The photometric observations (UBVRI) of nine cool R Coronae Borealis (RCB) stars have been collected at Mt John University Observatory, New Zealand, over a period of twelve years. The analysis of the magnitude–colour and colour–colour diagrams for the recovery phase demonstrates that all declines exhibit a similar asymptotic approach to their normal brightness. Declines return to maximum brightness along a line with essentially the same slope that does not depend on the star or the depth of the decline. Assuming a uniform obscuration of the photosphere by the dust cloud during the recovery phase, the extinction properties of the material were determined. The ratio of total to selective extinction (RV) for the RCB stars in our sample is in the range 2.5 to 4.6, indicating that the obscuring dust has extinction properties similar to that of the interstellar dust. Observations have been compared with the theoretical extinction curves for different sorts of grains.

An enormous effort is underway worldwide to attempt to detect gravitational waves. If successful, this will open a new frontier in astronomy. An essential portion of this effort is being carried out in Australia by the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA), with research teams working at the Australia National University, University of Western Australia, and University of Adelaide involving scientists and students representing many more institutions and nations. ACIGA is developing ultrastable high-power continuous-wave lasers for the next generation interferometric gravity wave detectors; researching the problems associated with high optical power in resonant cavities; opening frontiers in advanced interferometry configurations, quantum optics, and signal extraction; and is the world's leader in high-performance vibration isolation and suspension design. ACIGA has also been active in theoretical research and modelling of potential astronomical gravitational wave sources, and in developing data analysis detection algorithms. ACIGA has opened a research facility north of Perth, Western Australia, which will be the culmination of these efforts. This paper briefly reviews ACIGA's research activities and the prospects for gravitational wave astronomy in the southern hemisphere.

We have taken 88 dwarfs, covering the colour-index interval 0.37 ≤ (B–V)0 ≤ 1.07 mag, with metallicities –2.70 ≤ [Fe/H] ≤ +0.26 dex, from three different sources for new metallicity calibration. The catalogue of Cayrel de Stroble et al. (2001), which includes 65% of the stars in our sample, supplies detailed information on abundances for stars with determination based on high-resolution spectroscopy. In constructing the new calibration we have used as ‘corner stones’ 77 stars which supply at least one of the following conditions: (i) the parallax is larger than 10 mas (distance relative to the Sun less than 100 pc) and the galactic latitude is absolutely higher than 30°; (ii) the parallax is rather large, if the galactic latitude is absolutely low and vice versa. Contrary to previous investigations, a third-degree polynomial is fitted for the new calibration: [Fe/H] = 0.10 – 2.76δ – 24.04δ2 + 30.00δ3. The coefficients were evaluated by the least-squares method, without regard to the metallicity of Hyades. However, the constant term is in the range of metallicity determined for this cluster, i.e. 0.08 ≤ [Fe/H] ≤ 0.11 dex. The mean deviation and the mean error in our work are equal to those of Carney (1979), for [Fe/H] ≥ –1.75 dex where Carney's calibration is valid.

The Taurus Tunable Filter (TTF) has now been in regular use for seven years on the Anglo–Australian Telescope (AAT). The instrument was also used for three years (1996–1999) on the William Herschel Telescope (WHT). We present a brief review of the different applications in order to illustrate the versatility of tunable filters in optical/IR spectrophotometric imaging. Tunable filters are now either planned or under development for 6–10 m class telescopes which ensures their use for years to come.

The rare carbonaceous chondrite which fell around the township of Murchison in northern Victoria, Australia, in 1969 has probably been the subject of more scientific publications than any other meteorite. The discovery of grains formed in a presolar environment and the abundance of organic molecules within the Murchison meteorite have facilitated studies of the formation of the Solar System, the development of stars and the origins of life.

We present the study of ten random realisations of a density field characterised by a cosmological power spectrum P(k) at redshift z = 50. The reliability of such initial conditions for N-body simulations is tested with respect to their correlation properties. The power spectrum P(k) and the mass variance σM(r) do not show detectable deviations from the desired behaviour in the intermediate range of scales between the mean interparticle distance and the simulation volume. The estimator for ξ(r) is too noisy to detect any reliable signal at the initial redshift z = 50. The particle distributions are then evolved forward until z = 0. This allows us to explore the cosmic variance stemming from the random nature of the initial conditions. With cosmic variance we mean the fact that a simulation represents a single realisation of the stochastic initial conditions whereas the real Universe contains many realisations of regions of the size of the box; this problem affects most importantly the scales at about the fundamental mode. We study morphological descriptors of the matter distribution such as the genus, as well as the internal properties of the largest object(s) forming in the box. We find that the scatter is at least comparable to the scatter in the fundamental mode.

MRC B1221–423 is a compact steep spectrum (CSS) radio source in the core of a remarkable elliptical galaxy. We examine its environment with long-slit spectra and multicolour images. A high-resolution synthesis image shows the radio source to have a 1″.5 (5.7 kpc) double structure. We use the empirical relationship between jet kinetic power and narrow line luminosity to infer a source age of ˜105 yr. The z = 0.1706 host galaxy is clearly disturbed, with tidal features and shells providing plausible evidence for a merger with one or more close companions. This evidence leads us to conclude that B1221–423 may be the progenitor of a much larger source, caught at an early stage in its radio evolution. We speculate that it is the interaction and accompanying events which have triggered this young powerful radio source.

Recent advances in the knowledge of the evolutionary status of asymptotic giant branch (AGB) stars and of the nucleosynthesis processes occurring in them are discussed, and used to interpret abundance determinations for s-process elements, lithium and CNO isotopes in several types of AGB stars. We focus our attention mainly on carbon-rich AGB stars. By combining these different constraints we conclude that most carbon stars in the solar neighborhood are of low mass (M≤3 M⊙), their abundances being a consequence of the operation of thermal pulses and the third dredge-up. However, the observed abundances in carbon stars of the R and J types cannot be explained by this standard scenario. These stars may not be on the AGB, but possibly in the core-He burning phases; their envelopes may have been polluted with nuclear ashes of the core-He flash, followed by CNO re-processing enhancing 13C. Observational evidence suggesting the operation of non-standard mixing mechanisms during the AGB phase is also discussed.

The radio–far infrared correlation is one of the tightest correlations found in astronomy. Many of the models explaining this correlation rely on the association of global magnetic field strength with gas density. In this letter we put forward that the physical reason for this association lies within the processes of magnetohydrodynamic turbulence.

We discuss the production sites of the nuclei from C to Al in solar metallicity stars in the range 13–35 M⊙. We will show how, contrary to current beliefs, the advanced burning phases and the passage of the blast wave play a pivotal role in determining the final yields of quite a few ‘light’ nuclei. We will also show how the relative contributions of the hydrostatic and explosive burning depend on the initial mass of the star: the smaller the mass the larger the importance of the explosive burning.

A brief overview of the current radio source host galaxy state of affairs is given. All the evidence appears to point towards a scenario in which the young radio source expands through the host galaxy on timescales of 105–106 yr, before it ends its life as a large scale FR II radio galaxy. The place and role of the quasars in this evolutionary picture is unclear, however, and remains an issue of debate.

The Australia Telescope and Anglo-Australian Telescope were used in May 2000 to record the radio and optical emissions from the dMe flare star Proxima Centauri. Eight bright optical flares over a two-day interval resulted in no detectable excess short-term radio emission at 1.38 and 2.50 GHz. However, a slowly declining 1.38 GHz emission over the two-day interval was nearly 100% right circular polarised and was restricted to a relatively narrow bandwidth with total intensity (I) and circular polarisation (V) varying significantly over the 104 MHz receiver bandwidth. These are the first observations to show that highly-polarised narrowband flare star emission can persist for several days. This signature is attributed to sources of coherent radio emission in the star's corona. Similarities with various solar radio emissions are discussed; however, it is not possible with the existing observations to distinguish between fundamental plasma emission and electron–cyclotron maser emission as the responsible mechanism.

Comet C/1850 Q1 (Bond) is one of a number of comets catalogued with parabolic orbits. Given that there are sufficient observations, 104 in right ascension and 103 in declination, it proves possible to calculate a better orbit. Some of the difficulties of working with 19th century observations, which show considerable scatter, are discussed. Rectangular coordinates, both of the comet and the Sun, are interpolated by a recursive version of Aitken's method, rendering unnecessary the need to specify an order for the interpolation. Comet Bond's orbit is slightly hyperbolic.

The role of radio polarimetry in the understanding of GPS and CSS sources is explored. After an initial discussion of what can be learned from polarimetry, the expectations of a simple evolutionary sequence of GPS/CSO to CSS to FR I/FR II sources are explored. Observational results are then compared with the expectations. Conclusions include: the GPS category is likely not a single homogeneous class of objects; Faraday depth effects are very strong inside the inner 3 kpc of CSS and CSO sources; in at least 3C 138 the Faraday screen has very fine scale (subparsec) structure; and there is evidence for increased ionisation near bends in some CSS jets probably due to jet–ISM interaction. New results on 3C 138, 3C 43, and 3C 454 are given.

We test the hypothesis that high-velocity gas cloud Complex C is actually a high-latitude spiral arm extension in the direction of the Galactic warp, as opposed to the standard interpretation — that of a once extragalactic, but now infalling, gas cloud. A parallel Tree N-body code was employed to simulate the tidal interaction of a satellite perturber with the Milky Way. We find that a model incorporating a perturber of the mass of the Large Magellanic Cloud on a south to north polar orbit, crossing the disk at ˜15 kpc, does yield a high-velocity, high-latitude extension consistent with the spatial, kinematical, and column density properties of Complex C. Unless this massive satellite remains undiscovered because of either a fortuitous alignment with the Galactic bulge (feasible within the framework of the model), or the lack of any associated baryonic component, we conclude that this alternative interpretation appears unlikely.

A numerical model for ion implantation into spherical grains in free space has been developed. It can be applied to single grains or collections of grains with known grain-size distributions. Ion-scattering effects were taken into account using results of computer simulations. Possible isotope and element fractionation of the implanted species was investigated using this model. The astrophysical significance of the model lies in the possible identification of energetically different components (such as noble gases) implanted into presolar grains (such as diamond and SiC) and in establishing implantation energies of the components.

The chemical evolution of the Milky Way is investigated using a dual-phase metal-enriched infall model in which primordial gas fuels the earliest epoch of star formation, followed by the ongoing formation of stars from newly accreted gas. The latest metallicity distribution of local K-dwarfs is reproduced by this model, which allows the Galactic thin disk to form from slightly metal-enriched gas with α-element enhancement. Our model predicts ages for the stellar halo and thin disk of 12.5 and 7.4 Gyr respectively, in agreement with empirically determined values. The model presented in this paper is compared with a similar dual-phase infall model from Chiappini et al. (2001). We discuss a degeneracy that enables both models to recover the K-dwarf metallicity distribution while yielding different star formation histories.

The metallicity distribution function (MDF) of K-dwarfs is proposed to be more directly comparable to chemical evolution model results than the G-dwarf distribution because lower mass K-dwarfs are less susceptible to stellar evolutionary effects. The K-dwarf MDF should consequently be a better probe of star formation history and provide a stronger constraint to chemical evolution models than the widely used G-dwarf MDF. The corrections that should be applied to a G-dwarf MDF are quantified for the case of the outer halo of NGC 5128.