The influence of the upper layers of a star on p-mode frequencies can be described asymptotically by means of a phase function, which depends essentially only on the frequency of the mode. The extent to which the phase function may provide information about the superficial layers of a star is investigated. In particular, a linear relation between

Spectroscopy and mapping of the type I postmain-sequence source CRL 618, taken with the 45-m antenna of the Nobeyama Radio Observatory and the 12-m NRAO facility at Kitty Peak, are presented. It is shown that the exterior constant velocity envelope has a typical aspect ratio of about 0.8, extends over a range not less than 70 arcsec, and has an

Long-slit spectroscopy of the extended gas in the Seyfert galaxy NGC 3516 reveals considerable substructure in the narrow emission lines with several kinematically distinct components visible in H-alpha and N II lambda 6583. The velocity measurements cover almost all of the 3 kpc scale, Z-shaped emission-line structure seen in narrow-band images

Profiles of the Na I D doublet in three bright features (clusters of umbral dots), located in a relatively dark umbra, were analyzed by means of the 'local two-component modeling' to obtain the 'true' continuum intensities and temperatures of the bright features and their dark surroundings (background). The intensities of two central and one

Results are presented from simultaneous UBVRI photopolarimetric observations of eight blazars at the 2.56-m Nordic Optical Telescope during winter 1991. In 3C 66A the highest ever measured polarization, P(U) = 30.5 percent is observed, with small frequency dependence (FDP), P being lower toward longer wavelengths. In AO 0235 + 164, large changes in

Results of an investigation of 23 planetary nebulae whose post-AGB central stars have been previously analyzed using direct spectroscopic non-LTE methods are presented. A comparison of spectroscopic effective temperatures with Zanstra and Stoy temperatures shows that most PN in the present sample are optically thin in the H-Ly continuum. A good