Related papers: Xenon in Mercury-Manganese Stars
We have derived new detailed abundances of Mg, Ca, and the Fe-group elements Sc through Zn (Z = 21-30) for 37 main sequence turnoff very metal-poor stars ([Fe/H] <= -2.1). We analyzed Keck HIRES optical and near-UV high signal-to-noise…
We report new results for the elemental and isotopic abundances of the normally rare elements mercury and platinum in HgMn stars. Typical overabundances can be 4 dex or more. The isotopic patterns do not follow the fractionation model of…
We report on the discovery of seven low-metallicity stars selected from the Hamburg/ESO Survey, six of which are extremely metal-poor ([Fe/H]<-3.0), with four having [Fe/H]<-3.5. Chemical abundances or upper limits are derived for these…
We present equivalent widths, improved model atmosphere parameters, and revised abundances for 14 species of 11 elements derived from high resolution optical spectroscopy of 311 metal-poor stars. All of these stars had their parameters…
CONTEXT: Manganese is an iron-peak element and although the nucleosynthesis path that leads to its formation is fairly well understood, it remains unclear which objects, SN II and/or SN Ia, that contribute the majority of Mn to the…
Oxygen abundances for a large sample of dwarf and giant stars kinematically selected to be part of the Galactic thin and thick disks have been determined from a non-LTE analysis of the O I triplet lines at 777 nm. The abundance analysis was…
The Damped and sub-Damped Lyman-alpha (DLA and sub-DLA) systems seen in the spectra of QSOs offer a unique way to study the interstellar medium of high redshift galaxies. In this paper we report on new abundance determinations in a sample…
Using high resolution, high-S/N archival UVES spectra, we have performed a detailed spectroscopic analysis of 4 chemically peculiar HgMn stars (HD 71066, HD 175640, HD 178065 and HD 221507). Using spectrum synthesis, mean photospheric…
The nature of non-variable high-excitation emission lines detected in the optical spectra of normal late-B type and chemically peculiar HgMn and PGa stars is still poorly understood. To better understand the origin of the weak emission…
The abundance of elements in the interstellar medium (ISM) is a key facet for many fields of astrophysical study. In the soft X-ray spectra, absorption by interstellar gas can result in deep absorption features that affect continuum…
Magnesium abundances of cool stars with different metallicities are important for understanding the galactic chemical evolution. This study tests atomic data used in stellar magnesium abundance analyses. We evaluate non-local…
Phosphorus abundances of ~80 apparently bright sharp-lined early-to-late B-type stars on the upper main sequence are determined by applying the non-LTE analysis to the P II line at 6043.084 A, with an aim of getting information on the P…
We present a first systematic investigation of the iron abundance in very hot (Teff>50,000K) hydrogen-deficient post-AGB stars. Our sample comprises 16 PG1159 stars and four DO white dwarfs. We use recent FUSE observations as well as HST…
The inhomogeneous surface distribution of heavy elements is known to cause periodic light variability of magnetic chemically peculiar stars. It is unclear to what extent the same paradigm applies to mercury-manganese (HgMn) stars. We aim to…
We present UES@WHT high-resolution spectra of the low-mass X-ray binary (LMXB) Cygnus X-2. We have derived the stellar parameters of the secondary star using $\chi^{2}$ minimisation procedure, and taking into account any possible veiling…
We have derived Mn abundances for more than 200 stars in 19 globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field and disk stars possessing an overlapping range of metallicities and…
We present the first high resolution spectroscopic observations of one red giant star in the ultra-faint dwarf galaxy Segue 2, which has the lowest total mass (including dark matter) estimated for any known galaxy. These observations were…
The lack of FeVII lines in PG1159 stars had led to the conclusion that in some objects iron must be strongly depleted. We have now detected FeX lines in FUSE spectra of the very hottest PG1159 stars Teff=150,000 - 200,000 K; RXJ2117.1+3412,…
Context: Recent attention has been directed to abundance variations among very young stars. Aims: To perform a detailed abundance study of the Herbig Ae star HD 101412, taking advantage of its unusually sharp spectral lines. Methods:…
An empirical determination of the f-values of the far-UV Mg II lines at 1239 A and 1240 A is reported. The strong near-UV Mg II lines at 2796 A and 2803 A are generally highly saturated along most interstellar sightlines outside the local…