Future large and extremely large ground-based telescopes will demand stable geological settings.Remote sensing could be an unvaluable tool to analyse the impact of geological activity at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii)

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We present a complete study of the morphology of post-Asymptotic Giant Branch (post-AGB) stars. Post-AGB is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). We have defined the end of the post-AGB phase and the beginning of the PN phase as when the star

Context: Substructures - dark lanes and tails - of umbral dots (UDs) were predicted by numerical simulations of magnetoconvection and have been detected later in some observations. Aims: To provide constraints for realistic theoretical models of sunspot umbrae, we describe the observed properties and evolutionary characteristics of UDs (including

Based on the stellar orbit distribution derived from orbit-superposition Schwarzschild models, we decompose each of 250 representative present-day galaxies into four orbital components: cold with strong rotation, warm with weak rotation, hot with dominant random motion, and counter-rotating (CR). We rebuild the surface brightness (Σ) of each