A5068394297- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Astrophysics and Star Formation Studies
- Geophysics and Gravity Measurements
- Fluid Dynamics and Turbulent Flows
- Marine and environmental studies
- Astronomy and Astrophysical Research
- Advanced Thermodynamics and Statistical Mechanics
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Solar Radiation and Photovoltaics
- Planetary Science and Exploration
- Fluid dynamics and aerodynamics studies
University of Colorado Boulder
2022-2024
University of Colorado System
2023
Laboratory for Atmospheric and Space Physics
2020-2021
University of California, Santa Cruz
2017-2019
We study the dynamics associated with extension of turbulent convective motions from a convection zone (CZ) into stable region (RZ) that lies below latter. For purpose, we have run series three-dimensional direct numerical simulations solving Navier-Stokes equations under Boussinesq approximation in spherical shell geometry. observe overshooting stably stratified depends on three different parameters: relative stability RZ, transition width between two, and intensity turbulence. In cases...
ABSTRACT Ultra-massive white dwarfs ($1.05\, \rm M_\odot \lesssim M_{WD}$) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-massive thought harbour oxygen–neon (ONe) cores. However, recent theoretical studies new observations suggest some could carbon–oxygen (CO) Although several have attempted elucidate the core composition of dwarfs, date, it has not been possible...
Abstract Meridional circulation regulates the Sun’s interior dynamics and magnetism. While it is well accepted that meridional flows are poleward at surface, helioseismic observations have yet to provide a definitive answer for depth which those return equator, or number of cells in depth. Here, we explore observability multiple stacked radius. Specifically, examine seismic signature several flow profiles by convolving time–distance averaging kernels with mean obtained from suite 3D...
We examine the dynamics associated with weakly compressible convection in a spherical shell by running 3D direct numerical simulations using Boussinesq formalism [Spiegel and Veronis, Astrophys. J. 131, 442 (1960)AJLEEY0004-637X10.1086/146849]. Motivated problems astrophysics, we assume existence of finite adiabatic temperature gradient ∇T_{ad} use mixed boundary conditions for fixed flux at inner outer boundary. This setup is intrinsically more asymmetric than standard case Rayleigh-Bénard...
Overshooting of turbulent motions from convective regions into adjacent stably stratified zones plays a significant role in stellar interior dynamics as this process may lead to mixing chemical species, and contribute the transport angular momentum magnetic fields. We present series fully non-linear, three-dimensional (3D) anelastic simulations overshooting convection spherical shell which are focused on dependence density stratification rotation, both key ingredients stars however have not...
The propagation of meridional circulation below the base convection zone low-mass stars may play a crucial role in transport angular momentum and also significantly contribute to chemical species magnetic fields within their stable radiative zone. We systematically study these large-scale mean flows by performing three-dimensional (3D) global numerical simulations spherical shell that consists (CZ) overlying stably stratified region. find can penetrate distances as large $\sim 0.21r_o$...
Abstract The propagation of meridional circulation below the base convection zone (CZ) low-mass stars may play a crucial role in transport angular momentum and also significantly contribute to chemical species magnetic fields within their stable radiative (RZ). We systematically study these large-scale mean flows by performing three-dimensional global numerical simulations spherical shell that consists convective region overlying stably stratified region. find can penetrate distances as...
Whitepaper #105 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research; infrastructure/workforce/other programmatic. Additional solar physics; research tools infrastructure.
Motivated by the dynamics in deep interiors of many stars, we study interaction between overshooting convection and large-scale poloidal fields residing radiative zones. We have run a suite 3D Boussinesq numerical calculations spherical shell that consists zone with an underlying stable region initially compactly contains dipole field. By varying strength convective driving, find that, less turbulent regime, acts as diffusion removes field faster than solely molecular would do. However, more...
Abstract Convective motions extend beyond the nominal boundaries of a convection zone. These mix fluid through multiple mechanisms collectively called “convective boundary mixing.” In this note, we discuss three distinct dynamical processes: convective overshoot, entrainment, and penetrative convection. We describe structure that these processes create. To resolve discrepancies between models observations, stellar astrophysics community should distinguish parameterize each them separately in...
Simulations of astrophysical convection often use different thermal boundary conditions (TBC) at the domain top and bottom, but consequences using ``mixed'' TBC (MTBC) have not been thoroughly examined. Here we show that for MTBC, poorly chosen initial cause a long relaxation which is physically uninteresting computationally expensive. A couple mechanisms avoiding this are demonstrated. We also study asymmetries caused by MTBC find despite strong in temperature field near boundaries, do...
The operation of the solar dynamo, with all its remarkable spatio-temporal ordering, remains an outstanding problem modern physics. A number mechanisms that might plausibly contribute to have been proposed, but relative role played by each unclear. This uncertainty stems from continuing questions concerning speed and structure deep-seated convective flows. Those flows are in-turn thought sustain both Sun's turbulent EMF large-scale differential rotation meridional circulation suspected...
Meridional circulation regulates the Sun's interior dynamics and magnetism. While it is well accepted that meridional flows are poleward at surface, helioseismic observations have yet to provide a definitive answer for depth which those return equator, or number of cells in depth. Here, we explore observability multiple stacked radius. Specifically, examine seismic signature several flow profiles by convolving time-distance averaging kernels with mean obtained from suite 3D hydrodynamic...
In this paper, we investigate the dynamics of convection in a spherical shell under Boussinesq approximation but considering compressibility which arises from non zero adiabatic temperature gradient, relevant quantity for gaseous objects such as stellar or planetary interiors. We find that depth-dependent superiadiabaticity, combined with use mixed boundary conditions (fixed flux/fixed temperature), gives rise to unexpected were not previously reported.
Ultra-massive white dwarfs ($ 1.05 \rm M_\odot \lesssim M_{WD}$) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-massive thought harbour oxygen-neon (ONe) cores. However, recent theoretical studies new observations suggest some could carbon-oxygen (CO) Although several have attempted elucidate the core composition of dwarfs, date, it has not been possible distinguish them...