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A self-consistent numerical model of internal wave-induced mean flow oscillations in polar geometry
Florentin Daniel, Daniel Lecoanet
The Earth's Quasi-Biennial Oscillation (QBO) is a natural example of wave-mean flow interaction and corresponds to the alternating directions of winds in the equatorial stratospher…
The solar dynamo begins near the surface
Geoffrey M Vasil, Daniel Lecoanet, Kyle Augustson +5
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 yea…
An efficient tidal dissipation mechanism via stellar magnetic fields
Craig D. Duguid, Nils B. de Vries, Daniel Lecoanet +1
Recent work suggests that inwardly propagating internal gravity waves (IGWs) within a star can be fully converted to outward magnetic waves (MWs) if they encounter a sufficiently s…
Multidimensional Simulations of Core Convection
Daniel Lecoanet, Philipp V. F. Edelmann
The cores of main sequence intermediate- and high-mass stars are convective. Mixing at the radiative-convective boundary, waves excited by the convection, and magnetic fields gener…
The photometric variability of massive stars due to gravity waves excited by core convection
Evan H. Anders, Daniel Lecoanet, Matteo Cantiello +8
Massive stars die in catastrophic explosions, which seed the interstellar medium with heavy elements and produce neutron stars and black holes. Predictions of the explosion's chara…
The Puzzling Structure of Solar Convection: Window into the Dynamo
Nicholas A. Featherstone, Kyle C. Augustson, Jonathan M. Aurnou +25
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 pl…
The Stability of Prendergast Magnetic Fields
Emma Kaufman, Daniel Lecoanet, Evan H. Anders +4
Convection in massive main sequence stars generates large scale magnetic fields in their cores which persists as they evolve up the red giant branch. The remnants of these fields m…
Magnetohydrodynamic Simulations of the Tayler Instability in Rotating Stellar Interiors
Suoqing Ji, Jim Fuller, Daniel Lecoanet
The Tayler instability is an important but poorly studied magnetohydrodynamic instability that likely operates in stellar interiors. The nonlinear saturation of the Tayler instabil…
Asteroseismology reveals the near-core magnetic field strength in the early-B star HD 43317
D. M. Bowman, D. Lecoanet, T. Van Reeth
Spectropolarimetic campaigns have established that large-scale magnetic fields are present at the surfaces of approximately 10% of massive dwarf stars. However, there is a dearth o…
An Atlas of Convection in Main-Sequence Stars
Adam S. Jermyn, Evan H. Anders, Daniel Lecoanet +1
Convection is ubiquitous in stars and occurs under many different conditions. Here we explore convection in main-sequence stars through two lenses: dimensionless parameters arising…
Moosinesq Convection in the Cores of Moosive Stars
Evan H. Anders, Evan B. Bauer, Adam S. Jermyn +7
Stars with masses have core convection zones during their time on the main sequence. In these moosive stars, convection…
Convective Penetration in Early-Type Stars
Adam S. Jermyn, Evan H. Anders, Daniel Lecoanet +1
Observations indicate that the convective cores of stars must ingest a substantial amount of material from the overlying radiative zone, but the extent of this mixing and the mecha…
Schwarzschild and Ledoux are equivalent on evolutionary timescales
Evan H. Anders, Adam S. Jermyn, Daniel Lecoanet +4
Stellar evolution models calculate convective boundaries using either the Schwarzschild or Ledoux criterion, but confusion remains regarding which criterion to use. Here we present…
Asteroseismic inference of the near-core magnetic field strength in the main sequence B star HD 43317
Daniel Lecoanet, Dominic M. Bowman, Timothy Van Reeth
About 10 per cent of intermediate- and high-mass dwarf stars are observed to host a strong large-scale magnetic field at their surface, which is thought to be of fossil field origi…
Stellar convective penetration: parameterized theory and dynamical simulations
Evan H. Anders, Adam S. Jermyn, Daniel Lecoanet +1
Most stars host convection zones in which heat is transported directly by fluid motion, but the behavior of convective boundaries is not well understood. Here we present 3D numeric…
Surface Manifestation of Stochastically Excited Internal Gravity Waves
Daniel Lecoanet, Matteo Cantiello, Evan H. Anders +5
Recent photometric observations of massive stars show ubiquitous low-frequency "red-noise" variability, which has been interpreted as internal gravity waves (IGWs). Simulations of…
On the Origin of Stochastic, Low-Frequency Photometric Variability in Massive Stars
Matteo Cantiello, Daniel Lecoanet, Adam S. Jermyn +1
High-precision photometric observations have revealed ubiquitous stochastic low-frequency photometric variability in early type stars. It has been suggested that this variability a…
Single-hemisphere dynamos in M-dwarf stars
Benjamin P. Brown, Jeffrey S. Oishi, Geoffrey M. Vasil +2
M-dwarf stars below a certain mass are convective from their cores to their photospheres. These fully convective objects are extremely numerous, very magnetically active, and the l…
Physics of Tidal Dissipation in Early-Type Stars and White Dwarfs: Hydrodynamical Simulations of Internal Gravity Wave Breaking in Stellar Envelopes
Yubo Su, Daniel Lecoanet, Dong Lai
In binaries composed of either early-type stars or white dwarfs, the dominant tidal process involves the excitation of internal gravity waves (IGWs), which propagate towards the st…
Low-frequency variability in massive stars: Core generation or surface phenomenon?
Daniel Lecoanet, Matteo Cantiello, Eliot Quataert +6
Bowman et al. (2019) reported low-frequency photometric variability in 164 O- and B-type stars observed with K2 and TESS. They interpret these motions as internal gravity waves, wh…
Entropy Rain: Dilution and Compression of Thermals in Stratified Domains
Evan H. Anders, Daniel Lecoanet, Benjamin P. Brown
Large-scale convective flows called giant cells were once thought to transport the Sun's luminosity in the solar convection zone, but recent observations have called their existenc…
Black Hole Accretion Discs and Luminous Transients in Failed Supernovae from Non-Rotating Supergiants
Eliot Quataert, Daniel Lecoanet, Eric R. Coughlin
We show that for supergiants, net angular momentum is not a necessary condition for forming accretion discs during core-collapse. Even absent net rotation, convective motions in th…
Conversion of Internal Gravity Waves into Magnetic Waves
Daniel Lecoanet, Geoffrey M Vasil, Jim Fuller +2
Asteroseismology probes the interiors of stars by studying oscillation modes at a star's surface. Although pulsation spectra are well understood for solar-like oscillators, a subst…
Turbulent Chemical Diffusion in Convectively Bounded Carbon Flames
Daniel Lecoanet, Josiah Schwab, Eliot Quataert +6
It has been proposed that mixing induced by convective overshoot can disrupt the inward propagation of carbon deflagrations in super-asymptotic giant branch stars. To test this the…