A two-week time series of precise radial velocity measurements of Alpha Bootis (Arcturus) covering 7-8 hr per night is reported. The radial barycentric velocity of the star is found to be -5021 + or - 5 m/s. When data from the whole run are jointly analyzed, several equispaced peaks in the frequency appear in the range of a few microhertz, the

A new method has recently been developed to obtain the Fried's parameter from observations of granulation outside the disk center, based on the different degradation suffered by the images on the directions parallel and perpendicular to the solar limb, due to the geometrical foreshortening. This procedure has been applied to CCD images obtained at

Spectroscopic observations, with high spatial resolution, of Ca II K bright points very near the disk center are presented. Magnetic concentrations have been detected in these network (facular) points by only using intensity profiles of the well-known pair of lines Fe I 5250.22 A and 5247.06 A. No brightening of these structures with respect to the

The present study estimates the efficiency ratio for massive star formation between the arms and the interarm disks of three grand design spirals. The estimate is based on H-alpha mapping observations of the H II regions in the galaxies. It is found that this efficiency ratio is 10 or more in the zones between the Lindblad resonances and the radius

Evidence for circumnuclear starbursts in spiral galaxies can take the form of a blue excess near the nucleus, but more frequently (because of dust extinction) H I or radio continuum emission. Such bursts are quite common, even in objects with no interacting companions. One consequence of a burst is to sweep gas outward from the inner zone, so

The global behaviour and fine structure of the distribution of sunspot decay rates from activity cycle 13 to 20 are presented. It is shown that the distribution of this parameter is lognormal. Statistically significantly lower values of decay rates are found in cycles 13, 14, and 18 for isolated spots. The complex groups had no appreciable changes.