High-speed photometric observations were performed of the Ap stars HD62140 (49 Cam), HD81009, and HD22374 for more than 60 hr in Oct. and Dec. 1986. Photometric measurements in the B band were reduced and the residuals obtained were subjected to a harmonic analysis, searching for periodicities in the range of a few minutes to 2 hr. There is

Rotational splitting measurements of less than 5 p-modes are calculated using different sources of data. For l=1, data obtained from years 1981 to 1985 is used to find out the stretches where each particular mode remains excited; then its splitting is measured and the mean found. Cross-correlation of power spectra confirms these finding, and this

The Delta Scuti variable 63 Her was observed during 21 nights at two observatories (Observatorio del Teide, Tenerife Island, Spain and Observatorio Astronomico Nacional de San Pedro Martir in Baja California, Mexico). Six frequencies of pulsation are unambiguously detected, among which the fundamental radial mode, two non radial pressure-like modes

A method to obtain the Duvall phase function from the structure of a stellar model is presented. This can be a good tool for understanding the dependence of p-mode frequencies on the structure of the upper layers of the convection zone. A linear relation between phase function differences of two models and their equilibrium structure differences is

The suitability of the Eddington approximation as a theoretical framework for the study of the possibility of a k-like overstability mechanism as the driving force of solar modes of oscillation is assessed. A theoretical description of the interaction between the hydrodynamics of the motion and the radiative energy transport is needed. It is found

The small imaging photometer of the VIRGO (Variability in IRradiance and Gravity Oscillations) investigation on ESA's SOHO mission is presented. This instrument, the Luminosity Oscillations Imager (LOI), will observe the solar radiance with 12 pixels resolution. A prototype of the LOI was built mainly to test possible detector configurations, the