Studying the earliest stages in the birth of stars is crucial for understanding how they form. Brown dwarfs with masses between that of stars and planets are not massive enough to maintain stable hydrogen-burning fusion reactions during most of their lifetime. Their origins are subject to much debate in recent literature because their masses are

About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first results to illustrate how these data of unprecedented quality shed a new light on the field of stellar seismology.

The starburst galaxy M82 shows a system of Hα-emitting filaments that extend to each side of the galactic disk. We model these filaments as the result of the interaction between the winds from a distribution of super stellar clusters (SSCs). We first derive the condition necessary for producing a radiative interaction between the cluster winds (a

We give a progress report on the activities within the CIFIST Team related to the search for extremely metal-poor (EMP) stars in the Sloan Digital Sky Survey's (SDSS) spectroscopic catalogue. So far, the search has provided 25 candidates with metallicities around or smaller than -3. For 15 candidates, high-resolution spectroscopy with UVES at the

An increasing number of both photometric and spectroscopic observations over the last decade have shown the existence of distinct sub-populations in some Galactic globular clusters. This evidence severely challenges the paradigm of globular clusters as the prototypes of single, simple stellar populations. In this review, we briefly summarise the

Integrated spectroscopy is the method of choice for deriving the ages of unresolved stellar systems. However, hot stellar evolutionary stages, such as hot horizontal branch stars and blue straggler stars (BSSs), can affect the integrated ages measured using Balmer lines. Such hot, ``noncanonical'' stars may lead to overestimation of the temperature