The double-mode or beat Cepheids continue to pose a number of interesting questions in our search for an understanding of the pulsation properties of stars near the short period end of the instability strip. One such is how simultaneous pulsations in the fundamental and first overtone radial modes can occur for an appreciable fraction of Cepheids in the period range 1d < Pо < 5d.

Charles Todd was the first Government Astronomer and Superintendent of Telegraphs in South Australia. Most widely known for his instrumental role in the construction of the Overland Telegraph, linking Australia and England, Todd also established the Adelaide Observatory and made valuable contributions to both astronomy and meteorology.

Recently (Gleeson (1972), Quenby (1973), Gleeson and Webb (1974, 1978)) it has been shown that the mean rate of change of momentum of cosmic rays reckoned for a volume fixed in the solar system is

where G = (1/Up )(∂Up /∂r)si the cosmic-ray density gradient with Up , the differential number density with respect to momentum p at position r. (cf also the integral form of (1) by Jokipii and Parker 1967).

Operation of the six 13.7 m antennas of the Fleurs synthesis telescope as a sub-array has provided a new and surprisingly versatile astronomical tool. With enhanced reliability and fully automated operation, unattended observing over several days is possible. Interleaved ‘multiple-snapshot’ observations of many fields per day can be made.

The array has shown itself to be particularly suitable for the measurement of precision (a few arcsecond) positions for the optical identification of a large number of radio sources, a survey of compact sources and the monitoring of the activity of several radio stars over periods of weeks. At present a program of recalibration is under way to improve the positional accuracy and dynamic range of the instrument.

Surface photometry of the elliptical galaxy NGC 1700 is presented and discussed in terms of providing evidence for warping of the outer isophotes in elliptical galaxies.

We shall examine the question of whether the concentration of magnetic field, the downward motion and the temperature excess observed at the boundaries of supergranules can be interpreted consistently in terms of a steady flow along the magnetic lines of force. Before doing so, however, we shall first consider the development of the magnetic configuration driven by a supergranular convection overshooting into the photosphere.

Spectroscopic imaging of the SNR RCW 103 has revealed extensive emission in near-infrared lines of H2and [Fe II], where the blast wave is encountering a molecular cloud. The H2 appears to be located outside the [FeII], a morphology which challenges our understanding of shock wave physics. It is suggested that reverse shocks may be responsible for the phenomenom.

We present observational results obtained during the first three years following the explosion of Supernova 1987 A. We discuss aspects of the optical and near infrared spectra as well as results from spectropolarimetric observations. The observations of the circumstellar and interstellar medium are also briefly discussed.

The absolute measurements of flux emitted in the visible continua of some Galactic Wolf-Rayet stars were carried out by means of a two-channel scanner. The measurements lead to the determination of stellar angular diameters which enable us to compute log L */L ⊙. The stellar wind terminal velocity, V ∞ was obtained from the empirical relation of the effective temperatures by Underbill (1983) and V ∞, adopted from the work of Willis (1982). Also, we derived the rate of mass loss for the WR stars from the formula Ṁ = є(T eff)L/(V ∞ c) by using the obtained effective temperatures, luminosity and V ∞ in this work. The values of the rates range from 1.4 × 10−5 to 5.8 × 10−5M ⊙yr−1.

The lack of any direct measurements on the spin temperature of the neutral hydrogen in the Galaxy has led to considerable controversy in the past. Estimates of the temperature have depended strongly on whether they are based on emission or absorption studies. The widely accepted value of 125°K based on emission studies dates back to Schmidt. He adopted this figure on the premise that the maximum observed brightness temperatures in the galactic plane were in directions of high optical depth. The brightness temperature was then equated with the spin temperature on the assumption that the temperature did not fluctuate very much in a large region around the Sun.

The discovery of the variability of the eclipsing system UX Eri can be attributed to Soloviev (1937). Photographic observations were made by Zessewitsch (1934, 1954), Bodokia (1938) and Gaposchkin (1953). Photoelectric observations were obtained by Kitamura and Nakamura (1957). The most recent photoelectric data were obtained by Binnendijk (1967) who determined new orbital elements. During the 10-year period from 1967-1977 the variable appears to have received little attention.

Advances in digital computer technology since the middle decades of the twentieth century have transformed many subject areas in astrophysics. Topics which had previously been dealt with by analytic approximations (usually to a very limited number of special cases) suddenly became amenable to detailed numerical modelling for all cases. Frequently, insights derived from this modelling ran ahead of other techniques in predicting physical phenomena before they were either observed or discerned in purely analytic treatments.

It has sometimes been said that the second half of this century has seen the advent of a totally new modus operandi in scientific research, which ranks alongside the two traditional approaches–experimentation and theory. The most powerful computers now available have greatly accelerated these developments. They employ simultaneous computational techniques (either vector processing or parallel processing, or both), and their throughput is so large that, for most problems, the only way in which the human mind can fully appreciate the scientific content of the numerical results being calculated is by transforming those results into pictorial representations.

This paper draws on my experience as Academic Director of the ANU Supercomputer Facility during the first eighteen months of its operation, to describe the place which I believe super-computers will occupy in the development of astrophysics during the 1990s and into the next century.

The primary objective of the LYMAN Mission is to provide an Observatory for the study of the waveband between 900 and 1250Å. Only one previous mission, Copernicus, has given us a glimpse into the very rich astrophysical return offered in this far-ultraviolet part of the electromagnetic spectrum. However, LYMAN will provide a sensitivity some ten thousand times greater than Copernicus.

It is the enormous richness of this part of the electromagnetic spectrum which is the prime justification of the mission. No other region offers such a density and variety of atomic, ionic and molecular absorption lines. Collectively, these represent a tool of great diagnostic power in determining physical conditions and chemical compositions of astrophysical plasmas. These plasmas may be cool, and seen in absorption against a hot continuum source, or else they may be hot and emitting in their own right. In either case, LYMAN is the ideal vehicle for their study, be they in solar system objects, near newly-forming stars, in photospheres, transition layers, or coronae of stars, in interstellar or intergalactic space, or close to the active cores of galaxies. For this reason, LYMAN will be a uniquely powerful tool for use in all branches of modern day astrophysics.

Like the strong non-thermal radio bursts from the solar corona and from the earth’s magnetosphere, the Jupiter radio bursts are characterized by their duration which may be from milliseconds to seconds, and by their complex structure on the frequency-time plane. In addition, they exhibit a variety of periodicities in their rate of occurrence, the primary one of which is associated with the rotation of Jupiter. The smaller physical scale of Jupiter compared with the Sun naturally leads to a much shorter time scale in the various radio phenomena and it is only recently that suitable equipment has become available to permit the detailed investigation of the dynamic spectra of the bursts with the necessary high time resolution of the order of 10–3 sec (Ellis 1973a,b,c). As in the case of the solar radio bursts, a number of distinct types of dynamic spectra are observed and they provide a convenient basis for classification.

We present the initial results of a statistical comparison of CO emission and H I self-absorption in the galactic plane at large distances from the Sun. Evidence for self-absorption by cold atomic hydrogen (Ts < 60 K) over angular scales of 3 ´-20´ was reported by Baker and Burton (1979). They suggested that this hydrogen was associated with the molecular clouds of the ‘molecular ring’ located between 4 and 8 kpc from the galactic center (Burton and Gordon 1978). Burton, Lizst, and Baker (1978) did find a correspondence between CO emission and H I self-absorption; however, their observations were not extensive enough to prove that the correspondence was statistically significant or to test their prediction that all instances of H I self-absorption are accompanied by CO emission and thus associated with molecular clouds.

Quasi-simultaneous optical/near-IR photometry is presented for a sample of 37 luminous optically selected QSOs drawn from the Large Bright QSO Survey. Most of the QSOs have decreased in brightness since discovery; this is expected in flux-limited samples. The continuum shape of most of the QSOs can be represented by a power law of the form F(v) ∝ v −0·3, but a few have softer (redder) continuum slopes.

The Schmidt camera is conceptually elegant and has a remarkable performance, but it suffers from several practical disadvantages. Two of these concern us here. First, there are very few craftsmen who are competent to make the aspheric correcting plate of the Schmidt camera compared with the number of those competent to make spherical surfaces of high quality.

The organization of the Anglo-Australian Telescope Project and the major features of the telescope design have been reported previously so only a brief description of the design aspects most relevant to the potential user will be given here.