In this letter, we report the discovery of the first young early L-dwarf in the Serpens cloud. It is obscured by more than ten magnitudes of visual absorption and was found during a near infrared (NIR) photometric survey of a 50 square arcmin area in the Serpens cloud, deep enough to probe the substellar domain. After selection from NIR colour

The evolution of the morphology of C/1999 S4 (LINEAR) is examined from a series of images taken from shortly before the disruption of the nucleus until 10 days afterwards. This is combined with light curve data to provide a unique documentation of the early evolution of the disruption event. Neither images from the 1-m Jacobus Kapteyn Telescope nor

We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase-resolved spectroscopy revealed narrow emission line components from the irradiated secondary star. Radial velocity fits to the Bowen blend emission are used to establish an absolute orbital ephemeris and derive an accurate value for the systemic

Globular cluster systems of 17 elliptical galaxies have been studied in the Coma Cluster of galaxies. Surface-brightness fluctuations have been used to determine total populations of globular clusters, and specific frequency (SN) has been evaluated for each individual galaxy. Enormous differences in SN between similar galaxies are found. In

ES BIEN SABIDO QUE LA TURBULENCIA ATMOSFÉRICA LIMITA LAS PRESTACIONES DE LOS GRANDES Y EXTRA-GRANDES TELESCOPIOS POR ELLO ES IMPRESCINDIBLE DESARROLLAR ESTRATEGIAS E INSTRUMENTOS QUE SOSLAYEN ESTA LIMITACIONES. LA SOLUCIÓN PASA POR GENERAR ESTRELLAS ARTIFICIALES POR LASER, YA SEA EN LAS CAPAS BAJAS POR SCATTERING RAYLEYGH O EN LA MESOPAUSA A PARTIR

We present ultrahigh-resolution spectra for a set of nearby F-G-K stars on, or close to, the main sequence. The wavelength shifts of stellar lines relative to their laboratory wavelengths are measured for more than a thousand Fe I lines per star, finding a clear correlation with line depth. The observed patterns are interpreted as convective