Long duration gamma ray bursts (GRB's) have been identified as originating in type II SNa explosions, produced during the late stage evolution of massive stars. As the lifetimes of their progenitors are so short the GRB rate per unit (comoving) volume of space, on scales which include significant numbers of galaxies, could be proportional to the

We analyze central surface brightness, nuclear and global colors of intermediate redshift disk galaxies in WFPC2/HST Groth strip and ACS/HST GOODS-N. The aim is to obtain empirical information of relative ages of bulges and disks and to study the relation among surface densities and star formation history of galaxies at 0. 1 z 1. 3. We find that

We present the first results in our study of the bremsstrahlung emission of photons accompanying the spontaneous fission of the 252Cf nucleus. We compare calculations obtained on the basis of our fully quantum model with the experimental data available in literature for photon energies up to about 25 MeV. We find a well agreement between theory and

We present the first census of blue massive stars in NGC 55, a galaxy of the Sculptor group at 1.94 Mpc. This study is based on optical low-resolution spectra of approximately 200 objects taken with VLT-FORS2. We have performed the spectral classification of these objects. The estimated stellar radial velocities show general agreement with the

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We present the analysis of data performed in order to identify the events of the γ + n → π- + p reaction obtained by bombarding a liquid Deuterium target with a polarised γ beam of 0.55-1.5 GeV at the Graal-experiment. We show the effect of different kinematic and hardware constraints used to reduce the contamination coming from the concurrent