We present a wide field V-band imaging survey of approximately 1 deg2 (~7.2~h-275 Mpc2) in the direction of the nearby cluster of galaxies Abell 2151 (the Hercules Cluster). The data are used to construct the luminosity function (LF) down to MV ≈ -14.85, thus allowing us to study the dwarf galaxy population in A2151 for the first time. The obtained

We explore the formation and evolution of hydrogen-deficient post-AGB white dwarfs. To this end, we compute the complete evolution of an initially 2.7 ~M&sun; star from the zero-age main sequence through the thermally pulsing and mass-loss phases to the white dwarf stage. Particular attention is given to the chemical abundance changes during the

We subjected 106 new high-resolution spectra of the double-lined spectroscopic close binary epsilon Lupi, obtained in a time-span of 17 days from two different observatories, to a detailed study of orbital and intrinsic variations. We derived accurate values of the orbital parameters. We refined the sidereal orbital period to 4.55970 days and the

We present the CIDA-UCM-Yale (Centro de Investigaciones de Astronomía, Universidad Complutense de Madrid, and Yale University) Survey (CUYS) for Hα+[NII] 6549,6584Åemission-line galaxies (ELGs) using objective-prism spectra. The most important properties of a catalogue with 427 entries and significant subsets are analysed. The complete sample

The Advanced Technology Solar Telescope (ATST) will be the world's largest aperture solar telescope, and is being designed for high resolution, IR, and coronal research. It must be located at a site that maximizes the scientific return of this substantial investment. We present the instrumentation, analysis and results of the ATST site survey. Two

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