Related papers: Pre-supernova models at very low metallicity
We provide an individual analysis of 94 carbon enhanced metal-poor stars showing an s-process enrichment (CEMP-s) collected from the literature. The s-process enhancement observed in these stars is ascribed to mass transfer by stellar winds…
Extreme helium stars are very rare low-mass supergiants in a late stage of evolution. They are probably contracting to become white dwarfs following a violent phase of evolution which caused them to become hydrogen-deficient giants,…
Type I planetary nebulae (PNe) have high He/H and N/O ratios and are thought to be descendants of stars with initial masses of ~3-8Msun. These characteristics indicate that the progenitor stars experienced proton-capture nucleosynthesis at…
The elemental abundances of ten planetary nebulae, derived with high accuracy including ISO and IUE spectra, are analysed with the aid of synthetic evolutionary models for the TP-AGB phase. Model prescriptions are varied until we achieve…
The assembly of supermassive black holes poses a challenge primarily because of observed quasars at high redshift, but additionally because of the current lack of observations of intermediate mass black holes. One plausible scenario for…
Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two…
We study close encounters involving massive main sequence stars and the evolution of the exotic products of these encounters as common--envelope systems or possible hypernova progenitors. We show that parabolic encounters between low-- and…
We investigate the origin of carbon-enhanced metal-poor (CEMP) stars starting from the recently discovered $\rm [Fe/H]<-7.1$ star SMSS J031300 (Keller et al. 2014). We show that the elemental abundances observed on the surface of SMSS…
We used a recent grid of stellar models computed with and without rotation to make predictions concerning the WR populations and the frequency of different types of core-collapse SNe. Current rotating models were checked to provide good…
We calculate new evolutionary models of rotating primordial very massive stars, with initial mass from $100\,M_{\odot}$ to $200\,M_{\odot}$, for two values of the initial metallicity ${Z=0}$ and ${Z=0.0002}$. For the first time in this mass…
We present observational evidence that an aspherical supernova explosion could have occurred in the First stars in the early universe. Our results are based on the First determination of a Zn abundance in a Hubble Space Telescope/Cosmic…
The ratios of elemental abundances observed in metal-poor stars of the Galactic halo provide a unique present-day record of the nucleosynthesis products of its earliest stars. While the heaviest elements were synthesized by the r- and…
The origin of nucleosynthesis products of rapid neutron capture reactions (the r-process) is a longstanding astrophysical problem. Recent analyses of elemental abundances for extremely metal-poor stars shed light on the elemental abundances…
The abundance patterns of extremely metal-poor (EMP) stars provide us with important information on nucleosynthesis in supernovae (SNe) formed in a Pop III or EMP environment, and thus on the nature of the first stars in the Universe. We…
Evolutionary models for massive stars, accounting for rotational mixing effects, do not predict any core-processed material at the surface of B dwarfs with low rotational velocities. Contrary to theoretical expectations, we present a…
In the search of a sample of metal-poor bright giants using Str{\"o}mgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.We determined the…
Understanding the nucleosynthetic origin of nitrogen and the evolution of the N/O ratio in the interstellar medium is crucial for a comprehensive picture of galaxy chemical evolution at high-redshift because most observational metallicity…
We examine the contribution of electron-capture supernovae (ECSNe), low-mass SNe from collapsing Fe cores (FeCCSNe), and rotating massive stars to the chemical composition of the Galaxy. Our model includes contributions to chemical…
We present here a three-dimesional hydrodynamical simulation for star formation. Our aim is to explore the effect of the metal-line cooling on the thermodynamics of the star-formation process. We explore the effect of changing the…
The James Webb Space Telescope reveals anomalous nitrogen enrichment (high N/O ratios) in compact, star-forming galaxies, such as GN-z11 at $z\sim10$. The origin of this chemical signature provides an insight into the early star and galaxy…