We present new optical observations of the nearby barred spiral galaxy Dwingeloo 1 (Dw1) obtained with the Isaac Newton, William Herschel and Wise telescopes. Dw1 lies at Galactic coordinates (l=138.˚52, b=-0.˚11) and it is heavily obscured by dust and gas in the Milky Way. We infer that Dw1 is of morphological type SBb or SBc (T=4), has an

We present mid-resolution spectroscopic observations of 63 faint (V=12-16) stars identified by Kun (1992) as Hα emission candidates in an objective prism survey of several high galactic latitude molecular clouds. Only 4 stars in our sample (6%) are bona fide T Tauri stars on the basis of their strong Li I absorption and Hα emission features. They

The differences between observed solar p-mode frequencies and the frequencies of a reference model can be inverted to infer the structure of the Sun using a variety of linear inversion techniques. However, it is well known that the adiabatic description, which is often employed in frequency calculations, breaks down in the outermost layers of the

We present a new method based on artificial neural networks techniques aimed at determining the fraction of binary systems populating star clusters. We address the problem from a statistical point of view, avoiding the important biases induced by individual binary identification. The idea is to evaluate the percentage of binaries by comparing the

According to unified schemes for blazars, BL Lac objects are dominated by relativistic jets pointing along the line of sight. Their plane-of-the-sky counterparts are likely to be low-luminosity radio galaxies, which are generally luminous ellipticals that lie preferentially in clusters of galaxies. As part of a test of unification, and in order to

We analyze time sequences of photospheric spectral lines in the penumbra of two sunspots. Two spectral lines sensitive to velocity fluctuations at two different heights in the atmosphere (Ti I 8396.9A and Fe II 7224.5A) are used. The observations were taken using the Gregory-Coude Telescope (GCT) at the Observatorio del Teide (Tenerife). Velocity