Kyle Augustson
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View article: The solar dynamo begins near the surface
The solar dynamo begins near the surface Open
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating region of sunspot emergence appears around 30° latitude and vanishes near the equator every 11 years (ref. 1 ). Moreover, longitudinal flows called torsional o…
View article: The solar dynamo begins near the surface
The solar dynamo begins near the surface Open
The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional oscillat…
View article: Iterative Methods for Navier--Stokes Inverse Problems
Iterative Methods for Navier--Stokes Inverse Problems Open
Even when the partial differential equation underlying a physical process can be evolved forward in time, the retrospective (backward in time) inverse problem often has its own challenges and applications. Direct Adjoint Looping (DAL) is t…
View article: The Puzzling Structure of Solar Convection: Window into the Dynamo
The Puzzling Structure of Solar Convection: Window into the Dynamo Open
Whitepaper #105 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research; infrastructure/workforce/other programmatic. Additional topics: solar physics; research tools and infrastructure.
View article: The Puzzling Structure of Solar Convection: Window into the Dynamo
The Puzzling Structure of Solar Convection: Window into the Dynamo Open
The operation of the solar dynamo, with all of its remarkable spatio-temporal ordering, remains an outstanding problem of modern solar physics. A number of mechanisms that might plausibly contribute to its operation have been proposed, but…
View article: How tidal waves interact with convective vortices in rapidly rotating planets and stars
How tidal waves interact with convective vortices in rapidly rotating planets and stars Open
Context. The dissipation of tidal inertial waves in planetary and stellar convective regions is one of the key mechanisms that drive the evolution of star–planet and planet–moon systems. This dissipation is particularly efficient for young…
View article: How do tidal waves interact with convective vortices in rapidly-rotating planets and stars?
How do tidal waves interact with convective vortices in rapidly-rotating planets and stars? Open
The dissipation of tidal inertial waves in planetary and stellar convective regions is one of the key mechanisms that drive the evolution of star-planet/planet-moon systems. In this context, the interaction between tidal inertial waves and…
View article: Powering Stellar Magnetism: Energy Transfers in Cyclic Dynamos of Sun-like Stars
Powering Stellar Magnetism: Energy Transfers in Cyclic Dynamos of Sun-like Stars Open
We use the anelastic spherical harmonic code to model the convective dynamo of solar-type stars. Based on a series of 15 3D MHD simulations spanning four bins in rotation and mass, we show what mechanisms are at work in these stellar dynam…
View article: Rossby numbers and stiffness values inferred from gravity-mode asteroseismology of rotating F- and B-type dwarfs
Rossby numbers and stiffness values inferred from gravity-mode asteroseismology of rotating F- and B-type dwarfs Open
Context. Multi-dimensional (magneto-)hydrodynamical simulations of physical processes in stellar interiors depend on a multitude of uncalibrated free parameters, which set the spatial and time scales of their computations. Aims. We aim to …
View article: 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
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 Open
Multi-dimensional (magneto-)hydrodynamical simulations of physical processes in stellar interiors depend on a multitude of uncalibrated free parameters, which set the spatial and time scales of their computations. We aim to provide an aste…
View article: Magnetic signatures on mixed-mode frequencies
Magnetic signatures on mixed-mode frequencies Open
Context. The discovery of moderate differential rotation between the core and the envelope of evolved solar-like stars could be the signature of a strong magnetic field trapped inside the radiative interior. The population of intermediate-…
View article: Differential rotation and stellar magnetism impact star-planet tidal interactions
Differential rotation and stellar magnetism impact star-planet tidal interactions Open
Over 4000 exoplanets have been discovered in the past 25 years or so, most of which orbit cool stars. Star-planet tidal interactions are known to drive the late evolution of the shortest-period planetary systems via tidal dissipation. Such…
View article: Magnetic signatures on mixed-mode frequencies. I. An axisymmetric fossil field inside the core of red giants
Magnetic signatures on mixed-mode frequencies. I. An axisymmetric fossil field inside the core of red giants Open
The discovery of the moderate differential rotation between the core and the envelope of evolved solar-like stars could be the signature of a strong magnetic field trapped inside the radiative interior. The population of intermediate-mass …
View article: Probing the internal magnetism of stars using asymptotic magneto-asteroseismology
Probing the internal magnetism of stars using asymptotic magneto-asteroseismology Open
Context. Our knowledge of the dynamics of stars has undergone a revolution through the simultaneous large amount of high-quality photometric observations collected by space-based asteroseismology and ground-based high-precision spectropola…
View article: Probing the internal magnetism of stars using asymptotic magneto-asteroseismology
Probing the internal magnetism of stars using asymptotic magneto-asteroseismology Open
Our knowledge of the dynamics of stars has undergone a revolution thanks to the simultaneous large amount of high-quality photometric observations collected by space-based asteroseismology and ground-based high-precision spectropolarimetry…
View article: A Model of Rotating Convection in Stellar and Planetary Interiors. II. Gravito-inertial Wave Generation
A Model of Rotating Convection in Stellar and Planetary Interiors. II. Gravito-inertial Wave Generation Open
Gravito-inertial waves are excited at the interface of convective and radiative regions and by the Reynolds stresses in the bulk of the convection zones of rotating stars and planets. Such waves have notable asteroseismic signatures in the…
View article: IAU volume 15 issue 354 Cover and Front matter
IAU volume 15 issue 354 Cover and Front matter Open
An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.
View article: Magnetism in Massive Stars
Magnetism in Massive Stars Open
Massive stars are the drivers of star formation and galactic dynamics due to their relatively short lives and explosive demises, thus impacting all of astrophysics. Since they are so impactful on their environments, through their winds on …
View article: Probing the shape of the mixing profile and of the thermal structure at the convective core boundary through asteroseismology
Probing the shape of the mixing profile and of the thermal structure at the convective core boundary through asteroseismology Open
Aims: We investigate from a theoretical perspective if space asteroseismology can be used to distinguish between different thermal structures and shapes of the near-core mixing profiles for different types of coherent oscillation modes in …
View article: Rossby and Magnetic Prandtl Number Scaling of Stellar Dynamos
Rossby and Magnetic Prandtl Number Scaling of Stellar Dynamos Open
Rotational scaling relationships are examined for the degree of equipartition between magnetic and kinetic energies in stellar convection zones. These scaling relationships are approached from two paradigms, with first a glance at scaling …
View article: Rossby and Magnetic Prandtl Number Scaling of Stellar Dynamos
Rossby and Magnetic Prandtl Number Scaling of Stellar Dynamos Open
Rotational scaling relationships are examined for the degree of equipartition between magnetic and kinetic energies in stellar convection zones. These scaling relationships are approached from two paradigms, with first a glance at scaling …
View article: Rotating Convection and Gravito-Inertial Wave Generation in Stellar Interiors
Rotating Convection and Gravito-Inertial Wave Generation in Stellar Interiors Open
Gravito-inertial waves can be excited at the interface of convective and radiative regions and by the Reynolds stresses in the bulk of the convection zone. The magnitude of their energy flux will therefore vary with the properties of the c…
View article: On the stability of a general magnetic field topology in stellar radiative zones
On the stability of a general magnetic field topology in stellar radiative zones Open
This paper provides a brief overview of the formation of stellar fossil magnetic fields and what potential instabilities may occur given certain configurations of the magnetic field. One such instability is the purely magnetic Tayler insta…
View article: Impact of general differential rotation on gravity waves in rapidly rotating stars
Impact of general differential rotation on gravity waves in rapidly rotating stars Open
Differential rotation plays a key role in stellar evolution by triggering hydrodynamical instabilities and large-scale motions that induce transport of chemicals and angular momentum and by modifying the propagation and the frequency spect…
View article: Rotating Convection and Gravito-Inertial Wave Generation in Stellar Interiors
Rotating Convection and Gravito-Inertial Wave Generation in Stellar Interiors Open
Gravito-inertial waves can be excited at the interface of convective and radiative regions and by the Reynolds stresses in the bulk of the convection zone. The magnitude of their energy flux will therefore vary with the properties of the c…
View article: Does magnetic field modify tidal dynamics in the convective envelope of Solar mass stars?
Does magnetic field modify tidal dynamics in the convective envelope of Solar mass stars? Open
The energy dissipation of wave-like tidal flows in the convective envelope of low-mass stars is one of the key physical mechanisms that shape the orbital and rotational dynamics of short-period planetary systems. Tidal flows, and the excit…
View article: Perturbations of Stellar Oscillations: a General Magnetic Field
Perturbations of Stellar Oscillations: a General Magnetic Field Open
The purpose of this short paper is to give a summary of the derivation of a perturbative method to assess the impact of an arbitrary 3D magnetic field configuration, whose energy is everywhere small relative to the gravitational binding en…
View article: Penetration of Rotating Convection
Penetration of Rotating Convection Open
A simplified model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale with Rossby number as well as with thermal and viscous diffusivities. In…
View article: Waves in the radiative zones of rotating, magnetized stars
Waves in the radiative zones of rotating, magnetized stars Open
Asteroseismology has reached a level of accuracy that may allow us to detect the effect of a deep magnetic field on oscillation modes. We thus aim to develop an asymptotic theory for short-wavelength waves in radiative zones of rotating st…