Extensive study of HD 25558, a long-period double-lined binary with two SPB components

Sódor, Á.; Cat, P. De; Wright, D. E.; Neiner, C.; Briquet, Maryline; Lampens, P.; Dukes, R. J.; Henry, Gregory W.; Williamson, Michael H.; Brunsden, E.; Pollard, K. R.; Cottrell, P. L.; Maisonneuve, F.; Kilmartin, P. M.; Matthews, J. M.; Kallinger, T.; Beck, P. G.; Kambe, Eiji; Engelbrecht, C. A.; Czanik, R. J.; Yang, S.; Hashimoto, Osamu; Honda, Satoshi; Fu, Jian-Ning; Castanheira, B. G.; Lehmann, H.; Bognár, Zs.; Behara, N. T.; Scaringi, Simone; Winckel, H. Van; Menu, J.; Lobel, A.; Mathias, P.; Saesen, S.; Vučković, M.

doi:10.1093/mnras/stt2466

Cited by 8 publications

(5 citation statements)

References 37 publications

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“…The first detections of weak longitudinal magnetic fields (lower than 100 G) in the group of pulsating B stars have been achieved for the β Cep stars β Cephei (Henrichs et al 2000) and V 2052 Oph (Neiner et al 2003b). Following these discoveries, searches for magnetic fields in β Cep and SPB stars have been accomplished (e.g., Hubrig et al 2006;Hubrig et al 2009;Henrichs et al 2009;Silvester et al 2009;Alecian et al 2011;Briquet et al 2013;Neiner et al 2014c;Sódor et al 2014), definitely showing that magnetic fields are present among B-type pulsators. However, direct detections of a Zeeman signature in the Stokes V measurements has only been obtained for ∼70 magnetic massive stars and they remain limited for pulsat-Based on observations obtained at the Telescope Bernard Lyot (USR5026) operated by the Observatoire Midi-Pyrénées, Université de Toulouse (Paul Sabatier), Centre National de la Recherche Scientifique (CNRS) of France.…”

Section: Introductionmentioning

confidence: 99%

“…Following these discoveries, searches for magnetic fields in β Cep and SPB stars have been accomplished (e.g. Hubrig et al 2006Hubrig et al , 2009Henrichs et al 2009;Silvester et al 2009;Alecian et al 2011;Briquet et al 2013;Neiner et al 2014c;Sódor et al 2014), definitely showing that magnetic fields are present among B-type pulsators. However, direct detections of a Zeeman signature in the Stokes V measurements have only been obtained for ∼70 magnetic massive stars and they remain limited for pulsating B stars (∼15 targets).…”

Section: Introductionmentioning

confidence: 99%

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Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB starζCassiopeiae

Briquet¹,

Neiner²,

Petit³

et al. 2016

A&A

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Aims. The main-sequence B-type star ζ Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher precision to investigate the field strength, topology, and effect. Methods. We gathered data with the Narval spectropolarimeter installed at Télescope Bernard Lyot (TBL; Pic du Midi, France) and applied the least-squares deconvolution technique to measure the circular polarisation of the light emitted from ζ Cas. We used a dipole oblique rotator model to determine the field configuration by fitting the longitudinal field measurements and by synthesizing the measured Stokes V profiles. We also made use of the Zeeman-Doppler imaging technique to map the stellar surface and to deduce the difference in rotation rate between the pole and equator. Results. ζ Cas exhibits a polar field strength B pol of 100−150 G, which is the weakest polar field observed so far in a massive mainsequence star. Surface differential rotation is ruled out by our observations and the field of ζ Cas is strong enough to enforce rigid internal rotation in the radiative zone according to theory. Thus, the star rotates as a solid body in the envelope. Conclusions. We therefore exclude rotationally induced mixing as the cause of the surface N-enrichment. We discuss that the transport of chemicals from the core to the surface by internal gravity waves is the most plausible explanation for the nitrogen overabundance at the surface of ζ Cas.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB starζCassiopeiae

Briquet¹,

Neiner²,

Petit³

et al. 2016

A&A

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“…This can be partly overcome if enough observations are available, and the variability of the components is sufficiently large, that the contributions of the individual stars can be discerned. Spectral modelling accounting for all components has already been performed for HD 25558 (Sódor et al 2014) No analysis of log g carefully accounting for binarity is available for HD 36485, HD 149277, HD 136504, or HD 37017. For these systems a grid of at least 25 synthetic spectra was prepared for each stellar component, covering the approximate range in T eff and log g expected for the components, using either tlusty BSTAR2006 models (when both components are likely above T eff =15 kK) or ATLAS models (when one of the stars is below 15 kK).…”

Section: Appendix C: Surface Gravity Measurements Of Binary Starsmentioning

confidence: 99%

The Magnetic Early B-type Stars II: stellar atmospheric parameters in the era of Gaia

Shultz,

Wade,

Rivinius

et al. 2019

Preprint

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Atmospheric parameters determined via spectral modelling are unavailable for many of the known magnetic early B-type stars. We utilized high-resolution spectra together with NLTE models to measure effective temperatures T eff and surface gravities log g of stars for which these measurements are not yet available. We find good agreement between our T eff measurements and previous results obtained both photometrically and spectroscopically. For log g, our results are compatible with previous spectroscopic measurements; however, surface gravities of stars previously determined photometrically have been substantially revised. We furthermore find that log g measurements obtained with HARPSpol are typically about 0.1 dex lower than those from comparable instruments. Luminosities were determined using Gaia Data Release 2 parallaxes. We find Gaia parallaxes to be unreliable for bright stars (V < 6 mag) and for binaries; in these cases we reverted to Hipparcos parallaxes. In general we find luminosities systematically lower than those previously reported. Comparison of log g and log L to available rotational and magnetic measurements shows no correlation between either parameter with magnetic data, but a clear slow-down in rotation with both decreasing log g and increasing log L, a result compatible with the expectation that magnetic braking should lead to rapid magnetic spindown that accelerates with increasing massloss.

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“…The frequency identification and light-curve prewhitening was performed in a standard way. A more detailed description of the procedure can be found in Sódor et al (2014). 1/9 2/9 3/9 4/9 5/9 6/9 7/9 8/9 9/9 10/9 11/9 12/9 13/9 14/9 15/9 16/9 17/9 18/9 19/9 Table 1, is represented by thick vertical lines in the negative amplitude range.…”

Section: Light-curve Analysismentioning

confidence: 99%

“…The frequency identification and light-curve prewhitening was performed in a standard way. A more detailed description of the procedure can be found in Sódor et al (2014).…”

Section: Light-curve Analysismentioning

confidence: 99%

MOST light-curve analysis of theγDoradus pulsator HR 8799, showing resonances and amplitude variations

Sódor

Chené

Cat

et al. 2014

A&A

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Context. The central star of the HR 8799 system is a γ Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not accurately known because the estimation depends greatly on the age of the system, which is also not known with sufficient accuracy. Asteroseismic studies of the star might help to better constrain the age of HR 8799. We organized an extensive photometric and multi-site spectroscopic observing campaign to study the pulsations of the central star. Aims. The aim of the present study is to investigate the pulsation properties of HR 8799 in detail via the ultra-precise 47 d nearly continuous photometry obtained with the Microvariability and Oscillations in STars (MOST) space telescope, and to find as many independent pulsation modes as possible, which is the prerequisite for an asteroseismic age determination. Methods. We carried out Fourier analysis of the wide-band photometric time series. Results. We find that resonance and sudden amplitude changes characterize the pulsation of HR 8799. The dominant frequency is always at f 1 = 1.978 d −1 . Many multiples of one-ninth of the dominant frequency appear in the Fourier spectrum of the MOST data: n/9 f 1 , where n = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 17, 18}. Our analysis also reveals that many of these peaks show strong amplitude decrease and phase variations even on the 47 d time scale. The dependencies between the pulsation frequencies of HR 8799 make the planned subsequent asteroseismic analysis rather difficult. We point out some resemblance between the light curve of HR 8799 and the modulated pulsation light curves of Blazhko RR Lyrae stars.

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Extensive study of HD 25558, a long-period double-lined binary with two SPB components

Cited by 8 publications

References 37 publications

Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB starζCassiopeiae

Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB starζCassiopeiae

The Magnetic Early B-type Stars II: stellar atmospheric parameters in the era of Gaia

MOST light-curve analysis of theγDoradus pulsator HR 8799, showing resonances and amplitude variations

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