Related papers: 3D stellar atmospheres for stellar structure model…
Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of…
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 from stellar structure and parameters which emerge from the…
Broadening and asymmetry of spectral lines in slowly rotating late A-type stars provide evidence for high-amplitude convective motions. The properties of turbulence observed in the A-star atmospheres are not understood theoretically and…
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 is unclear what physical…
Starting from hydrodynamic equations, we have established a set of hydrodynamic equations for average flow and a set of dynamic equations of auto- and cross-correlations of turbulent velocity and temperature fluctuations, following the…
The lowest-mass stars, brown dwarfs and extrasolar planets present challenges and opportunities for understanding dynamics and cloud formation processes in low-temperature atmospheres. For brown dwarfs, the formation, variation and rapid…
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…
As a cool star evolves, it loses mass and angular momentum due to magnetized stellar winds which affect its rotational evolution. This change has consequences that range from the alteration of its activity to influences over the atmosphere…
Differential spectroscopy during exoplanet transits permits to reconstruct spectra of small stellar surface portions that successively become hidden behind the planet. The center-to-limb behavior of stellar line shapes, asymmetries and…
Molecular clouds are the principle stellar nurseries of our universe, keeping them in the focus of both observational and theoretical studies. From observations, some of the key properties of molecular clouds are well known but many…
Winds from young massive stars contribute a large amount of energy to their host molecular clouds. This has consequences for the dynamics and observable structure of star-forming clouds. In this paper, we present radiative…
In a series of papers, we have recently demonstrated that it is possible to construct stellar structure models that robustly mimic the stratification of multi-dimensional radiative magneto-hydrodynamic simulations at every time-step of the…
Magnetic activity is a ubiquitous feature of stars with convective outer layers, with implications from stellar evolution to planetary atmospheres. Investigating the mechanisms responsible for the observed stellar activity signals from days…
Extending our recent studies of two-dimensional stellar convection to 3D, we compare three-dimensional hydrodynamic simulations to identically set-up two-dimensional simulations, for a realistic pre-main sequence star. We compare…
Aims: Our aim is to study the presence and properties of small-scale swirls in numerical simulations of the atmospheres of cool main-sequence stars. Our particular focus is on understanding the variations in these properties for different…
Stars are changing entities in a constant evolution during their lives. At non-secular time scales (from seconds to years) the effect of dynamical processes such as convection, rotation, and magnetic fields can modify the stellar…
Context. Synthetic model atmosphere calculations are still the most commonly used tool when determining precise stellar parameters and stellar chemical compositions. Besides three-dimensional models that consistently solve for hydrodynamic…
Stars are not smooth. Their photosphere is covered by a granulation pattern associated with the heat transport by convection. The convection-related surface structures have different size, depth, and temporal variations with respect to the…
Spectroscopic studies of massive and luminous O-type stellar atmospheres and winds have primarily been done by using 1D, spherically symmetric and stationary models. Both observations and modern theoretical models show that such stars have…
The key to understanding an extrasolar giant planet's spectrum--and hence its detectability and evolution--lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets are in hand, atmosphere…