Our HST WFPC2 survey of 110 BL Lac objects, from six complete X-ray-, radio-, and optically-selected catalogs, probes the host galaxies of low-luminosity radio sources in the redshift range /0

Line intensities, visual extinction, abundances and ionization hardness parameter for HII regions in two spiral galaxies are presented. The following galaxies have been observed: NGC 5457 and NGC 4395. In NGC 5457 have been obtained data for 338 regions. In NGC 4395 have been obtained data for 158 regions. For each region position, visual

For decades, the grand-design SAB spiral galaxy NGC 5248 has been postulated to host a short bar of semimajor axis 22" (1.6 kpc). From dynamical and morphological arguments, however, we argue that its spiral structure is being driven by a large-scale bar whose corotation radius lies at ~115" (8.6 kpc). Our estimate is based partially on a deep R

Between Oct 1999 and Jun 2001 Chandra observed M31 on a nearly monthly schedule. These observations allowed the discovery of 14 X-ray transients, a few of which were followed up with HST in an attempt to find contemporaneous optical counterparts. The transient most luminous in X-rays shows a possible U ~23 counterpart in HST imaging. The ratio of

We present the first light curves in the infrared J and K filters of VV UMa and analyze them, together with a new set of BVR light curves obtained in different runs from 1997 to 2000. Based on the spectra of VV UMa and standard stars in the region 8440-8870 Å, we classify the primary component of the binary as a type A1.5-2 V star. Evidence of

We have derived beryllium abundances in a wide sample of stars hosting planets, with spectral types in the range F7V-K0V, aimed at studying in detail the effects of the presence of planets on the structure and evolution of the associated stars. Predictions from current models are compared with the derived abundances and suggestions are provided to