Coronal mass ejections (CMEs) are tightly related to filament eruptions and usually are their continuation in the upper solar corona. It is common practice to divide all observed CMEs into fast and slow ones. Fast CMEs usually follow eruptive events in active regions near big sunspot groups and associated with major solar flares. Slow CMEs are more related to eruptions of quiescent prominences located far from active regions. We analyse 10 eruptive events with particular attention to the events on 2013 September 29 and on 2016 January 26, one of which was associated with a fast CME, while another was followed by a slow CME. We estimated the initial store of free magnetic energy in the two regions and show the resemblance of pre-eruptive situations. The difference of late behaviour of the two eruptive prominences is a consequence of the different structure of magnetic field above the filaments. We estimated this structure on the basis of potential magnetic field calculations. Analysis of other eight events confirmed that all fast CMEs originate in regions with rapidly changing with height value and direction of coronal magnetic field.

A 4-m telescope for mm-wave observations, particularly of spectral lines, was erected in mid-1976 at Epping by Krupp Ltd., Rheinhausen. A cooled mixer receiver was installed on the telescope in April 1977 and a series of test observations made during the remainder of the year, subject to the availability of the receiver and the multi-channel filter bank which were shared with the Parkes 64-m telescope.

Motivated by recent suggestions that strange stars can be responsible for glitches and other observational features of pulsars, we review some possible equations of state and their implications for models of neutron, hybrid, and strange stars. We consider the MIT bag model and also strange matter in the colour–flavour locked phase. The central energy densities for strange stars are higher than the central densities of ordinary neutron stars. Strange stars are bound by the strong force and so can also rotate much faster than neutron stars. These results are only weakly dependent on the model used for the quark matter. If just one of the existing mass-to-radius ratio constraint is valid, most neutron stars equations of state are ruled out, but all the strange stars equations of state presented in this work remain consistent with the constraint.

We present the results of binary population simulations of carbon- and nitrogen-enhanced metal-poor (CEMP and NEMP) stars. We show that the observed paucity of very nitrogen-rich stars puts strong constraints on possible modifications of the initial mass function at low metallicity.

I report a model for the formation of Saturn's family of mid-sized icy moons to coincide with the first flypast of Rhea by the Cassini spacecraft on 2005 November 26. It is proposed that the moons had condensed from a concentric family of orbiting gas rings that were shed some 4.6 × 109 yr ago by the proto-Saturnian (hereafter p-Sat) cloud. The p-Sat cloud is made up of gas and residual grains of the gas ring that was shed by the proto-Solar cloud (hereafter PSC) at Saturn's orbit. The bulk of the condensate within this proto-Solar ring accumulates to form Saturn's central core of mass ∼10–20 M⊕ (M⊕ = Earth mass). The process of formation of Saturn's solid core thus provides an opportunity for the p-Sat cloud to become depleted in rock and water ice relative to the usual solar abundances of these materials. Nitrogen, which exists as uncondensing N2 in the PSC and as NH3 in the p-Sat cloud, retains its solar abundance relative to H2. If the depletion factor of solids relative to gas is ζdep = 0.25, as suggested by the low mass of Rhea relative to solar abundance expectations, the mass-percent ratio of NH3 to H2O in the dense p-Sat cloud is 36:64. Numerical and structural models for Rhea are constructed on the basis of a ‘cosmogonic’ bulk chemical composition of hydrated rock (mass fraction 0.385), H2O ice (0.395), and NH3 ice (0.220). It is difficult to construct a chemically differentiated model of Rhea whose mean density matches the observed value ρRhea = 1.23 ± 0.02 g cm−3 for reasonable bounds of the controlling parameters. Chemically homogeneous models can, however, be constrained to match the observed Rhea density provided that the mass fraction of NH3 is permitted to exceed the cosmogonic value by a factor ζNH3 = 1.20–1.35. A large proportion of NH3 in the ice mass inhibits the formation of the dense crystalline phase II of H2O ice at high pressure. This may explain the lack of compressional features on the surface of the satellite that are expected as a result of ice II formation in the cooling core. The favoured model of Rhea is chemically uniform and has mass proportions of rock (0.369), H2O ice (0.378), and NH3 ice (0.253). The enhancement factor of NH3 lies within the measured uncertainties of the solar abundance of nitrogen. The satellite is very cold and nearly isodense. The predicted axial moment-of-inertia coefficient is [C/MR2]Rhea = 0.399 ± 0.004.

We present deep, wide-field, Ks-band (2.14-μm) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14-μm point source catalogues (PSCs) towards each of the regions. For the regions between 10° < l < 350° and |b| < 1, we match the 2.14-μm sources with the GLIMPSE point source catalogue to generate a combined 2.14- to 8.0-μm point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.

In its normal synthesis mode of operation, the Molonglo Observatory Synthesis Telescope (MOST) tracks a region of sky for a period of 12 hours with 64 real-time fan beams having high sensitivity at 843 MHz (Mills 1981). It thus provides an excellent opportunity to monitor the sky at the same time for transient radio events. During a 12 hour synthesis observation the fan beams rotate 180° on the field. Thus any sources producing occasional radio transients can be located by analysing the positions of the beams on which the events are recorded. Futhermore, by rejecting events which occur simultaneously on non-adjacent beams, local terrestrial sources of impulsive interference may be eliminated. This technique for recognizing extra-terrestrial sources was of considerable value in the first Molonglo pulsar search when only two beams were used.

The Perth Automated Supernova Search uses the 61-cm PLAT (Perth Lowell Automated Telescope) at Perth Observatory, Western Australia. Since 1993 January 1, five confirmed supernovae have been found by the search. The analysis of the first three years of data is discussed, and preliminary results presented. We find a Type Ib/c rate of 0·43±0·43 SNu, and a Type IIP rate of 0·86±0·49 SNu, where SNu are ‘supernova units’, expressed in supernovae per 1010 LB⊙ galaxy per century. These values are for a Hubble constant of 75 kms−1 Mpc−1, and scale as (H0/75)2.

During its burst of intraday variation (IDV) in June 1996 quasar PKS 0405–385 exhibited rapid changes in the Stokes parameters Q and U that were even faster than the 1 hr timescale changes in I. Auto- and cross-correlation analyses of I,Q, and U at 8.6 GHz show systematic relations between the variations in I,Q, and U. These are well modelled by interstellar scintillation (ISS) of a 14 × 20 μ as source, with about 180 degree rotation of the polarisation angle along its long dimension. This success in explaining the remarkable IDV in polarisation confirms that ISS gives rise to the IDV in this quasar.

It has been known for about 5 years that the flux densities at 408 MHz of some sources change over time scales of a few months, but discovery of these variable sources has been largely accidental during the intensity calibration of various observing programs at Molonglo. This paper describes some results from systematic observation of 254 sources over a 12 month period, through which we hope to better understand the telescope performance, find more identifications in the southern sky, and recognise variable sources. An improved calibration will be applied to digital data from Molonglo observations since 1967 (both surveys and individual source observations), now stored on magnetic tape.

Recently, a new branch of astronomy has emerged following the detection of ultra-high energy (UHE) γ-ray emission from Cygnus X-3 by Samorski and Stamm (1983). This discovery was made using the extensive air shower (EAS) array of the University of Kiel, Germany. Such arrays are designed to detect EAS, the cascades of secondary particles (mainly electrons and protons), which are generated in the atmosphere by the interaction of cosmic ray nuclei of energy greater than ˜ 1015 eV. These arrays are also sensitive to EAS initiated by primary γ-rays and, depending on their design, have angular resolutions as good as the SAS-II and COS-B γ-ray telescopes which operated at ˜ 100 MeV energies. At present, there is no effective way to veto proton or nucleus-initiated EAS and so one must look for a significant excess of EAS from within a cone of resolution centred on a suspected source direction.

We compare two Type Ia supernova samples that are drawn from a spectroscopically confirmed Type Ia supernova sample: a host-selected sample in which SNe Ia are restricted to those that have a spectroscopic redshift from the host; and a broader, more traditional sample in which the redshift could come from either the SN or the host. The host-selected sample is representative of SN samples that will use the redshift of the host to infer the SN redshift, long after the SN has faded from view. We find that SNe Ia that are selected on the availability of a redshift from the host differ from SNe Ia that are from the broader sample. The former tend to be redder, have narrower light curves, live in more massive hosts, and tend to be at lower redshifts. We find that constraints on the equation of state of dark energy, w, and the matter density, ΩM, remain consistent between these two types of samples. Our results are important for ongoing and future supernova surveys, which unlike previous supernova surveys, will have limited real-time follow-up to spectroscopically classify the SNe they discover. Most of the redshifts in these surveys will come from the hosts.

The planetary nebula PB 8 around a [WN/WC]-hybrid central star is one of planetary nebulae with moderate abundance discrepancy factors (ADFs ~ 2–3), which could be an indication of a tiny fraction of metal-rich inclusions embedded in the nebula (bi-abundance). In this work, we have constructed photoionisation models to reproduce the optical and infrared observations of the planetary nebula PB 8 using a non-LTE stellar model atmosphere ionising source. A chemically homogeneous model initially used cannot predict the optical recombination lines. However, a bi-abundance model provides a better fit to most of the observed optical recombination lines from N and O ions. The metal-rich inclusions in the bi-abundance model occupy 5.6% of the total volume of the nebula, and are roughly 1.7 times cooler and denser than the mean values of the surrounding nebula. The N/H and O/H abundance ratios in the metal-rich inclusions are ~1.0 and 1.7 dex larger than the diffuse warm nebula, respectively. To reproduce the Spitzer spectral energy distribution of PB 8, dust grains with a dust-to-gas ratio of 0.01 (by mass) were also included. It is found that the presence of metal-rich inclusions can explain the heavy element optical recombination lines, while a dual-dust chemistry with different grain species and discrete grain sizes likely produces the infrared continuum of this planetary nebula. This study demonstrates that the bi-abundance hypothesis, which was examined in a few planetary nebulae with large abundance discrepancies (ADFs > 10), could also be applied to those typical planetary nebulae with moderate abundance discrepancies.

We have reviewed the X-ray pulse profiles from a large number of observations of the accreting binary pulsar GX 1+4 obtained during the last 25 years. The profiles cover various energy ranges between 1 and 100 keV. Using these data we present a coherent picture of present and past pulse profiles and the variations of these pulse profiles with time. The pulse shape is dependent on both the X-ray luminosity and whether the pulsar is spinning up or down. Profiles measured during the GX 1+4 high state in the 1970s are all trailing edge bright. Subsequently the profiles have generally been symmetric or leading edge bright. Rossi X-ray Timing Explorer (RXTE) satellite data taken in July 1996 show that similar pulse shape variations can occur on a timescale of hours. The implications of this new information for accretion models is discussed.

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.

Infrared observations of nova light curves reveal that classical novae form grains in the expanding shells, ejected into the interstellar medium as a consequence of a violent outburst. Such grains contain nucleo-synthetic fingerprints of the nova explosion. In this paper, we analyse different isotopic signatures expected to be present in nova grains on the basis of detailed hydrodynamic calculations of CO and ONe novae and compare them with recent determinations of presolar nova grains from the Acfer 094 and Murchison meteorites.

Clustering commodity displays into a Tiled Display Wall (TDW) provides a cost-effective way to create an extremely high resolution display, capable of approaching the image sizes now generated by modern astronomical instruments. Many research institutions have constructed TDWs on the basis that they will improve the scientific outcomes of astronomical imagery. We test this concept by presenting sample images to astronomers and non-astronomers using a standard desktop display (SDD) and a TDW. These samples include standard English words, wide field galaxy surveys and nebulae mosaics from the Hubble telescope. Our experiments show that TDWs provide a better environment than SDDs for searching for small targets in large images. They also show that astronomers tend to be better at searching images for targets than non-astronomers, both groups are generally better when employing physical navigation as opposed to virtual navigation, and that the combination of two non-astronomers using a TDW rivals the experience of a single astronomer. However, there is also a large distribution in aptitude amongst the participants and the nature of the content also plays a significant role in success.

High quality near-infrared (1-5 μm) spectra of SN 1987A have been obtained at MSSSO, AAO, ESO, CTIO and SAAO with good temporal coverage. These near-infrared observations are reviewed with particular reference to spectra obtained by the MSSSO group on the ANU 2.3m telescope at Siding Spring Observatory.

The cosmic ray ground-level enhancement (GLE) of 24 October 1989 was the last of a series of GLEs associated with the same solar active region. Intensity enhancements were observed by at least 31 neutron monitors in the worldwide network, with the largest increase (~200%) observed at South Pole, Antarctica around 20:30 UT. Using a least-squares model fit to all available neutron monitor data, spectra, apparent source directions and particle pitch angle distributions have been derived. The effect of disturbed geomagnetic conditions has also been taken into account.

We have observed eight AGN since 1993 in the energy region above several hundred GeV using the CANGAROO telescopes. We observed Mrk 421 for ten nights with the CANGAROO-II 10 m telescope during its active state in early 2001 using the very large zenith angle technique. Our preliminary result implies the detection of gamma-ray emission from Mrk 421 in the energy range above 9.3 TeV. The high energy peaked BL Lacs (HBLs) PKS 2005–489 and PKS 2155–304 have been also observed. No statistically significant signals are found for both HBLs and flux upper limits are obtained. A summary of results of observations of AGN is presented in this paper.