Related papers: High-precision stellar abundances of the elements …
We investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late-type galaxies using around 3740 published spectra of HII regions. We use these data in order to provide homogeneous abundance…
Much of modern astrophysics is grounded on the observed chemical compositions of stars and the diffuse plasma that pervades the space between stars, galaxies and clusters of galaxies. X-ray and EUV spectra of the hot plasma in the outer…
Systematic abundance differences that depend on the condensation temperatures of elements have been observed, in particular for stars similar to the Sun; solar twins and solar analogs. Similar differences have also recently been shown to…
HII regions, ionized nebulae where massive star formation has taken place, exhibit a wealth of emission lines that are the fundamental basis for estimating the chemical composition of the Universe. For more than 80 years, a discrepancy of…
We present atmospheric parameters and Fe abundances derived for the majority of dwarf stars (north of -30 degrees declination) which are up to now known to host extrasolar planets. High-resolution spectra have been obtained with the…
Context. Late O-type stars at luminosities $\log L/L_\odot \lesssim 5.2$ show weak winds with mass-loss rates lower than 10$^{-8} M_\odot$ yr$^{-1}$. This implies that their photospheric layers are not strongly affected by the stellar wind.…
We review recent observational studies of heavy element abundances in low metallicity stars and explore some implications of these results for nucleosynthesis and early Galactic chemical evolution.
The compositions of stars and planets are connected, yet, the definition of "habitability" and the "habitable zone" only take into account the physical relationship between the star and planet. Planets, however, are made truly habitable by…
We present our chemical abundance investigation of the metal-poor ([Fe/H]=-1.60 dex), r-process-enriched ([Eu/Fe]=0.73 dex) halo star HD 20 using novel and archival high-resolution spectra at outstanding signal-to-noise ratios. By combining…
We develop a new method to account for the finite lifetimes of stars and trace individual abundances within a semi-analytic model of galaxy formation. At variance with previous methods, based on the storage of the (binned) past star…
Estimating molecular abundances ratios from the direct measurement of the emission of the molecules towards a variety of interstellar environments is indeed very useful to advance in our understanding of the chemical evolution of the…
Results from detailed spectroscopic analyses of stars hosting massive planets are employed to search for trends between abundances and condensation temperatures. The elements C, S, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni and Zn are…
We used the UVES spectrograph (VLT-UT2 telescope) to obtain high-resolution spectra of 6 stars hosting transiting planets, namely for OGLE-TR-10, 56, 111, 113, 132 and TrES-1. The spectra are now used to derive and discuss the chemical…
We present newly derived stellar parameters and the detailed abundances of 19 elements of seven stars with small planets discovered by NASA's Kepler Mission. Each star save one has at least one planet with a radius <= 1.6 R_Earth,…
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…
Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD+10 2179, V1920 Cyg,…
We present a series of systematic abundance measurements for a group of hot DA white dwarfs in the temperature range 20,000-75,000K, based on far-UV spectroscopy with STIS on HST, IUE and FUSE. Using our latest heavy element blanketed…
Abundances of C, O, and Fe are determined for F and G main-sequence stars in the solar neighborhood in order to study trends and systematic differences in the C/Fe, O/Fe, and C/O ratios for stellar populations. Carbon abundances are…
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 galactic bulge is a significant part of our galaxy, but it is hard to observe, being both distant and covered by dust in the disk. Therefore there do not exist many hi-res optical spectra of bulge stars with large wavelength coverage,…