Results of almost simultaneous observations of the differential rotation of the Ca(plus) chromosphere and the photospheric plasma are reported. The observations (tracings of Ca(plus) mottles and Doppler shift measurements in a photospheric line) were performed at the Locarno station during two extended periods in 1976. Both data sets were used to

We present first-season infrared (IR) and optical photometry and spectroscopy of the Type Ia Supernova 1998bu in M96. We also report optical polarimetry of this event. SN 1998bu is one of the closest type Ia supernovae of modern times, and the distance of its host galaxy is well determined. We find that SN 1998bu is both photometrically and

A new empirical calibration of the (B-V) index versus the three fundamental stellar parameters T(eff), (Fe/H), and log g is presented whose range of validity is adequate to analyze the main sequence and turnoff regions of most of the stellar cluster systems. Significant systematic differences are found between this new calibration and previous ones

We report results of a spectrophotometric study of SBS 1150+599A, and discus s the nature of this object basing on our data. Our study shows that SBS 1150+599A is most probably a planetary nebula located in the Galactic halo and not a cataclysmic variable as originally proposed by the authors of the Second Byurakan Survey from low resolution

In the previous papers of this series, we introduced the implicit integral method (IIM) to solve those radiative transfer (RT) problems in which the source function depends on an integral of the specific intensity of the radiation field over directions and frequencies. The IIM rests upon a forward-elimination, back-substitution scheme naturally

Aims: The aim of this work was to use a multi-approach technique to derive the most accurate values possible of the physical parameters of the δ Sct star HD 174966, which was observed with the CoRoT satellite. In addition, we searched for a periodic pattern in the frequency spectra with the goal of using it to determine the mean density of the star