bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of 4U 1608-52
Authors: Thomas R. M.
Published: July 2016

Tananbaum et al. (1976) have recently added to the Uhuru catalogue 4U1608-52, a source varying by over an order of magnitude in a time span of some months. They identified the object with MXB1608-52, a highly variable X-ray source of flares and bursts. (Kaluzienski et al. 1976; Belian et al. 1976; Grindlay and Gursky 1976a, b; Li 1976). There have been a number of earlier X-ray observations of sources very close to 4U1608-52 (Cooke and Pounds 1971; Luyendyk et al. 1973; Thomas et al. 1975; Grindlay and Gursky 1976b; Ricker et al. 1976), and in this paper we propose the identification of these earlier sources with 4U1608-52. We thereby obtain additional spectral information and can now rule out a globular cluster as the optical counterpart of the object.
The LMC Cluster Hodge 11
Authors: Freeman K. C. , Gascoigne S. C. B.
Published: July 2016

Hodge 11 (= SL 868) is a red, globular-like cluster (V ≅ 12.1, B—V = 0.62), situated on the east side of the LMC about 5 kpc projected distance from its centre (Gascoigne 1966). It was included in a programme to study the chemical evolution of the LMC by determining ages and metal abundances for a number of its clusters. Figure 1 shows a preliminary colour-magnitude diagram, found from four AAT plates calibrated with the AAT two-channel photometer. The choice of the radius, 1′.37 (23 pc), within which the stars were measured, was guided by the surface photometry of the cluster described later (Figure 3). But while it makes the number of “clean” stars inside the radius rather small, those outside it are too unlikely to be cluster members. As yet the calibration extends only to V = 19.6, and the nature of the cluster cannot be determined unambiguously. But Figure 1 already shows an unusual feature, in the very blue colour of the group of stars at V ≅ 19, B—V = 0.60, which on the usual interpretation would point to a metal abundance possibly lower than any yet encountered.
Radio and Optical Spectra of Sources from the Molonglo Deep Survey
Authors: Murdoch H. S. , White G. L.
Published: July 2016

We present here preliminary results of further radio and optical work being carried out on the Molonglo Deep Survey (Robertson 1977a, b, c) which reaches a density of ∼ 20,000 sources per sterad at a limiting flux density of 84 mJy at 408 MHz in three small areas of sky at declinations -20° and -62°. The position errors range from 4 to 15 arc sec r.m.s. depending on flux density. Optical identifications are being made by G. W. using the Palomar Sky Survey in the -20° region and the ESO and SRC surveys in the -62° region. In the latter case, where only one colour is available more accurate positions are necessary to identify QSO candidates. The Fleurs synthesis telescope is being used to obtain accurate positions.
Search for Light Variations of HD 101065
Authors: Przybylski A.
Published: July 2016

The eighth magnitude star HD 101065 is an extremely peculiar star with a unique spectrum characterized by numerous strong lines of the rare earths and the absence, or at least a remarkable weakening, of the lines of the iron group (Cowley et al. 1977). Besides the lanthanides only yttrium, zirconium, calcium and barium are definitely present in the atmosphere in substantial quantities. The evidence for the presence of lithium and strontium is subject to some doubt since these elements are represented only by one or two reasonably strong lines, which is insufficient for a positive identification in a spectrum as complex as that of HD 101065. The evidence for the presence of other elements is the subject of a critical examination in a recent paper by Cowley et al. (1977). The effective temperature of the star is about 6100 K (Przybylski, 1977) which is substantially lower than the temperature of any known Ap star. However, the effective temperature of HD 101065 is still subject to controversy (Wegner, 1976).
Observations of NH3 in Southern Sources
Authors: Batchelor R. A. , Gardner F. F. , Knowles S. H. , Mebold U.
Published: July 2016

Ammonia was the first interstellar molecule with more than two atoms to be discovered (Cheung et al. 1968). Since that time it has been observed in many HII regions and dark clouds (Mayer et al. 1973; Morris et al. 1973; Cheung et al. 1973; Kaifu et al. 1975). The molecule has a rich rotation-inversion spectrum with about 10 transitions in the range 23-25 GHz. Each line has hyperfine structure which permits, in principle, the determination of optical depths, filling factors and excitation. Unfortunately line brightness temperatures are low (<1 K) so that a low-noise receiving system and long integration times are required to exploit these possibilities.
Three Frequency Observations of a Moving Type IV Burst at the Limb
Authors: Nelson G. J.
Published: July 2016

On 1975 August 22 an outburst above the west limb of the Sun was observed with the Culgoora radioheliograph at 43, 80 and 160 MHz. The first stages of the event included intense type III/V bursts followed by a type II burst with multiple, fundamental and harmonic bands and herringbone structure. While the type II burst was still in progress a moving type IV burst appeared. It was eventually observed out to a distance of more than 3 R⊙. This was the first moving type IV burst observed with the two-dimensional radioheliograph operating at three frequencies; as such it provides valuable constraints on models of moving type IV sources.
Galactic Cosmic Rays in a Finite Solar Cavity
Authors: Webb G. M. , Gleeson L. J.
Published: July 2016

In this paper we model mathematically the propagation of galactic cosmic-rays in the solar cavity and study the effects of changing the physical parameters; in particular the radius of the cavity. We assume spherical symmetry with heliocentric distance r, momentum p and work in terms of F0(r, p) the mean distribution function with respect to momentum; it is related to JT the mean differential intensity w.r.t. energy by JT = p2F0. The boundary is at r = rb beyond which the galactic spectrum prevails; there is free escape of particles incident on rb from within, and the distribution is steady state.
Evidence on Chromospheric Structure from Observations of Solar Brightness Distribution at Millimetre Wavelengths
Authors: Labrum N. R.
Published: July 2016

Observations of the distribution of millimetre-wavelength brightness over the quiet Sun provide an important test of models of the solar chromosphere. The author and colleagues have recently carried out two investigations of the quiet-Sun brightness at 3 mm wavelength — one by means of a total eclipse observation (Labrumet al. 1978) and the other by aperture synthesis with a two-element interferometer (Archeret al. 1978). I present here a preliminary discussion of these and other measurements of millimetre-wavelength brightness distributions and of their interpretation in terms of chromospheric structure.
Sidereal Variations in Cosmic Rays at 365 hg cm-2
Authors: Fenton A. G. , Fenton K. B. , Humble J. E.
Published: July 2016

The University of Tasmania has been operating muon telescopes since mid-1971 in an underground power station operated by the Hydro-Electric Commission at Poatina in Northern Tasmania. The equipment is located beneath ~ 150 m of rock, corresponding to a total absorption depth of ˜ 365 hg cm-2. The initial pilot experiment was reported (Fenton and Fenton 1972) at the May 1972 meeting of A.S.A., and results from the first two full years of operation were presented to the Hobart meeting of A.S.A. two years later (Fenton and Fenton 1974). We now have complete data for the 5-year period 1972-1976, together with provisional data for 1977.
New Observations of the Beat Cepheid U Trianguli Australis
Authors: Shobbrook R. R. , Faulkner D. J.
Published: July 2016

The double-mode or beat Cepheids continue to pose a number of interesting questions in our search for an understanding of the pulsation properties of stars near the short period end of the instability strip. One such is how simultaneous pulsations in the fundamental and first overtone radial modes can occur for an appreciable fraction of Cepheids in the period range 1d < Pо < 5d.
Stellar Evolution, Mass Loss and Nucleosynthesis on the Asymptotic Giant Branch
Authors: Wood P. R.
Published: July 2016

In this review, I will be concentrating on problems related to the evolution of stars on the asymptotic giant branch (AGB). AGB stars are defined as stars which have completed core helium burning and have subsequently developed degenerate carbon/oxygen cores surrounded by hydrogen and helium burning shells; such stars have main sequence masses M≤9 M⊙ (Paczynski 1971; Becker and Iben 1980). In the HR diagram most AGB stars sit on the red giant branch. An exception to this rule occurs in Population II systems, where the AGB stars evolve asymptotically to the red giant branch from the blue side as the luminosity increases after completion of core helium burning on the horizontal branch.
AST Parameters and the AST Astrophysics Sub-Committee
Authors: Whiteoak J. B.
Published: July 2016

There is no question that Australian radio astronomers are in urgent need of a telescope which can provide high angular resolution for both line and continuum projects. Planning for the Australian Synthesis Telescope (AST) began in 1975 (see Wellington 1976; Manchester 1977), and with the guidance of the AST Steering Committee and the Design Study Committee the instrument, although it may be overshadowed in some respects by the US Very Large Array (VLA), now has enough unique features to whet the scientific appetites of all Australian astronomers. The planning has reached a critical phase — a proposal, costed at $A17.3 million (in 1980), was submitted to the Minister for Science and technology in February 1981 for funding in the August 1981 budget.
HI in the Small Magellanic Cloud Re-examined
Authors: McGee R. X. , Newton Lynette M.
Published: July 2016

Our re-examination of the neutral hydrogen gas in the Small Magellan Cloud has led to four important results. Firstly, we find that Hindman’s (1967) total content HI map is a satisfactory representation of the gas in the line of sight. Secondly, we find that the HI gas in the SMC exists in four distinct large masses separated from one another in radial velocity by 20 to 30 km s−1. Thirdly, having made this division of the gas we show that there is good correlation between the radial velocities of HII regions, supergiant stars and HI. Finally, we believe that our observations reveal that the SMC is associated with an extremely large trailing halo of HI gas which forms the major component of the inter-cloud bridge region.
DDO Photometry of the HR 1614 Moving Group
Authors: Smith G. H.
Published: July 2016

The HR 1614 moving group of stars (Eggen 1978a) is one of a number of such groups identified by Eggen from amongst the disk population of the Galaxy (see e.g. Eggen 1969). The group was selected from a sample of 44 field stars south of + 30° declination, with right ascensions mainly > 12h and <2h, and with motions similar to that of the star HR 1614, which has a velocity of (U, V) = (−1, −58) km s−1, where U and V are the components of space motion in the direction of the galactic anticentre and galactic rotation respectively, measured relative to the Sun. The colours of these 44 stars, when plotted in a (b-y, R-I) diagram, were such that 26 of them had an excess blanketing of ~ 0.03 in b-y, measured with respect to the Hyades group. This excess blanketing was consequently chosen to be a criterion for group membership.
Towards a Pulsar Magnetosphere Model — Physical Principles
Authors: Burman R. R.
Published: July 2016

I shall outline the physical principles on which I believe pulsar magnetosphere models should be based. The principles follow from the equations of continuity and motion for each species and the two sourceless members of Maxwell’s set of equations, together with the steady-rotation constraint and boundary conditions at the stellar surface.
Secular Changes in the Flux Density of PSR 0833-45
Authors: McAdam W. B.
Published: July 2016

The pulsar 0833-45 associated with the Vela supernova remnant has been known as a strong source with fairly constant pulse amplitude since its discovery (Large, Vaughan & Mills 1968) using the east-west arm of the Molonglo telescope. The pulse stability together with the short period of 89 ms allowed its integrated flux to be seen also as a 1.7 Jy point source with the pencil beam of the full Cross, and a more precise declination was obtained. Further observations in 1971/72 with a beat period integrator used on the fan beams of the north-south arm showed that the pulsed radiation had the same declination as the point source within 2 arcsec (Vaughan & McAdam 1973). Monitoring observations in 1975/76 gave an independent position, and the mean of all Molonglo (408 MHz), Fleurs (1415 MHz) and NRAO interferometer (2700 MHz) positions led to the optical detection of the pulsar (Goss et al. 1977). The point source, therefore, is reliably identified with the pulsar.
Relative Positions of Type I and Type III Solar Metre-Wave Bursts
Authors: Duncan R. A.
Published: July 2016

Solar metre-wave noise storms commonly show continuum and short-lived narrow-band bursts (Type I) at high frequencies and fast-drift bursts (Type III) at low frequencies (Malville 1962; Hanasz 1966; Boischot et al. 1970; Moller-Pedersen 1974; see also Figs. 2-3 of this paper). The Type I and Type III emissions have the same sense of polarization (Komesaroff 1958; Suzuki 1978). Impressed by this spectral association, Malville (1962) and Boischot et al. (1970) suggested that the two types of emission might be excited by the same electron stream. However, Type I emission is associated with sunspots and strong photospheric magnetic fields (McCready et al. 1947; Payne-Scott and Little 1951; Le Squeren 1963) and for this reason Kai (1970) suggested that Type I emission arises on strong closed magnetic loops. Type III emission, by contrast, almost certainly arises on open or quasi-open (large-loop) magnetic field lines (Wild et al. 1959, 1963). Thus on these models one would expect Type I and Type III emissions to arise from different magnetic regimes and different areas of the Sun. Kai’s (1970) and Stewart and Labrum’s (1972) Culgoora radioheliograph observations, which suggested that Type I and Type III sources are always separated on the Sun, seemed to clinch the matter. Kai’s model and his statement ‘Type III sources avoid the precise location of Type I storm centres’ gained wide acceptance (e.g. Boischot et al. 1971; Elgaroy 1977; Stewart 1977).
The Digital Encoding System created for the 18-inch Telescope
Authors: Wade B. , Ihnat P.
Published: July 2016

The University of Wollongong operates an 18-inch telescope located on the escarpment behind Wollongong. The greatest contribution from a telescope of this size is gained by photoelectric observations which larger telescopes often do not undertake because they are time consuming. In addition such observations require ‘photometric weather’. The sky in Wollongong is ‘photometric’ often enough to support a viable programme. However, it is vital that the telescope (and its instruments) works quickly and efficiently to utilise the fine periods.
History of Australian Astronomy: The Pre-History of the Parkes 64-m Telescope
Authors: Bowen E. G.
Published: July 2016

A great deal has been written about the mechanical design and the electrical characteristics of the Parkes radio telescope, but very little has been written about the pre-history — the factors leading up to the construction of that instrument. I want to spend a little time today describing some of the events which led to its being built.
Radio Galaxies and Quasars in Clusters of Galaxies
Authors: Robertson J. Gordon
Published: July 2016

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.
Ca II Emission from Late-type Stars
Authors: Cram L. E.
Published: July 2016

Two recent observational surveys of the Ca II resonance lines (Zarro and Rodgers 1983; Linsky et al. 1979) illustrate the great diversity of line profile shapes found in the spectra of cool stars. This diversity reflects a corresponding wide range in the underlying chromospheric properties of the stars. There are, however, three well-marked systematic trends in the shapes of Ca II line profiles which presumably reflect systematic trends in chromospheric properties. One of these, the Wilson-Bappu effect (Wilson and Bappu 1957), describes the strong correlation betweeen the width of the emission core (see Figure 1) and the absolute visual magnitude of the star. Despite much work, it is still not clear whether this is due primarily to systematic changes of velocity fields (e.g. Hoyle and Wilson 1958) or optical depths (e.g. Jefferies and Thomas 1959) in stellar chromospheres.
Granulation and Supergranulation as a Diagnostic Test of Solar Structure
Authors: Borght R. Van der , Fox P.
Published: July 2016

One of the most difficult tasks facing theoretical astrophysics today is to find a satisfactory model for the convective transport of energy in regions where the temperature gradient is superadiabatic. A number of such models have been proposed, such as the mixing-length theory and its extensions (Vitense 1953, Böhm-Vitense 1958, Spiegel 1963, Travis and Matsushima 1973 a, b, Parson 1969), to take into account the combined effects of convection and turbulence but it is generally agreed that, to-date, no satisfactory theory has been put forward.
Post-Newtonian Collapse Calculations
Authors: Thompson Mark
Published: July 2016

If computer speed and storage keeps increasing at the present rate a three dimensional numerical code modelling the exact equations governing general relativistic collapse will soon be possible; however, at present it is necessary to use simplifying approximations. Provided the general relativistic effects are limited to a ‘small’ perturbation, the post-Newtonian equations of Chandrasekhar (1965) should be adequate. These equations take the form of the Newtonian equations for a self gravitating fluid with extra terms to incorporate the 1/c2 contributions, where c is the speed of light. The numerical solution of these equations can be achieved using any method appropriate for three dimensional Newtonian hydrodynamics.
Electron Cyclotron Masers during Solar Flares
Authors: White S. M. , Melrose D. B. , Dulk G. A.
Published: July 2016

It has been suggested (Holman et al 1980; Melrose and Dulk 1982a) that solar microwave spike bursts are due to electron cyclotron maser action. These bursts have been observed in the range 1-3 Ghz, and occur in conjunction with flare-associated impulsive microwave and hard X-ray bursts. The bursts have rise times of a millisecond or less (e.g. Slottje 1978).
Resonant Alfvén Wave Absorption in Solar Magnetic Fields
Authors: Cramer N. F. , Donnelly I. J.
Published: July 2016

A common form of wave propagation in the highly structured magnetic fields and density profiles of the solar atmosphere should be magnetohydrodynamic surface waves, i.e. waves with magnetic and velocity fields concentrated at an interface of two regions of plasma of differing properties. For example, local concentrations of equilibrium magnetic fields forming flux tubes will support these waves on their surfaces, in addition to the more commonly considered ‘body waves’ that are supported by an isolated flux tube, waves with an oscillatory radial dependence inside the tube. Mhd surface waves have recently been identified in a laboratory plasma at Sydney University (Collins, Cramer and Donnelly 1983).
The Symbiotic Star H1-36
Authors: Allen David A.
Published: July 2016

Since its discovery by Haro (1952) the star H1-36 has been catalogued as a planetary nebula despite its extremely high-excitation emission-line spectrum (e.g. [Fe VII], [Ne V]) and its imposing, variable infrared excess. Because its optical spectrum resembled those of many symbiotic stars, I have persistently classified H1-36 as such. A meaningful definition of a symbiotic star would necessarily include both the high-excitation emission-line spectrum and the presence of a cool (usually M-type or Mira) giant.
Na D and Ca K Emission Associated with HD 44179 (‘The Red Rectangle’)
Authors: Whiteoak J. B. , Gardner f. F.
Published: July 2016

HD 44179, a ninth-magnitude star of late B spectral type, is peculiar in several respects. At red wavelengths it appears to be located at the apex of a biconical nebular (‘The Red Rectangle’) of dimensions about 1′ arc. Cohen et al. (1975) identified the system with the bright infrared source AFGL 915 and carried out investigations at optical, infrared and radio wavelengths. The complexities of the spectra have continued to interest astronomers.
High-Resolution Maps of Two Supernova Remnants
Authors: Caswell J.L. , Haynes R.F. , Milne D.K. , Wellington K.J. , Smith R.M.
Published: July 2016

High-resolution radio maps of supernova remnants (SNRs) are indispensable for distinguishing the more common shell remnants from the centrally concentrated (Crab-like) remnants; such studies also reveal any departures from symmetry, and this can yield vital information concerning interaction of the ejecta with the surrounding interstellar medium.
Observations of NGC 253 at 843 MHz
Authors: Reynolds J.E. , Harnett J.I.
Published: July 2016

NGC 253 is the major member of the Sculptor group of galaxies. It is classified SAB(s)c by de Vaucouleurs, de Vaucouleurs and Corwin (1976) and is almost edge-on. Previous studies have revealed a peculiar velocity field near the nucleus (e.g. Ulrich 1978). The nucleus is also a moderately strong radio and infrared source (Beck et al. 1979, Klein and Emerson 1981, Elias et al. 1978, Telesco and Harper 1980, Rieke et al. 1980).
WASAR — A Novel Star Plate Measuring Machine
Authors: Mills J. , Candy M.P.
Published: July 2016

There are many thousands of photographic star plates in observatories throughout the world, and the number is being added to continually. A major difficulty in making use of the information contained in them lies in the measurement of position, and other data, of star images on the plates, and in bringing the data to a form suitable for computer processing. Manual methods are impossibly slow and laborious for an extended program of measurements, and automatic machines on the market are prohibitively expensive for small observatories with limited resources.
On Directions from which Cosmic Rays may Reach Earth Satellites
Authors: Humble J.E.
Published: July 2016

It is easy to feel, on an intuitive basis, that primary cosmic rays of at least some energy range will be able to reach a satellite in earth-orbit from all directions above the local geometric horizon and from essentially no directions below the horizon. This argument suggests that directional cosmic ray detectors on board satellites may safely assume that the only particles received from earthward directions must be splash or albedo particles from the atmosphere, and that any equipment liable to possible radiation damage should be preferentially located on the earthward side of the satellite. In actual fact primary cosmic rays can have quite sharply curved trajectories in the magnetosphere, thereby enabling some particles to gain access to a satellite from a range of directions below the local geometric horizon. The present work presents recent quantitative results on this matter.
A Confusion Limited Radio Survey from the Molonglo Cross
Authors: White Graeme L.
Published: July 2016

Several catalogues of radio sources at 408 MHz have been prepared from observations made with the Molonglo cross telescope. These include (in chronological order) ‘The Molonglo Radio Source Catalogue 1’, the MC1, by Davies et al. (1973), the MC2 and MC3 by Sutton et al. (1974), MC4 by Clarke et al. (1976), ‘The Molonglo Deep Sky Survey of Radio Sources’ by Robertson (1977a,b,d) and ‘The Molonglo Reference Catalogue of Radio Sources’ (MRC) by Large et al. (1981). The catalogues MC1-4 cover selected areas of sky to a flux density limit of ~0.2 Jy to 0.3 Jy. The MRC includes extragalactic radio sources between δ = +18° and δ = −85° and is essentially complete at S408 = 1.00 Jy with raany sources to ˜0.7 Jy. The Wyllie (1969a,b) scale of flux density is used throughout.
Some Notes on Astronomy in New Zealand
Authors: Dodd R. J.
Published: July 2016

A brief description of astronomy in New Zealand both amateur and professional, past and present is given, with particular emphasis on the work carried out by the two professional establishments; the Carter Observatory, Wellington and the Mt John University Observatory of the University of Canterbury.
The Australia Telescope—The Radio Astronomer’s Highway to the Future
Authors: Frater R. H.
Published: July 2016

This meeting provides the first opportunity for me to talk about the Australia Telescope as an established project. It has been formally approved at all levels and is now under way (see Fig. 1).
Electron Outflow in Pulsar Magnetospheres
Authors: Burman R. R.
Published: July 2016

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.
On the Variability of Some Parkes Radio Sources
Authors: Wright Alan E.
Published: July 2016

It is the usual practice during continuum radio observations at Parkes to observe ‘pointing sources’ concurrently with the program objects.
Further Observations of EX Hydrae
Authors: Hill K. M. , Watson R. D.
Published: July 2016

EX Hya was one of the earliest detected eclipsing cataclysmic variables. The 98 min orbital period was first documented as a result of the spectroscopy of Kraft and Krzeminski (1962) and the photometry of Mumford (1964, 1967). However, new properties of this system continue to be discovered and these have required a more complex model than was previously envisaged.
The RS CVn Type Star PZ Tel
Authors: Innis J. L. , Coates D. W. , Thompson K.
Published: July 2016

We present broadband photoelectric light curves for the RS CVn type star PZ Telescopium for 1980, 1982 and 1983. The photometric period is about 0.943 days. The V light curve shows radical changes in form and range over a few months, and may be continuously variable. B and V data were obtained in 1982 and 1983. In 1982 no (B-V) change with phase was detected. However, in the first part of the 1983 observing season, a (BV) change of around 0.02 magnitude was found. Also at this time, maximum light was some 0.05 magnitude above that measured previously. Our preliminary spectroscopic data obtained in 1983 indicate that PZ Tel is a double lined binary whose components are of approximately equal luminosities, but this is yet to be confirmed. We suggest that the photometric variations are due to the presence of large cooler starspots on the photosphere of one or both components, as seems to be the case for related systems. The rapid changes in the observed light curve imply equally rapid changes in the distribution of the starspots, and make this an interesting object for further study.
QED and X-Ray Pulsars
Authors: Allen Michelle C. , Melrose D. B. , Parle A. J.
Published: July 2016

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 Roche Problem for Stratified Polytropes
Authors: Brookshaw Leigh
Published: July 2016

Roche (1850) made the first study of the stability of binary systems. The problem he studied, and which now bears his name, is concerned with the stability of a liquid star in a synchronous, circular orbit about a point mass. Roche’s calculations predicted that if the separation between the liquid star and the point mass is S2.5rs’/3, where r is the unperturbed radius of the liquid star and s the ratio of the mass of the point to the mass of the liquid star, then the liquid star would be unstable. This result was generalised to two liquid stars orbiting each other by Darwin (1910, p. 436). Using the tensor virial method Chandrasekhar (1969) has given a uniform analysis of the classical result. The classical results have been extended by Hachisu and Eriguchi (1984a, b) who looked for the onset of instability in polytropes in binary orbits.
NGC 4945-A Galaxy with a Nucleus Full of Surprises
Authors: Whiteoak J. B.
Published: July 2016

At optical wavelengths NGC 4945 is a nondescript edge-on spiral galaxy, much of which is obscured by dense dust clouds. However, at longer wavelengths a prominent nucleus is exposed which possesses both Seyfert and star-burst characteristics. Microwave observations highlight dense molecular clouds located near the nucleus. The large velocity range of these clouds lacks an adequate interpretation.
HI Profiles in the Bridge Region of the Megallanic Clouds
Authors: McGee R. X. , Newton Lynette M.
Published: July 2016

Two hundred and seventeen HI profiles at positions approximately 1 ° apart in the bridge region between the Small and Large Magellanic Clouds have been observed with a 15’ arc beam. Diagrams of all the profiles, lists of column densities and average radial velocities are given, together with details of the extensive Gaussian analysis needed to account for the components.

It is shown that the bridge region is most complex. (a) Two radial velocity groups, +214 and +238 km s-1, represent the actual HI bridge between the two galaxies, (b) Three other components, at mean radial velocities of +155, +177 and +195 km s-1 are seen to be integral parts of the SMC, stretching east to R. A. ~ 04h. (c) A further three components in groups at mean radial velocities +253, +272 and +293 km s-1 appear to be extensions of HI from the main body of the LMC.

Nine sets of five closely spaced observations in the lower Magellanic Stream and in the bridge region at high sensitivity supply further information about the region.
The Variation of Lithium Equivalent Width in Active Cool Stars
Authors: Robinson R. D. , Thompson K. , Innis J. L.
Published: July 2016

In an attempt to determine whether the lithium Une at 6707 Å cornes mainly from the quiet photosphere or from the cooler spots on spotted active stars we have measured Une équivalent widths due to Li and also due to Cal at 6717 Å at various rotation phases on three fast rotating stars, AB Doradus, PZ Telescopium and V 1005 Orionis. The results for AB Dor and PZ Tel show there might be some small rotational modulation which can be linked to the best estimate of the spot position from the available photometry. This moduation is less than that expected on the basis of Giampapa’s work on sunspot spectra. The Li and Cal line equivalent widths were found to anticorrelate.
The Synthesised Beamshapes for the Fleurs Extension
Authors: Frater R. H. , Gough R. G. , Watkinson A.
Published: July 2016

A proposal for the siting of additional 14 metre antennas for the Fleurs Synthesis Telescope (FST) was previously presented by Christiansen (1976). Since that time, difficulties have arisen which preclude the use of two of the locations. In addition, solutions to the problems of data reduction for irregular antenna spacings have been found (Frater and Skellern, 1978; Frater, 1978; Frater, 1979). It has now been possible to choose the locations of the final antennas to optimise the performance of the array within broader geographic constraints — subject now to the availability of sites on ‘friendly’ land.
The Llanherne VHF Radio Telescope
Authors: Ferris R. H. , Turner P. J. , Hamilton P. A. , McCulloch P. M.
Published: July 2016

The Llanherne telescope is a meridian transit instrument with an instantaneous bandwidth of two octaves in the range 35 to 150 MHz, and was constructed primarily for studying the low frequency properties of pulsars. The antenna is a 78 × 156 metre filled aperture phased array comprising 4096 wire dipole elements arranged in a 64 × 64 matrix. Uniform illumination of the elements produces a single pencil beam response which is scanned electronically along the meridian from Declination -90° to +30°. The beamwidth at 100 MHz is 1 degree in right ascension and two degrees sec(Dec.) in declination and varies proportionally with wavelength, giving a transit time of 4 sec(Dec) × 100/f(MHz) minutes between half power points.
A Dedicated Variable Star Observatory
Authors: Vaughan A. E.
Published: July 2016

A small astronomical observatory has been constructed on the edge of the Macquarie University campus at North Ryde in Sydney. It will be used primarily for photoelectric observations of variable stars. Further improvements to the present observing system are being planned and observations have already started on β Cepheids.
Measurement of the Field Pattern of a Radio Telescope using a Geostationary Satellite
Authors: Green H. E.
Published: July 2016

The conventional method of measuring the radiation diagram of an antenna is to rotate it in the field produced by a fixed point source located in its Fraunhofer zone (Hollis et al. (1970)). With the very large antennas typically used in radio astronomy this presents difficulties. For example, to measure the 64 m telescope at ANRAO, Parkes at frequencies in the OH transition lines band (1.6-1.7 GHz), the source, to be located in the Fraunhofer zone, must be located at least 50 km away and then at a sufficiently high angle to allow measurements free from ground effects to be made. Clearly there are no terrestrial means to accomplish this.
A Finite Radius Solution for the Polytrope Index 5
Authors: Murphy J. O.
Published: July 2016

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.
Convection and Supergranulation
Authors: Borght R. Van der , Fox M. T.
Published: July 2016

In a previous paper (Van der Borght 1979) the techniques developed for studying finite amplitude convection in a compressible medium were applied to an investigation of super-granulation in the Sun. Assuming that the instability is due to He+ recombination, a model was derived which seems to indicate that convection in the upper 8000 km of the Sun may occur as an overtone and not as a fundamental mode. This investigation yielded results which were very close to those obtained from standard mixing-length theory.
Gravitational Lenses and QSO Redshifts
Authors: Suffern Kevin G.
Published: July 2016

The origin of QSO redshifts is an important problem for which there is still no definite answer (Burbidge 1979). Recent observations by Walsh et al. (1979) of what is probably a gravitational lens associated with the twin QSO’s 0957+ 561 A,B offers the possibility of testing whether the redshift of the QSO involved is cosmological in origin. In general, if a gravitational lens is responsible for splitting the image of a QSO into two or more distinct components, it is possible to calculate the redshift of the QSO provided we have enough observational data involving the lens. The calculated redshift must then be consistent with the observed redshift if it is entirely cosmological in origin. The quantities that must be observed before the redshift can be calculated are the differences in the light travel times along the different paths from the QSO to us, the redshift of the lens, the angular separation of the images, and their relative intensities.
Objective and Consistent Stellar Magnitudes from the Palomar Sky Survey Prints
Authors: White G. L.
Published: July 2016

Print copies of the Palomar Sky Survey (PSS) are widely used for optical identifications of radio sources north of δ = -33°.
Culgoora Radioheliograph Measurements of Interstellar Scattering of Pulsar Signals
Authors: Slee O. B. , Dulk George A. , Otrupcek Robina E.
Published: July 2016

The amplitude scintillations of pulsars and the broadening of their profiles are different manifestations of the scattering of the signal by fine structure in the ionized interstellar gas.
The CANGAROO Project: Very High Energy Gamma-ray Astronomy at Woomera
Authors: Edwards P.G. , Gregory A.G. , Patterson J.R. , Roberts M.D. , Rowell G.P. , Smith N.I. , Thornton G.J. , Wild N.R. , Ebisuzaki S. , Fujii H. , Kabe S. , Watase Y. , Fujimoto M. , Hara T. , Hayashida N. , Kifune T. , Ohno Y. , Teshima M. , Kakimoto F. , Ogio S. , Tanimori T. , Kobayakawa K. , Mizumoto Y. , Oda H. , Suda T. , Masaike A. , Matsubara Y. , Muraki Y.
Published: July 2016

In this paper the Very High Energy (VHE) gamma-ray astronomy program at the University of Adelaide is described. VHE gamma rays with energies above ~5 × 1011eV are observed using the atmospheric Cerenkov technique. Results from the first three years observations at Woomera and the current upgrading of the telecope are described. The CANGAROO project, a collaboration between the University of Adelaide and a number of Japanese institutions, is also introduced.
Advancements in Radiative Hydrodynamic Simulations of Early Phases of Type II Supernovae
Authors: Kelly D.
Published: July 2016

Between the time when the shock approaches the outside of the progenitor star, when the shocked material is highly ionized, and a few months later, when the material has cooled and recombination is almost complete, details of the coupling of radiation and the hydrodynamics of the shock propagation may be significant, with a subsequent effect on the photosphere and thus spectra. I argue for the inadequacy of current analyses of shock breakout and of the customary adoption of self-similar expansion of an initial structure for spectral synthesis of the first few months, in place of a complete hydrodynamic simulation. Progress towards a full radiative hydrodynamic simulation including relativistic effects and detailed line opacities is discussed.
Imaging the Hot Molecular Gas at the Centre of the Galaxy
Authors: Burton Michael , Allen David
Published: July 2016

The AAT’S new IR array camera, IRIS, has been used to image the Galactic Centre in the He I (2.058μm), H+ Br γ(2.166μm) and H2 1-0 S(l) (2.122μm) emission lines. The case is presented for UV-excitation of the molecular gas, as opposed to shocks.
Electron-Cyclotron Maser Emission and Propagation in Solar Microwave Spike Bursts
Authors: Robinson P. A. , Kuncic Z.
Published: July 2016

An improved model of the generation and propagation of cyclotron-maser radiation in flaring loops is discussed, which incorporates competition between driving of the maser instability and maser-induced relaxation of the unstable plasma. This model enables previous large discrepancies between the build-up, relaxation, and observed timescales to be resolved for solar microwave spike bursts. Also, it implies that emission via fundamental o-mode and second-harmonic x-mode instabilities can compete more effectively against fundamental x-mode emission than has previously been thought. Propagation of the radiation to the observer is discussed both theoretically and with reference to ray tracing calculations and it is shown that the observed levels of MHD waves in the corona make it significantly easier for the radiation to escape than in the unperturbed case. In the absence of nonlinear processes or mode conversion we argue that the escaping radiation is generated by either fundamental o-mode or second-harmonic x-mode instabilities.
Multi-wavelength Optical Aperture Synthesis
Authors: Marson R.G. , Bedding T.R. , Robertson J.G.
Published: July 2016

The technique of aperture synthesis is well developed in radio astronomy. When applied to the optical regime, aperture synthesis allows one to partially overcome the blurring effects of the atmosphere and increase the angular resolution of large telescopes to the diffraction limit.

MAPPIT (Masked APerture-Plane Interference Telescope) is a multi-element interferometer which operates at the coude focus of the 3.9 m Anglo-Australian Telescope. This instrument has recently been reconfigured to operate in a dispersed mode so that simultaneous observations in a band of wavelengths are possible. We will discuss this instrument’s new mode and present observations of the double star δ Sco and an angular diameter of the previously unresolved red giant β Gru.
s-Process Nucleosynthesis on the Asymptotic Giant Branch
Authors: Lattanzio John C.
Published: July 2016

In this article I review our understanding of s-process nucleosynthesis in Asymptotic Giant Branch (AGB) stars. The discussion begins with the nuclear back~ ground and then shows how the required conditions are found in thermally pulsing AGB stars. The two competing neutron sources (Ne22 and C13) are discussed, as is the observational and theoretical evidence for and against each of them. We conclude by discussing the recent evidence for hot bottom burning, including the observed enhancements of Li7 and Al26 in some AGB stars.
Observations of the 18.3-GHz Transition of C3H2 towards Sgr B2
Authors: Peng R.S. , Whiteoak J.B. , Reynolds J.E. , Kuiper T.B.H. , Peters W.L.
Published: July 2016

We have mapped the molecular clouds of Sgr B2 in the 110 → 101 ortho-transition of C3H2 at 18.3 GHz, using the 70-m NASA telescope at Tidbinbilla (beamwidth 55 arcsec). Three clouds show absorption against the Sgr B2 continuum emission at radial velocities of 50, 65 and 80 km s−1. The 65-km s−1 cloud covers most of the observed area (4 × 6 arcmin in right ascension and declination), has a peak optical depth of 2.7 and a corresponding C3H2 column density of 7.6 × 1015 cm−2. The C3H2 fractional abundance relative to H2 is 1.5 × 10−9. The 80-km s−1 cloud, located north of the Sgr B2 continuum peak, has a peak optical depth of 0.9 and a C3H2 column density of 1.9 × 1015 cm−2. The 50-km s−1 cloud is centred 2 arcmin south of the continuum peak; here the minimum optical depth of 0.5 yields a column density of 5.3 × 1014cm−2.
An Anomalous Stellar Image on an Astronomical Slide Photograph
Authors: McGee P.
Published: July 2016

There has been considerable interest in the appearance and nature of images on astronomical photographs which may suggest a transient optical event as the source of the image. In particular, much has been made of possible connections between such images and hypothesised optical activity associated with gamma-ray bursters. This paper describes the investigation of such an image, and discusses briefly various hypotheses as to the nature and source of the image under investigation.
An Improved Oblateness for the Earth’s Thermosphere from Lunar Eclipse Observations
Authors: Soulsby Byron W.
Published: July 2016

The current ephemerides include an allowance for umbral oblateness based on the flattening of the Earth’s geodetic reference spheroid; there are few published estimates for umbral oblateness derived directly from the geometry of a lunar eclipse. This paper reports umbral oblateness values which have been derived from 7,400 crater contact timing observations of twenty-one lunar eclipses by amateur and professional astronomers since 1972. The observed umbral oblateness was found to be typically three times the geodetic reference spheroid flattening.
Alfvénic Fronts and the turning-off of the Energy Release in Solar Flares
Authors: Wheatland M. S. , Melrose D. B.
Published: July 2016

The effect of impulsively turning off the dissipation in an existing model for energy propagation through Alfvénic fronts into the coronal site of energy release in a solar flare is examined. In the optimum case of impedance matching, the flux tube re-stresses on a much longer timescale than it relaxes, suggesting an explanation for the timescales observed in homologous flares.
Cosmic Ray Transient Variations Observed from the Earth
Authors: Duldig M. L.
Published: July 2016

Cosmic ray transient variations are signatures of the underlying solar processes which affect the heliomagnetic structure. They can be found in the data from surface systems, such as neutron monitors and muon telescopes, and from shallow underground muon telescopes. Although sometimes observable at all latitudes, the global distribution of the effects is important in determining the structures and causes. Three transient variation types are known, namely Forbush decreases, ground level enhancements, and quasi-periodic fluctuations. The latter category includes some variations which are, perhaps, too long-lived to be considered truly transient. In this review, the detection techniques and background of cosmic ray research are followed by a summary of some observations in each transient category. The heliomagnetic structures and dynamics inferred from such transients are discussed together with the possible impact such events can have on human activity.
The New Teaching and Public Access Observatory at the University of Western Sydney, Nepean
Authors: White Graeme L. , Jones Paul A. , Hons Alex , Edgar Ron , Suchting Mark , Burdett Chris
Published: July 2016

A grant from the Department of Employment, Education and Training and matching funding from the University of Western Sydney, Nepean, has allowed the construction of a teaching and public access observatory on the University’s Werrington North campus. The observatory consists of a lecture theatre for about 50 students, an office for administration and project/souvenir sales, and an enclosed office for research activities. The 6·5 m dome will house a fork-mounted 0·6 m (24 inch) Ritchey-Chrétien telescope working at f/10. There will also be two outside observation areas for tripod-mounted telescopes. The expected completion date for the entire project is mid-1994.
Observations of Wide Binary Pairs in the Far Southern Sky
Authors: Bauer Christina , White Graeme L. , Hons Alex
Published: July 2016

Astrometric CCD observations have been made of wide (~3 to 80 arcsec) southern binary pairs using the 0·6 m telescope at MSSSO. Separations ρ and position angles (PA) have been calibrated against known astrometrie pairs, and have rms uncertainties of 0·16 arcsec and 7·8/ρ degrees (ρ in arcsec) respectively. These stars have not been well studied; typically they have not been measured since approximately 1930, and 52% of them have been observed only once prior to our observations. A comparison has been made with values published in the Washington Double Star (WDS) catalogue. Of the 304 pairs measured in the declination range −60° to −70°, 82% show no evidence of motion since the last observation.
Detection of Cyclotron Lines in BL Hyi
Authors: Ferrario Lilia , Wickramasinghe Dayal T. , Bailey Jeremy
Published: July 2016

We present near-infrared spectroscopic observations over the wavelength range 0·9 to 2·5 μm of the AM Herculis system BL Hyi. During these observations, broad and resolvable cyclotron emission harmonics were visible near 1·25, 1·60 and 2·20 μm. We have interpreted these features as arising from a cyclotron emission region located near the white dwarf’s polar cap of magnetic field strength Bp = 23 MG.