Time series of white-light pictures of the sunspot NOAA 7522, obtained at the Swedish Vacuum Solar Telescope (La Palma), were analyzed to study the proper motion of bright features in sunspots. For the first time, its relation with the dark nuclei present in the umbra is investigated. The bright features are visible in the penumbra as bright grains

LA TESIS PRESENTA UN ESTUDIO OBSERVACIONAL DE LOS PROCESOS DE FORMACION ESTELAR A GRAN ESCALA Y SU RELACION CON LAS ONDAS DE DENSIDAD PRESENTES EN LAS GALAXIAS BIEN DISEÑADAS DE TIPO INTERMEDIO. SE HA DEMOSTRADO, CON UN ALTO GRADO DE FIABILIDAD, QUE LA INTENSIDAD DE LA ONDA Y LA INTENSIDAD DE FORMACION ESTELAR MEDIDAS A LO LARGO DE LOS BRAZOS NO

We present the results of a new multi-site campaign (COYOTES II) to monitor the light variations of T Tauri stars (TTS) of the Taurus-Auriga dark cloud. The UBVRI light curves of 19 TTS were obtained over a two months period to search for rotational modulation by spots. We report new period detections for IQ Tau (6.25d), LkCa-3 (7.2d), and LkCa-14

We have studied a sample of selected eclipsing binaries with eccentric orbits and accurate absolute dimensions in order to analyse the validity of available theories of tidal evolution concerning synchronization and circularization time scales. In the present investigation we pay special attention to stars with radiative envelopes though some stars

The stellar content of the Im galaxy NGC 2366 is discussed on the basis of CCD BVR photometry. The three brightest blue and red stars have been used to estimate its distance, obtaining a value of 2.9 Mpc. The spatial distribution of the young stellar population is discussed in the light of the integrated color indices and the color-magnitude

The silicon detectors used in the H1-PLUG calorimeter have shown increasing aging effects during the '94 run period of the electron proton storage ring HERA. These effects were particularly manifest as degradation of the signal to noise level and the calibration stability. The reasons for this behaviour have been found to be correlated with