From core to envelope: revealing the deep dynamics of stars with two convective zones

Abstract

On the Hertzsprung-Russell diagram, F-type solar pulsators connect the Sun to intermediate mass stars located on the instability strip. With respect to lower mass stars, they are structurally peculiar in the sense that they are constituted of three distinct dynamical layers: a small convective core, a deep radiative interior, and a shallow convective envelope. Current asteroseismic techniques only provide limited information on the interior dynamics of these stars. Indeed only gravity modes (g modes), for which unambiguous characterisation is lacking, are able to probe the deep stellar layers. A better understanding of the excitation and behaviour in F-type solar pulsators is therefore necessary in order to consider their detection. In this work, we simulate for the first time the global stellar structure of an F-type star (core, radiative interior, envelope). We show that the contribution of the core strongly affects the spectrum of excited g modes, with low-order high-degree modes unable to form due to their interaction with the turbulent convection of the core. Finally, by computing the disc-integrated signature of the modes, we are able to demonstrate that they preserve their integrity up to the top of the convective envelope, which is a strong argument in favour of their detectability with spaceborne photometry.

12 pages, 14 figures. Accepted for publication in A&A

References in corpus (18)

• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• Standing on the shoulders of Dwarfs: the Kepler asteroseismic LEGACY sample II - radii, masses, and ages
• Standing on the shoulders of Dwarfs: the $Kepler$ asteroseismic LEGACY sample I - oscillation mode parameters
• Asteroseismology of solar-type stars
• Stochastic excitation of nonradial modes II. Are solar asymptotic gravity modes detectable?
• Theoretical seismology in 3D : nonlinear simulations of internal gravity waves in solar-like stars
• Energy Conservation and Gravity Waves in Sound-proof Treatments of Stellar Interiors: Part I Anelastic Approximations
• The all-sky PLATO input catalogue
• Stochastic excitation of non-radial modes I. High-angular-degree p modes
• First evidence of inertial modes in $\gamma$ Doradus stars: The core rotation revealed
• Semi-analytic Expressions for the Isolation and Coupling of Mixed Modes
• Dynamical tide in stellar radiative zones. General formalism and evolution for low-mass stars
• Asteroseismology of the dip structure in period-spacings of rapidly rotating gamma Doradus stars caused by the coupling between core and envelope oscillations
• Stochastic excitation of internal gravity waves in rotating late F-type stars: A 3D simulation approach
• Amplitudes of Solar Gravity Modes: A Review
• In search of gravity mode signatures in main sequence solar-type stars observed by Kepler
• Constraining differential rotation in gamma Doradus stars from inertial dips properties
• Core-envelope coupling of gravito-inertial waves in pre-main-sequence solar-type stars