Solar inertial modes: Observations, identification, and diagnostic promise

Abstract

The oscillations of a slowly rotating star have long been classified into spheroidal and toroidal modes. The spheroidal modes include the well-known 5-min acoustic modes used in helioseismology. Here we report observations of the Sun's toroidal modes, for which the restoring force is the Coriolis force and whose periods are on the order of the solar rotation period. By comparing the observations with the normal modes of a differentially rotating spherical shell, we are able to identify many of the observed modes. These are the high-latitude inertial modes, the critical-latitude inertial modes, and the equatorial Rossby modes. In the model, the high-latitude and critical-latitude modes have maximum kinetic energy density at the base of the convection zone, and the high-latitude modes are baroclinically unstable due to the latitudinal entropy gradient. As a first application of inertial-mode helioseismology, we constrain the superadiabaticity and the turbulent viscosity in the deep convection zone.

arXiv commentForthcoming article, Astronomy and Astrophysics

References in corpus (18)

• Helioseismology
• Probing the interior physics of stars through asteroseismology
• Global-scale equatorial Rossby waves as an essential component of solar internal dynamics
• Giant Convection Cells Found on the Sun
• Time-distance helioseismology of solar Rossby waves
• Extended subadiabatic layer in simulations of overshooting convection
• On the Amplitude of Convective Velocities in the Deep Solar Interior
• Magnetic Quenching of Turbulent Diffusivity: Reconciling Mixing-length Theory Estimates with Kinematic Dynamo Models of the Solar Cycle
• Inertial waves in a differentially rotating spherical shell
• Solar overshoot region and small-scale dynamo with realistic energy flux
• Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars
• The turbulent diffusion of toroidal magnetic flux as inferred from properties of the sunspot butterfly diagram
• Evolution of Near-surface Flows Inferred from High-resolution Ring-diagram Analysis
• Exploring the latitude and depth dependence of solar Rossby waves using ring-diagram analysis
• Hydrodynamic Properties of the Sun's Giant Cellular Flows
• Convective velocity suppression via the enhancement of subadiabatic layer: Role of the effective Prandtl number
• Effect of latitudinal differential rotation on solar Rossby waves: Critical layers, eigenfunctions, and momentum fluxes in the equatorial $\beta$ plane
• The rotation rate of solar active and ephemeral regions -- I. Dependence on morphology and peak magnetic flux

Cited by in corpus (32)

• Theory of solar oscillations in the inertial frequency range: Linear modes of the convection zone
• Theory of solar oscillations in the inertial frequency range: Amplitudes of equatorial modes from a nonlinear rotating convection simulation
• Identification of inertial modes in the solar convection zone
• The Sun's differential rotation is controlled by high-latitude baroclinically unstable inertial modes
• Solar-like to Antisolar Differential Rotation: A Geometric Interpretation
• On the dynamics of overshooting convection in spherical shells: Effect of density stratification and rotation
• A spectral solver for solar inertial waves
• Viscous inertial modes on a differentially rotating sphere: Comparison with solar observations
• Doppler velocity of $m=1$ high-latitude inertial mode over the last five sunspot cycles
• Interaction of solar inertial modes with turbulent convection. A 2D model for the excitation of linearly stable modes
• A theoretic analysis of magnetoactive GES-based turbulent solar plasma instability
• Three-dimensional non-kinematic simulation of post-emergence evolution of bipolar magnetic regions and Babcock-Leighton dynamo of the Sun
• Imaging the Sun's near-surface flows using mode-coupling analysis
• Amplitudes of Solar Gravity Modes: A Review
• Overstable Convective Modes in a Polytropic Stellar Atmosphere
• Spectroscopic detection of Altair's non-radial pulsations
• In search of gravity mode signatures in main sequence solar-type stars observed by Kepler
• Simulations of entropy rain-driven convection
• Global Turbulent Solar Convection: a Numerical Path Investigating Key Force Balances in the context of the Convective Conundrum
• The impact of rotation on the stochastic excitation of stellar acoustic modes in solar-like pulsators
• Rossby waves on stellar equatorial beta-planes: uniformly rotating radiative stars
• Tidally driven inertial waves enhance eccentricity damping and spin evolution in planets and stars
• Assessing the validity of the anelastic and Boussinesq approximations to model solar inertial modes
• Oscillations of the solar photospheric magnetic field caused by the m = 1 high-latitude inertial mode
• Radial Trapping of Thermal Rossby Waves within the Convection Zones of Low-Mass Stars
• Supergranulation and Poleward Migration of the Magnetic Field at High Latitudes of the Sun
• The rush to the poles and the role of magnetic buoyancy in the solar dynamo
• Effects of the radiative interior on solar inertial modes
• The stability of propagating plane inertial waves in rotating fluids
• Towards inertial-mode helioseismology: Direct sensing of solar rotation at 75 deg latitude and 0.8 Rsun
• Activity-Cycle Variations of Convection Scales in Subsurface Layers of the Sun
• Confinement of the Solar Tachocline by Dynamo Action in the Radiative Interior