.000004 d. The inclination angle between the rotation axis and the observer's line of sight remains ill-defined, because of the low level of variability in Stokes V and deformations in the intensity profiles by stellar pulsation modes. The obliquity angle between the rotation and magnetic axes is constrained to β ∈ [67, 90] • , and the strength of the dipolar magnetic field is of the order of 1 kG to 1.5 kG. This magnetic field at the stellar surface is sufficiently strong to warrant a uniformly rotating radiative envelope, causing less convective core overshooting, which should be visible in future forward seismic modeling.

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“…Some β Cep stars appear to have strong magnetic fields (Silvester et al 2009;Hubrig et al 2011;Neiner et al 2012) while others have weak magnetic fields or none at all (Silvester et al 2009;Fossati et al 2015); some rotate rapidly (Aerts et al 1994;Handler et al 2012), while others rotate slowly (Shultz et al 2015). Most, if not all, β Cep stars tend to have weak stellar winds (Martins et al 2005;Huenemoerder et al 2012) and are also X-ray sources.…”

Section: Introductionmentioning

confidence: 99%

Period change and stellar evolution ofβCephei stars

Neilson

Ignace

2015

A&A

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The β Cephei stars represent an important class of massive star pulsators that probe the evolution of B-type stars and the transition from main sequence to hydrogen-shell burning evolution. By understanding β Cep stars, we gain insights into the detailed physics of massive star evolution, including rotational mixing, convective core overshooting, magnetic fields, and stellar winds, all of which play important roles. Similarly, modeling their pulsation provides additional information into their interior structures. Furthermore, measurements of the rate of change of pulsation period offer a direct measure of β Cephei stellar evolution. In this work, we compute state-of-the-art stellar evolution models assuming different amounts of initial rotation and convective core overshoot and measure the theoretical rates of period change, that we compare to rates previously measured for a sample of β Cephei stars. The results of this comparison are mixed. For three stars, the rates are too low to infer any information from stellar evolution models, whereas for three other stars the rates are too high. We infer stellar parameters, such as mass and age, for two β Cephei stars: ξ 1 CMa and δ Cet, which agree well with independent measurements. We explore ideas for why models may not predict the higher rates of period change. In particular, period drifts in β Cep stars can artificially lead to overestimated rates of secular period change.

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A multisite photometric study of two unusual β Cep stars: the magnetic V2052 Oph and the massive rapid rotator V986 Oph

Cited by 28 publications

References 56 publications

Stellar variability in open clusters

Stellar variability in open clusters

Magnetic characterization of the SPB/β Cep hybrid pulsator HD 43317

Period change and stellar evolution ofβCephei stars

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