We have monitored spectroscopically the classical T Tauri star UZ Tau East. Most observations were obtained with the Intermediate Dispersion Spectrograph at the Isaac Newton Telescope in La Palma Observatory. Several additional spectra were obtained with other telescopes at La Palma, ESO and Lick observatories. Radial velocities were measured via

This paper presents first complete uvby light curves of the late-type detached eclipsing binary ZZ UMa (G0V + G8V, P=2.2993d). This binary system has been observed during eight campaigns at the Calar Alto Observatory (Almeria, Spain) and at the Sierra Nevada Observatory (Granada, Spain). 294 points distributed over the binary period and covering

This paper presents new complete uvby light curves of the late-type detached eclipsing binary BH Vir (G0V + G5V, P=0.81687099d). This binary system has been observed during four campaigns at the Calar Alto Observatory (Almeria, Spain) and at the European Southern Observatory (La Silla, Chile). This observations are part of a 6 year uvby and H{beta}

(Hα+[NII])/[OIII] ratio images have been used to search for low-ionization small-scale structures in a sample of 258 planetary nebulae. Radially symmetrical knots or jet-like structures, which are enhanced in the ratio images compared to the neighbouring regions of the nebulae, have been identified in 23 objects. Some of these features are barely

Not Available

We present three-dimensional numerical calculations of superbubbles evolving in a two-component interstellar medium composed of small diffuse clouds and a low-density intercloud medium. Cold H I clouds with internal densities n ˜ 10 cm-3 and radii Rcl = 3-5 pc were assumed to be embedded in a warm plane-stratified intercloud medium. The fraction of