Related papers: Evolution of O Abundance Relative to Fe
We conducted an investigation on the chemical abundances of 4,316 stars in the red giant branch (RGB) phase from the recently released APO-K2 catalogue. Our aim was to characterize the abundance trends of the single elements with…
In recent observations of extremely metal-poor low-mass starburst galaxies, almost solar Fe/O ratios are reported, despite N/O ratios consistent with the low metallicity. We investigate if the peculiar Fe/O ratios can be a distinctive…
Metal-poor stars provide the fossil record of Galactic chemical evolution and the nucleosynthesis processes that took place at the earliest times in the history of our Galaxy. From detailed abundance studies of low mass, extremely…
We propose and apply a new classification for the CEMP-no stars, which are "carbon-enhanced metal-poor" stars with no overabundance of s-elements and with [Fe/H] generally inferior or equal to -2.5. This classification is based on the…
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…
An overview of the sources for heavy elements in the early Galaxy is given. It is shown that observations of abundances in metal-poor stars can be used along with a basic understanding of stellar models to guide the search for the source of…
The chemical abundance patterns of gas and stars in galaxies are powerful probes of galaxies' star formation histories and the astrophysics of galaxy assembly but are challenging to measure with confidence in distant galaxies. In this…
We have attributed the elements from Sr through Ag in stars of low metallicities ([Fe/H] < -1.5) to charged-particle reactions (CPR) in neutrino-driven winds, which are associated with neutron star formation in low-mass and normal…
Inhomogeneous chemical evolution models of galaxies which try to reproduce the scatter seen in element-to-iron ratios of metal-poor halo stars are heavily dependent on theoretical nucleosynthesis yields of core-collapse supernovae. Hence…
We investigate stellar elemental abundance patterns at z = 0 in 8 low-mass (M_* = 10^6 - 10^9 M_sun) galaxies in the Feedback in Realistic Environments (FIRE-2) cosmological simulations. Using magnesium (Mg) as a representative…
Ground- and space-based observations of stellar heavy element abundances are providing a clearer picture of the chemical evolution of the Galaxy. A large number of (r)apid and (s)low neutron capture process elements, including the first…
We compare elemental abundance patterns of $\sim 200$ extremely metal-poor (EMP; [Fe/H]$<-3$) stars with supernova yields of metal-free stars in order to obtain insights into the characteristic masses of the first (Population III or Pop…
Because of their low gravitational energies dwarf galaxies are greatly exposed to energetical influences by the interstellar medium, like e.g.\ stellar radiation, winds or explosions, or by their environment. While the metallicity depletion…
Oxygen abundances in a sample of ultra-metal-poor subdwarfs have been derived from measurements of the oxygen triplet at 7771--5 A and OH lines in the near UV performed in high-resolution and high signal-to-noise spectra obtained with…
We have determined beryllium abundances for 25 metal-poor stars based on the high resolution and high signal-to-noise ratio spectra from the VLT/UVES database. Our results confirm that Be abundances increase with Fe, supporting the global…
Recent work presented increasing evidence of high, non-constant S/O abundance ratios observed in star-forming metal-poor galaxies, showing deviations from the constant canonical S/O across a large range of O/H abundance. Similar peculiar…
We investigate the evolution of the star formation rate in the early Galaxy using beryllium and oxygen abundances in metal poor stars. Specifically, we show that stars belonging to two previously identified kinematical classes (the…
High-resolution, high-signal-to-noise (<S/N> = 85) spectra have been obtained for five stars -- CD-24:17504, CD-38:245, CS 22172-002, CS 22885-096, and CS 22949-037 -- having [Fe/H] < -3.5 according to previous lower S/N material. LTE…
The first stars are assumed to be predominantly massive. Although, due to the low initial abundances of heavy elements the line-driven stellar winds are supposed to be inefficient in the first stars, these stars may loose a significant…
The abundances of iron and oxygen are homogeneously determined in a sample of 523 nearby (d<150 pc) FGK disk and halo stars with metallicities in the range -1.5<[Fe/H]<0.5. The oxygen abundances were inferred from a restricted non-LTE…