A5087581366- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astronomy and Astrophysical Research
- Computational Fluid Dynamics and Aerodynamics
- Meteorological Phenomena and Simulations
- Numerical methods for differential equations
- Ionosphere and magnetosphere dynamics
- Galaxies: Formation, Evolution, Phenomena
- Planetary Science and Exploration
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- Gas Dynamics and Kinetic Theory
Heidelberg Institute for Theoretical Studies
2020-2024
University of Stuttgart
2023-2024
Technical University of Munich
2017-2020
Max Planck Institute for Astrophysics
2017-2020
There is strong observational evidence that the convective cores of intermediate-mass and massive main sequence stars are substantially larger than those predicted by standard stellar-evolution models. However, it unclear what physical processes cause this phenomenon or how to predict extent stratification stellar boundary layers. Convective penetration a thermal-timescale process likely be particularly relevant during slow evolution on sequence. We use our low-Mach-number S EVEN -L EAGUE H...
Stellar evolution codes, as all other numerical tools, need to be verified. One of the standard stellar objects that allow stringent tests theory and models, are detached eclipsing binaries. We have used 19 such test our code, in order see whether methods assumptions suffice reproduce observed global properties. In this paper we concentrate on three effects contain a specific uncertainty: atomic diffusion for solar model calculations, overshooting from convective regions, simple effect spots...
The extent of mixed regions around convective zones is one the biggest uncertainties in stellar evolution. 1D overshooting descriptions introduce a free parameter ($f_{ov}$) that general not well constrained from observations. Especially small central value highly uncertain due to its tight connection pressure scale height. Long-term multi-dimensional hydrodynamic simulations can be used study size region and involved mixing processes. Here we show how calibrate an by performing 2D Maestro...
Our ability to predict the structure and evolution of stars is in part limited by complex, 3D hydrodynamic processes such as convective boundary mixing. Hydrodynamic simulations help us understand dynamics stellar convection boundaries. However, codes used compute are usually tested on extremely simple problems reliability reproducibility their predictions for turbulent flows unclear. We define a test problem involving plane-parallel box, which leads mass entrainment from, internal-wave...
Fully compressible magnetohydrodynamic (MHD) simulations are a fundamental tool for investigating the role of dynamo amplification in generation magnetic fields deep convective layers stars. The flows that arise such environments characterized by low (sonic) Mach numbers (M_son < 0.01 ). In these regimes, conventional MHD codes typically show excessive dissipation and tend to be inefficient as Courant-Friedrichs-Lewy (CFL) constraint on time step becomes too strict. this work we present new...
Convection is one of the most important mixing processes in stellar interiors. Hydrodynamic mass entrainment can bring fresh fuel from neighboring stable layers into a convection zone, modifying structure and evolution star. Because flows zones are highly turbulent, multidimensional hydrodynamic simulations fundamental to accurately capture physics processes. Under some conditions, strong magnetic fields be sustained by action turbulent dynamo, adding another layer complexity possibly...
Accurate simulations of flows in stellar interiors are crucial to improving our understanding structure and evolution. Because the typically slow merely tiny perturbations on top a close balance between gravity pressure gradient, such place heavy demands numerical hydrodynamics schemes. We demonstrate how discretization errors grids reasonable size can lead spurious orders magnitude faster than physical flow. Well-balanced schemes deal with this problem. Three were applied implicit,...
Context . TZ Fornacis (TZ For) is an evolved detached binary system that difficult to model and interpret, but very useful for testing stellar evolution theory physics. Aims We aim search solutions are self-consistent determine the necessary physics input. also check found previously their internal consistency reproducibility. Methods use both a single code, take into account all known properties. physical parameters by imposing models match radii identical ages. The has be consistent with...
There is strong observational evidence that convective cores of intermediate-mass and massive main-sequence stars are substantially larger than standard stellar-evolution models predict. However, it unclear what physical processes cause this phenomenon or how to predict the extent stratification stellar boundary layers. Convective penetration a thermal-time-scale process likely be particularly relevant during slow evolution on main sequence. We use our low-Mach-number Seven-League Hydro...
High-order Godunov methods for gas dynamics have become a standard tool simulating different classes of astrophysical flows. Their accuracy is mostly determined by the spatial interpolant used to reconstruct pair Riemann states at cell interfaces and solver that computes interface fluxes. In most Godunov-type methods, these two steps can be treated independently, so many schemes in principle built from same numerical framework. this work, we use our fully compressible Seven-League Hydro...
High-order Godunov methods for gas dynamics have become a standard tool simulating different classes of astrophysical flows. Their accuracy is mostly determined by the spatial interpolant used to reconstruct pair Riemann states at cell interfaces and solver that computes interface fluxes. In most Godunov-type methods, these two steps can be treated independently, so many schemes in principle built from same numerical framework. Because simulations often test out limits what feasible with...
Convection is one of the most important mixing processes in stellar interiors. Hydrodynamic mass entrainment can bring fresh fuel from neighboring stable layers into a convection zone, modifying structure and evolution star. Under some conditions, strong magnetic fields be sustained by action turbulent dynamo, adding another layer complexity possibly altering dynamics zone at its boundaries. In this study, we used our fully compressible Seven-League Hydro code to run detailed highly resolved...
Fully compressible magnetohydrodynamic (MHD) simulations are a fundamental tool for investigating the role of dynamo amplification in generation magnetic fields deep convective layers stars. The flows that arise such environments characterized by low (sonic) Mach numbers (M_son < 0.01 ). In these regimes, conventional MHD codes typically show excessive dissipation and tend to be inefficient as Courant-Friedrichs-Lewy (CFL) constraint on time step becomes too strict. this work we present...