We present Na, Mg and Al abundances in a set of 98 stars with known giant planets, and in a comparison sample of 41 "single" stars. The results show that the [X/H] abundances (with X = Na, Mg and Al) are, on average, higher in stars with giant planets, a result similar to the one found for iron. However, we did not find any strong difference in the

We present medium-resolution optical spectra of the secondary star in the high Galactic latitude black hole X-ray binary XTE J1118+480 and determine the abundance of Mg, Al, Ca, Fe, and Ni in its atmosphere. For all the elements investigated, we find supersolar abundances; thus, we reject the hypothesis that the black hole came from the direct

Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LS I +61 303. Six orbital cycles were recorded. Several

We have expressed in linearized form the five classical coupled equations representing the rotating gas disk of a standard disk galaxy. We solve them in three limiting cases for the gas disk: (1) infinite thickness and uniform rotation, (2) finite thickness and uniform rotation, and (3) infinite thickness and a shearing box approximating

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In order to characterize the low surface brightness component in blue compact dwarf galaxies, we determine their structural parameters for eight objects by fitting a Sérsic law to the starburst-free regions of their deep B, V and R images using a two-dimensional fitting technique. We exclude the starburst emission by using color maps and Hα images