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

The idea of finding extrasolar planets (ESPs) through observations of drops in stellar brightness due to transiting objects has been around for decades. It has only been in the last ten years, however, that any serious attempts to find ESPs became practical. The discovery of a transiting planet around the star HD 209458 (Charbonneau et al. cite

We present new photometric data for seven high-amplitude delta Scuti stars. The observations were acquired between 1996 and 2002, mostly in the Johnson photometric system. For one star (GW UMa), our observations are the first since the discovery of its pulsational nature from the Hipparcos data. The primary goal of this project was to update our