Related papers: News on the s process from young open clusters
The chemical evolution of the Universe is governed by the chemical yields from stars, which in turn is determined primarily by the initial stellar mass. Even stars as low as 0.9Msun can, at low metallicity, contribute to the chemical…
A brief overview of the r-process is given with an emphasis on the observational implications for this process. The conditions required for the major production of the heavy r-process elements (r-elements) with mass numbers A >130 are…
We present a review of the possible sources for r-process nuclei. It is known that there is as yet no self-consistent mechanism to provide abundant neutrons for a robust r-process in the neutrino-driven winds from nascent neutron stars. We…
Young open clusters (t<200 Myr) have been observed to exhibit several peculiarities in their chemical compositions, from a slightly sub-solar iron content, super-solar abundances of some atomic species (e.g. ionised chromium), and atypical…
The main component of the s process is produced by low mass stars (between 1.5 and 3 Mo), when they climb for the second time the red giant branch and experience a series of He shell flashes called thermal pulses. During the relatively long…
Energy in stars is provided by nuclear reactions, which, in many cases, produce radioactive nuclei. When stable nuclei are irradiated by a flux of protons or neutrons, capture reactions push stable matter out of stability into the regime of…
High-resolution, high signal-to-noise spectral data are presented for four young B-type stars lying towards the Galactic Centre. Determination of their atmospheric parameters from their absorption line profiles, and uvby photometric…
To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn), yttrium (Y), lanthanum (La), europium (Eu), and lead (Pb). Our sample of 161…
Globular Cluster (GC) formation seems to be a widespread mode of star formation in extreme starbursts triggered by strong interactions and mergers of massive gas-rich galaxies. We use our detailed chemically consistent evolutionary…
The recent downward revision of the solar photospheric abundances now leads to severe inconsistencies between the theoretical predictions for the internal structure of the Sun and the results of helioseismology. There have been claims that…
Carbon-enhanced metal-poor (CEMP) stars in the Galactic Halo display enrichments in heavy elements associated with either the s (slow) or the r (rapid) neutron-capture process (e.g., barium and europium respectively), and in some cases they…
In the past years the observational evidence that s-process elements from Sr to Pb are produced by stars ascending the socalled Asymptotic Giant Branch (or AGB) could not be explained by self-consistent models, forcing researchers to…
We report abundance estimates for neutron-capture elements, including lead (Pb), and nucleosynthesis models for their origin, in two carbon-rich, very metal-poor stars, LP625-44 and LP706-7. These stars are subgiants whose surface…
In massive stars (initial mass of > 9 solar masses), the weak s (slow neutron capture) process produces elements between Fe and Zr, enriching the Galaxy with these elements through core-collapse supernova explosions. The weak s-process…
We report the abundances of neutron-capture elements in eight carbon-rich, metal-poor (-2.7=<[Fe/H]=<-1.9) stars observed with the Subaru Telescope High Dispersion Spectrograph. The derived abundance patterns indicate that the…
Galaxy clusters contain much more metal per star, typically 3 times as much, than is produced in normal galaxies. We set out to determine what changes are needed to the stellar mass function and supernovae rates to account for this excess…
We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity and initial main sequence masses between 15 M$_\odot$ and 40 M$_\odot$. We improve previous…
The abundances derived from planetary nebula emission show the presence of a metallicity gradient within the disk of the Milky Way up to Galactocentric distances of ~10 kpc, which are consistent with findings from studies of different types…
We test the hypothesis that the observed first-peak (Sr, Y, Zr) and second-peak (Ba) s-process elemental abundances in low-metallicity Milky Way stars, and the abundances of the elements Mo and Ru, can be explained by a pervasive r-process…
Robust generation of gamma-ray bursts (GRBs) implies the formation of outflows with very low baryon loads and highly relativistic velocities, but more baryon-rich, slower outflows are also likely to occur in most GRB central engine…