Symbiotic stars are at the same time perplexing and rewarding to study. Their spectra contain great numbers of emission lines due to atoms in a range of ionization states from neutral to coronal. The continua are weak and usually unobtrusive: the strongest lines may have equivalent widths of thousands of Angstroms. But the crowding of weak lines complicates their measurement and, often, their identification. Many symbiotic stars probably emit weak lines which currently defy identification, but which cannot be distinguished from their neighbours. It is, however, rather rare to find a strong unidentified emission line.

There is reasonably strong evidence to suggest that the periodic X-ray, radio and optical variable Cir X-1 is a highly eccentric orbit (e ~ 0.8), binary system comprising an OB supergiant primary and a compact object, probably a neutron star (Whelan et al. 1977; Haynes, Lerche and Murdin 1980).

Mestel, Wang and Westfold (1984; ‘MWW’) have recently introduced a pulsar magnetosphere model in which electrons leave the star with non-negligible, but not highly-relativistic, speeds, and flow with moderate acceleration along magnetic field lines before reaching a limiting surface, near which rapid acceleration occurs. Such moderately accelerated flows are analysed here. A second class of flows, which do not encounter a region of rapid acceleration, is found.

The study of radio galaxies situated within clusters of galaxies has become a broad field, with hundreds of papers published in the last few years. This review will therefore be restricted mainly to consideration of the interactions between the extended components of radio sources in clusters and the diffuse gas (intracluster medium, ICM) which occurs in clusters. In particular, attention will be focused on what we can learn about the ICM from this interaction, in conjunction with other data such as X-ray observations. In the case of quasars in clusters of galaxies the emphasis is rather different, so discussion of this topic is deferred to section 6.

It is generally assumed from an inspection of prints of non-magellanic spiral galaxies that all constituents, including the HI, are distributed with a large-scale circular symmetry in the plane of the galaxy. This assumption is supported by the expectation that any primordial asymmetry in the mass distribution would have disintegrated by the present epoch under the shearing effects of differential rotation into an approximately circularly symmetric ring. It is therefore surprising to find that the recent high-resolution studies of M 31, M 101, NGC 300 and our own galaxy all show that the HI centroid is significantly displaced from the nucleus. This is a sign that the HI distribution is markedly asymmetric.

Techniques in QED (quantum electrodynamics) have been developed previously (see for example Melrose and Parle 1983) allowing one to treat electron-photon and photon-photon interactions exactly in the magnetized vacuum and allowing one to include the effects of a medium. These techniques are extended to include particle-particle interactions. Exact cross-sections for electron-electron collisions are derived and compared with known expressions. Such calculations have application in studies of the formation and transfer of radiation in the atmospheres surrounding neutron stars.

The design of the Australia Telescope is discussed, particularly in reference to the compact array, the frequency ranges of operation, the field of view, dynamic range, polarization, bandwidth, correlators, time resolution and flexibility. Site preparation at Culgoora, antenna design, reflector panel construction, feed horns, receivers an cryogenics, and computing are receiving full attention.

This paper describes the first results from a 20 deg2 mosaic of the Small Magellanic Cloud (SMC) in the λ21-cm line of neutral hydrogen. The mosaic consists of 320 separate pointings with the 375-m array of the Australia Telescope Compact Array. The angular resolution is 1′· 5 (26 pc, for a distance of 60 kpc) and the velocity resolution is l·6kms−1. The images reveal a structure of remarkable complexity, with much of the spatial power contained in high-brightness temperature compact knots and filaments. Numerous wind-blown ‘bubbles’ and ‘supershells’ are evident in the data, both inside and outside the stellar confines of the SMC. Some high-density H I regions are seen to correlate with Hα regions, indicating sites of current star formation. However, many high-column-density H I regions are devoid of optical emission and may represent regions of future star formation. These regions may be under-abundant in diffuse molecular gas due to the high radiation field and low metallicity of the SMC.

The extensive body of broad-band photometric data for SN 1987A obtained at SAAO has been used to derive the bolometric light curve up to day 450 after the outburst. The salient features of the curve are discussed in this paper.

The five major members of the Sculptor Group of galaxies and NGC 45 have been observed with the Molonglo observatory synthesis telescope. NGC 247 and NGC 300 were not detected and upper limits to their 843 MHz flux densities are given. Radio emission from NGC 7793 is discussed with particular attention to its morphology, radial dependence compared with that of the blue light and possible coincidences between HII regions and 843 MHz peak flux densities.

Recent observational results are presented which strongly suggest that a much wider range of upper-main-sequence stars have appreciable surface magnetic fields than has previously been believed.

The Parkes radio telescope was commissioned in 1961, with an anticipated operational life of 15 years. Twentyfive years later the telescope has been refurbished with the aim of extending its life yet another decade or two. A major undertaking has been the complete replacement of the drive and control System. This presentation outlines the main features of the new System and its effect on the observing facilities offered at the observatory.

During the second half of 1986 tests were made of a new Q-band (43 GHz) receiver designed for the Parkes radio telescope. As part of the trial observation program 12 symbiotic stars were examined for SiO maser emission. No significant new emission was detected from any of the candidates, although several previously known SiO sources (including one symbiotic star) were confirmed. We conclude that potential SiO maser action near the Mira star in most symbiotic systems is prevented by the presence of the hot companion star.

We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.

An HI survey of the Large Magellanic Cloud (LMC) has been reanalyzed to find the transverse velocity of the LMC, and derive an upper limit of 4.5 × 1011 M⊙ for the mass of our Galaxy out to 50 kpc. A rotation curve is derived for the LMC from the HI data giving a best mass estimate of (4.0±0.4)×109 M⊙. Velocity observations of 97 planetary nebulae (PN) in the Large Cloud are used to compare the old and young components. Our results are found to be at odds with an earlier sample of 9 old clusters, which is interpreted as being due to the low number of objects in that sample. The w-component of velocity dispersion of the PN population is 35 km s-1 and that of the HI 10 km s-1. If this difference is a result of stellar diffusion then the average age of the PN population is 1.3 × 109 yr, implying a precursor mass of 1.8 M⊙ and a remnant mass of 0.63 M⊙.

This paper presents a brief discussion of the apparent underdepletion of the heavy neutron-capture elements (elements heavier than Ba), compared with Fe in the Magellanic Clouds. The s-process appears to have been only effective in forming elements in the light neutron-capture group (Sr, Y, Zr) in the Magellanic Clouds, but to have much reduced effectiveness in forming the heavy neutron-capture group. The abundances of the elements heavier than Ba have a distribution that indicates that they were produced by the r-process alone.

We have detected OH maser radiation from the comet Giacobini-Zinner using the Parkes radio telescope. The emission was detected in two transitions of the ground state of OH, at an intensity consistent with the predicted OH molecular production rate. We also searched unsuccessfully for OH emission from comet Halley, from which we are able to place a significant upper limit on the intensity of OH emission.

A survey of the optical spectra of IRAS galaxies, made with the AAT, has shown that the majority have strong emission lines. Ratios of the emission lines have been plotted on the Veilleux-Osterbrock diagram ([O III]/Hβ against [N II]/Hα); this shows that the IRAS galaxies comprise several classes. In our sample the majority appear to be starburst galaxies, but Seyfert, Liner and narrow-line galaxies are also represented. Co-added spectra of the galaxy classes are presented. On the basis of optical spectroscopy, it appears that the starburst phenomenon is capable of generating luminosities exceeding 1012L⊙.

The main objectives of this series of papers are: (1) to demonstrate the existence of serious mutual disagreements between established total (and other integrated) magnitude scales forVirgo galaxies; (2) to attempt to quantify both the systematic and random errors present within these magnitude scales; (3) to investigate the origins of any large error uncovered; and thereby (4) to encourage the general adoption of rigorous total-magnitude measurement procedures by the astronomical community. The ramifications of the findings presented in this series of papers will be discussed in detail at a later date.

In this paper, the first in the series, a self-consistent dataset of trustworthy total-magnitude measurements is compiled for a sample of Virgo galaxies spanning a range of 10 000 in apparent brightness, based on only the most reliable measurements and photometry currently available. This reference dataset, which includes luminosity profile shape information, will be used in subsequent papers as one of the bases for assessing existing magnitude scales forVirgo galaxies. As most published magnitudes are based on B–band observations, this series of papers will also focus primarily on B–bnd measurements.

We used an Artificial Neural Network (ANN) to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of seven double-lined spectroscopic binary systems V373 Cas, V2388 Oph, V401 Cyg, GM Dra, V523 Cas, AB And and HD 141929, we found corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by others using more traditional methods.