We present a time-dependent semiempirical model of the chromospheric umbral oscillation in sunspots. This model has been obtained by applying recently developed non-LTE inversion techniques to a time series of spectropolarimetric observations. The model consists of two optically thick unresolved atmospheric components: a ``quiet'' component with

We show that the normalized Lorentzian state sum is finite on any triangulation. It thus provides a candidate for a perturbatively finite quantum theory of general relativity in four dimensions with Lorentzian signature.

We have studied the kinematics of the ionized gas in the nearly face-on galaxy NGC 3938 by means of observations made with the Fabry-Perot interferometer TAURUS II at the William Herschel Telescope, using the H_α line. We have been able to produce high-resolution velocity and velocity-dispersion maps which allow us to make a detailed study of the

We present the preliminary results obtained from two-dimensional spectroscopy with optical fibres of the circumnuclear region of the Seyfert 2 galaxy NGC 2992. The inner region of NGC 2992 seems not to be perturbed by the interaction with its companion, NGC 2993.

We report the discovery of two new field variable stars based on CCD observations carried out between October and December, 2000. Using multicolour photometry we could classify these stars as W UMa type variables, and we could determine accurate period for each of them.

Standard cosmology predicts that dwarfs were the first galaxies to be formed in the universe and that many of them merge afterward to form bigger galaxies such as the Milky Way. This process would have left behind traces such as tidal debris or star streams in the outer halo. We report here the detection of a very low density stellar system at 50+/