The distribution of sunspot decay rates is studied using the Greenwich Photoheliographic Results (GPR) for a total of approximately hundred years between 1874 and 1976. The decay rates are seen to be lognormally distributed. The discrepancies between the decay rates given in the past by different authors are shown to originate as a consequence of

Predictions about the angular behavior of the emission line spectrum from the ENLR for three plausible models of the nuclear engine are presented. Results are given for the different intensities at different inclination angles with respect to the symmetry axis.

We have used a numerical method based on elliptical fitting of isophotes to analyze the structural parameters of three pairs of elliptical galaxies containing radio jets. The relationship between tidal interactions and radio activity is also investigated.

We present a new H-alpha image of high quality of the grand-design galaxy NGC 6814, and describe statistical properties of the H II region population. We have determined positions, angular sizes, and calibrated fluxes of 735 individual H II regions. We construct luminosity functions (LFs) for the complete sample, separately for arm and interarm

We analyze the data from narrow band H-alpha and forbidden O III CCD imaging of a sample of nearby spiral galaxies with active nuclei. The results show that the large scale star formation depends on the level of nuclear activity, with Seyfert 2 presenting the strongest disk and circumnuclear star formation, while Seyfert 1 shows very little. We

A sample of actively star forming H II galaxies has been observed in the radio continuum and several optical bands. These galaxies are currently undergoing very active star formation and have been selected on the basis of strong radio continuum emission. Most of the galaxies are irregular and have been associated with merger or interaction events