The dynamics of mergers between two unequal elliptical systems was studied with self-consistent numerical simulations. Comparisons of these models to real ellipticals are made in a variety of properties, which include the mean central surface brightness, the shape of the surface brightness profile, and the type of rotation curve and dispersion

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Azimuthal profiles of the spiral NGC 7479 in the B and I passbands have been analyzed using a subset of the azimuthal parameters proposed by Beckman and Cepa (1989), to look for the presence of shock fronts in the arms, as predicted by the density wave theory. The sign of the skewness parameter, showing that beyond the corotation radius the concave

Spectroscopy of selected areas of the two Giant H II Regions (GHR) NGC 5471 and NGC 604 shows convincing evidence for the existence of ionized gas at high velocities (1000 km/sec or greater) from the analysis of the profile of the Balmer (in NGC 604) and the forbidden O III (in NGC 5471) lines. The association of these effects with the presence of

The efficiency ratio of massive star formation in the arms of the spiral NGC 628 to that in the interarm region has been determined from the sizes and positions of its H II regions following the method described in Cepa and Beckman (1989). The variation of this relative star formation efficiency with radius shows a very similar behaviour for each