We present Doppler Images of the RS CVn binary system HR 1099 (V711 Tau) from spectra taken in two different sites, KPNO and MSO, during the MUSICOS 1998 campaign. Contemporaneous APT photometry is used to constrain the Doppler Images. The resulting maximum entropy reconstructions based on the least-squares deconvolved profiles, derived from ~ 2000

The theoretical understanding of the linear standing or propagating magnetohydrodynamic waves in a variety of solar coronal structures is far from complete since analytical solutions to the linearised MHD equations can only be found for very simple magnetic configurations. In this paper, we use a numerical code to solve the linear fast and Alfvén

We have cross-correlated 2MASS and DENIS point sources in 17 galactic fields in order to find systematic astrometric or photometric shifts between the surveys. No significant differences have been found between the data of the two filters in common (J and K_s). This allows to combine data from the two surveys for a further analysis of galactic

In the chaotic quantization approach one replaces the Gaussian white noise of the Parisi-Wu approach of stochastic quantization by a deterministic chaotic process on a very small scale. We consider suitable coupled chaotic noise processes as generated by Tchebyscheff maps, and show that the vacuum energy of these models is minimized for coupling

We have conducted a detailed study of the object NGC 2451, which actually consists of two different open clusters A and B along the same line of sight at 206 pc and 370 pc distance, respectively. Although belonging to the nearest clusters, they have not been much investigated until present due to strong contamination by field stars. ROSAT X-ray

Near-infrared images are useful for analyzing the stellar backbone of disk galaxies, and in particular can be used to derive gravitational potentials (Quillen, Frogel, and Gonzalez 1994, ApJ, 437, 162). We have shown (Buta and Block 2001, ApJ, 550, 243) that from such potentials, the maximum value of the ratio of the tangential force to the mean