An analysis has been carried out of the center-to-limb variation of the apparent sizes of the umbra, penumbra, and whole spot. It has revealed that the umbral size decreases with height. This result is interpreted in terms of the penumbral geometrical height scale. A value of 230 km, which is larger than that of the photosphere or the umbra

Over the past two decades, helioseismology has revolutionized our understanding of the interior structure and dynamics of the Sun. Asteroseismology will soon place this knowledge into a broader context by providing structural data for hundreds of Sun-like stars. Solar-like oscillations have already been detected from the ground in several stars

Context: The Galactic H ii region NGC 2579 has stayed undeservedly unexplored due to identification problems which persisted until recently. Both NGC 2579 and its companion ESO 370-9 have been misclassified as planetary or reflection nebula, confused with each other and with other objects. Due to its high surface brightness, high excitation

The authors present the results of a survey made at 1.65 μm (H) and 2.2 μm (K) in 15 small areas on the galactic equator between l = 0° and l = 10°. 775 distinct objects were counted in a total area of 0.17 deg2 to limiting magnitudes H = 10.5 and K = 9.5 (equivalent to detecting M giants at 6 - 7 kpc). Source confusion was the limiting factor in

We describe a Fourier-based method of separating bars from spirals in near-infrared images. The method takes advantage of the fact that a bar is typically a feature with a relatively fixed position angle and uses the simple assumption that the relative Fourier amplitudes due to the bar decline with radius past a maximum in the same or a similar

We present 53 simultaneous photometric (I band) and spectroscopic (6900-9500Å) observations of GRO J0422+32, taken during 1997 December. From these we determine that J0422+32 was in its lowest state yet observed, at I=20.44+/-0.08. Using relative spectrophotometry, we show that it is possible to correct very accurately for telluric absorption