A new semi-empirical method to derive the absolute flux calibration in the near infrared (J,K,L and L' bands) is proposed. The method consists of the application of the InfraRed Flux Method (IRFM) to a selected sample of stars with accurate direst measurements of their angular diameters. The absolute fluxes in each band are obtained minimizing the

As part of a continuing study of the lithium abundances in pre-main sequence (PMS) low mass stars, we present Li observations for 13 K-type and 3 M-type stars belonging to the Pleiades and alpha Persei open clusters, respectively. We have supplemented our measurements with previous data taken from the literature and derived abundances in LTE and

Lines with no linear polarization induced by Zeeman effect are unaffected by instrumental polarization. We compile 86 such electric dipole lines with differing temperature and magnetic field sensitivities. In addition, we list 420 spectral lines which produce negligible linear polarization. In most cases, this second set can also be regarded as

The back-reaction of an incompressible two-dimensional flow of constant strain to the accelerated motion of a straight cylinder is calculated in the general case that the flow is inhomogeneous, nonstationary, and with nonvanishing (although constant) vorticity. The resulting enhanced inertia of the cylinder is basically given by its relative

We present in this work the results of a five-month monitoring campaign of the active galactic nucleus in NGC 3227. Both the Balmer H-beta and H-alpha emission lines, as well as the optical continuum have been analyzed. A deblending procedure has been applied which allows for the separation of the contributions to the line emssion from the narrow

We report high-resolution spectroscopic observations for a sample of 38 T Tauri stars (TTS), complemented by UBVRI photometry of 13 TTS, and CCD VRI photometry for 2 visual binaries. Based on these observations and data taken from the literature, we derive lithium abundances in 53 TTS, concentrating on weak-line TTS (WTTS). The sample spans the