The equation of motion, derived from the basic Lagrangian equations for the conservation of momentum and the conservation of energy, for non-linear non-adiabatic radial oscillations of a pulsating star takes the form

For many reasons, it is important to have a sound body of reliable photometry for the globular clusters in the Milky Way galaxy. Given the striking appearance of the globular clusters and their historical and astrophysical interest, it is perhaps surprising that the available photoelectric photometry for globular clusters is of mixed quality (see Harris and Racine 1979). Here I present a homogeneous body of photometry through a single aperture and in the UBV system for 31 globular clusters south of declination +12°.

Recent observations with the Australia Telescope Compact Array show that the elliptical galaxy NGC 5266 has a disk of neutral hydrogen extending to almost 10R e. This HI disk lies along the galaxy’s major axis, at right angles to the inner minor-axis dust lane. The geometry and kinematics of the gas will allow us to determine both the intrinsic shape of the stellar galaxy and the mass distribution. The mass-to-light ratio M/L B rises from about 2 in the central regions to ~12 at 9R e (H0 = 50km s−1 Mpc −1).

Many excellent reviews of gravitational wave astronomy have appeared in the literature (see for example Thorne 1980 and references cited there). Much has also been written on the potential of the second generation of Weber-bar detectors which, operating at low temperatures and exploiting superconducting technology, have design sensitivities up to a million times greater than those of a decade ago. Indeed such has been the intensity of activity in this area, that even before this generation of cryogenic detectors has come of age, a third generation, quantum mechanical in outlook, is already being conceived.

Observations of the vector magnetic field imply that there is a net current flowing through the corona, and there is also evidence that this current is directly related to flares. It is argued that if the currents are unneutralised, then this requires a radical rethinking of several widely accepted ideas on solar magnetic fields and their role in solar flares.

Waves of variation in the daily average cosmic ray intensity at the Earth’s surface were first detected in the neutron monitor record. Following the abnormal cosmic ray storm of September 1978, a sinusoidal 13.5 day periodicity was observed in the average intensity (Pomerantz and Duggal 1979), persisting for at least two solar rotations. Further observations, including underground data from the southern hemisphere, confirmed that not only were the waves isotropic but exhibited approximately a p−1 variational dependence on primary rigidity p (Duggal et al. 1981). No further evidence for this kind of wave has yet come to light. However, in the latter half of 1982 a series of 27-day waves that were apparently of a different character were detected. The evidence for their presence resulted from an analysis of the disturbed period that followed the occurrence of the large Forbush Decrease commencing 13 July 1982. It seemed at first that they could be described as anisotropic waves of the well-known interplanetary North-South asymmetry (Jacklyn and Pomerantz 1983).

The flux densities of 220 radio sources have been accurately measured at 408 MHz in order to provide a useful set of calibration sources accessible to southern radio astronomers. The flux densities are based on a scale defined by absolute measurements. This scale appears to be 10% higher than the commonly accepted CKL scale and about 8% higher than the scale defined by Kellermann when averaged over common sources.

It is evident that the limited duration of a single rocket or balloon flight is a severe handicap to the study of variable X-ray sources like Cen XR-2, the early history of which can only be conjectured from the few available rocket observations. The whole question of the variability of X-ray sources remains in doubt because of the difficulty of relating infrequent high-altitude flux measurements of short duration made with a variety of instruments. There are obvious advantages in a method of monitoring celestial X-ray fluxes from the ground for prolonged periods of time. Such a method has recently been found and, although presently restricted to strong sources like Sco XR-1 and Cen XR-2, is capable of considerable refinement.

Astronomical spectrographs are usually mounted at one of three focal positions on a reflecting telescope: (1) the Newtonian focus, at the top of the telescope tube, with only one reflection from the primary mirror, where the spectrograph must be small and light, and designed for low resolution on faint objects; (2) the Cassegrain focus, behind the cell of the primary mirror, with a total of two reflections, where the spectrograph can be appreciably larger, to give intermediate resolution; and (3) the coude focus, at a fixed location below the end of the polar axis, with three, four or five reflections, where there is no limit to the size of the instrument, and where resolution is limited only by the brightness of the object and the light efficiency of the system. This is the ideal location for image tubes, Fabry-Perot interferometers, and equipment for Fourier spectroscopy.

Four catalogues based on the survey made with the Molonglo Cross-type radio telescope have so far been completed, the largest of which is MCI (Davies, Little and Mills,1973). These catalogues were noise limited and had a 5α lower limit of about 0.3 Jy. This paper gives an outline of deep surveys that have been made in order to reach significantly fainter sources, but only in a small solid angle of sky.

SV Cen is an eclipsing variable of the Beta Lyrae type and is especially known by its rapid changes of period. The system was studied photometrically and spectroscopically by Irwin and Landolt (1972). According to the previous study by O’Connell (1951) the system exhibits a 34-year periodicity.

This programme was undertaken because the preliminary observations of Beta Centauri with the Narrabri stellar interferometer (Hanbury Brown, Davis, Allen, and Rome) show that the correlation received is not consistent with that expected from a single star. The Lick Catalogue of Radial Velocities states that β Cen is a Bl II star. The Narrabri results are consistent with several models; in particular, it may be a double star with components of similar brightness, or it may have a very luminous, extended atmosphere or shell surrounding it. The latter possibility is perhaps unlikely on the spectroscopic evidence, as there are neither emission nor sharp absorption components in the spectral lines.

Molecular hydrogen in spiral galaxies is distributed in clumps, i.e., molecular clouds, which have mass between 103M ⊙ and 106M ⊙ and a mass spectrum of n(m) ∝ m −1.6. Molecular clouds with masses greater than 105M ⊙, are called giant molecular clouds (GMCs). It is generally accepted that GMCs are formed by the coalescence of molecular clouds through their collision. This process is studied by both numerical simulation and numerical integration. The observation with high resolution identified a great number of CO emission cores in galaxies. Based on this result, the aggregation or clustering formation of GMCs is numerically simulated. In the process of either coalescence or clustering, spiral perturbation plays an important role.

Observations of pulsar radio-emission at high time resolutions are severely constrained by interstellar dispersion.

This paper discusses several aspects of radio emission and star formation in dwarf galaxies.

Observations of polarized emission and consequently the investigation of magnetic fields in northern galaxies, have been conducted successfully for some time with, for example, the 100-m Effelsberg telescope of the Max-Planck-Institut-für Radioastronomie and the VLA. However, the opportunity to make corresponding studies in the southern hemisphere has only recently become possible. Therefore, we have begun a long-range project aimed at studying the morphology and dynamics of southern galaxies using the facilities of the Parkes and Molonglo radio telescopes, the Siding Spring optical facilities and the Australia Telescope. Here we present preliminary results from Parkes observations of the three well known galaxies: NGC 253, NGC 4945 and M 83.

This meeting provides the first opportunity for me to talk about the Australia Telescope as an established project. It has been formally approved at all levels and is now under way (see Fig. 1).

A coronal hole is a region of the solar corona characterised by diverging magnetic fields of single polarity and lower-than-average densities (and probably temperatures). It is now generally accepted that coronal holes are the source of high-speed streams in the solar wind (Munro and Withbroe 1972, Kopp and Holzer 1976, Steinolfson and Tandberg-Hanssen 1977, Munro and Jackson 1977; see Pneuman 1980 for references to most of the theoretical and observational papers on coronal holes since their recognition in 1968). We consider an infinitesimal field-aligned flow tube with cross-sectional area A(r) where r is the heliocentric radius (Figure 1), and we adopt the functional form

A(r)/A(r ) = (r/r0 )8

where r is the coronal base radius, and 5 is a parameter which measures the divergence of the flow. If s = 2 then the flow is purely spherically symmetric, while if s > 2 the flow is more strongly divergent as is expected to be the case for a coronal hole. The cross-section of a typical coronal hole is shown schematically in Figure 2.

Given an ordered set of samples {ai } of some function, then the autocorrelation of that function is the mean lagged product of these samples.