LANZ , T.

International audience

International audience

International audience

International audience

We report on a study of 9 nearby primitive galaxies observed by Hubble's COS far-UV spectrograph that can serve as templates of high-z galaxies to be observed by JWST. By "primitive galaxies," we mean galaxies having a low stellar mass, and low gas metallicity, , whether they are local or at high redshift. We find that far-UV spectra of these...

Astron. & Astrophys., 422, pp. 193-203 (2004)

Context. Material accreted onto classical T Tauri stars is expected to form a hot quasi-periodic plasma structure that radiates in X-rays. Simulations of this phenomenon only partly match observations. They all rely on a static model for the chromosphere and on the assumption that radiation and matter are decoupled.Aims. We explore the effects...

International audience

We present a spectroscopic analysis of HST/COS observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with VLT/X-shooter by Tramper et al. (2011, 2014) who claimed that their mass-loss rates are higher than expected from theoretical predictions for the underlying...

Background: Appendectomy is increasingly performed as a 'short stay' or 'ambulatory' procedure, yet there is no consensus for selection of patients with acute appendicitis for ambulatory surgery (AS). We aimed to compare characteristics and outcomes of complicated and uncomplicated appendectomies performed in ambulatory vs. conventional...

Context. The evolution of massive stars depends on several physical processes and parameters. Metallicity and rotation are among the most important, but their quantitative effects are not well understood.Aims. To complement our earlier study on main-sequence stars, we study the evolutionary and physical properties of evolved O stars in the...

Context. Theoretical arguments and numerical simulations of radiative shocks produced by the impact of the accreting gas onto young stars predict quasi-periodic oscillations in the emitted radiation. However, observational data do not show evidence of such periodicity. Aims. We investigate whether physically plausible...

Context. According to the magnetospheric accretion model, hot spots form on the surface of classical T Tauri stars (CTTSs) in regions where accreting disk material impacts the stellar surface at supersonic velocity, generating a shock.Aims. We investigate the dynamics and stability of postshock plasma that streams along nonuniform stellar...

This paper presents the sharpest near‐IR images of the massive cluster R136 to date, based on the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode. The crowded stellar population in the core of the R136 starburst compact cluster remains still to be...