bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversal of the Sense of Polarisation in Solar and Stellar Radio Flares
Authors: Melrose D. B. , Robinson P. A.
Published: July 2016

It is shown that numerical integration of the equation of polarisation transfer for generalised Faraday rotation provides an alternative to mode-coupling theory for treating propagation through a quasi-transverse (QT) region. At a QT region, where the sign of the component of the magnetic field along the ray path reverses, the sense of circular polarisation reverses below a frequency ωt, and is unchanged above ωt. There is a long-standing difficulty in the interpretation of the polarisation of radio emission from bipolar regions on the Sun: observational and theoretical estimates of ωt appear inconsistent. The alternative approach may help resolve this difficulty.
Shock Drift Acceleration and Type II Solar Radio Bursts
Authors: Street Arthur G. , Ball Lewis , Melrose D. B.
Published: July 2016

Shock drift acceleration of the electrons which produce herringbone structure in type II bursts is considered. A non-coplanar component of the magnetic field within the shock front and an electric field across the shock are taken into account. A quantitative difficulty with shock drift acceleration is identified, and possible ways of overcoming the difficulty are outlined.
The Cosmic Ray Ground-level Enhancement of 24 October 1989
Authors: Cramp J. L. , Humble J. E. , Duldig M. L.
Published: July 2016

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.
Variable Radio Sources at 843 MHz
Authors: Campbell-Wilson D. , Hunstead R. W.
Published: July 2016

This paper is a preliminary report on the flux density monitoring of calibration sources used at the Molonglo Observatory Synthesis Telescope. We show two examples of large amplitude variability at 843 MHz which we attribute to refractive scintillation in the Galactic interstellar medium.
Increasing the Field Size of the Molonglo Observatory Synthesis Telescope
Authors: Large M. I. , Campbell-Wilson D. , Cram L. E. , Davison R. G. , Robertson J. G.
Published: July 2016

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.
Magnetic Fields and Shocks in Molecular Clouds
Authors: Byleveld S. E. , Melrose D. B. , Pongracic H.
Published: July 2016

We discuss the expected properties of shocks in molecular clouds when the effect of a magnetic field is included. The results suggest that shocks should have magnetic precursors, and may be C-shocks rather than J-shocks, but the observations are not obviously consistent with this prediction. The effect of these shock properties on cloud collisions triggering star formation is discussed.
How Similar are Type Ia Supernovae?
Authors: Stathakis Raylee A. , Sadler Elaine M.
Published: July 2016

We have compared the spectra of six Type Ia supernovae, at ages between 4 and 404 days after maximum light, to see whether all show similar evolutionary behaviour. We find that the spectral lines between 6800 Å and 8000 Å follow a smooth evolutionary trend, but that lines redward of 8000 Å show significant differences. SN 1987I and SN 19880 show extra emission over a broader wavelength region, possibly due to OI 8446 Å emission which would indicate higher envelope densities for these objects. Our results are consistent with the trend of expansion velocity with parent galaxy type reported by Branch and van den Bergh (1993). Variations within the class of Ia SNe may affect their use as standard candles.
Diffusive Shock Acceleration by Multiple Shock Fronts with Differing Properties
Authors: Pope M. H. , Melrose D. B.
Published: July 2016

The effect of diffusive shock acceleration on a distribution of particles is explored for multiple shocks, taking into account adiabatic expansion between the shocks. Specifically, the spectral index is calculated numerically for two cases: a sequence of identical shocks, and a sequence of pairs of shocks with alternating shock strength. How these two cases evolve to the asymptotic limit is examined, and it is shown that the evolution of the paired-shock case can be described by a sequence of identical shocks with shock strength equal to the mean of the two.
Accretion Geometry of Synchronously Rotating Magnetic Cataclysmic Variables: Theories versus Observations
Authors: Wu Kinwah , Wickramasinghe D. T. , Bailey J. , Tennant A. F.
Published: July 2016

We review the magnetic locking of the white dwarf and the companion star in AM Herculis-type binaries for various white dwarf magnetic field structures, and compare the theoretical results with observations. The model in which the white dwarf has a dipole plus a quadrupole field is found to be in closest agreement with the recent observations.
An H I Mosaic of the Small Magellanic Cloud
Authors: Staveley-Smith L. , Sault R. J. , McConnell D. , Kesteven M. J. , Hatzidimitriou D. , Freeman K.C. , Dopita M. A.
Published: July 2016

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.
Induced Compton Scattering in a Pulsar Wind
Authors: Hardy S. J. , Melrose D. B.
Published: July 2016

We resolve a conflict in the literature concerning the effect of induced Compton scattering on the propagation of radio waves through the electron–positron wind surrounding a pulsar.
Multi-wavelength Observations of Galactic Winds
Authors: Bland-Hawthorn J.
Published: July 2016

It has long been suspected that winds of thermal and/or relativistic particles are a common feature of both active and normal galaxies. Galactic winds are likely to be an important mechanism, particularly at high redshift, by which energy and metals from galaxies are subsequently dumped into the intergalactic medium. Both observational and theoretical studies of wind processes remain in their infancy, largely because astrophysical winds are difficult to detect. Future satellite missions will make systematic surveys possible for the first time. In this review, we summarise the current evidence for galactic-scale winds, particularly in energy bands where the wind emission is spatially resolved. We also discuss observational limitations and problems of interpretation.
Solar Second Harmonic Plasma Emission and the Head-on Approximation
Authors: Willes A. J. , Robinson P. A. , Melrose D. B.
Published: July 2016

The coalescence of two Langmuir waves, L and L′, produces emission at twice the plasma frequency in type II and type III solar radio bursts. The analysis of the coalescence process is usually simplified by assuming the head-on approximation, where the wavevectors of the coalescing waves satisfy kL′ ≈ −kL, corresponding to the two Langmuir waves meeting head on. However, this is not always a valid approximation, particularly when the peak of the Langmuir spectrum lies at small wavenumbers, for narrow band spectra, and for spectra with broad angular ranges. Realistic Langmuir wave spectra are used to investigate the effects of relaxing the head-on approximation.
Asteroid Discovery Efficiencies for Telescope Systems at Siding Spring
Authors: Steel Duncan
Published: July 2016

Relative efficiencies for the discovery of Earth-crossing asteroids (ECAs) are modelled for various telescopes at Siding Spring. It is found that the narrow-field instruments—the Anglo-Australian Telescope and the 40 in and 2·3m reflectors—are not competitive in this regard for present CCD imaging systems. The UK Schmidt Telescope (UKST), if used to take short-exposure stereo pairs of photographs, would be an effective search tool, outperforming all current systems apart from the Ground-based Electro-Optical Deep Space Surveillance (GEODSS) systems now being implemented by the US Air Force for ECA searches. If a CCD mosaic were fitted to the UKST, its performance would far exceed that of any other device at Siding Spring, and it would produce ECA discoveries at a rate around 3–4 times as high as GEODSS, but at considerable expense. The most sophisticated search instrument currently in use is the University of Arizona’s Spacewatch telescope; a notable result found here is that even with its present CCD, the Automated Patrol Telescope (APT) of the University of New South Wales would be able to match or outperform Spacewatch for all ECA sizes, including ~10m objects, should this modelling be a reasonable representation of its real performance. In terms of cost-effectiveness and telescope availability, the conclusion arrived at herein is that the APT, equipped with small-pixel but large-format CCD chips of high quantum efficiency, would be an extremely effective ECA search instrument: if operated with 12 μm pixel chips covering a 4° × 4° field it might produce ECA discoveries at a rate well in excess of the combined rate for all current search programs.
Using the COSMOS/UKST Southern Sky Object Catalogue
Authors: Drinkwater Michael J. , Barnes David G. , Ellison Sara L.
Published: July 2016

A complete copy of the compressed COSMOS/UKST Southern Sky Object Catalogue is now available on-line at the Anglo-Australian Observatory and the Australia Telescope National Facility. The catalogue lists image parameters for all objects detected to a limit of BJ ≈ 21·5 in the UK Schmidt Southern Sky Survey. We have written software to access the catalogue efficiently and generate finding charts or text listings of the image parameters. In this paper we describe the software and give some examples of its use. We also discuss the astrometric precision of the catalogue.
Why Antarctica?
Authors: Burton Michael G.
Published: July 2016

The dry, cold, tenuous and stable air above the Antarctic Plateau provides superb conditions for the conduct of many classes of astronomical observations. We review in particular the rationale for undertaking near-IR, mm and particle astronomy in Antarctica, disciplines where telescopes are now operating at the US Amundsen-Scott South Pole Station.
An Automated DIMM Telescope for Antarctica
Authors: Dopita Michael A. , Wood Peter R. , Hovey Gary R.
Published: July 2016

A knowledge of the on-ice seeing is a key requirement for planning future Antarctic observatories. In this paper we discuss the likely negative impact on seeing produced by the development of the deep winter surface temperature inversion (Ekman layer). The Automated Astronomical Site Testing Observatory (AASTO) will deploy, as one of its complement of site-testing instruments, an automated differential image motion monitor (DIMM) telescope designed to generate seeing data throughout the Antarctic winter. Here we describe the multi-aperture concept which has been developed for this mission, and touch upon some of the critical technological considerations associated with the low power budget and with the requirement of autonomous operation at very low temperature (–90°C).
POST: A Polar Stratospheric Telescope for the Antarctic
Authors: Dopita Michael A. , Ford Holland C. , Bally John , Bely Pierre
Published: July 2016

The tropopause, typically at 16 to 18 km altitude at the lower latitudes, dips down to only 8 km in the polar regions, allowing access to the cold, dry and nonturbulent lower stratosphere by tethered aerostats. These can float as high as 12 km, have long operating lifetimes, and are extremely reliable. In contrast to free-flying balloons, they can stay on station for weeks at a time, and payloads can be safely recovered for maintenance and adjustment and relaunched in a matter of hours. We propose to use such a platform, located first near Fairbanks, Alaska, and later in the Antarctic, to operate a new-technology 4 m telescope with diffraction-limited performance in the near infrared. Thanks to the low ambient temperature (~200 K), thermal emission from the optics is of the same order as that of the zodiacal light in the 2–3 μm band. Since this wavelength interval is the darkest part of the zodiacal light spectrum from optical wavelengths to 100 μm, the combination of high-resolution images and a very dark sky make it the spectral region of choice for observing galaxies, QSOs and clusters of galaxies at the formation epoch of galaxies.
Educational Outreach Programs at the Center for Astrophysical Research in Antarctica
Authors: Sweitzer J. S. , Brass C. , Harper D. A. , Hawkins L. , Kron R. G. , Whitt A. S.
Published: July 2016

The Center for Astrophysical Research in Antarctica conducts various educational outreach programs as part of its mission as a National Science Foundation Science and Technology Center. The method behind the outreach programs is one of forging partnerships between Center researchers and other educational organisations. The main program serves primary and secondary students in Chicago. The core of the program is called Space Explorers and is targeted at high school students. These students attend a summer residential institute at the University of Chicago’s Yerkes Observatory. The high school Space Explorers then extend the reach of the program during the academic year by teaching in primary schools using a portable planetarium. The Center also pursues many other outreach activities and is in the process of forming an Antarctic Education Alliance.
SPH Simulations of Accretion Disks and Narrow Rings
Authors: Maddison Sarah T. , Murray James R. , Monaghan Joe J.
Published: July 2016

We model a massless viscous disk using smoothed particle hydrodynamics (SPH) and note that it evolves according to the Lynden-Bell & Pringle (1974) theory until a non-axisymmetric instability develops at the inner edge of the disk. This instability may have the same origin as the instability of initially axisymmetric viscous disks discussed by Lyubarskij, Postnov & Prokhorov (1994). To clarify the evolution we evolved single and double rings of particles. It is actually inconsistent with the SPH scheme to set up a single ring as an initial condition because SPH assumes a smoothed initial state. As would be expected from an SPH simulation, the ring rapidly breaks up into a band. We analyse the stability of the ring and show that the predictions are confirmed by the simulation.
Accretion Phenomena in Cataclysmic Variables
Authors: Bailey Jeremy
Published: July 2016

The processes of accretion onto the white dwarf in a cataclysmic variable are reviewed. These systems provide the most easily observable examples of accretion disks, and enable the structure of the accretion region to be studied in detail. The properties of column accretion onto magnetic cataclysmic variables are also described.
Production of Pairs by Linear Acceleration Emission
Authors: Melrose D. B.
Published: July 2016

The possibility is considered that core emission in pulsars results from secondary e± pairs generated through linear acceleration emission (LAE), rather than the conventional curvature emission (CE). It is found that this is possible in principle, but only under conditions that appear not to be satisfied in practice.
Molecular Clouds and Millimetre Astronomy
Authors: Burton Michael
Published: July 2016

A condensed summary of molecular cloud astrophysics is presented. Some examples of the power of combining near-IR and mm molecular line observations are given.
The Jets in Radio Galaxy B1308–441
Authors: Jones Paul A.
Published: July 2016

The giant radio galaxy B1308–441 has prominent two-sided jets, typical of Fanaroff–Riley class I radio galaxies, but there is an unusual bright spot in the SE jet 2 arcmin from the core that gives a marked asymmetry to the source. Observations at 1·37 and 2·37 GHz with the Australia Telescope Compact Array show that the bright spot has a flattened spectrum and high polarisation, and changes the direction of the SE jet. There is a diffuse optical object close to the bright spot which may be related to a shock in the jet.
Angular Pointing and Guidance for the Sydney University Stellar Interferometer
Authors: Tango W. J. , Thorvaldson E. D.
Published: July 2016

The Sydney University Stellar Interferometer (SUSI) uses siderostats (plane, alt–azimuth mounted mirrors) to reflect starlight into the instrument. The analysis of the pointing and guidance of the siderostats by traditional methods is not practical and vector algebra has been used to develop the required algorithms. Real siderostats will not be ideal and can be modelled by a set of parameters. The methods for determining the model parameters and for incorporating them into the guidance and pointing algorithms are described. Field rotation also affects the operation of SUSI, and the field rotation angle and related quantities are also determined.
A Simple Model of a Coronal Hole
Authors: Summers D.
Published: July 2016

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.
Multiple-Frequency Measurements of a Flare Continuum Event
Authors: Robinson R.D.
Published: July 2016

A type of metre-wavelength continuum is observed in close association with solar flares and Type II radio bursts. This continuum is stationary in position, often intense, of a long duration (occasionally lasting well over an hour) and highly polarized (Robinson and Smerd 1975; Robinson 1978). It is thought to be produced by the conversion of Langmuir waves to electromagnetic waves near the local plasma frequency. Because of its close association with Type II bursts, the class has been designated as Type II related flare continuum, or FCII. In this paper I examine a particularly clear example of such an event, with emphasis on the relation between the Type II and the start of the continuum.
A Study of Multiple Type II Solar Radio Events
Authors: Robinson R.D. , Sheridan K.V.
Published: July 2016

A Type II solar radio burst is a relatively narrow-bandwidth metre-wavelength emission which drifts outward in the solar corona at a velocity between 500 and 1500 km s-1. It was first described by Wild and McCready (1950) and since then it has been the subject of numerous investigations (see e.g. McLean 1974; Nelson and Robinson 1975).
A Radio Continuum Survey of Southern E and SO Galaxies at 2.7 GHz and 5.0 GHz
Authors: Sadler E. M.
Published: July 2016

The reason why some early-type galaxies contain powerful radio sources is not yet well understood, but it is often suggested that an external factor such as interaction with a neighbouring galaxy may be involved in triggering a radio source (Gisler 1976, Dressel 1981, Hummel 1981b). Radio emission may be enhanced in galaxies which have a close companion for several reasons, such as a gravitational perturbation or the possibility of gas accreted from the companion fuelling a central source. The latter effect might be expected to be more pronounced in elliptical galaxies, which are generally gas-poor (Faber and Gallagher 1976).
The Medium Dispersion Prism of the UK Schmidt Telescope
Authors: Cannon R. D. , Dawe J. A. , Morgan D. H. , Savage Ann , Smith M. G.
Published: July 2016

The U.K. 1.2 metre Schmidt Telescope acquired its first full aperture objective prism in 1975. This was a very low dispersion prism (2400 Å/mm at 4300 Å) which has been found to be particularly useful in searching for faint QSO’s.
A Survey of Australian Sites Suitable for Telescopes Operating at mm-wavelengths
Authors: Fourikis N. , Taylor K. N. R. , Sakelis S.
Published: July 2016

MM-(millimetre) wave astronomy offers over one hundred gigahertz of explorable spectrum within which the transitions of a large number of important molecules occur. Some of these molecules are as simple as carbon monoxide while others are as complex as trans-ethyl alcohol and methylamine; the former species are widely distributed in the Galaxy while the latter species are more localized in extent.
A Catalogue of Major Metre-Wavelength Solar Events Recorded by the Dapto and Culgoora Solar Radio Observatories (1961-1981)
Authors: Robinson R. D. , Tuxford Jennifer M. , Sheridan K. V. , Stewart R. T.
Published: July 2016

We present a catalogue of 668 major metre-wavelength radio events. The data was collected from dynamic spectra (taken at Dapto, N.S.W. until 1966 and at Culgoora, N.S.W. thereafter) by means of a radio spectrograph, which records the intensity of radio emission as a function of both frequency and time. A description of the major types of metre-wavelength phenomena can be found in Wild et al. (1963), Kundu (1965), Wild and Smerd (1972) and Kruger (1979), and details of the radio spectrograph in Sheridan (1963, 1967) and Labrum (1972).
A search for prompt ultra-high-energy gamma rays from supernova 1987a
Authors: Bird D. J. , Bruce T. E. G. , Ciampa D. , Clay R. W. , Corani C. L. , Edwards P. G. , Gregory A. G. , Patterson J. R. , Protheroe R. J.
Published: July 2016

A search has been made using the Buckland Park air shower array for evidence of any excess of events from the direction of the recent supernova in the Large Magellanic Cloud. Upper limits resulting from this search and their significance are discussed in this paper.
A Proposal for an Australian Space Astronomy Data Centre
Authors: Tuohy Ian R.
Published: July 2016

The concept of a national centre for the analysis of archival and contemporary space astronomy data has been identified as a highly desirable objective by the Australian astronomical community for a number of years. With the approaching launch of the Hubble Space Telescope (HST), the time is now appropriate to actively pursue this objective. HST will generate a data archive of unique astrophysical significance over the course of the ≥ 20 year mission. It is essential that Australian astronomers have efficient access to this resource, both to maintain our position at the forefront of astronomical research, and to complement our major ground-based facilities (particularly the AAT and the Australia Telescope). An Australian facility would provide efficient access to HST data and also to the analysis tools and expertise necessary for utilizing the data. Archival data from other NASA and ESA missions could also be supported, and in the longer term, the facility could become the science centre for the Lyman/Quasat missions.

This paper presents the case for an Australian Space Astronomy Data Centre, reviews the astronomy missions of relevance, and addresses the role, scope and implementation timescale of the facility. Preliminary estimates are given for the resources that will be required, and possible routes for funding the centre are outlined. Above all, the report is intended as a Discussion Paper to promote further consideration of the concept and of the service that could be provided to the Australian astronomical community.
Evolution of a Horizontal Scale for Magnetoconvection
Authors: Murphy J. O. , Lopez J. M.
Published: July 2016

The non-linear modal equations governing magnetoconvection in a fluid layer have been integrated forward in time incorporating a discrete spectrum of horizontal wave numbers, distributed within the range supporting convection. By progressively deleting some of the decaying modes and introducting additional modes within the range of growth it is possible to establish the evolution, or otherwise, of a preferred horizontal scale, which determines the horizontal cell size of the convective motions. Further, the influence of the magnetic field strength on cell extent can also be determined.
Star Formation in Cooling Flows (Invited Paper)
Authors: Nulsen P. E. J. , Johnstone R. M. , Fabian A. C.
Published: July 2016

X-ray data show that substantial quantities of hot gas are cooling near the centres of many clusters and groups of galaxies. The existence of such cooling flows has been challenged because of the lack of evidence for star formation from the cooled gas. Spectra of cooling flow galaxies show filling in of the continuum shortward of the break at 4000 Å relative to normal elliptical galaxies. This is consistent with some continuing star formation. Extended regions of line emission are commonly associated with cooling flows. If the initial-mass-function of the newly formed stars which affect the 4000 Å break is like that which applies in the solar neighbourhood, then these stars can also power the line emission. The strength of the 4000 Å break is shown to correlate with the Hβ flux in the manner expected when this is the case. This allows us to esimate the star formation rate from the line luminosity.

The rate of star formation required to account for the line emission still falls well short of the rate at which gas is inferred to be cooling. It is argued that, nevertheless, the cooling gas is probably forming into stars. The overall initial-mass-function must be different from that which applies in the solar neighbourhood, but this should not be surprising given the different ambient conditions in a cooling flow.
Gamma-Ray Astronomy From Balloons and Satellites (Invited Paper)
Authors: Sood R. K.
Published: July 2016

Gamma-ray astronomy has traditionally been a difficult field of research due to the low fluxes from astronomical objects and the inherently poor angular response of detectors. Progress made in the field in the last twenty years is reviewed. Many major astrophysical problems can only be addressed with the future operation of more sensitive satellite experiments. Recent gamma-ray observations of the supernova SN1987 a are briefly discussed.
A Multi-Purpose, Multi-Channel Radiospectrograph for the Parkes Telescope
Authors: Lim J. , Nelson G. J. , Vaughan A. E.
Published: July 2016

The design and scientific applications of a 96-channel filter spectrograph of 1 MHz resolution are presented. The spectrograph is currently under construction and will be installed on the Parkes telescope in 1987-1988. Its main scientific objective is dynamic spectral studies of decimetre- and metre-wavelength bursts from flare stars. However, it will also be used for performing large-scale pulsar surveys, and dynamic spectral observations of interplanetary scintillation of compact sources, interstellar scintillation of compact extragalactic sources, and interesting radio sources in general.

We show that plasma emission generated in the coronae of flare stars should be detectable at metre- and decimetre-wavelengths. We plan to search for fundamental and second-harmonic plasma radiation by observing in two harmonically related bands, 200 to 250 MHz and 400 to 500 MHz. With noise-adding to stabilize receiver gain, the sensitivity (3σ) of each channel of the spectrograph is ∼ 1.5 Jy for a 1-s integration. Previous studies have reported peak flux densities of up to ∼ 35 Jy and ∼ 12 Jy at 240 MHz and 410 MHz respectively for radio bursts from flare stars.
How unique was SN 1987A?
Authors: van den Bergh S.
Published: July 2016

Supernovae of type II (SN II) are found to exhibit a correlation (r = 0.45 ± 0.15) between M(max) and parent galaxy luminosity. This correlation might be understood by assuming that the metal-rich red supergiant progenitors of SN II in luminous galaxies have more extended photospheres than do those of the more metal-deficient evolved progenitors of SN II on low-luminosity galaxies. For h = 0.5 it is found that SN 1987A was ∼1.5 mag fainter at maximum in blue light than any other well-observed SN II. For h = 1.0 SN 1948B, SN 1973R, SN 1972Q and SN 1987A exhibit comparable MB(max). It would be important to undertake systematic searches for sub-luminous SN II in dwarf galaxies and in the metal-poor extreme outer regions of giant- and supergiant spirals.
Infrared Observations of SN 1987A: Probing the Ejecta and its Surrounding Medium
Authors: Dwek E.
Published: July 2016

The extremely rare occurrence of a relatively nearby supernova, SN 1987A, provides astronomers with a unique opportunity to conduct the most detailed multi-wavelength analysis of this event and its effect on the ambient medium. Looking inside the supernova, astronomers are getting their first ‘unbiased’ view of the composition of the expanding ejecta. The infrared (IR) region of the spectrum can carry the signature of products ranging from heavy elements, synthesised during the early phases of the expansion, to molecules and dust formed after the ejecta underwent significant cooling. Probing the ambient medium, IR observers can gain information on the presence and distribution of dust in close proximity (∼1 pc) to the supernova (SN), and on the interaction of the SN blast wave with the surrounding dusty medium. At larger distances from the SN, they can set constraints on dust properties in the scattering dust layers detected at distances of ∼120 and ∼330 pc from the supernova.
Observations of SN 1987A from Ginga
Authors: Inoue H.
Published: July 2016

Results of the observations of SN 1987A from Ginga are presented. The first detection of X-rays from the SN 1987A was July, 1987. The energy spectrum is quite unnusual for any of the known classes of X-ray sources, and apparently consists of two seperate components; a soft and a hard component. The soft component is significantly time-variable, and also showed a flarelike increase in January, 1988. Whereas, the intensity of the hard component has remained fairly stationary for more than 300 days. The origins of the two components are also discussed.
Shells around Hot Stars
Authors: Lozinskaya T.A.
Published: July 2016

The influence of the progenitor’s stellar wind on the supernova event, and subsequent development of a remnant are discussed. Various morphological differences between SN remnants and the implications for previous wind activity are described. A detailed look at the effects in the ring nebula NGC 6888 is presented.
Taxonomy of Supernovae
Authors: Filippenko Alexei V.
Published: July 2016

I review the observed properties of supernovae (SNe), concentrating on recent results obtained from high-quality optical spectra. Although most SNe Ia have similar characteristics at comparable phases, there are some notable variations, particularly in the velocities of the ejecta. Moreover, there is very preliminary evidence for significant differences between the spectra of SNe Ia in H II regions and in elliptical galaxies. SNe II exhibit a wide range of spectral properties, as expected if they are produced by massive stars. At late times strong lines of [O I] and [Ca II] appear in most SNe II, including SN 1987A. In some objects, however, these are absent; the spectrum of SN 1987F, for instance, closely resembled that of a Seyfert 1 nucleus, with prominent H I and Fe II emission lines. Type Ib SNe, which lack the 6150Â absorption band typical of SNe la near maximum brightness, develop strong emission lines of [O I] and [Ca II] many months past maximum, but hydrogen is absent. Hα emission with a P-Cygni profile has, on the other hand, been detected in the early-time spectrum of SN 1987K, an object which later became spectroscopically indistinguishable from an old SN Ib. There is evidence for very weak Hα in the early spectra of several additional SNe Ib. Moreover, 7 – 8 months past maximum the [O I]/Hα and [Ca II]/Hα intensity ratios in SN 1987A were higher than in a few other well-observed SNe II at corresponding times. Hence, Type II and Type Ib SNe may form a continuous sequence in which the mass of the hydrogen envelope is the main variable.
A Model for Solar Flares Invoking Weak Double Layers
Authors: Khan J. I.
Published: July 2016

A simple model for solar flares is described which invokes many ion-acoustic double layers in the source region. The ability of the model to explain some of the observed characteristics of solar flares is discussed, particular attention being paid to the well-observed high-energy flare examined by de Jager et al. (1987).
The Buoyancy of U-Loops
Authors: Wilson P. R.
Published: July 2016

The problem of the surface migration of solar magnetic fields is discussed. It is shown that, unless some form of reconnection takes place below the surface, magnetic tension should effectively prevent such migration and the possibility of U-loop formation and transport is considered. As a first step, the buoyancy of a magnetic ‘U-loop’ within an isothermal atmosphere is considered. It is shown that such a configuration may form by the reconnection of the arms of an Ω-loop associated with an active region, and is likely to be buoyant initially and rise through the region. However, as it rises, the net buoyancy decreases and, provided that the temperature within the loop is even marginally less than that outside, it will reach a sub-surface configuration in which the net buoyancy is zero. The significance of this result for solar magnetic fields is then assessed.
The Stability of Swirling Jets
Authors: Coleman Colin S.
Published: July 2016

The stability of a swirling cylindrical jet of compressible fluid is examined by performing a normal mode analysis and numerically solving the eigenvalue problem. Perturbations of the form f(r)exp[i(ωt-mϕ-kz)] are considered, where f is any fluid variable. Instabilities which are characteristic of both a non-swirling (top-hat) jet and a Rankine vortex are investigated for a particular axial wavenumber.

The vortex instabilities are weak, and are found to remain weak when axial flow is present. The jet instabilities are much stronger, but axial flow is a stabilizing influence. The positive helicity (km > 0) non-axisymmetric modes (m ≠ 0) are stabilized by a small component of azimuthal flow. The axisymmetric mode (m = 0) and the negative helicity non-axisymmetric modes persist in rapidly swirling jets, but with a greatly reduced growth rate.
The Design and Construction of the University of Adelaide Bicentennial Gamma-Ray Telescope
Authors: Clay R. W. , Giles D. H. , Gregory A. G. , Patterson J. R. , Prescott J. R. , Protheroe R. J. , Smith N. I. , Taaffe L , Wild N.
Published: July 2016

The design and construction of the 30 m2 Bicentennial Gamma Ray Telescope at Woomera South Australia is described. This novel instrument is now completed and commissioning is underway. It is designed to observe astronomical sources at energies greater than ∼ 500 GeV by means of atmospheric Cerenkov light. It contains 55 spherical, glass mirrors of focal length 2.66 m arranged in three groups of 10 m2, to focus the light onto three sets of detectors operated in fast co-incidence. The recording electronics includes a rubidium clock to enable pulsars to be studied.
Development of the Buckland Park Air Shower Array for Anisotropy Measurements
Authors: Bird D. J. , Clay R. W.
Published: July 2016

The cosmic ray array at Buckland Park is being developed to extend its useful collecting area at 1016 eV to ∼105m2 so that anisotropy measurements can be made at higher energies than previously possible with that system. A new array is also being designed to assist with this investigation. Design considerations for the new arrays are discussed.
Photometric Observations of Flares on Proxima Centauri
Authors: Kroupa P. , Burman R. R. , Blair D. G.
Published: July 2016

Proxima Centauri was observed photoelectrically in the period July-September 1987 with a newly-installed computer-interfaced photometer. Four definite flares and six further possible events were recorded. The level of Proxima’s flaring activity was examined and no significant change since 1969 found.
The Fleurs Southern Benchmark Program
Authors: Batty Michael J. , White Graeme L. , Bunton John D. , Brown David R. , Corben Julian B.
Published: July 2016

A program to determine accurate radio positions and optical identifications of southern flat-spectrum radio sources has been undertaken with the six-dish array of the Fleurs synthesis telescope at 1.4 GHz and using the SERC J sky survey. This sample covers the declination range −80° to −50° and comprises all 198 sources from the Parkes catalogue with α of > −0.5 and flux density of 0.25 Jy.

The radio astrometric phase of the program is complete. We conclude that by comparison with accurate VLBI positions the FST positions have r.m.s. uncertainties of ∼0″.9. There is no global bias in the FST positions at the 0″.2 to 0″.3 level relative to the JPL VLBI extragalactic reference frame. A comparison with positions from the Parkes catalogue shows that in the southern regions the Parkes catalogue has rms position errors of about 9″. There is no significant bias between the FST and Parkes positions.
Radio Polarization and Magnetic Fields in Six Supernova Remnants
Authors: Milne D. K. , Caswell J. L. , Kesteven M. J. , Haynes R. F. , Roger R. S.
Published: July 2016

8.4 GHz linear polarization maps, obtained with the Parkes radio telescope, are presented for six southern supernova remnants. These results are compared with published and unpublished polarization maps at 5 GHz to derive the magnetic field direction and Faraday rotation measure distribution.

These results are part of a program to map the magnetic fields in galactic supernova remnants and complement our program to obtain high-resolution maps of galactic SNRs using the Molonglo Observatory Synthesis Telescope; five new Molonglo maps are presented here.
The Space Distribution of Local Radio and X-ray Galaxies
Authors: Shaver P. A.
Published: July 2016

Extended abstract

Local large scale structure is best studied using statistically complete samples which cover the entire sky, and for which full redshift information is available. The optical galaxy redshift surveys which have been made to date involve many thousands of objects but cover only limited parts of the sky, and so provide only a fragmented picture of local large scale structure. Complete samples of radio and X-ray galaxies are available, however, with large sky coverage. While the number of objects is small, they may still suffice to define the dominant local structures, particularly as they may preferentially sample the deeper gravitational potentials and so provide a more efficient tracer of dominant structure.
Australian Tree Ring Chronologies as Proxy Data for Solar Variability
Authors: Murphy J. O.
Published: July 2016

Data from the Solar Maximum Mission satellite suggests that there is a 0.1 percent variation in solar luminosity over the 11-year solar cycle with maximum output corresponding to maximum sunspot number. Tree ring chronologies can be utilized as proxy data to compile a record of the magnitude of past solar variability. Spectral analysis of tree ring series compiled from a site in Tasmania has established, among others, significant periodicities of about 90 and 11 years. The application of band pass filter techniques shows that the 11-year cycle present in some tree ring series correlates with the Zurich sunspot numbers over the period from AD1700, the extent of accurate sunspot records, with a time lag of about three years.
(UK) Schmidt–AAO Style into the 1990s
Authors: Savage A.
Published: July 2016

This is a brief description of the way I see the Schmidt functioning through the next three years. There are four important functions which must be maintained: (a) The Science from the Schmidt material must continue to be of the same high quality as that on which the Schmidt’s reputation has been built; (b) The service we provide to the Australian and British communities must continue despite the new trim (slim) appearance of the Schmidt staff and budget; (c) We must maintain our links with ROE, its Plate Library, which is the archive for Schmidt plate material, and Photolabs which provide some of the survey atlases; (d) We are being actively encouraged to promote Australian and British usage of the UK’s large measuring machines APM and COSMOS. Additionally, we are continually being encouraged to improve our efficiency. There is still at least one area in which we can do this and this is discussed.
Preliminary Results from the Automated Patrol Telescope CCD Camera
Authors: Brooks P. W.
Published: July 2016

The University of NSW Automated Patrol Telescope (APT), a modified 0.5 m Baker-Nunn Schmidt telescope situated at Siding Spring Observatory, Coonabarabran, Australia, was opened in June 1989. It features the unique combination of an extremely fast (f/1) optical system with a CCD (Charge-Coupled Device) camera at the prime focus, capable of both fast (50 Hz TV-rate) imaging and slow-scan integrated readout via a low noise Correlated Double Sampling amplifier. This combination of optics and detector gives a wide field (0.9° × 1.4°) suited to observing extended objects including the LMC, SMC and galaxies in the Sculptor group. First images from the APT are presented along with the results of noise, linearity and dark current measurements made to date with a 12-bit analog-to-digital converter. Results were (ADU = Analog-Digital Unit):
APM Surveys for High Redshift QSOs
Authors: Irwin M. J. , McMahon R. G.
Published: July 2016

The first QSO with a redshift z > 4 was found using a combination of UK Schmidt Telescope (UKST) plates and the APM automatic plate measuring machine (Warren et al. 1987a). By continuing to make use of UKST survey plates plus the APM facility we have added substantially to the number of known QSOs with z > 4. A brief description of the general survey technique is presented together with a preliminary discussion of some of the results obtained so far.
Observations of Six Southern Galaxies in the12CO(J = 1—0) Transition
Authors: Harnett J. I. , Wielebinski R. , Bajaja E. , Reuter H-P. , Hummel E.
Published: July 2016

We have mapped the southern galaxies NGC 613, 1313, 1433, 1566, 1672 and 2442 in the12CO(J = 1 → 0) transition with the 15-m Swedish European Submillimetre Telescope (SEST). The sample is based on galaxies previously observed in radio continuum with the Molonglo Observatory Synthesis Telescope (MOST). Strong emission is seen from the barred galaxies NGC 613 and NGC 2442 and from the active galaxies NGC 1566 and 1672. The weakest emission was from NGC 1433, while the Sd spiral NGC 1313 was not detected.
The Period Change Rate in the RS CVn Binary HD 5303
Authors: Thompson K. , Coates D. W. , Anders G.
Published: July 2016

From the observed timings of primary eclipse of HD 5303 we find that its 2.7 day period is increasing at a rate of about one second per year. In this paper we consider the implications of this in terms of mass transfer or mass loss from the system.
Starspot Parameters of the W UMa Type Eclipsing Binary SW Lacertae
Authors: Lee Woo-Baik , Sung Eon-Chang , Kang Young Woon
Published: July 2016

We present UBV photometry of SW Lac and analyse its light–curve to deduce starspot parameters for this star.
Two-channel Photometry of Cataclysmic Variables
Authors: Sullivan Denis J.
Published: July 2016

High-speed photometry of two cataclysmic variables is presented. The observations were made using a two-channel photometric system and the Mt John 0.6 or 1-m telescopes at Lake Tekapo in New Zealand. Both objects have only recently been identified as cataclysmic variables. One of the objects is a high inclination system featuring a deep eclipse in the light curve and a 5.5 hour period, while the other object, despite being relatively faint, clearly exhibits a 2.5 hour period and out of eclipse variability. Simultaneous monitoring of a nearby comparison star for this latter object was particularly beneficial, even during good photometric conditions.
The Atmospheric Extinction at Yonsei University Observatory in 1982–89
Authors: Jeong Jang Hae
Published: July 2016

More than 1000 coefficients of atmospheric extinction in the U, B and V passbands were obtained as a secondary result of long-term photometric monitoring of stellar objects at Yonsei University Observatory during 1982–1989. The long-term variation of the extinction coefficients of each passband are presented in this paper.
Chemical Fractionation in Gas Rings and the Formation of the Solar System
Authors: Prentice A. J. R.
Published: July 2016

The anomalously high density of the planet Mercury and the higher-than-solar rock-to-ice ratio in Jupiter’s moons Ganymede and Callisto cannot be explained by the conventional disc models of solar system formation. It is shown here that the unusual chemical signature of these bodies is the outcome of a process of chemical fractionation and orbital focussing which is peculiar to gas ring models of planet and regular satellite formation. Good numerical agreement with the observational data is obtained if the temperature of condensation of the planetary system closely followed the law Tn ≃ 680[R⊕/Rn]0.9 K, where Rn denotes the radial distance from the Sun.
A Cloud Detector for Automated Telescopes
Authors: Ashley M. C. B. , Jurcevic J. S.
Published: July 2016

An instrument is described that can detect clouds at night-time by sensing their infrared emission. The device can readily detect clouds that are difficult to see with the unaided eye on a moon-lit night. It can be used to provide an indication of how photometric the conditions are, to terminate exposures when cloud forms, and to close the dome when conditions become unsuitable for observing. The detector also has applications as an astronomical site-surveying instrument.
The Formation and Evolution of White Dwarfs
Authors: Bessell M. S.
Published: July 2016

A white dwarf is a body of stellar mass, but of planetary dimensions. It is self luminous with a surface temperature that has been observed as high as 70,000 K or as low as 4,000 K. Because of its low surface area the star is far fainter than a main sequence star of the same colour; equally the light it emits is bluer than that from a main sequence star of similar luminosity. Figure 1 is the HR diagram from data obtained by the US Naval Observatory showing the dwarf and white dwarf sequences.