All the observations were made at the Harlan J. Smith 2.7-m telescope at McDonald Observatory, using the 2dcoude echelle spectrometer (Tull et al., 1995PASP..107..251T) with a 2048x2048 pixel Tektronix charge-coupled device (CCD) as detector. (3 data files).

We have obtained series of images in the near infrared J and Ks bands for seven L-type dwarfs with a duration of 3 to 6 hours. We present results on: 1) the amplitude of variability associated with atmospheric changes over time scales from minutes to several hours; 2) the search for cool companions in wide orbits; 3) the search for transits of

In this paper we present the Johnson-Cousins UBVR CCD photometry of the stars in King 2, an old open cluster towards the galactic anticenter. We have obtained the colour-magnitude diagram, the colour excess, the reddening, an estimate of the metallicity, and the distance modulus. The comparison of the observational colour-magnitude diagram with the

The σ Orionis cluster (˜3 Myr, 350 pc) is an ideal site to investigate the early evolution of substellar (brown dwarf and planetary mass) objects. To date, the cluster photometric and spectroscopic sequence of free-floaters is known for a wide mass range from 1M&sun; down to roughly 3MJup. The substellar domain covers spectral types that go from

We present new deep color-magnitude diagrams at different galactocentric distances of the Local Group dwarf spheroidal galaxy Fornax, and preliminary results on metallicities of individual stars, obtained from Ca II triplet spectroscopy. These data will be used to reliably derive the star formation and chemical enrichment histories of this galaxy

VLT/FORS spectroscopy and 2MASS near-infrared photometry, together with previously known data, have been used to establish the membership and the properties of a sample of low-mass candidate members of the sigma Orionis cluster with masses spanning from 1 Msun down to about 0.013 Msun (i.e., deuterium-burning mass limit). We have observed K-band