Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F- and G-type main-sequence stars (0.2

We present a detailed comparison of the ionizing spectral energy distributions (SEDs) predicted by four modern stellar atmosphere codes, TLUSTY, CMFGEN, WM-basic and FASTWIND. We consider three sets of stellar parameters representing a late O-type dwarf (O9.5V), a mid-O-type (O7V) dwarf and an early O-type dwarf (O5.5V). We explore two different

We present stellar metallicities derived from Ca II triplet spectroscopy in over 350 red giant branch stars in 13 fields distributed in different positions in the Small Magellanic Cloud, ranging from ~1° to ~4° from its center. In the innermost fields, the average metallicity is [Fe/H] ~-1. This value decreases when we move away toward outermost

Here we describe the first results of the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey, which provides cosmic tomography of the evolution of the contents of the universe over most of cosmic history. Our novel approach employs 20 contiguous, equal-width, medium-band filters covering from 3500 Å to 9700 Å, plus

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Photometry and long-slit spectroscopy are presented for 14 S0 and spiral galaxies of the Fornax, Eridanus and Pegasus clusters and the NGC 7582 group. The age, metallicity and α/Fe enhancement of the stellar population in the centres and their gradients are obtained using stellar population models with variable element abundance ratios. Most of the