BIGOT , Lionel

This paper presents the results of a detailed investigation of the validity of oscillator strengths in the spectral domain of the Gaia spectrometer 848-875 nm. This analysis is performed by fitting the most significant Fe I and Si I solar lines in this spectral range with synthetic profiles calculated by 3D radiative hydrodynamical (RHD)...

Journal of Physics Conference Series, 130, p. 2001, http://dx.doi.org./10.1088/1742-6596/130/1/012001

International audience

We investigate NLTE effects for magnesium and calcium in the atmospheres of late-type giant and supergiant stars. The aim of this paper is to provide a grid of NLTE/LTE equivalent width ratios W/W* of Mg and Ca lines for the following range of stellar parameters: Teff in [3500, 5250] K, log g in [0.5, 2.0] dex and [Fe/H] in [-4.0, 0.5] dex. We...

For the nearby dwarf star α Cen B (K1 V), we present limb-darkening predictions from a 3D hydrodynamical radiative transfer model of its atmosphere. We first compared the results of this model to a standard Kurucz's atmosphere. Then we used both predictions to fit the new interferometric visibility measurements of α Cen B obtained with the...

The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars α Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb...

For the nearby dwarf star α Cen B (K1 V), we present limb-darkening predictions from a 3D hydrodynamical radiative transfer model of its atmosphere. We first compared the results of this model to a standard Kurucz's atmosphere. Then we used both predictions to fit the new interferometric visibility measurements of α Cen B obtained with the...

Results on the effects of microscopic diffusion on the modeling and oscillations of solar-like stars are discussed. Comparisons between models with and without microscopic diffusion, subjected to observational constraints, namely effective temperature, luminosity, surface metallicity and mass derived from photometry, spectroscopy and...

This book book contains lectures and tutorials offered to PhD students willing to learn the impact of stellar interferometry to its main scientific application : stellar physics. Indeed, stars are seen different, now that their surface or environments can be resolved by these incredibly complex systems that are long-baseline interferometers....

Memorie della Societa Astronomica Italiana Supplement, 77, p. 411 (2006)

Asteroseismology aims at constraining the stellar evolution theory, and allows to determine the age of stars together with other fundamental parameters. We present recent results obtained by interferometry, and prospects for the future.

International audience

International audience

High-precision photometric data from space missions have improved our understanding of stellar granulation. These observations have shown with precision the stochastic brightness fluctuations of stars across the HR diagram, allowing us to better understand how stellar surface convection reacts to a change in stellar parameters. These...