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

In this work we present a multiwavelength study of narrow-line Seyfert 1 galaxies (NLS1s) discovered in the Second Byurakan Survey (SBS). The sample consists of 26 objects, which have MB>=-23.0, or -19.9>MB>-23.0, 0.0243 1). The traditional linear correlation LX and Lop, which seems to hold for active galactic nuclei in general, is found for SBS

High spatial resolution visible and NIR observations of the bar of NGC 5850, a prototype of double barred spirals, together with visible intermediate and high dispersion spectra along the primary bar, are being used, with the aid of simple stellar population synthesis models, to investigate the mean age and metallicity of the different stellar

We present optical and near IR follow up observations of the dark GRB 001109, 1-300 days after the event. No transient emission has been found for these wavelengths within this GRB's (Gamma Ray Burst) BeppoSAX 1' radius error box. Strong limits are set with K' > 20. A highly reddened galaxy, with variable radio emission, was found at z = 0.398. It