Photometric detection of internal gravity waves in upper main-sequence stars. I. Methodology and application to CoRoT targets

Bowman, D. M.; Aerts, C.; Johnston, C.; Pedersen, M. G.; Rogers, T. M.; Edelmann, P. V. F.; Simón-Díaz, S.; Van Reeth, T.; Buysschaert, B.; Tkachenko, A.; Triana, S. A.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 621, id.A135, 41 pp.

Fecha de publicación:
1
2019
Número de autores
11
Número de autores del IAC
1
Número de citas
77
Número de citas referidas
67
Descripción
Context. Main sequence stars with a convective core are predicted to stochastically excite internal gravity waves (IGWs), which effectively transport angular momentum throughout the stellar interior and explain the observed near-uniform interior rotation rates of intermediate-mass stars. However, there are few detections of IGWs, and fewer still made using photometry, with more detections needed to constrain numerical simulations. Aims: We aim to formalise the detection and characterisation of IGWs in photometric observations of stars born with convective cores (M ≳ 1.5 M⊙) and parameterise the low-frequency power excess caused by IGWs. Methods: Using the most recent CoRoT light curves for a sample of O, B, A and F stars, we parameterised the morphology of the flux contribution of IGWs in Fourier space using an MCMC numerical scheme within a Bayesian framework. We compared this to predictions from IGW numerical simulations and investigated how the observed morphology changes as a function of stellar parameters. Results: We demonstrate that a common morphology for the low-frequency power excess is observed in early-type stars observed by CoRoT. Our study shows that a background frequency-dependent source of astrophysical signal is common, which we interpret as IGWs. We provide constraints on the amplitudes of IGWs and the shape of their detected frequency spectrum across a range of mass, which is the first ensemble study of stochastic variability in such a diverse sample of stars. Conclusions: The evidence of a low-frequency power excess across a wide mass range supports the interpretation of IGWs in photometry of O, B, A and F stars. We also discuss the prospects of observing hundreds of massive stars with the Transiting Exoplanet Survey Satellite (TESS) in the near future.
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