The properties of the photosphere in magnetic and non magnetic regions, at two levels in the solar atmosphere, have been studied, using two virtually simultaneous time sequences of 109 mn duration of CCD images taken at the Vacuum Tower Telescope of the Sacramento Peak Observatory. The selected wavelengths correspond to the true continuum and to

This article presents a statistical-mechanical treatment of a relationship (the force equation) between the gravitational potential for two particles and the correlation functions in a relaxed distribution of particles with different masses. This relationship is used in the case of galaxies interacting through a Newtonian potential in a Universe in

After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic

The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10-7 to 10-2 Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as well as the splitting

We have acquired narrow and broad band imaging, together with high and low resolution spectroscopy for the source IRAS 09371+1212. As a result, we are able to show the presence of systematic colour gradients within the interior and exterior envelopes. Whilst the interior bright lobes are characterised by relatively high values of V-R (a regime of

In this paper all the travel-time data from crustal earthquakes that occurred in the period 1978-1991 along the southern Tyrrhenian sea have been re-examined. In particular, 410 local earthquakes recorded at a minimum number of seven seismic stations and 52 shots fired on sea have been utilized to infer a tomographic image of the velocity model