The warm star sample (7000 Teff 10,000 K) in SDSS is comprised of field horizontal branch (FHB) stars and a large number of blue straggler (BS) stars. Because these stars have a higher intrinsic luminosity than their cooler, turnoff and main-sequence counterparts, they are an ideal sample for probing both the global properties of the thick disk

We present a long-term project to study the characteristics and evolution of current star-forming galaxies at different redshifts. Our results support the idea that the higher Star Formation Density measured at redshift z=0.24 is due to an increase of the density of bursting galaxies and not to an intrinsic change on overall galaxy properties.

We present results of an optical and near-infrared (IR) 1.8 deg2 survey in the Pleiades open cluster to search for substellar objects. From optical I-band images from the CFHT and J-band images from the 3.5 m CAHA Telescope, we identify 18 faint and very red L brown dwarf candidates, with I> 20.9 and I-J> 3.2. The follow-up observations of nine

The origin and sources of rejuvenated volcanism in Hawaii has been long debated with the depleted isotopic features commonly attributed to assimilation of the 110 Ma-old Pacific oceanic lithosphere underlying Hawaii. Alternatively, it has been recently suggested that this depleted component is a long-lived feature intrinsic to the Hawaiian plume [1

We report recent observational results of some ULXs collected with the 8.2m Subaru and with the ESO VLT telescopes. These observations have provided important information on the (inter-) stellar environments and have allowed to detect the optical counterparts of several ULXs. In two cases spectroscopic observations show stellar HeIIλ4686 optical

We present high-resolution spectral observations, covering the entire optical region (3800-9000 Å), of a solar flare observed during a multi-wavelength campaign. The flare, recorded on 2002 January 11, was a medium solar flare event (GOES class C7.5). The spectral observations were carried out using the Hamilton echelle spectrograph on the coudé