1 In this paper we concentrate more on other elemental abundances (such as O, Ne, S, Ar) and their implications for the evolution of the progenitor stars. We use a much larger sample of 183 objects, of which 65 are our own observations, where the abundances have been re-derived in a homogeneous way. For 156 of them, the quality of data is considered to be satisfactory for further analysis. We c...

The atomic resonance lines of the major elements have been observed in the atmospheres of a few comets, by using vacuum ultraviolet spectrographs on board rockets or orbiting observatories. Dust-to-gas ratios have also been deduced for two comets through a Finson-Probstein's analysis of their dust-tail isophotes. The geometric albedo of the dust for the phase angle a of the observations is not ...

We study the origin of iron and-elements (O, Mg, Si) in clusters of galaxies. In particular, we discuss the O/Fe] ratio and the iron mass-to-luminosity ratio in the intracluster medium (ICM) and their link to the chemical and dynamical evolution of elliptical and lenticular galaxies. We adopt a detailed model of galactic evolution incorporating the development of supernovae-driven galactic wind...

Mean ages and metal abundances are estimated for the stellar populations in a sample of 115 E and S0 galaxies in the central 64 × 70 of the Coma cluster. The estimates are based on the absorption line indices Mg2, and HβG, and the mass-to-light ratios (M/L). Single stellar population models from Vazdekis et al. were used to transform from the measured line indices and M/L ratios to mean ag...

Mean ages and metal abundances are estimated for the stellar populations in a sample of 115 E and S0 galaxies in the central 64′× 70′ of the Coma cluster. The estimates are based on the absorption line indices Mg2, and HβG, and the mass-to-light ratios (M/L). Single stellar population models from Vazdekis et al. were used to transform from the measured line indices and M/L ratios to mean a...

High quality spectrophotometric observations of 30 Planetary Nebulae in the Galactic Bulge have been made. Accurate reddenings, plasma parameters, and abundances of He, O, N, S, Ar, Cl are derived. We find the abundances of O, S, Ar in the Planetary Nebulae in the Galactic Bulge to be comparable with the abundances of the Planetary Nebulae in the Disk, high abundances being maybe slightly more ...

We use ultraviolet spectra of Capella from the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer satellites to study interstellar absorption lines from the Local Interstellar Cloud (LIC). Measurements of these lines are used to empirically determine the ionization states of carbon, nitrogen, and silicon in the LIC, for comparison with the predictions of theoretical photoionizati...

We analyze the effect of variation of fundamental couplings and mass scales on primordial nucleosynthesis in a systematic way. The first step establishes the response of primordial element abundances to the variation of a large number of nuclear physics parameters, including nuclear binding energies. We find a strong influence of the n−p mass difference (for the He abundance), of the nucleon ma...

Chemical abundances provide important clues to the evolution of galaxies. Ionized nebulae are one of the main sources of chemical abundance measurements, especially in external galaxies. Studies of H II regions have shown that the overall metallicity of galaxies increases with galactic luminosity, and that spiral galaxies characteristically have radial gradients in chemical composition. There a...

The VLT-Flames Survey for Massive Stars [1, 2] provides precise measurements of rotational velocities and nitrogen surface abundances of massive stars in the Magellanic Clouds. Specifically, for the first time, such abundances have been estimated for stars with significant rotational velocities. This extraordinary data set gives us the unique possibility to calibrate rotationally and magnetical...