Related papers: R-Process in Collapsing O/Ne/Mg Cores
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements…
We suggest that part of the infalling material during the core-collapse of a massive star goes into orbit around the compact core to form a hot, dense, centrifugally-supported accretion disk whose evolution is strongly influenced by…
After a successful core-collapse supernova, a neutrino-driven wind develops where it is possible to synthesize lighter heavy elements ($30<Z<45$). In the early galaxy, the origin of these elements is associated to the r-process and to an…
The huge neutrino pulse that occurs during the collapse of a massive stellar core, is expected to contribute to the origination of a number of isotopes both of light chemical elements and heavy ones. It is shown that, in general, the…
We explore the influence of non-axisymmetric modes on the dynamics of the collapsed core of rotating, magnetized high-mass stars in three-dimensional simulations of a rapidly rotating star with an initial mass of $M_{ZAMS}$ = 35 solar…
We show that long-range correlations for nuclear masses have a significant effect on the synthesis of heavy elements by the r-process. As calculated by Delaroche et al. [1], these correlations suppress magic number effects associated with…
Recent observations of r-process-enriched metal-poor star abundances reveal a non-uniform abundance pattern for elements $Z\leq47$. Based on non-correlation trends between elemental abundances as a function of Eu-richness in a large sample…
We investigate nuclear reactions and feedback in hyperaccreting neutron star environments, considering accretion rates in the range 0.3 - $3\times10^4$ $M_\odot$ yr$^{-1}$, typical of short-period compact object binaries in common…
A large star-to-star variation in the abundances of r-process elements, as seen in the [Eu/Fe] ratio for Galactic halo stars, is a prominent feature that is distinguishable from other heavy elements. It is, in part, caused by the presence…
Recent observations of heavy elements produced by rapid neutron capture (r-process) in the halo have shown a striking and unexpected behavior: within a single star, the relative abundances of r-process elements heavier than Eu are the same…
It has long been suggested that fission cycling may play an important role in the r-process. Fission cycling can only occur in a very neutron rich environment. In traditional calculations of the neutrino driven wind of the core-collapse…
Neutron star mergers (NSMs) are rapid neutron capture (r-process) nucleosynthesis sites, which eject materials at high velocities, from 0.1c to as high as 0.6c. Thus the r-process nuclei ejected from a NSM event are sufficiently energetic…
A number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-process. It has been found that massive stars can produce p-nuclei through photodisintegration of pre-existing intermediate and heavy…
The neutrino driven wind during a core collapse supernova is an attractive site for r-process nucleosynthesis. The electron fraction $Y_e$ in the wind depends on observable neutrino energies and luminosities. The mean antineutrino energy is…
The enrichment history of $r$-process elements has been imprinted on the stellar abundances that change in accordance with increasing metallicity in galaxies. Close examination of the [Eu/Fe] feature caused by stars in nearby galaxies,…
Recent studies suggest that binary neutron star (NS-NS) mergers robustly produce the heavy r-process nuclei above the atomic mass number A ~ 130 because of their ejecta consisting of almost pure neutrons (electron fraction of Y_e < 0.1).…
We use results from long-time core-collapse supernovae simulations to investigate the impact of the late time evolution of the ejecta and of the nuclear physics input on the calculated r-process abundances. Based on the latest…
New measurements of neutron-capture elements are presented for two very metal-poor stars ([Fe/H] ~ -3). One (LP 625-44) has an s-process signature believed to be due to mass transfer from a now-extinct metal-poor AGB companion, and the…
Recent stellar evolutionary calculations of low-metallicity massive fast-rotating main-sequence stars yield iron cores at collapse endowed with high angular momentum. It is thought that high angular momentum and black hole formation are…
Accurate relative abundances have been obtained for a sample of 21 mildly metal-poor stars from the analysis of high resolution and high signal-to-noise spectra. With these accurate results, correlations between relative abundances have…