To understand the physical processes governing accretion discs we can study active galactic nuclei (AGNs), X-ray binary systems (XRBs), and cataclysmic variables (CVs). It has been shown that XRBs and CVs show similar observational properties such as recurrent outbursts and aperiodic variability. The latter has been extensively studied for XRBs

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Data obtained at the Observatorio del Teide (Tenerife) during the years 1978 to 1988 using a resonant scattering spectrophotometer, is analyzed to look for variations of the low degree p-mode frequencies along the solar cycle. The analysis based on the cross-correlation of power spectra suggests that the variation of its maximum correlation

Aims: The present study reports measurements of the rotation period of a young solar analogue, estimates of its surface coverage by photospheric starspots and of its chromospheric activity level, and derivations of its evolutionary status. Detailed observations of many young solar-type stars, such as the one reported in the present paper, provide

For a number of reasons, the properties of integrated stellar populations are distributed. Traditional synthesis models usually return the mean value of such distribution, and a perfect fitting to observational data is sought for to infer the age and metallicity of observed stellar populations. We show here that, while this is correct on average

Although it is clear that the circumnuclear regions of galaxies are intimately related to their host galaxies, most directly through their bars, it remains unclear what exactly initiates and fuels nuclear stellar (starburst) and non-stellar (AGN) activity. Deviations from axisymmetry in the gravitational potential of a galaxy, set up by a bar or an