We present results of intermediate resolution spectroscopy of 131 optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south of the Taurus-Auriga dark cloud complex. These objects have been selected as candidate young stars from a total of 1084 ROSAT sources in a ~300 square degree area. We identify 30 objects as low-mass PMS stars on the

Not Available

Context. The formation and evolution of dwarf galaxies is relatively difficult to understand because of their faint emission in all regimes that require large aperture telescopes. Aims: We intend to study the evolution of star-forming dwarf galaxies in clusters. We selected Fornax and Hydra clusters to complement our previous study of Virgo. On the

Observing the first galaxies formed during the reionisation epoch, i.e. approximately within the first billion years after the Big Bang, remains one of the challenges of contemporary astrophysics. Several efforts are being undertaken to search for such remote objects. Combining the near-IR imaging power of the VLT and the natural effect of strong

We present a fully differential chemical abundance analysis using very high resolution (λ/δλ >~ 85, 000) and very high signal-to-noise (S/N ~800 on average) HARPS and UVES spectra of 7 solar twins and 95 solar analogs, of which 24 are planet hosts and 71 are stars without detected planets. The whole sample of solar analogs provides very accurate

Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on