This paper presents the results of a detailed theoretical investigation of the impact of non-LTE (NLTE) effects and of granulation inhomogeneities on the derived iron and oxygen abundances in the metal-poor halo subgiant HD 140283. Our analysis is based on both the ``classical'' one-dimensional stellar atmosphere models and on the new generation of

We study the two main corrections generally applied to narrow-band Hα fluxes from galaxies in order to convert them to star formation rates, namely for [NII] contamination and for extinction internal to the galaxy. From an imaging study using carefully chosen narrow-band filters, we find the [NII] and Hα emission to be differently distributed

Let $mathcal{K}$ be the space of properly embedded minimal tori in quotients of $R^3$ by two independent translations, with any fixed (even) number of parallel ends. After an appropriate normalization, we prove that $mathcal{K}$ is a 3-dimensional real analytic manifold that reduces to the finite coverings of the examples defined by Karcher, Meeks

From Hα images of a carefully selected sample of 57 relatively large, Northern spiral galaxies with low inclination, we study the distribution of the Hα emission in the circumnuclear and nuclear regions. At a resolution of around 100 parsec, we find that the nuclear Hα emission in the sample galaxies is often peaked, and significantly more often so

We have used archival survey data, most importantly from the SuperCOSMOS Sky Surveys, to derive accurate proper motions and thus confirm the membership of two previously announced isolated brown dwarfs in the nearby, ˜10 Myr old TW Hydrae Association (TWA), 2MASSW J1207334-393254 and 2MASSW 1139511-315921 (Gizis cite{gizis02}), and to discover a

We present an investigation of a single sunspot observed in the neutral Fe line at 1089.6 nm with the Tenerife Infrared Polarimeter at the Vacuum Tower Telescope on Tenerife. Using the SIR code, we obtain maps of the magnetic field strength, inclination and azimuth, and Doppler velocities. The magnetic field strength drops from 2800 G in the umbra