To investigate the distribution of dust in Sb and Sc galaxies we have analyzed near-infrared and optical surface photometry for an unbiased sample of 37 galaxies. Since light in the K-band is very little affected by extinction by dust, the B - K colour is a good indicator of the amount of extinction, and using the colour-inclination relation we can

We present stellar population models for starbursts in a sample of eleven Wolf-Rayet galaxies. Taking into account the observational data available, we try to reconstruct the number of Wolf-Rayet stars observed and estimate the number of type II supernovae that have exploded in the ionizing cluster. Using the stellar yields of the most recent

The authors analyze the statistical properties of observed sunspot numbers. Near the Maunder minimum, the dynamics of successive sunspot maxima is low-dimensional and has properties similar to the intermittent logistic map. The long-term statistics is well described by an intermittent random injection model with Poissonian injection statistics

We present spectroscopic observations of supernova 1994D in NGC 4526, an S0_3_ galaxy in the Virgo cluster 15Mpc distant. The datasets consist of the interstellar Ca II and Na I lines towards the supernova at high spectral resolution (FWHM 6km/s), H α and [N II] observations at lower resolution (FWHM 33km/s) of the nucleus of NGC 4526 and the

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We investigate the formation and the nature of the extended wings of the UV resonance lines of Si IV 1394, 1402A and C IV 1548 and 1550A in the spectrum of the LBV P Cyg. The effects of line blending in the neighbourhood of these lines were estimated by means of a grid of theoretical synthetic spectra, computed for the P Cyg model atmosphere. It is