We review different surveys, in the optical and infrared, conducted in the very young (age 1 8 Myr), nearby (d ˜ 350 pc) σ Orionis cluster aimed to characterize the substellar population. We describe spectral characteristics of very low mass stars, brown dwarfs and planetary mass objects in the cluster with spectral types from K7 to T6. We study

We present the oxygen abundance determination for 90 H II regions in the inner parts of the grand design galaxy M 101. The abundances were derived employing the P method (Pilyugin cite{Pilyugin2001a}). A comparison is made with previous determinations using another calibration and direct measurements of electron temperature to derive the oxygen

We present fully sampled high angular resolution two-dimensional kinematics in the Hα spectral line, optical and near-infrared imaging, as well as 21 cm atomic hydrogen data of the spiral galaxy NGC 278. This is a small non-barred galaxy, which has a bright star forming inner region of about 2 kpc in diameter, reminiscent of nuclear rings seen

We present an analysis of high resolution Chandra spectra of late-type stars. Our sample includes giant stars from the Hetzsprung gap to the ''clump'' phase, active stars that have similar fundamental parameters but which have followed quite different evolutionary paths, and RS CVn binary systems. Using a new technique based on the ratios of

The magnetic activity in the atmosphere of the Sun, possibly of most other magnetically active late-type stars, is a consequence of the emergence of magnetic flux from the stellar interior. Research in this field has to consider the rise of magnetized plasma from the depths of the convective envelope through the stellar surface and out across the

We present the 2-D, two fluid (ions + neutrals) numerical simulations that we are carrying out in order to study the ambipolar filamentation process, in which a magnetized, partially ionized plasma is stirred by turbulence in the ambipolar frequency range. The higher turbulent velocity of the neutrals in the most ionized regions gives rise to a non