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

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)

A generalization of the Theoretical Spectral Access Protocol (TSAP) standard called Simple Self-described Service Protocol (S3P) has been used to search and access stellar model data. In particular, a Web server has been implemented that searches for synthetic isochrones and tracks computed using the FRANEC code and stored inside the BaSTI (a Bag

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We present initial results from a study of a sample of low-perihelion near-Earth asteroids (NEAs) using the Infrared Spectrograph (IRS) on NASA’s Spitzer Space Telescope. The 7-14 μm thermal emission spectra have been fitted with models of the thermal continuum to derive the asteroid’s effective diameter, geometric albedo and beaming parameter η

We present the discovery and follow-up observations of eclipses of the cataclysmic variable star SDSS J100658.40+233724.4, fom which we determine the orbital period and the masses and radii of the two stellar components. Time-resolved optical spectroscopic observations covering the full orbital period were obtained on three consecutive nights. Time