Related papers: Compositional differences between the component st…
We have analysed high-resolution spectra of 28 A and 22 F stars in the Kepler field, observed with the FIES spectrograph at the Nordic Optical Telescope. We provide spectral types, atmospheric parameters and chemical abundances for 50…
Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming the stars formed in the same environment/from the same material, any compositional anomalies between…
We present the light curve variations of the two active binaries with hot subdwarf component. According to the brightness variations outside of the eclipses, the giant components of the systems are chromospherically active stars. The dark…
We study how chemical abundances of late B-, A- and early F-type stars evolve with time, and we search for correlations between the abundance of chemical elements and other stellar parameters, such as effective temperature and Vsini. We…
Eclipsing binary systems play a vital role in astrophysics, as they provide a direct means of measuring fundamental stellar parameters. By combining high-precision space-based observations with ground-based multicolor photometric data,…
Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the…
Using a high resolution spectrum of the secondary star in the neutron star binary {Cen X-4}, we have derived the stellar parameters and veiling caused by the accretion disk in a consistent way. We have used a $\chi^{2}$ minimization…
We have observed high-dispersion echelle spectra of main-sequence stars in five nearby young associations -- Argus, Carina-Near, Hercules-Lyra, Orion and Subgroup B4 -- and derived abundances for elements ranging from Na to Eu. These are…
CCD light curves of the Algol type eclipsing binaries DP Cep, AL Gem, FG Gem, UU Leo, CF Tau and AW Vul were analysed using the Wilson-Deninney code and new geometric and absolute parameters were derived. Due to cyclic apparent orbital…
While monitoring a sample of apparently slowly rotating superficially normal early A stars, we have discovered that HR 8844 (A0 V), is actually a new Chemically Peculiar star. We have first compared the high resolution spectrum of HR 8844…
The magnetic chemically peculiar (CP2) stars of the upper main sequence are well-suited for investigating the impact of magnetic fields on the surface layers of stars, which leads to abundance inhomogeneities (spots) resulting in…
PG1159 stars are hot, hydrogen-deficient (pre-) white dwarfs with atmospheres mainly composed of helium, carbon, and oxygen. The unusual surface chemistry is the result of a late helium-shell flash. Observed element abundances enable us to…
The secondary photometric standard star #79 for the FS Aur field (Henden & Honeycutt 1997) designated as [HH97] FS Aur-79 (GSC 1874 399) is a short period (0.2508 days) eclipsing binary whose light curve is a combination of the $\beta$ Lyr…
The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large…
Exoplanetary properties depend on stellar properties: to know the planet with accuracy and precision it is necessary to know the star as accurately and precisely as possible. Our immediate aim is to characterize in a homogeneous and…
We derive metallicities for 41 cataclysmic variables (CVs) from near-infrared spectroscopy. We use synthetic spectra that cover the 0.8 $\mu$m $\leq \lambda \leq$ 2.5 $\mu$m bandpass to ascertain the value of [Fe/H] for CVs with K-type…
HD 98088 is a synchronised, double-lined spectroscopic binary system with a magnetic Ap primary component and an Am secondary component. We study this rare system using high-resolution MuSiCoS spectropolarimetric data, to gain insight into…
Context. Various element transport processes modify the photospheric chemical composition of low-mass stars during their evolution. The most prominent one is the first dredge-up that occurs at the beginning of the red giant branch. Then,…
The chemical composition of exoplanet host stars is an important factor in understanding the formation and characteristics of their orbiting planets. The best example of this to date is the planet-metallicity correlation. Other proposed…
We present an analysis of a high resolution (R~50,000) optical spectrum of the central region of the proto-planetary nebula CRL 2688. This object is thought to have recently moved off the AGB, and display abundance patterns of CNO and heavy…