Hans-G Ludwig

Radiation-hydrodynamics simulations of surface convection in low-mass stars: connections to stellar structure and asteroseismology (2008)

Ludwig, Hans-G., Caffau, Elisabetta, Kucinskas, Arunas

Radiation-hydrodynamical simulations of surface convection in low-mass stars can be exploited to derive estimates of i) the efficiency of the convective energy transport in the stellar surface...

The photospheric solar oxygen project: I. Abundance analysis of atomic lines and influence of atmospheric models (2008)

Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, Ayres, Thomas R., Bonifacio, Piercarlo, Cayrel, Roger, ...

The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....

The photospheric solar oxygen project: I. Abundance analysis of atomic lines and influence of atmospheric models (2008)

Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, R. Ayres, Thomas, Bonifacio, Piercarlo, Cayrel, Roger, ...

The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....

The photospheric solar oxygen project: I. Abundance analysis of atomic lines and influence of atmospheric models (2008)

Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, R. Ayres, Thomas, Bonifacio, Piercarlo, Cayrel, Roger, ...

The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....

The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)

Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo

aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...

3D spectral synthesis and rotational line broadening (2007)

Ludwig, Hans-G.

Spectral synthesis calculations based on three-dimensional stellar atmosphere models are limited by the affordable angular resolution of the radiation field. This hampers an accurate treatment of...

Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)

Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias

context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...

Hydrodynamical model atmospheres and 3D spectral synthesis (2007)

Ludwig, Hans-G., Steffen, Matthias

We discuss three issues in the context of three-dimensional (3D) hydrodynamical model atmospheres for late-type stars, related to spectral line shifts, radiative transfer in metal-poor 3D models, and...

Prospects of using simulations to study the photospheres of brown dwarfs (2007)

Ludwig, Hans-G.

We discuss prospects of using multi-dimensional time-dependent simulations to study the atmospheres of brown dwarfs and extrasolar giant planets, including the processes of convection, radiation,...

Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)

Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias

context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...

The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)

Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo

aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...

The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)

Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo

aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...

Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)

Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias

context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...

Hydrodynamical simulations of convection-related stellar micro-variability. I. Statistical relations for photometric and photocentric variability (2005)

Ludwig, Hans-G.

Local-box hydrodynamical model atmospheres provide statistical information about the spatial dependence, as well as temporal evolution, of a star's emergent radiation field. Here, we consider...