In order to fully understand the gravitational collapse of molecular clouds, the star formation process, and the evolution of circumstellar disks, these phenomena must be studied in different Galactic environments with a range of stellar contents and positions in the Galaxy. The young massive association Cygnus OB2, in the Cygnus-X region, is a

Observations of the gravitational lens system 0957+561A, B in the R band are presented in this Letter. The observations, taken with the 82 cm IAC-80 telescope, at Teide Observatory, Spain, were made from the beginning of 1996 February to June, as part of an on-going lens monitoring program to obtain the time delay between the two components of the

The linear optical polarimetry was obtained during several observing runs at the CASLEO in San Juan, Argentina, during 2003-2007. The Torino five-channel photopolarimeter was used on the 2.15-m telescope. All observations were obtained simultaneously through the five Johnson-Cousins broad-band UBVRI filters centred at λUeff=0.360um, λBeff=0.440um

We present a time-resolved spectrophotometric study of the optical variability in the quiescent soft X-ray transient A0620-00. Superimposed on the double-humped continuum light curve are the well-known flare events, which last tens of minutes. Some of the flare events that appear in the continuum light curve are also present in the emission-line

We present a detailed spectroscopic investigation, spanning four winters, of the asymptotic giant branch (AGB) star IRAS 02091+6333. Zijlstra & Weinberger (cite{ZW}) found a giant wall of dust around this star and modelled this unique phenomenon. However their work suffered from the quality of the optical investigations of the central object. Our

We have obtained low resolution optical spectra of 15 isolated planetary mass objects (IPMOs) in the sigma Orionis cluster, and derived spectral types by comparison with nearby M and L dwarfs. The spectral types are in the range late M - mid L, in agreement with our expectations based on colors and magnitudes for bona fide members. Therefore, most