We report an increase of more than 0.2 mag in the optical brightness of the leading image (A) of the gravitational lens Q0957+561, detected during the 2000 September to 2001 June monitoring campaign (2001 observing season). The brightening is similar to or even greater than the largest change ever detected during the 20 yr of monitoring of this

Using photometric and redshift data for the Virgo and Coma Clusters, we present evidence for a correlation between the light concentration of elliptical galaxies (including dwarf ellipticals) and the local three-dimensional (i.e., nonprojected) density of the clusters: more concentrated ellipticals are located in denser regions. The null hypothesis

A bright X-ray transient was detected by Chandra on 2002 June 2 with a series of 5 HRC-I snapshots. The new source CXOU J004154.6+405648 (R.A.=00h41m54s.64, Dec.=+40d56m48s.0, +/- 1", J2000) is discovered at a luminosity (0.3-10 keV) of 1.5 x 1038 erg/s (assuming an absorbed power-law model with photon index = 2 and NH = 1021 cm-2 at a distance of

We undertook a study of the star formation and chemical enrichment history of the Fornax dSph galaxy. We used the VLT with FORS1 to obtain photometry reaching the oldest main-sequence turnoffs and Ca II triplet spectroscopy of a sample of red giant branch stars in the same fields. The observations and the main results are described.

The kinematics and physical conditions of the bipolar planetary nebula M 2-48 are analysed from high and low dispersion long-slit spectra. Previous CCD narrow-band optical observations have suggested that this nebula is mainly formed by a pair of symmetric bow-shocks, an off-center semi-circular shell, and an internal bipolar structure. The bipolar

The heat flow and temperature structure within and surrounding a magnetic flux tube stored in mechanical equilibrium in a stellar convection zone are considered. The stationary thermal equilibrium state is determined through the analytical solution of a two-dimensional heat diffusion problem for an infinitely long cylinder with different thermal