Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
Excitation of Radial P-Modes in the Sun and Stars (2004)
Stein, Robert, Georgobiani, Dali, Trampedach, Regner, Ludwig, Hans-Günter, Nordlund, Åke
P-mode oscillations in the Sun and stars are excited stochastically byReynolds stress and entropy fluctuations produced by convection in theirouter envelopes. The excitation rate of radial...
Excitation of Radial P-Modes in the Sun and Stars (2004)
Stein, Robert, Georgobiani, Dali, Trampedach, Regner, Ludwig, Hans-Günter, Nordlund, Åke
P-mode oscillations in the Sun and stars are excited stochastically byReynolds stress and entropy fluctuations produced by convection in theirouter envelopes. The excitation rate of radial...
Wedemeyer, Sven, Freytag, Bernd, Steffen, Matthias, Ludwig, Hans-Günter, Holweger, Hartmut
Three-dimensional numerical simulations with CO5BOLD, a new radiation hydrodynamics code, result in a dynamic, thermally bifurcated model of the non-magnetic chromosphere of the quiet Sun. The 3-D...
Intrinsic spectral blueshifts in rapidly rotating stars? (2003)
Madsen, Søren, Dravins, Dainis, Ludwig, Hans-Günter, Lindegren, Lennart
Spectroscopic radial velocities for several nearby open clusters suggestthat spectra of (especially earlier-type) rapidly rotating stars aresystematically blueshifted by 3 km s-1 or more, relative...
Modelling the Chromospheric Background Pattern of the Non-magnetic Sun (2003)
Wedemeyer, Sven, Freytag, Bernd, Steffen, Matthias, Ludwig, Hans-Günter, Holweger, Hartmut
Not Available
3D Simulation of the Solar Granulation: A Comparison of two Different Hydrodynamics Codes (2003)
Steffen, Matthias, Ludwig, Hans-Günter, Freytag, Bernd
Not Available
Convection and Small-scale Magnetic Fields in M-type Atmospheres (2003)
Ludwig, Hans-Günter, Dorch, Søren Bertil Fabricius
Not Available
Model Atmospheres and Spectra: The Role of Dust (2003)
Allard, France, Guillot, Tristan, Ludwig, Hans-Günter, Hauschildt, Peter H., Schweitzer, Andreas, Alexander, David R., ...
Brown dwarf atmospheres form molecules, then high temperaturecondensates (corundum, titanates, silicates, and iron compounds), andthen low temperature condensates (ices) as they cool down over...
Convection and Dust in Cool Stellar Atmospheres (2003)
Ludwig, Hans-Günter, Freytag, Bernd, Höfner, Susanne, Allard, France, Hauschildt, Peter H.
We report on recent progress in hydrodynamical modelling of the surfacelayers of late M- and L-type main- as well as pre-main-sequence objects.Despite the complex chemistry encountered in the cool...
3D Hydrodynamical Modelling of the Solar Chromosphere (2003)
Ludwig, Hans-Günter, Steffen, Matthias, Wedemeyer, Sven, Freytag, Bernd, Holweger, Hartmut
We report on 3D radiation-hydrodynamics modelling of the non-magneticsolar atmosphere with emphasis on the problem of the acoustic heating ofthe chromosphere. Our models include the generation of...
EXCITATION OF RADIAL P-MODES IN THE SUN AND STARS (2003)
Robert Stein, Dali Georgobiani, Regner Trampedach, Hans-günter Ludwig, Åke Nordlund
Abstract. P-mode oscillations in the Sun and stars are excited stochastically by Reynolds stress and entropy fluctuations produced by convection in their outer envelopes. The excitation rate of...
Radiation-hydrodynamics Simulations of Surface Convection in a Late M-dwarf (2001)
Ludwig, Hans-Günter, Hauschildt, Peter
Based on detailed 2D and 3D numerical radiation hydrodynamicscalculations of time-dependent compressible convection, we have studiedthe dynamics and thermal structure of the convective surface layers...
Acoustic Energy Generated by Convection: 3-D Numerical Simulations for the Sun (2001)
Wedemeyer, Sven, Freytag, Bernd, Holweger, Hartmut, Ludwig, Hans-Günter, Steffen, Matthias
Dissipation of acoustic waves may be an efficient heating mechanism forthe lower and middle chromosphere of the quiet Sun. The basic idea isthat turbulent motions at the top of the solar convection...
Overtures to the pulsational instability of ZZ Ceti variables (1995)
Gautschy, Alfred, Ludwig, Hans-Günter, Freytag, Bernd
Results of nonradial, nonadiabatic pulsation calculations on hydrogen-rich white dwarf models are presented. In contrast to earlier attempts, the modeling builds on hydrodynamically simulated...