We present results of the search for variable stars in a sample of Local Group isolated dwarf galaxies, namely LGS3, IC1613, Cetus, and Tucana, based on very deep HST/ACS data. About 900 variables and candidates have been found in total. Among the confirmed variables, we identified about 700 RR Lyrae stars, 60 Cepheids, and 50 eclipsing binaries

The requirements for excellent image quality of current large and future very large telescopes demand a proper knowledge of atmospheric turbulence. Thus several projects are already pursuing this aim. The precise characterization of the turbulence above a particular site requires long-term monitoring. In this sense, due to the lack of long-term

We use the integral-field spectrograph SAURON to measure the stellar line-of-sight velocity distribution and absorption line strengths out to four effective radii (Re) in the early-type galaxies NGC 3379 and 821. With our newly developed observing technique, we can now probe these faint regions in galaxies that were previously not accessible with

This paper is part of a series devoted to the study of the stellar populations in brightest cluster galaxies (BCGs), aimed at setting constraints on the formation and evolution of these objects. We have obtained high signal-to-noise ratio, long-slit spectra of 49 BCGs in the nearby Universe. Here, we derive single stellar population (SSP)

The proper characterization of the turbulence structure in an astronomical site requires a statistical analysis of the refractive index structure constant, CN2(h). Our team has been monitoring this variable since November 2002 at the Teide Observatory (Tenerife, Canary Islands, Spain). We have derived the seasonal evolution of turbulence structure

This paper presents the first results of an Hα imaging survey of galaxies in the central regions of the A2151 cluster. A total of 50 sources were detected in Hα, from which 41 were classified as secure members of the cluster and 2 as likely members based on spectroscopic and photometric redshift considerations. The remaining seven galaxies were