The colour-magnitude diagram (CMD) of NGC1851 presents two subgiant branches (SGBs), probably due to the presence of two populations differing in total C+N+O (carbon+nitrogen+oxygen) content. We test the idea that a difference in total C+N+O may simulate an age difference when comparing the CMD of clusters to derive relative ages. We compare

Galaxy mergers and interactions are mechanisms which should drive the formation of bars. Therefore, we could expect that the fraction of barred galaxies increases with the local density. Here we show the first results of an extensive search for barred galaxies in different environments. We conclude that the bar fraction on bright (L>L*) field

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A photometric analysis is conducted of the open cluster NGC 7044, on the basis of UBVR CCD observations of 896 stars in the cluster field. Reddening and metallicity estimates are highly dependent on whether reddening slopes and absorption coefficients vary with spectral type. The color-magnitude diagram obtained is compared with selected sets of

Context. It has been reported that the intrinsic dispersion at constant magnitude in the structural relations of early-type galaxies is a useful tool to study the universality of these structural relations, that is to say, to study whether the structural relations depend on luminosity, wavelength, redshift, and/or environment. Aims: We study the