We present intermediate resolution spectroscopy of the dwarf nova CY UMa in quiescence. From the radial velocities of the Hα emission, we derive an orbital period of 0.067 95+/-8x10^-5 d, which disagrees with previous photometric estimates. We also constrain the system parameters. The core of the Hα emission seems to be dominated by a component

T Tauri, the prototype of a class of low-mass pre-main sequence stars, was observed with the 3.6m Canada-France-Hawaii telescope (CFHT) and the CP40 photon-counting camera in November 1989. The data have been analysed using techniques of Speckle Interferometry to obtain diffraction-limited information on the spatial extent of T Tauri in narrow

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