The B0.5 IVe CoRoT target HD 49330

Floquet, M.; Hubert, A. M.; Huat, Anne-Laure; Frémat, Y.; Janot-Pacheco, E.; Gutiérrez‐Soto, J.; Neiner, C.; Batz, B. de; Leroy, B.; Poretti, E.; Amado, P. J.; Catala, C.; Rainer, M.; Diaz, David; Uytterhoeven, K.; Andrade, L.; Diago, P. D.; Emílio, M.; Lara, F. Espinosa; Fabregat, J.; Martayan, C.; Semaan, T.; Suso, J.

doi:10.1051/0004-6361/200911927

Cited by 17 publications

(18 citation statements)

References 16 publications

(23 reference statements)

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“…Furthermore, although not to the same extent, HD 49330 also exhibited enhanced pulsation amplitudes during the outburst. However, in contrast to the weak Be signatures observed in KIC 11971405, the CoRoT target showed a very strong (and varying) emission component (Floquet et al 2009). …”

Section: Kic 11971405mentioning

confidence: 82%

Signatures of internal rotation discovered in theKeplerdata of five slowly pulsating B stars

Pápics

Tkachenko

Reeth

et al. 2017

A&A

155

232

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Context. Massive stars are important building blocks of the Universe, and their stellar structure and evolution models are fundamental cornerstones of various fields in modern astrophysics. The precision of these models is strongly limited by our lack of understanding of various internal mixing processes that significantly influence the lifetime of these objects, such as core overshoot, chemical mixing, or the internal differential rotation. Aims. Our goal is to calibrate models by extending the sample of available seismic studies of slowly pulsating B (SPB) stars, providing input for theoretical modelling efforts that will deliver precise constraints on the parameters describing the internal mixing processes in these objects. Methods. We used spectral synthesis and disentangling techniques to derive fundamental parameters and to determine precise orbital parameters from high-resolution spectra. We employed custom masks to construct light curves from the virtually uninterrupted four year long Kepler pixel data and used standard time-series analysis tools to construct a set of significant frequencies for each target. These sets were first filtered from combination frequencies, and then screened for period spacing patterns. Results. We detect gravity mode period series of modes, of the same degree with consecutive radial order n, in four new and one revisited SPB star. These series (covering typically 10 to 40 radial orders) are clearly influenced by moderate to fast rotation and carry signatures of chemical mixing processes. Furthermore, they are predominantly prograde dipole series. Our spectroscopic analysis, in addition to placing each object inside the SPB instability strip and identifying KIC 4930889 as an SB2 binary, reveals that KIC 11971405 is a fast rotator that shows very weak Be signatures. Together with the observed photometric outbursts this illustrates that this Be star is a fast rotating SPB star. We hypothesise that the outbursts might be connected to its very densely compressed oscillation spectrum.

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Section: Kic 11971405mentioning

confidence: 82%

Signatures of internal rotation discovered in theKeplerdata of five slowly pulsating B stars

Pápics

Tkachenko

Reeth

et al. 2017

A&A

155

232

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“…) for the transport of angular momentum in the outbursting Be star HD 49330 observed with CoRoT Floquet et al 2009). Samadi et al (2010) examined the stochastic excitation of gravity modes by turbulent convection in massive stars.…”

Section: Stochastically Excited Gravito-inertial Modesmentioning

confidence: 99%

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452

Neiner

Floquet

Samadi

et al. 2012

A&A

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Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD 51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods. We analyzed the CoRoT and spectroscopic data with several methods: Clean-NG, FreqFind, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d −1 . The main frequencies are also recovered in the spectroscopic data. In particular we find that HD 51452 undergoes gravito-inertial modes that are not in the domain of those excited by the κ-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD 51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts. Conclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD 51452, which are stochastically excited gravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot Be stars.

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“…In Table 4, a short summary of the results for the observed stars is given (for details: see overview of Gutiérrez-Soto et al, these proceedings). HD 49330 showed a moderate outburst of 30 mmag during the corot observations Floquet et al 2009). The outburst could be subdivided in four phases: quiescent, precursor, outburst and relaxation.…”

Section: Hd Numbermentioning

confidence: 95%

Asteroseismic observations of OB stars

et al. 2010

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Abstract. The region of the hot end of the main-sequence is hosting pulsating stars of different types and flavours. Pulsations are not only observed for Slowly pulsating B stars (mid to late B-type stars; high order g-modes) and β Cephei stars (early B-type stars; low order p/g-modes) but are also causing variability in Be stars and OB-supergiants. In this review we give an overview of the asteroseismic observations that are currently available for these types of stars. The first asteroseismic results were solely based on ground-based observations. Recently, the arrival of space-based data gathered by space missions like most, corot and kepler has led to important discoveries for massive stars, highlighting their excellent asteroseismic potential. We show that, despite the unprecedented precision of the space-based data, there is still a clear need for ground-based follow-up observations.

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The B0.5 IVe CoRoT target HD 49330

Cited by 17 publications

References 16 publications

Signatures of internal rotation discovered in theKeplerdata of five slowly pulsating B stars

Signatures of internal rotation discovered in theKeplerdata of five slowly pulsating B stars

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452

Asteroseismic observations of OB stars

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