We have obtained projected rotation velocities (vrotsini) of a sample of 19 ultracool dwarfs with spectral types in the interval M6.5-T8 using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. Among our targets there are two young brown dwarfs, two likely field stars, and 15 likely brown dwarfs (30-72 MJup) in

We present seeing measurements from Mt. Holomon (Chalkidiki, Greece), a possible site for the establishment of a new University of Thessaloniki Observatory, using the Hartman - DIMM method. After two years of systematic observations we present the first robust results and give a first evaluation of the astronomical seeing characteristics, which are

We study the broadband polarization of hydrogen lines produced by scattering of radiation, in the presence of isotropic electric fields. In this paper, we focus on two distinct problems: (a) the possibility of detecting the presence of turbulent electric fields by polarimetric methods and (b) the influence of such fields on the polarization due to

We report the identification of RXJ0636 as a new intermediate polar. The system's light curves and spectral analysis, together with a variety of its physical parameters are presented. A brief description of the observations leading to the above mentioned identification is also given.

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We study the quiet Sun magnetic fields using spectropolarimetric observations of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648, and 15653 Å. Magnetic field strengths and filling factors are inferred by the simultaneous fit of the observed Stokes profiles under the MISMA hypothesis. The observations cover an intranetwork region at the