Ground-based observations of the sunspot irradiance deficit Ψ and the excess by facular regions in the period 1989 June 3-15 are analyzed using photometric techniques. The results are compared with solar irradiance measurements taken by the Nimbus 7 satellite. The photographic sunspot data were obtained at the Vakuum Newton Teleskop, Observatorio

We present new J=1->0 ^12^CO observations along the northern spiral arm of the grand-design spiral galaxy M 100 (NGC 4321), and study the distribution of molecular hydrogen as derived from these observations, comparing the new data with a set of data points on the southern arm published previously. We compare these measurements on both spiral arms

JHK imaging photometry is reported of an area of approximately 2'x3' centred on the far infrared source NGC 6334 I with limiting magnitudes J=18.3, H=17.8 and K=16.2. More than 224 sources were detected in K-band, increasing by a factor of more than seven the number of objects found in previous near-IR surveys. Most of the sources are located in an

It is shown here that the ejecta from type II supernovae follow a long excursion into the galactic environment before they mix with the ISM. We point to the various changes in temperature, density, and pressure experienced by the ejecta along their inevitable ride, indicating the main hydrodynamical events and physical processes taking part in

We present high-resolution He I 4471, Mg II 4481 and Hγ line profiles of the Be star 31 Peg obtained simultaneously at four observing dates. In this paper we focus on the He I 4471 line and on the absorption wings of the Hγ line which showed important variations. Models of static stellar atmospheres were calculated to determine the photospheric

We present observations of the evolution of a prominent spiral jet in the inner coma of comet Hale-Bopp (1995 O1). The observations, taken with the 82 cm IAC-80 telescope at the Teide Observatory, were made on 1995 August 25, 27, 28, and 31, and on September 4--7, as part of an ongoing program of monitoring the comet in Tenerife. The jet is