Thick disks are faint and extended stellar components found around several disk galaxies including our Milky Way. The Milky Way thick disk, the only one studied in detail, contains mostly old disk stars (≈10 Gyr), so that thick disks are likely to trace the early stages of disk evolution. Previous detections of thick disk stellar light in external

We present relations between thermal and magnetic quantities in a simple, isolated sunspot, as deduced from the inversion of 1.56 μm spectropolarimetric data. We used a combination of two infrared Fe I lines at 15 648.5 Å and 15 652.8 Å/ in the inversions. Due to the high Zeeman sensitivity of these lines, we can study this relationship in the

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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