In a recent Letter, we showed the remarkable result that the atomic alignment of the levels P1/2 and S1/2 of the D1 line of Na I is practically destroyed in the presence of magnetic fields sensibly larger than 10 G, irrespective of the field direction. In this paper, we analytically demonstrate that this property is a consequence of the decoupling

We present here preliminary results of our wide-field study of NGC 3109: a low luminosity galaxy in the outskirts of the Local Group. Its edge-on orientation (which simplifies the study of a possible halo) and the possibility that it could, in fact, be a small spiral (the smallest in the Local Group) makes its deep analysis of major relevance to

Faint meteors observed with Super-Schmidt cameras are re-examined in order to assess whether their dynamical and photometric behavior can be described by means of the single body theory. Velocities, decelerations and magnitudes are fitted simultaneously to synthetic curves resulting from integration of the appropriate set of differential equations

We show evidences that gas outflows occur in starburst galaxies as superbubbles evolve. We then question whether hot gas will be expelled and enrich the IGM with metals or be retained within the host galaxy. For this purpose we construct three extreme scenarios of the star formation histories for a sample of dwarf galaxies using either their

Optical CCD spectra are used to determine the element{Fe} abundances at several positions inside seven bright Galactic H Ii regions. The observed [Fe Iii] line ratios are compared with the predictions of different sets of collision strengths and transition probabilities for this ion to select the atomic data providing the best fit to the

Accurate determination of the rotation rate in the inner radiative zone (0.2