The surface gravity of Arcturus is estimated from the strength of the MgH features (the Mg abundance being derived from MgI lines), from strong metal lines and from the FeI/FeII ionization equilibrium. The MgH lines give log g = 1.7 (cgs units) and 4375 K for the effective temperature. This value of log g is consistent with the gravity derived from the sample of strong pressure-broadened lines from FeI, CaI and NaI which gives log g = 1.6, and what we obtain from the ionization equilibrium of Fe, log g = 1.4. The corresponding estimates of the maximum error are 0.3, 0.2 and 0.5 dex, respectively. The mass of Arcturus is found to be in the interval 0.6–1.0 solar masses. It is concluded that the MgH features offer good possibilities for determining gravities of late-type stars, when good estimates of effective temperatures are available.

Effective temperatures have been determined for G and K stars by comparing synthetic colors computed from model atmospheres to observed colors measured at near-infrared continuum points. Results are presented for giant stars in the range K0 III - K4 III.

An extensive project for the investigation of abundances, especially of light elements, in F-type stars is described and some preliminary results are given.

Sd0 stars have particular importance in astrophysics due to their position in the HR diagram between the hot horizontal-branch stars and the precursors of the white dwarfs. A careful determination of their parameters is therefore highly desirable.

Radial velocities of bright IAU standards have been obtained photographically over the past decade using the long camera of the DAO 1.2 meter telescope's coudé spectrograph. Most of the stars observed have been found to be constant in velocity to better than 0.15 km/s over that interval. The mean velocities agree with the IAU velocities, on the average, within 0.10 km/s, although mean velocities of some individual stars differ considerably more than this from the IAU value. A preliminary determination of the zero point of the long camera system, and hence of the IAU system, has been made from observations of the asteroid Vesta, whose actual radial velocity has been calculated from its orbital elements.

By imposing absorption lines of HF in stellar spectra we can measure changes in r.v. with a precision of ~10m/s from a single spectrum, provided stellar line profiles are not distorted by atmospheric motions. The precision of absolute radial velocities is currently limited to ~100m/s by knowledge of rest wavelengths. Representative results are presented from our three, active PRV programs: velocity variations of δ Scuti stars; a search for unseen companions to late-type stars; and routine observations of certain IAU velocity ‘standards’.

From the list of observed and derived parameters of 330 pulsars published by Manchester and Taylor (1981), we have selected sixteen “standard” pulsars whose position and radio luminosity fit well a statistical relation found by Antonello and Fracassini (1984). This relation shows also that these pulsars may be considered as probes of the galactic places where the observed 408 MHz continuum background temperature, T408, and the computed electron densities, ne, of the interstellar medium, ISM, are best correlated.

In the study of the changes induced by the Compton effect and Thomson scattering on the shape of spectral lines in light traversing a chromosphere or a planetary nebula it is necessary to have accurate wavelength measurements, central intensities and half widths (FWHM) of the lines. In the comparison of FWHM measures belonging to different spectra it is useful to have the intensities of the continuum at the wavelengths of the lines. The studied spectra should have a dispersion higher than 10 Å/mm and a spectral range larger than 700 Å. A short recommendation is also given about the comparison spectrum and the calibration plate.

Trigonometric parallaxes are reported for ten bright, southern late-type MK giant stars. The plate material was obtained with the 66 cm Yale-Columbia refractor at the Mt. Stromlo Observatory and measured with the PDS 1010A at Mt. Stromlo. The ten stars include HR 794 (KO III), HR 1247 (M2 IIIab), HR 2245 (M2.5 III), HR 2773 (K3 Ib), HR 3518 (K3 III), HR 3803 (K5 III), HR 5287 (K2 III-IIIb), HR 5603 (M3 IIIa), HR 6832 (M3.5 III), and HR 6913 (K1 IIIb). The modern parallaxes are compared with earlier results and the luminosity calibration for these stars is discussed.

NGC 40 is an extended, very inhomogeneous planetary nebula, with a WC8 central star. Very discrepant determinations exist in the literature for the extinction towards this object and the temperature of its nucleus. We review here the various methods which can be used to derive these quantities, discussing the assumptions underlying each method and their inherent limitatons, and the uncertainties that arise when they are applied to this particular object. The results are compared to the values which we derive from far UV spectrophotometry: E(B-V) = 0.50 and T* ≍ 90000K.