Related papers: Observations of Neutron-Capture Elements in the Ea…
A previous study (Nissen & Schuster 2010) of 94 dwarf stars with -1.6 < [Fe/H] < -0.4 has revealed the existence of two distinct halo populations with a systematic difference in [alpha/Fe] at a given metallicity. In continuation of that…
We obtain the chemical abundances of six barium stars and two CH subgiant stars based on the high signal-to-noise ratio and high resolution Echelle spectra. The neutron capture process elements Y, Zr, Ba, La, Eu show obvious overabundance…
We present a chemical abundance distribution study in 14 $\alpha$, odd-Z, even-Z, light, and Fe-peak elements of approximately 3200 intermediate metallicity giant stars from the APOGEE survey. The main aim of our analysis is to explore the…
Two alternative scenarios concerning the origin and evolution of extremely metal-poor halo stars are investigated. The first one assumes that the stars have been completely metal-free initially and produced observed carbon and nitrogen…
Selected topics in neutrino astrophysics are reviewed. These include the production of low energy neutrino flux from cores of collapsing stars and the expected high energy neutrino flux from some other astrophysical sites such as the…
The first galaxies contain stars born out of gas with little or no metals. The lack of metals is expected to inhibit efficient gas cooling and star formation but this effect has yet to be observed in galaxies with oxygen abundance relative…
We present numerical simulations to describe the nucleosynthesis and evolution of pre-Galactic clouds in a model which is motivated by cold dark matter simulations of hierarchical galaxy formation. We adopt a SN-induced star-formation…
The enrichment history of heavy neutron-capture elements in the Milky Way disc provides fundamental information about the chemical evolution of our Galaxy and about the stellar sources that made those elements. In this work we give new…
The genesis and chemical patterns of the metal poor stars in the galactic halo remains an open question. Current models do not seem to give a satisfactory explanation for the observed abundances of Lithium in the galactic metal-poor stars…
By measuring the elemental abundances of a star, we can gain insight into the composition of its initial gas cloud -- the formation site of the star and its planets. Planet formation requires metals, the availability of which is determined…
Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two…
Chemically peculiar stars define a class of stars that show unusual elemental abundances due to stellar photospheric effects and not due to natal variations. In this paper, we compare the elemental abundance patterns of the ultra metal-poor…
By using the high-dispersion spectra of 14 bright planet-harboring stars (along with 4 reference stars) observed with the new coude echelle spectrograph at Okayama Astrophysical Observatory, we investigated the abundances of volatile…
Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive Population III stars. We…
The connection between the neutron halo observed in light neutron rich nuclei and the neutron radiative capture process is outlined. We show how nuclear structure information such as spectroscopic factors and external components of the…
The idea of slow-neutron capture nucleosynthesis formulated in 1957 triggered a tremendous experimental effort in different laboratories worldwide to measure the relevant nuclear physics input quantities, namely ($n,\gamma$) cross sections…
The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing…
We present results on carbon, nitrogen, and oxygen abundances for a sample of unevolved metal-poor stars with metallicities in the range -0.3< [Fe/H]< -3. Oxygen abundances derived from different indicators are compared showing consistently…
We present a detailed chemical analysis study of 16 candidate metal-poor stars, previously identified with 2dF + AAOmega, using X-Shooter spectra and the Korg 1D local thermodynamic equilibrium spectral synthesis code. We confirm the…
We discuss the detailed composition of 28 extremely metal-poor dwarfs, 22 of which are from the Hamburg/ESO Survey, based on Keck Echelle spectra. Our sample has a median [Fe/H] of -2.7 dex, extends to -3.5 dex, and is somewhat less…