[en] Tables are presented that facilitate the derivation of column densities for interstellar atoms using Stroemgrens's doublet-ratio method for s-p transitions. Two approximations that are normally made are examined and shown each to affect the results only by a few per cent. (author)

[en] Radial velocities derived from 70 spectrograms of the binary system β Arietis are presented. The resultant orbit of high eccentricity (e = 0.89) is in excellent agreement with previous studies. The short-period (≅ 0.05 day) variations in radial velocity reported by previous authors and attributed by them to pulsational instability are not confirmed by these data. (author)

[en] It has been suggested that the low-red shift quasar 1928 + 738 be utilized in the establishment of an extragalactic reference frame. We have observed the quasar in blue light during an interval of 137 days and found it essentially constant, varying by no more than about I 0.15 magnitude from its average value. Slowly varying long-term changes are not ruled out and others are encouraged to monitor this source in the future. (author)

[en] This, the 1985 Halley lecture in Oxford, reviews the current status of the interpretation of cosmological evolution, from the origin of the big bang to the present epoch. The work covers mainly cosmology in general, relativity theory, the relict radiation, and the evolution and distribution of galaxies and their clustering. Many other topics are also discussed, including present knowledge of the background continuum radiation throughout the observable regions of the electromagnetic spectrum, from radio through to γ-rays. The lecture also ranges over associated problems in cosmology, such as missing mass, neutrinos, intergalactic plasmas, magnetic fields and quasars. (U.K.)

[en] Synthetic spectra based on LTE model atmospheres have been used to calculate the expected equivalent widths of the Ca II K and Na I D₂ lines as a function of effective temperature for the B stars. Calculations have also been performed for lines of S II(λ3933.29) and C II (λ5889.78), which occur in the same spectral regions as Ca K and NaD₂. The results will be of interest to those wishing to estimate the importance of stellar lines in studies of interstellar Ca II and Na I. (author)

[en] The small group of hydrogen-deficient carbon-rich variables known as R Coronae Borealis (RCB) stars contains about 40 stars, some of which have been classified RCB on rather flimsy evidence. Earlier notes in this series have shown V₅₀₄ Cen, previously classified RCB:, to be a cataclysmic variable and AE Cir, classified RCB, to be a symbiotic star. In the present paper, spectroscopy of V618 Sgr and MT Pup is reported; the former appears to be a symbiotic star, the latter a cataclysmic variable. (author)

[en] Consideration is given to observational relationships in inflationary universes, and in a universe dominated by relativistic particles at recent times, in which the cosmological constant vanishes. In this context, the predicted redshifts of observed minimum angular diameters are also reconsidered; it is pointed out that these are independent of the Hubble constant. (author)

[en] Optical photometry for a sample of red giants in the open cluster NGC3532 is presented. The Fe + CNO-sensitive Δ(M-T₁) and CN-contaminated Δ(C-M) abundance indices yield results in excellent agreement ([Fe/H] ≅ 0.1). No CN strength variations are detected among the cluster giants. We conclude that NGC3532, with a nearly solar metal content, lies on the metal-rich side of the distribution of intermediate-age open clusters. (author)

[en] A useful approximate formula is derived which relates non-linear density and velocity perturbations in an expanding Universe. The formula can be used even when the time since the Big Bang and the value of the Hubble constant are unknown. This simple '-2/3 formula' holds for expanding systems but with a minor modification it extends to cover systems in collapse. (author)

[en] The purpose of this paper is to present observations made of interstellar CaII, CH, and CH⁺ towards the southern fifth magnitude early-type star HD 110432. As seen on the sky, this star (l = 302⁰ · O, b = -O⁰ · 2, V = 5^m · 4) lies within the Southern Coalsack. However, it is probably considerably more distant than the dark clouds which comprise the Coalsack, a situation which lends some interest to its interstellar spectrum. (author)