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Context. The surface structures and dynamics of cool stars are characterized by the presence of convective motions and turbulent flows which shape the emergent spectrum. Aims. We used realistic three-dimensional radiative hydrodynamical…

Solar and Stellar Astrophysics · Physics 2018-03-14 A. Chiavassa , L. Casagrande , R. Collet , Z. Magic , L. Bigot , F. Thevenin , M. Asplund

Radiative hydrodynamic simulations of solar and stellar surface convection have become an important tool for exploring the structure and gas dynamics in the envelopes and atmospheres of late-type stars and for improving our understanding of…

Solar and Stellar Astrophysics · Physics 2015-06-03 B. Beeck , R. Collet , M. Steffen , M. Asplund , R. H. Cameron , B. Freytag , W. Hayek , H. -G. Ludwig , M. Schüssler

We use the three-dimensional hydrodynamic code of Stein and Nordlund to realistically simulate the upper layers of the solar convection zone in order to study physical characteristics of solar oscillations. Our first result is that the…

Astrophysics · Physics 2009-10-31 D. Georgobiani , A. G. Kosovichev , R. Nigam , A. Nordlund , R. F. Stein

Three-dimensional large eddy simulations of solar surface convection using realistic model physics are conducted. The thermal structure of convective motions into the upper radiative layers of the photosphere, the range of convection cell…

Astrophysics · Physics 2007-10-17 Sergey Ustyugov

The computationally demanding nature of radiative-hydrodynamical simulations of stellar surface convection warrants an investigation of the sensitivity of the convective structure and spectral synthesis to the numerical resolution and…

Astrophysics · Physics 2007-05-23 M. Asplund , H. -G. Ludwig , AA. Nordlund , R. F. Stein

We compare Fourier spectra of photospheric velocity fields from very high resolution IMaX observations to those from recent 3D numerical magnetoconvection models. We carry out a proper comparison by synthesizing spectral lines from the…

Solar and Stellar Astrophysics · Physics 2015-06-18 L. Yelles Chaouche , F. Moreno-Insertis , J. A. Bonet

I represent results three-dimensional numerical simulation of solar surface convection on scales local supergranulation with realistic model physics. I study thermal structure of convective motions in photosphere, the range of convection…

Astrophysics · Physics 2009-11-13 Sergey Ustyugov

Finding low-mass planets around solar-type stars requires to understand the physical variability of the host star, which greatly exceeds the planet-induced radial-velocity modulation. This project aims at analyzing - observationally and…

Solar and Stellar Astrophysics · Physics 2025-09-24 Dainis Dravins , Hans-Günter Ludwig

This paper describes a series of 3D simulations of shallow inefficient convection in the outer layers of the Sun. The computational domain is a closed box containing the convection-radiation transition layer, located at the top of the solar…

Astrophysics · Physics 2009-11-07 F. J. Robinson , P. Demarque , L. H. Li , S. Sofia , Y. -C. Kim , K. L. Chan , D. B. Guenther

Realistic numerical simulations, i.e., those that make minimal use of ad hoc modeling, are essential for understanding the complex turbulent dynamics of the interiors and atmospheres of the Sun and other stars and the basic mechanisms of…

Solar and Stellar Astrophysics · Physics 2015-07-30 Alan A. Wray , Khalil Bensassi , Irina N. Kitiashvili , Nagi N. Mansour , Alexander G. Kosovichev

Three-dimensional numerical simulations of solar surface magnetoconvection using realistic model physics are conducted. The thermal structure of convective motions into the upper radiative layers of the photosphere, the main scales of…

Solar and Stellar Astrophysics · Physics 2015-05-13 Sergey D. Ustyugov

Based on detailed 2D and 3D numerical radiation-hydrodynamics (RHD) simulations of time-dependent compressible convection, we have studied the dynamics and thermal structure of the convective surface layers of a prototypical late-type…

Astrophysics · Physics 2009-11-07 H. -G. Ludwig , F. Allard , P. H. Hauschildt

We present first realistic numerical simulations of 3D radiative convection in the surface layers of main sequence A-type stars with Teff = 8000 K and 8500 K, log g = 4.4 and 4.0, recently performed with the CO5BOLD radiation hydrodynamics…

Astrophysics · Physics 2007-05-23 M. Steffen , B. Freytag , H. -G. Ludwig

Three-dimensional (3D) radiative magnetohydrodynamics (MHD) simulations are the only way to model stellar atmospheres without any ad hoc parameterisations. Several 3D radiative MHD codes have achieved good quantitative agreement with…

High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material -- the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar…

Solar and Stellar Astrophysics · Physics 2011-12-14 Bernd Freytag , Matthias Steffen , Hans-Günter Ludwig , Sven Wedemeyer-Böhm , Werner Schaffenberger , Oskar Steiner

There exists a large body of previous work using reduced two-dimensional models of the SOL, which model fluctuations in the drift-plane but approximate parallel transport with effective loss terms. Full size three-dimensional simulations of…

Plasma Physics · Physics 2022-07-27 T. E. G. Nicholas , J. Omotani , F. Riva , F. Militello , B. Dudson

We simulate convection near the solar surface, where the continuum optical depth is of order unity. Hence, to determine the radiative heating and cooling in the energy conservation equation, we must solve the radiative transfer equation…

Astrophysics · Physics 2007-05-23 Robert Stein , Aake Nordlund

Spectral inversion codes are powerful tools to analyze spectropolarimetric observations, and they provide important diagnostics of solar magnetic fields. Inversion codes differ by numerical procedures, approximations of the atmospheric…

Solar and Stellar Astrophysics · Physics 2015-06-04 H. Balthasar , M. L. Demidov

We present 3D numerical simulations and an analytic model of reflection-driven MHD turbulence in the solar wind. Our simulations describe transverse, non-compressive MHD fluctuations within a narrow magnetic flux tube that extends from the…

Space Physics · Physics 2019-09-04 Benjamin D. G. Chandran , Jean C. Perez

Three-dimensional magnetohydrodynamical large eddy simulations of solar surface convection using realistic model physics is conducted. The effects of magnetic fields on thermal structure of convective motions into radiative layers, the…

Astrophysics · Physics 2007-05-23 Sergey Ustyugov
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