Related papers: An abundance analysis for Vega: Is it a lambda Boo…
High signal to noise, high resolution spectra were obtained for a sample of normal, mild barium, and barium giants. Atmospheric parameters were determined from the FeI and FeII lines. Abundances for Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn,…
We present the photometric properties of 1279 blue variable stars within the LMC. Photometry is derived from the MACHO database. The lightcurves of the sample exhibit a variety of quasi-periodic and aperiodic outburst behavior. A…
We determine the elemental abundances for the ejecta of the slow nova PW Vul 1984. Our technique uses a minimization of the emission line fits of a photoionization model to available ultraviolet, optical and infrared spectra. We find the…
It is debated whether the Milky Way bulge has the characteristics of a classical bulge sooner than those of a pseudobulge. Detailed abundance studies of bulge stars is a key to investigate the origin, history, and classification of the…
We have performed a detailed abundance analysis of the content of s-process elements of two dwarf stars with suspected overabundace of those elements. Such stars belong to a special kinematic sample of the solar neighborhood, with peculiar…
The chemical compositions of stars from the Asymptotic Giant Branch are still poorly known due to the low temperatures of their atmospheres and therefore the presence of many molecular transitions hampering the analysis of atomic lines. One…
The microlensing surveys, such as OGLE or MACHO, have led to the discovery of thousands of RR Lyrae stars in the Galactic Bulge and in the Magellanic Clouds, allowing for detailed investigation of these stars, specially the still mysterious…
We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16…
New information on the relations between the Galactic disks, the halo, and satellite galaxies is being obtained from elemental abundances of stars having metallicities in the range -1.5 < [Fe/H] < -0.5. The first results for a sample of 26…
The chemical abundances of very metal-poor stars provide important constraints on the nucleosynthesis of the first generation of stars and early chemical evolution of the Galaxy. We have obtained high-resolution spectra with the Subaru…
We present a mini-survey of Galactic B[e] stars mainly undertaken with the Large Binocular Telescope (LBT). B[e] stars show morphological features with hydrogen emission lines and an infrared excess, attributed to warm circumstellar dust.…
The nature of the tenuous disks around A stars has raised considerable controversy in the literature during the past decade. The debate whether or not the disk around beta Pictoris contains gaseous molecular hydrogen is only the most recent…
A spectroscopic study was carried out for the double-line A-type eclipsing binary system RR Lyn A+B based on the disentangled spectra, with an aim of clarifying the differences in photospheric chemical compositions between the components,…
Monitoring magnetic and activity variations in A- and B-type stars with ultra-weak magnetic fields is essential to understand the origin and evolution of these fields in this region of the HR diagram, with Vega standing as the prototype of…
We have obtained accurate circular spectropolarimetric observations for a sample of Vega-like and Herbig Ae/Be stars with FORS1 at the VLT in an attempt to detect their magnetic fields. No magnetic field could be diagnosed in any Vega-like…
We have taken K-band spectroscopy of a sample of 13 pre-CVs in order to examine them for anomalous chemical abundances. In particular, we study the strength of the 12CO and 13CO absorption bands that have been found diminished and enhanced,…
We report the first extensive model atmosphere and detailed chemical abundance study of eight RR Lyrae variable stars of c subclass throughout their pulsation cycles. Atmospheric parameters effective temperature, surface gravity,…
The chemical evolution of neutron capture elements in the Milky Way is still a matter of debate. Although more and more studies investigate their chemical behaviour, there is still a lack of a significant large sample of abundances of a key…
Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive…
Near-infrared (2.2 um) long baseline interferometric observations of Vega are presented. The stellar disk of the star has been resolved, and the data have been fitted with a limb darkened stellar disk of diameter Theta_{LD} = 3.28 +/- 0.01…