Related papers: Stellar Archaeology: New Science with Old Stars
The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent progress in understanding the assembly…
Metal-poor stars in the Milky Way are local relics of the epoch of the first stars and the first galaxies. However, a low metallicity does not prove that a star formed in this ancient era, as metal-poor stars form over a range of redshift…
Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the…
In many evolutionary stages, low- and intermediate-mass stars show signs of mixing of the surface material with material from the interior. To account for all the details revealed by the observations it is necessary to include non-standard…
The understanding and modeling of the structure and evolution of stars is based on statistical physics as well as on hydrodynamics. Today, a precise identification and proper description of the physical processes at work in stellar…
Low-mass stars play a key role in many different areas of astrophysics. In this article, I provide a brief overview of the evolution of low-mass stars, and discuss some of the uncertainties and problems currently affecting low-mass stellar…
Stars are fossils that retain the history of their host galaxies. Elements heavier than helium are created inside stars and are ejected when they die. From the spatial distribution of elements in galaxies, it is therefore possible to…
We review some important observed properties of massive stars. Then we discuss how mass loss and rotation affect their evolution and help in giving better fits to observational constraints. Consequences for nucleosynthesis at different…
I address the issue of dust and gas as seeds for metal-poor star formation by reviewing what we know about star formation in nearby dwarf galaxies and its relationship to the gas and dust. I (try to) speculate on the extent to which…
Recently, measurements of abundances in extremely metal poor (EMP) stars have brought new constraints on stellar evolution models. In an attempt to explain the origin of the abundances observed, we computed pre--supernova evolution models,…
A significant fraction of very metal-poor stars have unexpectedly high carbon abundances. I recap on their discovery, describe the results of high-resolution spectroscopic studies of their composition, and consider possible origins. It is…
Massive stars have a profound influence on the Universe, but their formation remains poorly understood. We review the current status of observational and theoretical research in this field, describing the various stages of an evolutionary…
Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this review, we first recall the effect…
The observable characteristics and subsequent evolution of young stellar populations is dominated by their massive stars. As our understanding of those massive stars and the factors affecting their evolution improves, so our interpretation…
Thanks to the long-term collaborations between nuclear and astrophysics, we have good understanding on the origin of elements in the universe, except for the elements around Ti and some neutron-capture elements. From the comparison between…
The presence of elements heavier than helium ("metals") is of fundamental importance for a large number of astrophysical processes occurring in planet, star and galaxy formation; it also affects cosmic structure formation and evolution in…
Massive stars are essential to understand a variety of branches of astronomy including galaxy and star cluster evolution, nucleosynthesis and supernovae, pulsars and black holes. It has become evident that massive star evolution is very…
Very metal-deficient stars that exhibit enhancements of their carbon abundances are of crucial importance for understanding a number of issues -- the nature of stellar evolution among the first generations of stars, the shape of the Initial…
The origin of low alpha/Fe ratios in some metal-poor stars, so called low-alpha stars, is discussed. It is found that most of low-alpha stars in the Galaxy are on the main-sequence. This strongly suggests that these stars suffered from…
The kinematics and elemental abundances of resolved stars in the nearby Universe can be used to infer conditions at high redshift, trace how galaxies evolve and constrain the nature of dark matter. This approach is complementary to direct…