6 papers
Model Collapse: On Recursion, Noise, and Uncharted Machine Visions
Violaine Boutet de Monvel
Since 2023, computer scientists have warned against model collapse -- the contamination of training sets with AI-generated outputs that progressively degrade model performance. Exe…
Abundances of CNO in candidate young metal-poor stars
Piercarlo Bonifacio, Elisabetta Caffau, Luca Sbordone +6
In this contribution we investigate the CNO abundances in five apparently young evolved stars, with the aim of discriminating between truly young stars and stars that were rejuvena…
TOPoS VII. Age-metallicity relation in the Galactic halo and assembly of the Milky Way
P. Bonifacio, Y. Lebreton, I. Koutsouridou +8
One technique for determining stellar ages is to compare the position of a star in the Hertzsprung-Russell diagram to theoretical stellar evolutionary tracks. The sub-giant evoluti…
Some polarized lines of the second solar spectrum (SrI, CaI, BaII, C2, MgH, NdII) observed at the Meudon Solar Tower spectropolarimeter
Jean-Marie Malherbe
The second solar spectrum is the spectrum of the Stokes parameter Q (linear polarization) close to the solar limb. It is made of a few polarized lines with Q/I of about 1% (such as…
Polarized lines of the second solar spectrum (SrI, SrII, CaI, BaII) observed at the Pic du Midi Turret Dome spectropolarimeter with the slit orthogonal to the limb
Jean-Marie Malherbe
The second solar spectrum is the spectrum of the Stokes parameter Q (linear polarization) close to the solar limb. It differs significantly of the usual intensity spectrum (Stokes…
Datacubes of H, CaII K, CaII H and H line profiles of the full solar disk recorded daily at Meudon observatory since 2017 and some typical profiles of solar features
Jean-Marie Malherbe
Systematic observations of the Sun are performed at Meudon observatory since 1908 under the form of monochromatic images. However, a major technical improvement occurred in 2017; s…