In theories of the heating of the solar corona a number of authors have recently considered the propagation and damping of fast and slow magnetohydrodynamic waves, in the form of surface waves localized on the interfaces of coronal flux tubes (Ionson 1978, Wentzel 1979, Roberts 1981, Cramer and Donnelly 1983). The damping of these waves occurs, in addition to a rather weak global damping due to viscous or resistive dissipation, by means of a localized absorption at a so-called ‘resonance’ in the density or magnetic field profile forming the flux tube. At such a resonance, the wave frequency is equal to the local value of the Alfven wave frequency, in the case of Alfven resonance absorption, or at the local slow mhd wave frequency, in the case of the ‘cusp’ or ‘compressive singularity’ resonance in a finite pressure plasma.

We have measured the 2.3 GHz total and correlated flux densities on a baseline of 275 km of all sources in the Parkes catalogue which

1. (i) are south of declination +10°,

2. (ii) have a catalogued 2.7 GHz total flux density exceeding 0.5 Jy, and

3. (iii) have a 2.7/5.0 GHz spectral index flatter than −0.5.

More than 14% of the sample showed visibility amplitudes greater than 0.9, and more than 72% showed visibility amplitudes greater than 0.5. Of the sources with optical or other identifications 79% were quasars. In this paper we briefly summarise the results of this survey.

There has been considerable speculation in recent years about the evolution of radio galaxies in clusters. The discovery of powerful X-ray emission with an apparently thermal spectrum from a considerable number of clusters has been attributed to a hot (108K) intracluster gas with an electron density of ∼ 10-3 cm -3 at the cluster centre (see e.g. McHardy 1978). Such a gas surrounding a radio galaxy may conceivably retard the expansion or diffusion of the relativistic electrons and thus allow the source to retain its identity for longer intervals than is the case for field galaxies.

A major crisis facing theoretical nuclear astronomers and physicists today is the apparently very low flux of neutrinos emitted by the Sun. Davis et al. report a measurement of 1.5 ± 1 s.n.u. (1 s.n.u. = 10−36 capture/Cl37/sec) which is a factor of 6 or so smaller than the theoretically predicted values. Numerous suggestions, often quite bizarre, have been made to account for the low flux, but so far no convincing explanation has been offered – see Fowler.

This paper summarises the function of the Inter-University Centre for Astronomy and Astrophysics in India.

The atmosphere of a star presents a real challenge to the astronomer or physicist. We can observe but the thinnest skin of the star; yet from the information obtained therefrom we must deduce the star’s temperature, chemical composition, its rotation (if any), the state of agitation in its outer layers, and eventually the surface gravity, total luminosity, mass, and evolutionary stage.

Polytropic models have played a significant part in the historical development of stellar structure theory and in other related branches of theoretical astronomy such as stellar pulsations and rotation. In modern astronomy polytropic solutions, because of their wide range of density distributions and our ability to introduce them analytically if necessary, now have an acknowledged role in large scale numerical experiments especially during the developmental stages.

The question of modelling a wide variety of astrophysical phenomena is discussed. It is argued that the combination of new computing equipment and algorithms has created the opportunity for a concerted attack on problems ranging from star formation to the evolution of the universe.

In 1975, Hoessel, Elias, Wade and Huchra commenced a near infrared survey of 80 fields in the northern Milky Way with the Palomar 1.2 m Schmidt telescope, (Hoessel et al. 1979). This has now been issued as an atlas reproduced in the form of photographic paper prints. In 1977, the SRC 1.2 m Schmidt telescope at Siding Spring was authorized to commence a complementary survey of the southern Milky Way, consisting of the 151 ESO/SRC survey fields which have centres within 10° of the galactic plane and negative declinations (see Fig. 1). A further 12 fields have subsequently been added to the survey to permit coverage of the Large and Small Magellanic Clouds.

A recent analysis of the spectra of about 2000 sources in the Culgoora-3 list (Slee 1977) of radio sources (Slee et al. 1981) has revealed some interesting features which may be the result of source evolution. The Culgoora-3 spectra were obtained by combining the 80 and 160 MHz flux densities from the Culgoora radioheliograph with other published flux data between 10 and 10,000 MHz; this is probably the most accurate set of spectra yet derived for a large number of sources selected for observation in a reasonably consistent manner. In addition to fitting the log S-log v data for each source with a straight line (its slope is the usual definition of spectral index) Slee et al. also fitted second-degree and third-degree polynomials to search for curvature in the spectra.

The Molonglo Observatory Synthesis Telescope (MOST), which at present images a fully synthesised 70′ field in 12 h, is being converted to enable observing modes which extend the field size to 160′. The new observing modes will allow the MOST to survey completely the sky south of δ = −30° to a (5σ) sensitivity limit of about 5 mJy. The result will be a catalogue of over 400,000 radio sources with a spatial density of less than 1 source per 100 beam areas, providing the foundation for a number of novel astronomical and cosmological investigations. The conversion involves construction of 352 low-noise HEMT preamplifiers, 88 digitally controlled UHF quad phase shifters, 88 mixers and IF sections, a new communication and control system, and several other new sub-systems. The project has been funded and developments are well advanced.

The only planet with observed secular motion between the body and the axis of rotation is the Earth itself, which rotates both progressively and with unexplained librations about equatorial axes.

The proposal that the complex spectral line changes seen in the large amplitude β Cephei variable BW Vul resulted from a shock effect, driven by an underlying radial pulsation, was first made by Odgers (1955). Stamford and Watson (1978) examined some suitable atmospheric models for this star, which were driven by a hard subphotospheric piston under an isothermal assumption. These models displayed strong shock development and had some encouraging similarities with the BW Vul phenomenon. However, particularly because of the use of a hard piston, they were not very physically realistic. Here we discuss the results of a more sophisticated approach to this modelling problem. This modelling problem is of specific current importance because Odell’s (1981) recent observations of a variable polarization in BW Vul have renewed the debate over possible nonradial pulsations in this star. Since nonlinear effects are clearly substantial in BW Vul, it is evident that the implications of these on the observed spectral line changes should be carefully examined on a radial pulsation hypothesis, before turning to the complexities of nonlinear nonradial profile modelling.

Spectrophotometric optical fluxes of SN 1987A have been measured at high accuracy with the 61cm telescope equipped with a rapid spectrum scanner. This highly homogeneous data set covers the wavelength range 3200-8700Å at 10Å resolution. Selected wavelength regions, e.g. around Hα, have also been measured at 3Å resolution. The Hα line shows an undisturbed P Cygni-type profile until March 15, superimposed by variable fine-structure thereafter, developing within a few days into a blue-shifted, peak-like flux excess and a red-shifted flux deficiency. This fine-structure is intrinsic to Hα. Similar fine-structure is also observed in Na I-D, in Paschen-α and possibly in Hβ. We discuss our observations in terms of the ‘mystery spot’, and of models involving a jet and interactions with surrounding pre-existing material, and we propose density inhomogeneities, or occupation number deficits due to NLTE effects, within the inner regions of the envelope as origin.

During the last solar cycle a number of observations of solar radio emissions were made in a wide frequency range from which an enormous amount of information has been obtained. However the results obtained so far are limited by rather poor angular resolution. Observations with much higher resolution (of the order of 1′ arc) have been required for further studies of solar radio emissions. At the present stage such observations have proceeded in the microwave range; also the radioheliograph at 80 MHz has just started at the Culgoora Observatory. At the Tokyo Astronomical Observatory a high-resolution study of radio bursts in the metre-wave range has been planned since 1960, and the construction of a new compound interferometer operating at 160.3 MHz was started in April 1967 at a new site, Nobeyama. This site, located about 150 km north-west of Tokyo, is surrounded by mountains and quite free from man-made interference. We shall give a brief description of this equipment; details will be published later.

The Perth Astronomy Research Group (PARG), consisting of members from Curtin University of Technology, Perth Observatory and the University of Western Australia, is in the process of developing an automated supernova search system, using the 61-cm Lowell-Perth reflector, a CCD camera and an 80386-based computer for image analysis. Computer control of the telescope and dome, a liquid-nitrogen-cooled CCD camera, and modified VISTA image analysis software will be completed in late 1990, allowing initial semi-automatic searching of external galaxies, together with CCD photometry of flare stars and newly discovered supernovae. Full-scale automation will be introduced subsequently, in collaboration with the Berkeley group. This paper describes the project, and reports on its current status.

New observations of the Magellanic Stream were made in December 1976 with the 64-m radio telescope at the Parkes Observatory of CSIRO. The ridges of H I emission of the Stream were traced from near its tip at ℓ = 90°, b = -40° to the Magellanic Clouds. This was the first time that the total length of the Stream was observed with the one system (only possible from the southern hemisphere) and with high spatial (15’ of arc) and velocity (4 km s-1) resolution. The results of this survey are presented in Figures 1 and 2 and the main features are listed below.