Auto-correlation measures of the coarse Ca+ network made on selected spectroheliograms obtained during the solar minimum period of 1964 and 1965 are described. The full width at half maximum of the normalised A.C. curve ...

Spectra of the H-alpha line obtained with high dispersion and high spatial resolution are used to study some of the characteristics of chromospheric mottling on the solar disk. The fluctuations in intensity, indicated by ...

The Wolf-Rayet stars form a group of objects that have numerous peculiar features in their spectra. They are so named after their discoverers Wolf and Rayet of the Paris Observatory who first picked out three examples ...

A critical discussion of present-day knowledge regarding the Wolf-Rayet atmosphere is presented. It is shown that the large widths usually ascribed to the emission lines are formed by heavy blending, and that the individual ...