The joint consideration of theoretical and observational arguments is used to conclude that two different spot populations co-exist in the Sun.

The discrete structure in the 5 min velocity oscillations of the solar surface has been confirmed by a re-analysis of data obtained between 1976 and 1979, and in addition a preliminary analysis of 1980 data show excellent consistency of the determined frequencies over the five year period. It is further shown that atmospheric transparency, as

Evidence for the rapid internal rotation of the sun obtained from Doppler shift measurements of the Fraunhofer absorption lines is reported. An improved version of the Doppler shift optical resonance spectrometer was used to record the resonantly scattered intensities corresponding to the two wings of the 769.9-nm Fraunhofer absorption lines of

An attempt is made to confirm the observation of Allen (1980) of a 3.3-micron emission feature attributed to thermal dust emission in the quasar 3C 273. Spectrophotometric observations of 3C 273 were obtained on May 18, 19 and 24 with the 1.5-m telescope of the Mount Lemmon Observatory. No evidence is found for the 3.3-micron feature in excess of 7

Maps in the CO (J = 2-1) line of the southern H II region complexes Carina Nebula and G333.6-0.2/RCW 106 are presented and discussed. Results for the Carina Nebula indicate a complicated spatial structure; an extended molecular cloud appears to be wrapped partly around the brightest parts of the H II region (Car I and Car II). The situation in

Mg II resonance lines at 2800 A were studied in the spectra of F and G main sequence stars, observed with the IUE satellite in high resolution mode. Correlation with other chromospheric indicators were investigated and a search was conducted for the best candidates to continue further studies of differential rotation. An attempt has been made to