Related papers: Heavy Elements in the Early Galaxy
The early-R stars are carbon-rich K-type giants. They are enhanced in C12, C13 and N14, have approximately solar oxygen, magnesium isotopes, s-process and iron abundances, have the luminosity of core-helium burning stars, are not rapid…
A substantial fraction of the lowest metallicity stars show very high enhancements in carbon. It is debated whether these enhancements reflect the stars' birth composition, or if their atmospheres were subsequently polluted, most likely by…
We exploit the recent observations of extremely metal-poor (EMP) stars in the Galactic halo and investigate the constraints on the IMF of the stellar population that left these low-mass survivors of [Fe/H]<-2.5 and the chemical evolution…
Low-metallicity stars preserve the signatures of the first stellar nucleosynthesis events in the Galaxy, as their surface abundances reflect the composition of the interstellar medium from which they were born. Aside from primordial Big…
The chemical composition of extremely metal-poor stars (EMP stars; [Fe/H]<~ -3) is a unique tracer of early nucleosynthesis in the Galaxy. As such stars are rare, we wish to find classes of luminous stars which can be studied at high…
An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as their iron abundance, [Fe/H], decreases below [Fe/H] = -2.0. The CEMP-s stars have the highest absolute carbon abundances, [C/H], and are thought to owe their…
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…
The nature of the first massive stars may be inferred by investigating the origin of the extremely metal-poor (EMP) stars, likely formed from the ejecta of one or a few previous massive stars. We investigate the rotational properties of…
We discuss the star formation history of the Galaxy, based on the observations of extremely metal-poor stars (EMP) in the Galactic halo, to gain an insight into the evolution and structure formation in the early universe. The initialmass…
We use the growing data sets of very-metal-poor stars to study the impact of stellar winds of fast rotating massive stars on the chemical enrichment of the early Galaxy. We use an inhomogeneous chemical evolution model for the Galactic halo…
The main astronomical source of r-process elements has not yet been identified. One plausible site is neutron star mergers (NSMs), but from perspective of the Galactic chemical evolution, it has been pointed out that NSMs cannot reproduce…
The surface chemical compositions of a large fraction of Carbon-Enhanced Metal-Poor (CEMP) stars, the so-called CEMP-r/s stars, are known to exhibit enhancement of both s- and r-process elements. For these stars, the heavy element…
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…
We studied a sample of high proper motion, old and metal-rich dwarf stars, selected from the NLTT catalogue. The low pericentric distances and eccentric orbits of these solar neighbourhood stars indicate that they might have originated in…
It is known that the carbon-enhanced, extremely metal-poor (CEMP) stars constitute a substantial proportion in the extremely metal-poor (EMP) stars of the Galactic Halo, by far larger than CH stars in Population II stars. We investigate…
We determined chemical abundances of the Extremely Metal-Poor (EMP) star S15-19 ([Fe/H]=-3.0) in the Sextans dwarf galaxy. While heavy neutron-capture elements (e.g., Ba) are generally deficient in EMP stars in dwarf galaxies, this object…
We model the evolution of the abundances of light elements in carbon-enhanced metal-poor (CEMP) stars, under the assumption that such stars are formed by mass transfer in a binary system. We have modelled the accretion of material ejected…
Our current understanding of the chemical evolution of the Universe is that a first generation of stars was formed out of primordial material, completely devoid of metals (Pop III stars). This first population of stars comprised massive…
Many observed CEMP stars are found in binary systems and show enhanced abundances of $s$-elements. The origin of the chemical abundances of these CEMP-$s$ stars is believed to be accretion in the past of enriched material from a primary…
The low-mass metal-poor stars in the Galaxy that preserve in their atmosphere, the chemical imprints of the gas clouds from which they were formed can be used as probes to get insight into the origin and evolution of elements in the early…