874 citations · 2.1k across the 20 of their papers we have counts for
20 papers
Spatially resolved spectroscopy across stellar surfaces. IV. F, G, & K-stars: Synthetic 3D spectra at hyper-high resolution
Dainis Dravins, Hans-Günter Ludwig, Bernd Freytag
High-precision stellar analyses require hydrodynamic 3D modeling. Such models predict changes across stellar disks of spectral line shapes, asymmetries, and wavelength shifts. For…
Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. II. The role of convection accross the H-R diagram
A. Kučinskas, J. Klevas, H. -G. Ludwig +3
We studied the influence of convection on the spectral energy distributions, photometric magnitudes, and colour indices of different types of stars across the H-R diagram. The 3D h…
Spectroscopic properties of a two-dimensional time-dependent Cepheid model II. Determination of stellar parameters and abundances
V. Vasilyev, H. -G. Ludwig, B. Freytag +2
Standard spectroscopic analyses of variable stars are based on hydrostatic one-dimensional model atmospheres. This quasi-static approach has theoretically not been validated. We ai…
Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. I. Grids of 3D corrections in the UBVRI, 2MASS, Hipparcos, Gaia, and SDSS systems
P. Bonifacio, E. Caffau, H. -G. Ludwig +9
The atmospheres of cool stars are temporally and spatially inhomogeneous due to the effects of convection.The influence of this inhomogeneity, referred to as granulation, on colour…
Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere
Flavio Calvo, Oskar Steiner, Bernd Freytag
Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aim…
Enhanced methods for computing spectra from CO5BOLD models using Linfor3D. Molecular bands in metal-poor stars
A. J. Gallagher, M. Steffen, E. Caffau +3
Molecular features such as the G-band, CN-band and NH-band are important diagnostics for measuring a star's carbon and nitrogen abundances, especially in metal-poor stars where ato…
On The Evolution of Magnetic White Dwarfs
P. -E. Tremblay, G. Fontaine, B. Freytag +5
We present the first radiation magnetohydrodynamics simulations of the atmosphere of white dwarf stars. We demonstrate that convective energy transfer is seriously impeded by magne…
3D Model Atmospheres for Extremely Low-Mass White Dwarfs
P. -E. Tremblay, A. Gianninas, M. Kilic +4
We present an extended grid of mean three-dimensional (3D) spectra for low-mass, pure-hydrogen atmosphere DA white dwarfs (WDs). We use CO5BOLD radiation-hydrodynamics 3D simulatio…
Calibration of the Mixing-Length Theory for Convective White Dwarf Envelopes
P. -E. Tremblay, H. -G. Ludwig, B. Freytag +3
A calibration of the mixing-length parameter in the local mixing-length theory (MLT) is presented for the lower part of the convection zone in pure-hydrogen atmosphere white dwarfs…
White Dwarfs In The UKIRT Infrared Deep Sky Survey Data Release 9
P. -E. Tremblay, S. K. Leggett, N. Lodieu +4
We have identified eight to ten new cool white dwarfs from the Large Area Survey (LAS) Data Release 9 of the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKI…
Spectroscopic analysis of DA white dwarfs with 3D model atmospheres
P. -E. Tremblay, H. -G. Ludwig, M. Steffen +1
We present the first grid of mean three-dimensional (3D) spectra for pure-hydrogen (DA) white dwarfs based on 3D model atmospheres. We use CO5BOLD radiation-hydrodynamics 3D simula…
Convective line shifts for the Gaia RVS from the CIFIST 3D model atmosphere grid
C. Allende Prieto, L. Koesterke, H. -G. Ludwig +2
To derive space velocities of stars along the line of sight from wavelength shifts in stellar spectra requires accounting for a number of second-order effects. For most stars, grav…
Atmospheres from very low-mass stars to extrasolar planets
France Allard, Derek Homeier
Within the next few years, several instruments aiming at imaging extrasolar planets will see first light. In parallel, low mass planets are being searched around red dwarfs which o…
Simulations of the solar near-surface layers with the CO5BOLD, MURaM, and Stagger codes
B. Beeck, R. Collet, M. Steffen +6
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 atmospher…
Solution to the problem of the surface gravity distribution of cool DA white dwarfs from improved 3D model atmospheres
P. -E. Tremblay, H. -G. Ludwig, M. Steffen +2
The surface gravities of cool (Teff < 13,000 K) hydrogen-atmosphere DA white dwarfs, determined from spectroscopic analyses, are found to be significantly higher than the canonical…
Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
Elisabetta Caffau, Hans-Günter Ludwig, Matthias Steffen +2
In the last decade, the photospheric solar metallicity as determined from spectroscopy experienced a remarkable downward revision. Part of this effect can be attributed to an impro…
The metal-poor end of the Spite plateau. 1: Stellar parameters, metallicities and lithium abundances
L. Sbordone, P. Bonifacio, E. Caffau +16
We present VLT-UVES Li abundances for 28 halo dwarf stars between [Fe/H]=-2.5 and -3.5, 10 of which have [Fe/H]<-3. Four different T_eff scales have been used. Direct Infrared Flux…
Solar abundances and 3D model atmospheres
H. -G. Ludwig, E. Caffau, M. Steffen +3
We present solar photospheric abundances for 12 elements from optical and near-infrared spectroscopy. The abundance analysis was conducted employing 3D hydrodynamical (CO5BOLD) as…
Inter-network regions of the Sun at millimetre wavelengths
S. Wedemeyer-Boehm, H. -G. Ludwig, M. Steffen +2
The continuum intensity at wavelengths around 1 mm provides an excellent way to probe the solar chromosphere. Future high-resolution millimetre arrays, such as the Atacama Large Mi…
3-D hydrodynamic simulations of convection in A stars
O. Kochukhov, B. Freytag, N. Piskunov +1
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…