A5023542279- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical and nuclear sciences
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Geomagnetism and Paleomagnetism Studies
- Photocathodes and Microchannel Plates
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Nuclear physics research studies
- Crop Yield and Soil Fertility
University of Geneva
2021-2024
Context. The first stars might have been fast rotators. This would important consequences for their radiative, mechanical, and chemical feedback. Aims. We discuss the impact of initial rotation on evolution massive Population III models nitrogen oxygen stellar yields. Methods. explore with masses in range 9 M ⊙ ≤ ini 120 , starting an zero-age main sequence equal to 70% critical one. Results. find that physics considered here, our rapidly rotating do not follow a homogeneous evolution. They...
We present an analysis of the chemical compositions in high-redshift galaxies, with a focus on nitrogen-enhanced galaxies GN-z11 and CEERS-1019. used stellar models massive stars initial masses ranging from 9 to 120 M ⊙ various metallicities deduce abundances ejecta for few light elements (H, He, C, N, O). Our study reveals insights into processes elemental synthesis early Universe. find that Population III stars, particularly at fast equatorial rotation sampled top-heavy mass function, as...
This work presents new $^{12}$C + reaction rates in the form of numerical tables with associated uncertainty estimation, as well analytical formulae that can be directly implemented into stellar evolution codes. article further describes impact these on C-burning stars. We determine for two cross-section extrapolation models: one based fusion-hindrance phenomenon, and other plus a resonance, compare our results to previous data. Using GENEC code, we study how phases sets models stars 12...
Context. Grids of stellar evolution models with rotation using the Geneva code (G ENEC ) have been published for a wide range metallicities. Aims. We introduce last remaining grid G models, metallicity Z = 10 −5 . study impact this extremely metal-poor initial composition on various aspects evolution, and compare it to results from previous grids at other provide electronic tables that can be used interpolate between tracks population synthesis. Methods. Using same physics as in papers...
The origin of fluorine is still a debated question. Asymptotic giant branch stars synthesise this element and likely contribute significantly to its synthesis in the present-day Universe. However, it not clear whether other sources contribute, especially early We discuss variations surface abundances coming from our massive star models compare them with available observations. compute contribution single producing $ $F over metallicities covering whole cosmic history ( i.e. zero up...
The first stars are thought to be one of the dominant sources hydrogen reionization in early Universe, with their high luminosities and surface temperatures expected drive ionizing photon production rates. In this work, we take our Geneva stellar evolution models zero-metallicity predict rates photons capable ionize H, He I II, based on a blackbody approximation. We present analytical fits range 1.7-500 solar masses. then explore impact initial mass, rotation, convective overshooting for...
The first stars might have been fast rotators. This would important consequences for their radiative, mechanical and chemical feedback. We discuss the impact of initial rotation on evolution massive Population III models nitrogen oxygen stellar yields. explore with masses in range 9Msol < Mini 120Msol starting an Zero Age Main Sequence equal to 70% critical one. find that physics considered here, our rapidly-rotating do not follow a homogeneous evolution. They lose very little mass case...
We present an analysis of the chemical compositions in high-redshift galaxies, with a focus on nitrogen-enhanced galaxies GN-z11 and CEERS-1019. use stellar models massive stars initial masses ranging from 9 to 120 Msol across various metallicities deduce abundances ejecta for few light elements (H, He, C, N, O). Our study reveals insights into processes elemental synthesis early universe. find that Population III stars, particularly at fast equatorial rotation sampled top-heavy mass...
Grids of stellar evolution models with rotation using the Geneva code (Genec) have been published for a wide range metallicities. We introduce last remaining grid Genec models, metallicity $Z=10^{-5}$. study impact this extremely metal-poor initial composition on various aspects evolution, and compare it to results from previous grids at other provide electronic tables that can be used interpolate between tracks population synthesis. Using same physics as in papers series, we computed...
Context . Carbon, nitrogen, and oxygen are the most abundant elements throughout universe, after hydrogen helium. Studying these in low-metallicity stars can provide crucial information on chemical composition early Galaxy possible internal mixing processes that alter surface of stars. Aims This work aims to investigate abundance patterns for CNO Li a homogeneously analyzed sample 52 metal-poor halo giant From results, we have been able determine whether taken place Methods We used...
Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout universe, after hydrogen helium. Studying these in low-metallicity stars can provide crucial information on chemical composition early Galaxy possible internal mixing processes that alter surface of stars. Aims. This work aims to investigate abundance patterns for CNO Li a homogeneously analyzed sample 52 metal-poor halo giant Methods. We used high-resolution spectra with high signal-to-noise ratio (S/N) carry...
Among the reactions driving stellar evolution during carbon burning, 12 C + fusion provides key ingredients. This system reveals many resonances, but also regions with suppressed cross-sections. The reaction was recently measured by STELLA collaboration utilizing gammaparticle coincidence technique for precise cross-section measurements reaching down to Gamow window of massive stars. From experimental data, rates were determined approximating a hindrance parametrization and adding on top...
Abstract The first stars in the Universe have inherited their composition from primordial nucleosynthesis, so they no metal. These stars, which are also named population III (pop III) began process of reionization and contributed to metal enrichment with heavy elements. Previous studies showed that should been rotating fast due small or angular momentum loss, reaching easily critical velocity since massive very low stellar winds, thus mass loss is zero. Our aim study how production primary...