We present the results of a study comparing the stellar populations in the elliptical galaxies of Hickson compact groups (HCGs) with those in low-density environments. We analyze a sample of intermediate-resolution (4.25 Å FWHM) spectra of 22 galaxies in HCGs and 12 in the field or in loose groups. Three different population-synthesis models and

We present a detailed study of the spectral and temporal properties of the X-ray and optical emission of GRB050713a up to 0.5 day after the main Gamma Ray Burst (GRB) event. The X-ray light curve exhibits large amplitude variations with several rebrightenings superposed on the underlying three-segment broken power-law that is often seen in Swift

Aims:We study the structure and reveal the physical nature of the reversed granulation pattern in the solar photosphere by means of 3-dimensional radiative hydrodynamics simulations. Methods: We used the MURaM code to obtain a realistic model of the near-surface layers of the convection zone and the photosphere. Results: The pattern of horizontal

Context: The study of asteroids that present sporadic cometary activity is of fundamental importance to address several astronomical problems including the end states of comet nuclei, the abundance of water in main belt asteroids, and its role as a possible source of terrestial water. Aims: We studied the composition of the surface of asteroid

Recent Galactic Legacy Infrared Mid-Plane Survey Extraordinaire data have further confirmed the hypothesis of the existence of an in-plane long bar different from the bulge of the Milky Way with the same characteristics as emphasized some years ago by our team. In this paper we present two new analyses that corroborate recent and earlier claims

Accurate estimates of spectral parameters are essential to investigate the physical conditions in active galactic nuclei (AGNs). In particular, intrinsic reddening can be estimated from the Hα/Hβ ratio of the narrow-line components. The mass of the central black hole can be obtained from the stellar velocity dispersion in the bulge, which can be