Related papers: The evolution of C and O abundances in stellar pop…
We present oxygen abundances for 72 F and G dwarf stars in the solar neighbourhood. Using the kinematics of the stars we divide them into two sub-samples with space velocities that are typical for the thick and thin disks, respectively. The…
We measured $^{35}$Cl abundances in 52 M giants with metallicities between -0.5 $<$ [Fe/H] $<$ 0.12. Abundances and atmospheric parameters were derived using infrared spectra from CSHELL on the IRTF and from optical echelle spectra. We…
We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large…
Using the standard infall model of Galactic chemical evolution, we explore the origin of carbon and calculate the abundance evolution of CNO elements for 8 different models of stellar nucleosynthesis yields. The results show that, in the…
Atmospheric parameters and chemical compositions for ten stars with metallicities in the region of -2.2< [Fe/H] <-0.6 were precisely determined using high resolution, high signal to noise, spectra. For each star the abundances, for 14 to 27…
Ultraviolet nebular emission lines are important for understanding the time evolution and nucleosynthetic origins of their associated elements, but the underlying trends of their relative abundances are unclear. We present UV spectroscopy…
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…
Spectral data on early type galaxies is analyzed for chemical abundance with an emphasis on obtaining detailed abundances for the elements O and Si in addition to C, N, Na, Mg, Ca, Fe, and Ba. The abundance trends with velocity dispersion…
We present a detailed and uniform study of oxygen abundances in 155 solar type stars, 96 of which are planet hosts and 59 of which form part of a volume-limited comparison sample with no known planets. EW measurements were carried out for…
Recent studies of spectral lines of the CNO elements in the Sun and unevolved disk and halo stars show that most published abundance data may be affected by systematic errors due to inadequate 1D modelling of stellar atmospheres. This…
The abundances of the {\it rare} light elements, Li, Be, and B, provide clues about stellar structure and evolution, about Galactic evolution and about their nucleosynthesis, including production during the Big Bang. The abundances of the…
Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by…
We present chemical evolution models aimed at reproducing the observed (N/O) vs. (O/H) abundance pattern of star forming galaxies in the Local Universe. We derive gas-phase abundances from SDSS spectroscopy and a complementary sample of…
A study of the O/Fe ratio in metal-poor main sequence and subgiant stars is presented using the [OI] 6300A line, the OI 7774A triplet, and a selection of weak FeII lines observed on high-resolution spectra acquired with the VLT UVES…
Oxygen is the most abundant "metal" element in stars and in the cosmos. But determining oxygen abundances in stars has proven challenging, because of the shortage of detectable atomic oxygen lines in their optical spectra as well as…
The Hipparcos orbiting observatory has revealed a large number of helium-core-burning "clump" stars in the Galactic field. These low-mass stars exhibit signatures of extra-mixing processes that require modeling beyond the first dredge-up of…
Carbon-rich (C-rich) stars can be found at all metallicities and evolutionary stages. They are often the result of mass-transfer from a companion, but some of the most metal-poor C-rich objects are likely carrying the imprint of the…
In an attempt to carry out a systematic study on the behavior of the photospheric abundances of Li, C, and O (along with Fe) for Hyades main-sequence stars in the T_eff range of ~5000-7000K, we conducted an extensive spectrum-synthesis…
Massive BA-type supergiants are among the visually brightest stars in galaxies with active star formation. As such they are versatile tools for studies of stellar and galactochemical evolution. Moreover, they can act as distance indicators…
Methods to determine abundances of the elements in the atmospheres of F, G, and K stars with precisions of 0.01-0.03 dex are reviewed. Such high-precision stellar abundances have led to the discovery of unexpected phenomena and relations…