Observations of interstellar absorptions superposed on the chromospheric Mg II emissions of nearby cool stars have been used to explore the structure of the local interstellar medium along many lines of sight. The interstellar cloud in which the sun is immersed (the 'local cloud', hereafter LC) has not previously been detected using this technique

The photometric distortion waves in the light curves of the short-period RS CVn system BH Vir by a dark, circular spot model for the active regions on the primary star is parameterized. Recent observations and archival sources are used to infer the positions and areas of the active regions. For light curves with simultaneous B and R or V and I data

From H-alpha CCD observations taken with the 4.2-m William Herschel Telescope, a catalog of 456 H II regions of the inner zone of the spiral galaxy NGC 4321 has been compiled. The radial distribution, the distribution of diameters, and the luminosity function for the arm and the interarm H II regions are presented, together with the spatial

Results are presented on an analysis of rapid photometric data of the F2 V star HD 155543, obtained simultaneously from the Observatorio del Teide (Spain) and the Observatorio de San Pedro Martir (Mexico) during May-June, 1987. Strong evidence was found of the presence in this star of acoustic p-mode spectrum; when performing a squared amplitude of

The expected mass loss rates from horizontal branch (HB) and red giant branch models are investigated. The expected dependence of those rates on luminosity, metallicity, helium content, giant mass, and HB morphology is discussed. For an HB distribution depending on metallicity, the values found for the fitting factors in the Reimers

The BBKS (Bardeen, Bond, Kaiser and Szalay) expression for the number density of maxima above a threshold in a random Gaussian field (RGF) is used to develop a mathematical technique that would allow the computation of the probability density of filamentary structures arising at random in such a field. A description is given of a procedure for the