First evidence of inertial modes in $\gamma$ Doradus stars: The core rotation revealed

Abstract

Gamma Doradus stars present an incredibly rich pulsation spectra, with gravito-inertial modes, in some cases supplemented with delta Scuti-like pressure modes and in numerous cases with Rossby modes. The present paper aims at showing that, in addition to these modes established in the radiative envelope, pure inertial modes, trapped in the convective core, can be detected in Kepler observations of gamma Doradus stars, thanks to their resonance with the gravito-inertial modes. We start by using a simplified model of perturbations in a full sphere of uniform density. Under these conditions, the spectrum of pure inertial modes is known from analytical solutions of the so-called Poincare equation. We then compute coupling factors which help select the pure inertial modes which interact best with the surrounding dipolar gravito-inertial modes. Using complete calculations of gravito-inertial modes in realistic models of gamma Doradus stars, we are able to show that the pure inertial/gravito-inertial resonances appear as dips in the gravito-inertial mode period spacing series at spin parameters close to those predicted by the simple model. We find the first evidence of such dips in the Kepler gamma Doradus star KIC5608334. Finally, using complete calculations in isolated convective cores, we find that the spin parameters of the pure inertial/gravito-inertial resonances are also sensitive to the density stratification of the convective core. In conclusion, we have discovered that certain dips in gravito-inertial mode period spacings observed in some Kepler stars are in fact the signatures of resonances with pure-inertial modes that are trapped in the convective core. This holds the promise to finally access the central conditions , i.e. rotation and density stratification, of intermediate-mass stars on the main sequence.

11 pages, 8 figures, accepted for publication in A&A

References in corpus (16)

• Slowing the Spins of Stellar Cores
• Probing the properties of convective cores through g modes: high-order g modes in SPB and gamma Doradus stars
• CLES, Code Liegeois d'Evolution Stellaire
• Asteroseismic measurement of surface-to-core rotation in a main sequence A star, KIC 11145123
• The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
• Simulations of core convection in rotating A-type stars: Magnetic dynamo action
• Asteroseismic measurement of slow, nearly-uniform surface-to-core rotation in the main sequence F star KIC 9244992
• A new asteroseismic diagnostic for internal rotation in $\gamma$ Doradus stars
• The Liege Oscillation Code
• Angular Momentum Transport via Internal Gravity Waves in Evolving Stars
• Angular momentum redistribution by mixed modes in evolved low-mass stars. II. Spin-down of the core of red giants induced by mixed modes
• Period spacings of $\gamma$ Doradus pulsators in the \textit{Kepler} field: Rossby and gravity modes in 82 stars
• Can plume-induced internal gravity waves regulate the core rotation of subgiant stars?
• Hydromagnetic quasi-geostrophic modes in rapidly rotating planetary cores
• The puzzling new class of variable stars in NGC 3766 : old friend pulsators?
• Pulsations of rapidly rotating stars: II. Realistic modelling for intermediate-mass stars

Cited by in corpus (47)

• Probing the interior physics of stars through asteroseismology
• Constraining stellar evolution theory with asteroseismology of $\gamma$ Doradus stars using deep learning
• Gaia Data Release 3: Pulsations in main sequence OBAF-type stars
• Detection of nonlinear resonances among gravity modes of slowly pulsating B stars: results from five iterative prewhitening strategies
• Highlights of Discoveries for $\delta$ Scuti Variable Stars From the Kepler Era
• Internal rotation and inclinations of slowly pulsating B stars: Evidence of interior angular momentum transport
• A comparison of the dynamical and model-derived parameters of the pulsating eclipsing binary KIC9850387
• Detection of period-spacing patterns due to the gravity modes of rotating dwarfs in the TESS southern continuous viewing zone
• Dynamical tidal Love numbers of rapidly rotating planets and stars
• Identification of inertial modes in the solar convection zone
• Asteroseismology of the young open cluster NGC 2516 I: Photometric and spectroscopic observations
• Predictions for gravity-mode periods and surface abundances in intermediate-mass dwarfs from shear mixing and radiative levitation
• Asteroseismic g-mode period spacings in strongly magnetic rotating stars
• Rossby numbers and stiffness values inferred from gravity-mode asteroseismology of rotating F- and B-type dwarfs: consequences for mixing, transport, magnetism, and convective penetration
• Overstable Convective Modes in Rotating Early Type Stars
• Detecting deep axisymmetric toroidal magnetic fields in stars. The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field
• The Asteroseismic Imprints of Mass Transfer: A Case Study of a Binary Mass Gainer in the SPB Instability Strip
• Age-dating the young open cluster UBC 1 with g-mode asteroseismology, gyrochronology, and isochrone fitting
• Calibrating angular momentum transport in intermediate-mass stars from gravity-mode asteroseismology
• Asteroseismology of the dip structure in period-spacings of rapidly rotating gamma Doradus stars caused by the coupling between core and envelope oscillations
• The traditional approximation of rotation for rapidly rotating stars and planets. II. Deformation and differential rotation
• Tidally perturbed g-mode pulsations in a sample of close eclipsing binaries
• TIC 308396022: a $\delta$ Scuti--$\gamma$ Doradus hybrid with large-amplitude radial fundamental mode and regular g-mode period spacing
• On the feasibility of structure inversions for gravity-mode pulsators
• Stochastic excitation of internal gravity waves in rotating late F-type stars: A 3D simulation approach
• Angular momentum transport near convective-core boundaries of Gamma Doradus stars
• V456 Cyg: An eclipsing binary with tidally perturbed g-mode pulsations
• The ESO UVES/FEROS Large Programs of TESS OB pulsators. I. Global stellar parameters from high-resolution spectroscopy
• The near-core rotation of HD 112429: a gamma Doradus star with TESS photometry and legacy spectroscopy
• Semi-Analytical Expression of G-Mode Period Spacing: The Case of Brunt-Väisälä Frequency with Not a Jump But a Ramp
• Mode coupling coefficients between the convective core and radiative envelope of $\gamma$Doradus and slowly pulsating B stars
• The efficiency of mixed modes for angular momentum transport
• Non-linear excitation of low frequency modes by overstable convective modes in rotating stars
• Chemical evolution of close massive binaries -- tidally-enhanced or tidally-suppressed mixing?
• Asteroseismology and Buoyancy Glitch Inversion with Fourier Spectra of Gravity Mode Period Spacings
• Distinguishing super-Nyquist frequencies via their temporal variation in $\gamma$ Doradus stars from continuous photometry
• Constraining differential rotation in gamma Doradus stars from inertial dips properties
• Properties of observable mixed inertial and gravito-inertial modes in γ Doradus stars
• Exploring the probing power of gamma-Dor's inertial dip for core magnetism: case of a toroidal field
• Core-envelope coupling of gravito-inertial waves in pre-main-sequence solar-type stars
• From core to envelope: revealing the deep dynamics of stars with two convective zones
• Probing the internal magnetism of stars using asymptotic magneto-asteroseismology
• Radial Trapping of Thermal Rossby Waves within the Convection Zones of Low-Mass Stars
• Finger on the pulse of asteroseismology
• Co-existence of Internal Gravity Waves and Tayler-Spruit Magnetic Fields in the Radiative Core of Low-mass Stars
• Towards a systematic treatment of observational uncertainties in forward asteroseismic modelling of gravity-mode pulsators
• Effects of the radiative interior on solar inertial modes