bluuebunny/crossref_metadata_2025 huggingface dataset:
Zeeman Doppler Imaging of Stars with the AAT
Authors: Carter Brad , Brown Steve , Donati Jean-François , Rees David , Semel Meir
Published: July 2016

Zeeman Doppler Imaging (ZDI) is a recent technique for measuring magnetic fields on rapidly rotating, active stars. ZDI employs spectropolarimetry taken at different rotational phases to derive information on the magnetic field distribution over the stellar surface. The Zeeman effect is used to identify the presence of a magnetic field, and variations in Doppler wavelength shifts across the rapidly rotating star allow fields to be resolved on different parts of the visible disk. Analysis of the spectra can be used to produce both thermal and surface magnetic images. ZDI requires very high S/N spectra to be acquired within a time interval short compared to the stellar rotation period. As a result, a large-aperture telescope is needed. Since an initial successful test in 1989, the 3·9 m Anglo-Australian Telescope has been used to obtain ZDI spectra of active stars of different evolutionary stages. The observations have concentrated on the K subgiant in the RSCVn system HR 1099 to monitor changes on this bright and active star. With the advent in 1991 of ZDI spectropolarimetry with the AAT échelle spectrograph, it has become possible to co-add the polarisation signature from the many magnetically sensitive lines recorded simultaneously. As a result, stellar magnetic field detections of unprecedented quality have been obtained. The aims of this paper are to briefly outline the principles of ZDI, describe the instrumental setup at the AAT and present some preliminary results from recent observations.
Education and Public Astronomy Programs at the Carter Observatory: An Overview
Authors: Orchiston W. , Dodd R. J.
Published: July 2016

This paper outlines the extensive range of public programs offered by the Carter Observatory, including ‘public nights’, new planetarium and audio-visual shows, displays, the Carter Memorial Lectures, the annual Astronomical Handbook and other publications, a monthly newspaper column and three monthly radio programs. It also deals with the Observatory’s involvement in undergraduate and postgraduate astronomy at Victoria University of Wellington, various adult education training programs, ‘Overnight Extravaganzas’, holiday programs, and the recent development of the Education Service in response to the introduction of an astronomy curriculum into schools throughout New Zealand. Some possible future developments in the public astronomy and education areas are also discussed.
Millimetre Observations of Protostellar Disks
Authors: Maddison Sarah T.
Published: July 2016

I look briefly at protostellar environments and at what information can be gained from the millimetre waveband. A short overview of the theory of protostellar environments and evidence of disks will be followed by a more detailed review of recent publications of observations of protostellar halos/disks, specifically in 3 mm.
Five Crucial Tests of the Cosmic Distance Scale Using the Galaxy as Fundamental Standard
Authors: Vaucouleurs G. de
Published: July 2016

The traditional approach to the extragalactic distance scale rests on a pyramid of primary, secondary and tertiary indicators of increasing range and decreasing accuracy. This
multi-step procedure, fraught with the danger of cumulative errors, has led in recent years to two main, widely diverging scales: the ‘long’ scale (Sandage and Tammann 1974, 1975, 1976) implying a Hubble constant and the ‘short’ scale (de Vaucouleurs 1978, 1979; de Vaucouleurs and Bollinger 1979; de Vaucouleurs and Peters 1981; de Vaucouleurs et al. 1981) leading to H0 ≃ 100. Several authors have already shown that the long scale rests on very precarious foundations (Capaccioli and Fasano 1980, de Vaucouleurs 1981, Hanes 1980); counter arguments have been offered in its defence and to criticize the short scale (Tammann, Sandage and Yahil 1979, Sandage and Tammann 1982). For want of a conclusive test a consensus was still lacking.
Solar Polarimetry: Observations and Theories
Authors: Rees David E.
Published: July 2016

This review surveys some recent observations of polarization in solar spectral lines with emphasis on their theoretical interpretation. Solar optical polarimetry is concerned primarily with measuring solar magnetic fields, a quest which began with Hale’s (1908) observation of Zeeman splitting in a sunspot. Today a wide range of optical polarimeters is used for solar research (see Bauer (1981) for a comprehensive review). For example, a standard magnetograph (Babcock 1953) detects circular polarization in selected wavelength bands in the wings of a Zeeman sensitive line, providing information on the line of sight or longitudinal field component. The most sophisticated instrument is a Stokes polarimeter (e.g. Bauer et al 1980, 1981) which measures with high spectral resolution the profiles of all four Stokes parameters (I,Q,U,V) across a spectral line. Such a device potentially provides all the data needed to infer the vector magnetic field.
‘History of Australian Astronomy’:Radio Astronomy at Dover Heights
Authors: Bolton J.G.
Published: July 2016

In this contribution, which is an expanded version of an invited lecture at the 1982 A.G.M. at Noosa Heads, the author recalls some of the early work in radio astronomy from Dover Heights.
Coherent Gyromagnetic Emission
Authors: White S.M. , Melrose D.B.
Published: July 2016

Observations of extremely high brightness temperatures in astrophysical objects imply that coherent emission processes must be occurring. An emission process may be coherent due to an inverted energy distribution leading to maser action, or due to bunching of particles in a region less than or of order of the wavelength of the radiation. Calculations of emission by bunches have generally used either a fluid model, e.g. Buschauer and Benford (1976), or a single-particle approach which requires all particles to have the same velocity, e.g. Saggion (1975) uses elements of both. In this paper we investigate gyromagnetic emission by bunches using a single-particle approach which includes the effects of differing particle velocities on the radiation.
Numerical Simulations of Collapsing, Isothermal, Magnetic Clouds
Authors: Phillips G.J.
Published: July 2016

In recent years, a number of numerical experiments have simulated various aspects of the early stages of star formation (see Tscharnuter 1980 for a discussion and review). In all but one of these experiments, however, the effects of the interstellar magnetic field have been neglected, although observations (for example, see Verschuur 1969) suggest that in some interstellar clouds, the magnetic energy is comparable to, or even greater than, the gravitational and thermal energies. It is also believed (Mouschovias 1981), that at least at the early, diffuse stages of collapse, where the ionizing radiation can penetrate deep into the cloud, the bulk of the neutral matter will feel the magnetic forces via collisional coupling with the ionized matter. Thus there exist no observational, nor theoretical reasons justifying the neglect of the interstellar magnetic field in these numerical simulations.
The Metallic Hydride Dwarfs
Authors: Bessell M.S.
Published: July 2016

The properties of the M dwarfs have been investigated by spectroscopic and photometric observations of over 150 red, high proper motion stars. Most of these stars have red magnitudes fainter than 12 magnitude.
Infrared Images of Southern HII Regions
Authors: Storey J. W. V. , Bailey J.
Published: July 2016

We present 2.2 μm maps of four southern HII regions. Although each of these objects has been extensively studied at radio wavelengths with low spatial resolution, they have so far (with the exception of G333.6 – 0.2) received little attention in the infrared. As a first step towards understanding the structure of these objects we have therefore produced images of each in the K-band (2.2 μm) continuum.
1733-565: A Compact Radio Galaxy at Low Galactic Latitude
Authors: Hunstead R. W. , Durdin J. M. , Little A. G. , Reynolds J. E. , Kesteven M. J. L.
Published: July 2016

The strong unidentified radio source 1733-565 (≡ PKS 1733-56) was chosen as a test source during the commissioning of the Molonglo Observatory Synthesis Telescope (MOST) in 1981 July. Previous radio maps have been obtained at 1410 MHz with the Parkes interferometer (Schwarz et al. 1974), at 408 MHz with the Molonglo Cross (Schilizzi & McAdam 1975) and at 1415 MHz with the Fleurs Synthesis Telescope (Christiansen et al. 1977).
H76α Recombination Line Emission near Sgr A
Authors: Whiteoak J. B. , Gardner F. F.
Published: July 2016

Our previous observations of the distribution of the H110α recombination line emission (rest frequency 4.87 GHz) towards Sgr A, obtained with the Parkes 64-m telescope and a 4′ .5 arc beam (Gardner and Whiteoak 1977 — to be referred to as Paper I), suggested that the emission was concentrated around the outer edge of the ‘arc’ of continuum radiation which extends 15′ arc to the north-east of the galactic nucleus.
A New Installation for Studying the Sidereal Anisotropy of Cosmic Rays
Authors: Fenton A. G. , Fenton K. B , Humble J. E. , Jacklyn R. M. , Vrana A. , Murakami K. , Fijii Z. , Yamada T. , Sakakibara S. , Fujimoto K. , Ueno H. , Nagashima N. , Kondo I.
Published: July 2016

It is now firmly established that a small anisotropy of the galactic cosmic rays exists, observable from Earth as a variation of intensity in sidereal time. The problem now is to determine more clearly the characteristics of the anisotropy and, in particular, its detailed spatial structure and how it depends upon the energy and composition of the cosmic rays. This is a very difficult task and, in the final analysis, may not be fully achievable from Earth-based observations. The purpose of the present paper is to describe briefly an installation now operating in Tasmania to provide further information on the spatial structure of the anisotropy.
The Electric Field in Axisymmetric Pulsar Magnetospheres
Authors: Burman R.
Published: July 2016

In an earlier paper with the same title, I showed how knowledge of the non-corotational electric potential required to support particles in corotation with the star can be used to deduce the global qualitative forms that the potential can take in axisymmetric pulsar magnetospheres, in the absence of outflowing particles. Those arguments will now be combined with work on the outflow zone to deduce qualitative features of the potential structure in the MRW2 model.
A 3072 Channel Surface Acoustic Wave Spectrum Analyser
Authors: Ellis G. R. A. , Hall P. J.
Published: July 2016

A spectrum analyser based on SAW (surface acoustic wave) devices has been developed for Jupiter, solar and pulsar observations. It has an overall frequency range of 100 MHz and a frequency resolution of 30 kHz. A complete spectrum is produced every 80 μs. It is initially being used with a 4000 dipole broadband array in the frequency range 30-130 MHz and for Jupiter observations from 8-38 MHz.
An Emission Line Model for AM Herculis Systems: Application to E1405-451
Authors: Ferrario Lilia , Wickramasinghe D. T. , Tuohy I. R.
Published: July 2016

The optical spectra of the AM Herculis binaries are characterized by extremely complex emission lines whose profiles can be resolved into at least three components which are formed in different regions of the accretion stream leading from the companion star towards the magnetic white dwarf. We present a theoretical model which localizes the formation region of the broad emission line component and provides information regarding the structure of this emitting region. In our model the particle trajectories are integrated in a Roche potential and the volume between the white dwarf and the companion has been divided into two different regimes of motion. In one region the gas escapes from the secondary near the inner Lagrange point and is accelerated along a straight line towards the white dwarf. In the other region the magnetic field is strong enought to divert the gas out of the orbital plane and to channel it towards the white dwarfs surface. The model has been used to interpret radial velocity and velocity dispersion data from the AM Herculis system E1405-451.
A Spectroscopic and Photometric Study of 1H0542-407: A New Magnetic Variable
Authors: Buckley D. A. H. , Tuohy I. R.
Published: July 2016

We report spectroscopic and photometric observations of the new DQ Hercuis system 1H0542-407, recently discovered by us to be the optical counterpart of a HEAO-1 X-ray source. Medium resolution spectroscopy using the AAT in the region λ3930 to λ4960 conducted over consecutive nights shows radial velocity variations at periods of ∼ 1910 s, consistent with the white dwarf rotation period, and 5.7 h, in agreement with the orbital period derived from our EXOSAT observations. The K semi-amplitude velocities are ∼ 50 and 20 km s-1 respectively, leading to a mass function f(M) = 3.3 ± 0.6 × 10-3M⊙ and an orbital inclination close to 20°. The emission line profiles are characterized by simple Gaussians whose FWHM vary at the rotation period. A time series analysis of high resolution photometry conducted on the ANU 2.3 metre telescope reveals the presence of several periodicities, including the orbital sidebands. The dominant sideband (Vr − Vo) arises from X-rays reprocessed in a region corotating at the orbital frequency. A model is developed for 1H0542-407 which indicates that the accretion disk is disrupted at ∼5Rwd by the primary’s magnetic field. The short period velocity variations arise within the magnetosphere. A white dwarf magnetic field strength of < ∼ 3 MG is implied.
The Structure and Size of Radio Galaxy 1308-441
Authors: Jones P. A.
Published: July 2016

The structure of the radio source 1308-441 has been determined with the Molonglo and Fleurs radio telescopes. The nuclear component has been identified with a magnitude 15 galaxy and an optical spectrum, obtained with the Anglo-Australian Telescope shows galactic absorption features with a redshift of 0.0515 but no emission lines. The radio image shows the nuclear component linked by a well defined bridge to diffuse lobes extending for 11 arcmin west and 6 arcmin east. The asymmetry is believed to be due to projection effects. The projected size is 670 kpc (Ho = 100 km s-1 Mpc-1). The bridge contains several peaks with one strong unresolved peak 90 kpc from the galaxy.
The Calamity of the Great Melbourne Telescope
Authors: Hyde W. Lewis
Published: July 2016

Sir William Herschel and his sister, Caroline, had swept the skies over England as members of the court of George III. They had made amazing discoveries: a new planet in our solar system, the movement of the solar system with respect to the fixed stars, and hundreds of new nebulae and star clusters.

Then Sir William’s son John swept the southern skies from Cape Town, South Africa (1834 to 1838), mapping and sketching many more stars and nebulae.
Recent Results on SN 1987A
Authors: Woosley S.E. , Pinto P.A. , Weaver T.A.
Published: July 2016

Several critical issues recently raised by observations of SN 1987A are addressed. These include: 1) the evolution of the pre-supernova star, why it was blue, what its composition and core structure were; 2) the detailed isotopic composition of the ejecta; 3) why and to what extent the supernova composition was mixed in velocity space; 4) the interpretation of recently observed infrared lines, especially their profiles and the existence of red-shifted ‘wings’; and 5) what has become of the neutron star.
Protoneutron Star Formation
Authors: Burrows Adam
Published: July 2016

The theory of neutron star formation is addressed in the light of the detected neutrino burst from SN 1987A. A brief review of how supernova neutrino theory has evolved over the last 30 years and a general analysis of the SN 1987A detections is presented.
The Elusive Radio Source SN 1987A
Authors: Reynolds John E. , Livermore R.W. , Jauncey David L. , Preston Robert A. , Gulkis Samuel , Bartel Norbert
Published: July 2016

Following the ‘prompt’ radio outburst seen soon after the neutrino emission in SN 1987A (Turtle et al. 1987), we initiated a program to monitor the supernova at the Tidbinbilla Deep Space Communications Complex at 8.4 GHz in a search for radio emission from the expanding remnant. No radio emission has been detected to date (DOY 151, May 30 1988).
The Early Spectra of SN 1987A
Authors: Harkness R.P. , Wheeler J.C.
Published: July 2016

Spectra computed from hydrodynamical models for SN 1987A at very early times (t < 2 days) are presented and discussed.
New Developments in Theoretical Modelling of SN 1987A
Authors: Nomoto Ken’ichi , Shigeyama Toshikazu , Kumagai Shiomi , Hashimoto Masa-aki
Published: July 2016

We summarise recent developments in modelling SN 1987A including the progenitor’s evolution, explosive nucleosynthesis, optical, X- and γ-ray light curves, and dust formation. The distribution of heavy elements in the ejecta is inferred from the light curves. The pre-peak optical light curve as well as early emergence of X- and γ-ray indicate the mixing of 56Ni into the hydrogen-rich envelope. The plateau-like peak of the optical light curve is well reproduced if hydrogen is mixed into the deep core. The flat X-ray light curve observed by Ginga would be due to the clumpy structure of the core. The progenitor’s blue-red-blue evolution and nitrogen abundance suggest that the progenitor’s hydrogen-rich envelope had mass Menv = 7 − 11 M⊙ and was almost completely mixed.
Space Telescopes: an International Perspective
Authors: Tuohy Ian R
Published: July 2016

The purpose of this paper is to review current and planned Space Astronomy missions from an international perspective, with principal attention to the programs of the USA, Europe, Japan and the USSR. The review focusses on extra-solar astrophysics, and the capabilities and broad research objectives of numerous individual spacecraft are described. These collectively span more than seventeen decades in wavelength and thus provide an essential complement to ground-based astronomy. Many of the missions offer significant opportunities for Australian participation via three complementary routes. First through Guest Investigator programs analogous to that offered for the Hubble Space Telescope (HST). Second, through the proposed establishment of an Australian Space Astronomy Data Centre to gain access to archival data from HST and other missions (the creation of such an archival facility in Canada is highlighted as a pertinent example). Third, via the contribution of instrumentation or ground support services. This latter category includes the Radioastron VLBI mission for which an agreement with the USSR has already been signed. In addition, an unprecedented opportunity has arisen for Australia to provide a ground station for the Infrared Space Observatory (ISO), due to be launched by ESA in 1993. In return for providing this service, the Australian astronomical community would receive a guaranteed share of the ISO observing time during the two year mission. Finally, Australian astronomers have been invited to contribute an advanced All-sky X-ray Monitor for the Soviet Spectrum-X-Gamma mission in 1993. This opportunity, and also the Radioastron initiative, have arisen under the USSR-Australia Space Research Agreement signed in December 1987.
Search for Ultra-High-Energy Gamma-Rays from SN1987A
Authors: Bird D. J. , Ciampa D. , Clay R. W.
Published: July 2016

We report here a search of data recorded by the Buckland Park air shower array from the first year after the supernova and set an upper limit to the proton luminosity of SN1987A of 7.7 × 1040 ergs s−1.
The Chromospheres of Pre-Main Sequence Flare Stars
Authors: Carter Bradley D.
Published: July 2016

Optical spectra of pre-main sequence flare stars in Orion are presented and analysed by the use of stellar chromospheric models. The stars observed divide into three groups on the basis of their quiescent spectra. The majority of the sample are similar to the dMe stars, with prominent Ca II and Balmer line emission. A second group possesses very strong emission spectra, including He I lines. Stars in third group, however, show little or no emission spectrum. Amongst the emission line stars observed progressively brighter stars exhibit increased Ca II and Balmer line surface fluxes relative to the fainter stars. This trend is also exhibited as a rise in emission line surface fluxes with increasing effective temperature. To analyse this trend a set of non-LTE stellar models were calculated. Using this analysis the trend in line fluxes between stars of different brightness and temperature is interpreted as a spread in the level of chromospheric heating. Furthermore, this trend is interpreted as indicating a spread in the effectiveness of the stellar magnetic dynamos within these stars, perhaps arising from shallowing in their convective layers as they contract to the main sequence.
Continuum Radio Spectrum of the Flare Star AT Mic.
Authors: Large M. I. , Beasley A. J. , Stewart R. T. , Vaughan A. E.
Published: July 2016

The binary flare star AT Mic has been observed with the VLA (5 GHz and 1.5 GHz) and, nearly simultaneously, with the MOST (0.843 GHz). There appears to be a slowly varying component of the radio intensity, with a flux density greater at 0.843 GHz than at higher frequencies. It is suggested that above 1 GHz the emission is possibly produced by incoherent gryosynchrotron radiation, whereas below 1 GHz a coherent mechanism predominates.
Application of the Dipole Model to Selected Magnetic White Dwarfs
Authors: Achilleos N. , Wickramasinghe D. T.
Published: July 2016

Various authors have reported observations of the flux and circular polarization for the three stars PG 1658 + 441, PG 1533 − 057 and K 813 − 14. On the basis of the observational data, the stars were classified as magnetic white dwarfs. To place constraints on the magnetic field strengths and geometries of these stars, the relevant authors qualitatively compared the data with available theory and, in two cases, used a model of optically thin hydrogen threaded by a magnetic field.

In this paper we use a more detailed model for magnetic white dwarfs to assess the results previously obtained for these three stars. We find that, in two cases, the observed spectra can be explained by the Zeeman splitting of hydrogen lines in a stellar magnetic field which takes the form of a dipole situated at the centre of the star. The circular polarization data for PG 1658 + 441, however, may indicate a field geometry for this star which is significally different from that of a centred dipole.
Upper limit to the number of galactic sources of ultra-high-energy gamma-rays
Authors: Bird D. J. , Clay R. W. , Edwards P. G.
Published: July 2016

The extreme isotropy of cosmic ray events allows one to put upper limits on any possible non-isotropic contribution to the flux. In particular, one can investigate any excess of events which may be confined to the galactic plane. Such extra events would be expected from galactic ultra-high-energy (UHE) gamma-ray sources. Under the assumption of an isotropic cosmic ray flux, recent Buckland Park data place a 95% confidence level limit on the total southern hemisphere (declination −15° to −55°) flux of UHE gamma-rays at between 0.6 and 6 equivalent Cygnus X-3 sources, depending on assumptions concerning the gamma-ray spectrum.
A Search for Transient Events at 843 MHz
Authors: Amy S. W. , Large M. I. , Vaughan A. E.
Published: July 2016

The Molonglo Observatory Synthesis Telescope is equipped with a transient event monitoring system which operates during normal synthesis observations. The device is designed to respond to impulsive signals which occur within the passband (843.0 ± 1.5 MHz) with time scales between 0.001 ms and 800 ms. The multiple beam facility of the telescope provides some discrimination against local interference. An upper limit of 1.7 × 10−2 events s−1 sr−1 has been placed on celestial events with durations between 1 ms and 25 ms and energy density ≥ 10−28 J m−2 Hz−1. The monitoring system has been recently reconfigured to improve the recognition and rejection of impulsive signals of non-celestial origin.
The Magellanic Stream: New Observations
Authors: Wayte S. R.
Published: July 2016

New HI observations of the Magellanic Stream have been made using the Parkes 64 m telescope. These observations highlight in detail its complicated structure and uncover new features of the Stream. The extreme velocity clouds (EVCs) are morphologically linked to the Stream indicating that these HI clouds are very likely truly part of the Stream. Also it is suggested that many of the high velocity clouds seen around the Stream are indeed part of the Magellanic Stream itself, and that the stream consists of many different velocity components in bulk motion.
The New Generation of Radio Telescopes
Authors: Wielebinski R.
Published: July 2016

The highest frequency at which a radiotelescope can be used depends on the surface accuracy. The rms error of the surface should be less then l/16th of the shortest wavelength. This should be not only under static conditions but also when the telescope is being driven, under the influence of wind and temperature changes. With this in mind we can trace back the development of the paraboloidal dish since the time when Grote Reber constructed his antenna in Wheaton, Illinois.
Helium in Three H II Galaxies and the Helium Abundance
Authors: Pagel B. E. J. , Simonson E. A.
Published: July 2016

Extended abstract

The mass-fraction Y of helium in the interstellar medium is between 0.22 and 0.30 wherever it has been measured and it is believed to be the sum of two components: YP from Big Bang nucleosynthesis (BBNS) at about 100 s after the Big Bang (ABB) and a temperature near 0.1 MeV, and ΔY due to processing in stars. Precise measurements of Yp, along with balances of trace elements D, 3He, 7Li also resulting from BBNS, provide important tests of BBNS theory and of parameters of cosmology and particle physics, notably the contribution ΩBO of baryons to the mean density of matter in the universe (in units of the closure density), the number Nv of light neutrino flavours (or families of quarks and leptons) and the half-life т½ of the neutron (Shaver et al. 1983; Yang et al. 1984; Boesgaard and Steigman 1985). Figure 1 shows the predicted abundances from Standard BBNS theory (SBBN) as a function of η = μB/nλ the ratio of baryons to photons (unchanged since e± annihilation a few seconds ABB), which is proportional (through the known temperature of the microwave background) to ΩBOh20 where h0 is the Hubble constant in units of 100 km s−1 Mpc−1. SBBN theory (which assumes a homogeneous Friedmann universe and small lepton numbers), when combined with reasonable ideas on Galactic chemical evolution that predict a primordial (D + 3He)/H ratio below 10−4, imply that η ≥ 3 × 10−10 (shown by the tall vertical line in Fig. 1), which in turn implies YP≥0.210 if Nv = 3 and т½≥10.4 minutes. But this limit can be somewhat relaxed if т½ is smaller (current measurements permit values down to 9.0 minutes, e.g. Last et al. 1988) and/or if the quark-hadron phase transition around 200 MeV is first-order and leads to significant density fluctuations (Kurki-Sunonio et al. 1989; Reeves 1989).
Radio Polarization Observations of Three Southern Galaxies
Authors: Harnett J. I. , Haynes R. F. , Wielebinski R. , Klein U.
Published: July 2016

Observations of polarized emission and consequently the investigation of magnetic fields in northern galaxies, have been conducted successfully for some time with, for example, the 100-m Effelsberg telescope of the Max-Planck-Institut-für Radioastronomie and the VLA. However, the opportunity to make corresponding studies in the southern hemisphere has only recently become possible. Therefore, we have begun a long-range project aimed at studying the morphology and dynamics of southern galaxies using the facilities of the Parkes and Molonglo radio telescopes, the Siding Spring optical facilities and the Australia Telescope. Here we present preliminary results from Parkes observations of the three well known galaxies: NGC 253, NGC 4945 and M 83.
Search for Ultra High Energy Gamma Rays from Centaurus A
Authors: Bird D. J. , Clay R. W.
Published: July 2016

An analysis has been made of events recorded in one year from the direction of the active galaxy Centaurus A using the Buckland Park UHE gamma-ray telescope. No statistically significant excess was observed over this period. Data collected between 1984 and 1989 show evidence for an excess of events from this direction at shower sizes in the range of 2 × 105 to 5 × 105 particles.
Solar Cycle Graphics 1700–1988 AD
Authors: Murphy J. O.
Published: July 2016

A graphical format has been adopted to depict some characteristic variations associated with the solar activity cycle up to 1988, for both the Zurich annual and monthly mean values over the respective periods from 1700 and 1750. Both low pass and band pass filtering techniques have been employed to smooth the data, the autocorrelation coefficients determined for a high number of lags to illustrate the secular modulation of the maximum values in each cycle and the spectral amplitudes computed to establish periodicities in the chronologies.
The Role of Supercomputers in Astronomical Modelling
Authors: Faulkner D. J.
Published: July 2016

Advances in digital computer technology since the middle decades of the twentieth century have transformed many subject areas in astrophysics. Topics which had previously been dealt with by analytic approximations (usually to a very limited number of special cases) suddenly became amenable to detailed numerical modelling for all cases. Frequently, insights derived from this modelling ran ahead of other techniques in predicting physical phenomena before they were either observed or discerned in purely analytic treatments.

It has sometimes been said that the second half of this century has seen the advent of a totally new modus operandi in scientific research, which ranks alongside the two traditional approaches–experimentation and theory. The most powerful computers now available have greatly accelerated these developments. They employ simultaneous computational techniques (either vector processing or parallel processing, or both), and their throughput is so large that, for most problems, the only way in which the human mind can fully appreciate the scientific content of the numerical results being calculated is by transforming those results into pictorial representations.

This paper draws on my experience as Academic Director of the ANU Supercomputer Facility during the first eighteen months of its operation, to describe the place which I believe super-computers will occupy in the development of astrophysics during the 1990s and into the next century.
Polarization in the Magellanic Clouds
Authors: Haynes R. F. , Wayte S. , Harnett J. I. , Klein U. , Wielebinski R. , Buczilowski U. R. , Bajaja E. , Malin D. , Murray J. D. , Hunt A. J. , Wark R. , Sciacca L.
Published: July 2016

We present preliminary results from a number of deep radio polarization surveys being made of the Magellanic Clouds at 2.3 GHz, 4.75 GHz and 8.55 GHz. Extended and linearly polarized radio emission has been found at 2.3 and 4.75 GHz from both the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). However, as the analysis of these data is not yet complete we present only some of the 4.75 GHz results at this time.
A Linear Acceleration Emission Mechanism
Authors: Rowe E. T.
Published: July 2016

A theory of linear acceleration emission, with possible application to pulsars, is developed. The equation of motion for a relativistic charged particle accelerated in the field of a longitudinal wave is solved to first order in the electric potential and used to derive the first order current. The power emitted and the absorption coefficient are calculated and the conditions under which masing can occur are discussed.
Comets: pre- and post-Halley
Authors: Swamy K. S. Krishna
Published: July 2016

The recent intensive study of Comet Halley based onin situmeasurements, observations carried out with rockets and satellites and supplemented with co-ordinated Earth based observations has not only confirmed pre-Halley results, but also has given new insight into the nature of the nucleus, dust, gas and the interaction of cometary plasma with the solar wind. These observations also have raised many new questions and problems. Several of these aspects will be discussed. For a better understanding of these problems, the planned future missions to comets will also be discussed.
Space Astronomy in India
Authors: Agrawal P. C.
Published: July 2016

Astronomical observations from space-borne instruments are carried out in India in the areas of infrared, X-ray and gamma-ray astronomy. This paper briefly describes the facilities available in India for conducting experiments in space astronomy using balloons, rockets and satellites. It briefly reviews the important results obtained by Indian astronomers from observations made in India with the balloon, rocket and satellite experiments. The present status of research in different disciplines of space astronomy is discussed.
The Radial Velocity and Metal Abundance of the Sextans Dwarf Spheroidal Galaxy
Authors: Da Costa G. S. , Hatzidimitriou D. , Cannon R. D. , Irwin M. J. , McMahon R.
Published: July 2016

Extended abstract

The multi-object spectroscopic facility FOCAP at the Anglo-Australian Telescope has been used to obtain spectra centred at the Ca II IR triplet of 14 stars in the field of the Sextans dwarf spheroidal (dSph) galaxy. This satellite of our own Galaxy was recently discovered by Irwin et al. (1990) from APM measures of UK Schmidt Telescope photographic plates.
The Core Jet and Relic Radiation in the Radio Source 1343–601
Authors: McAdam W. B.
Published: July 2016

A high-resolution image of the strong extragalactic source 1343–601 has been made with the Molonglo Observatory Synthesis Telescope (MOST) at 843 MHz. The source is identified with a 10 mag galaxy (Mv = −24) which is heavily obscured through our Galaxy. A recent redshift (z = 0.01215) gives a distance of 73 Mpc and a corresponding radio luminosity of log P843 = 24.9.

The MOST image shows a core linked by a double jet to asymmetric lobes which are surrounded by a confined balloon (400 × 200 kpc2) of low-brightness plasma. This has a complex network of ridges or flows which lead out into the wider cluster medium. If similar balloons exist around other double sources, they could provide the depolarising medium required by the Laing-Garrington effect.

Separate observations show the core is compact with strong X-ray emission.
The Berkeley-AAO Distant Supernova Search
Authors: Couch W. J. , Perlmutter S. , Newburg H. J. M. , Pennypacker C. , Goldhaber G. , Muller R. , Boyle B. J.
Published: July 2016

A search for Type Ia supernovae at cosmological distances is being undertaken in an attempt to exploit their standard candle property to constrain the mass density of the universe. We describe the rationale for such a program, the observational approach and strategy taken, and the progress made to date. The science that is being generated by the project in additional to supernova detection is also discussed briefly.
The Possible Progenitors of Planetary Nebulae among OH/IR Stars
Authors: Hekkert P. te Lintel , Zijlstra A. A.
Published: July 2016

Based on a new sample of (IRAS based) OH/IR stars, and a catalogue of planetary nebulae compiled by Acker (1983), we study the relation between these two groups of objects, in terms of the kinematics and the Galactic distribution. In contrast with earlier analyses of samples of OH/IR stars, we find a close correlation between the kinematics of the planetary nebulae and the IRAS based sample of OH/IR stars. In particular, we find that the distribution of the planetary nebulae (PN) shows a good correlation with the OH/IR stars which have a low outflow velocity (Vexp < 12.5 km s−1). Whether the high outflow velocity OH/IR stars also have a counterpart among PN is not clear.
Quantum Theory of Stokes Parameters for Thomson Scattering in a Magnetised Plasma
Authors: Chou Chih-Kang , Chen Hui-Hwa
Published: July 2016

Extended abstract

Thomson scattering in pulsar magnetospheres has previously been studied by several authors. The most distinguishing feature is the fact that the super-strong magnetic field (B ~ 1012 G) greatly affects the Thomson scattering process, resulting in resonances in the scattering cross-section (Canuto et al. 1971; Herold 1979; Chou 1986; Daugherty and Harding 1986). The important consequences of these cyclotron resonances are the increase in the photon mean free path in the scattering regions, and strongly affecting the angular distribution, and polarisation properties of the scattered photons (Chou 1986; Chou et al. 1989).
Studies on Molecules of Astrophysical Interest
Authors: Singh Markandey , Chaturvedi Jai Prakash
Published: July 2016

Extended abstract

Our recent papers have been devoted to basic studies of diatomic and polyatomic molecules (Singh and Chaturvedi 1989 a,b,c,d; 1990a,b,c). A critical analysis of the 456 available references in literature has been made to select 135 polyatomic molecules, molecular ions and radicals containing from three to thirteen atoms of astrophysical significance. The results have been arranged in a text-cum-tabular form (Singh and Chaturvedi 1989 b,d). The compilation contains various information for each molecule, such as the spectral region, transition levels, and astrophysical objects where the respective molecules have been detected (say, comet, meteorite, Sun, planet, star, interstellar medium. Galaxy, etc.).
Some Recent Explorations of the Solar Corona from the Culgoora Solar Radio Observatory
Authors: Sheridan K. V.
Published: July 2016

The complex flare related events taking place in the solar corona are becoming better understood as more observations are made with high spatial and temporal resolution nearly simultaneously at widely separated radio frequencies. Similarly the magneto-plasma structures related to the so-called quiet Sun, which have been extensively studied during the recent cycle (No. 20), are now better understood because of such high resolution observations.
Energy Changes of Cosmic Rays
Authors: Gleeson L. J. , Webb G. M.
Published: July 2016

Recently (Gleeson (1972), Quenby (1973), Gleeson and Webb (1974, 1978)) it has been shown that the mean rate of change of momentum of cosmic rays reckoned for a volume fixed in the solar system is

where G = (1/Up)(∂Up/∂r)si the cosmic-ray density gradient with Up, the differential number density with respect to momentum p at position r. (cf also the integral form of (1) by Jokipii and Parker 1967).
A Possible Association of Solar Type III Bursts and White Light Transients
Authors: Jackson* B. V. , Sheridan K. V. , Dulk* G. A. , McLean D. J.
Published: July 2016

During the Skylab period from June 1973 to January 1974 approximately 1500 type III metre-wave radio bursts or burst groups were reported (Solar Geophysical Data Prompt Reports). The longitudinal distribution of these type III bursts closely resembles that of sunspots and of the coronal transients observed above 2 R⊙ by the white-light coronagraph on Skylab. White light ejection transients appear as large loop or blob-like structures which carry material outward from the Sun and rearrange the corona. In front of the main, bright structures there are weak enhancements of brightness, termed forerunners (Jackson and Hildner 1978; Jackson 1978). In this paper we enquire into whether or not type III bursts are in any way related to the onset of solar mass ejections indicated by coronal transients.
Planetary Nebulae: Origin and Evolution
Authors: Mallik D. C. V.
Published: July 2016

There has been a great deal of progress in our understanding of planetary nebulae and their central stars during the past decade and a half. Most of this has come about through progress in observational techniques covering almost the entire electromagnetic spectrum. Theories of planetary nebula evolution have been put to better and better tests as more and more discriminating data have become available.

This review describes some of the progress made in observations and their interpretation, particularly in the context of the evolution of the nebulae and the central stars. It includes a discussion on the improved determinations of magnitudes and temperatures of the central stars, and of progress in the measurement of distances, and a reassessment of the observed mass-distribution of the central stars. The last topic has been at the centre of a lively debate for almost a decade now and has been responsible for a large number of studies of central star evolution, some this review briefly touchs upon.
Objective Determination of the Large-scale Distribution of Galaxies
Authors: Dodd R. J. , MacGillivray H. T.
Published: July 2016

Observations of the large-scale organisation of matter in the Universe are of great importance in present day astronomy. In the visible part of the spectrum such observations are mainly of the distribution of galaxies on the plane of the sky.

Direct and objective prism plates obtained using large Schmidt telescopes form the bulk of the material used. The direct plates provide the observations from which the surface distribution of galaxies may be determined and the prism plates and FLAIR, via redshifts, yield extragalactic distances and hence the three dimensional distribution of galaxies.

For large-scale surveys the measuring machines used need to be multi-purpose and fast such as COSMOS and SUPER-COSMOS at the Royal Observatory Edinburgh. More specific programs can make use of smaller, slower machines such as iris photometers and microdensitometers.

The method of analysing the data produced rely on seeking density enhancements in the general field of galaxies for cluster detection or using correlation techniques for analysis of the galaxy distribution.

A description is given of a southern sky catalogue containing 109 objects recently completed and an outline of some of the extragalactic projects underway using this large body of data.
Prospects for an Antarctic Observatory
Authors: Gillingham P. R.
Published: July 2016

Following a 1989 USA conference on Astrophysics from Antarctica, a number of proposals have been advanced to exploit the great astronomical potential of this region. The most interesting is for an international station at a new site chosen for optimum astronomical performance. Near the highest point of the ice plateau (where the pressure altitude is about 5000 m), the extremely dry cold atmosphere will allow effective observation through many wavelength ranges currently inaccessible from the ground. There is also reason to believe that better seeing than is otherwise obtainable from the Earth’s surface may be achievable. Astronomers interested in future Antarctic observing should co-operate in presenting cases to their governments for support facilities there.
Space Astrophysics in Japan
Authors: Makishima Kazuo
Published: July 2016

This paper describes some of the space science programs currently underway and planned in Japan.
Newly Installed Radio and Optical Telescopes in China
Authors: Wang Jing-Sheng
Published: July 2016

New radio and optical telescopes installed in recent years in China are summarised. These include the 2.16-m optical telescope, the solar magnetic field telescope, the Miyun synthesis radio telescope, the 1.26-m infrared telescope (Beijing Astronomical Observatory), the 25-m radio telescope as the first station of China’s VLBI network, the 1.56-m astrometric telescope (Shanghai Observatory), and the 13.7-m millimetre wave radio telescope.
A CCD Hα Survey of Nearby Southern Spiral Galaxies
Authors: Ryder Stuart D. , Dopita Michael A.
Published: July 2016

Some initial results of a flux-calibrated CCD Hα imaging program of bright, nearby southern spiral galaxies are presented. Very few southern hemisphere spiral galaxies have ever been completely imaged in Hα, let alone with a CCD. This survey (which mainly uses the MSSSO 1.0-m reflector with an f/3.5 focal reducer) will, when combined with spectrophotometry of the H II regions thus revealed, allow us to trace the chemical evolution of each galaxy. Furthermore, since the absolute Hα flux is a reliable measure of the high-mass star formation rate in a galaxy, such observational data will permit us to test the predictions of the various star formation theories.
On the Nature of the Redshifts of the Twin Quasars with Discrepant Redshifts
Authors: Sapre A. K. , Mishra V. D.
Published: July 2016

We examine the nature of the redshifts of twin quasars with discrepant redshifts (θ < 100 arcsec, Δz ≥ 0.5) by considering their Hubble diagram. If such twins are physically associated one expects a large scatter in their Hubble diagram. However, we find a statistically significant linear correlation between log (cz) and Vc magnitudes of such quasars, consistent with the hypothesis that their redshifts are cosmological in nature.
Mass Loss in Dwarf Galaxies
Authors: Meurer Gerhardt R.
Published: July 2016

Four examples of dwarf galaxies apparently undergoing mass loss are discussed. All have an Hα morphology suggesting a minor axis flow. This is supported by velocity field measurements in three cases. All also have at least one compact central object, probably a young star cluster, apparently powering the flow. Some implications of these results are briefly discussed.
Demise of a Galactic Supernova Remnant Candidate, G274.68–2.84
Authors: Caswell J. L. , Stewart R. T.
Published: July 2016

Young supernova remnants are poorly understood and few are known. Further examples may be present, but unrecognised, within existing catalogues of radio sources. G274.68–2.84 was recently suggested as one such candidate but our new radio map from the Australia Telescope indicates that it is not a supernova remnant. Rather, it appears to be extragalactic with a strong, variable, flat-spectrum nucleus, and a bright X-ray counterpart.
SN 1987A: the Light Curve
Authors: Whitelock Patricia , Menzies John , Caldwell John A. R.
Published: July 2016

The changing total luminosity of SN 1987A between 2 and 1200 days after core collapse is illustrated and discussed. From about four weeks after outburst the supernova light curve was dominated by the release of radioactive decay energy; the major contributor being 0.078M⊙ of 56Co. Recently an additional contribution probably from the decay of 57Co and 44Ti appears to be manifesting itself in the light curve. A gradually increasing fraction of the radioactive decay energy has probably been emitted at X- and γ-ray wavelengths; the fluxes are low and no recent measurements have been published. Most of the remaining radioactive decay energy appears to be emitted in the IR and is very difficult to measure. Other factors influencing the interpretation of the recent light curve are the uncertain contribution from long-lived radioactive isotopes and light-echoes. It is therefore premature to make any definitive statements on the contribution from the neutron star, although it is probably less than a few times 1037 erg s−1.
X-ray Observations of SN 1987A with Ginga
Authors: Inoue H. , Hayashida K. , Itoh M. , Kondo H. , Mitsuda K. , Takeshima T. , Tanaka Y. , Yoshida K. , Makishima Kazuo
Published: July 2016

This paper summarises Ginga X-ray observations of SN 1987 A.
The AAT SN 1987A Data Archive
Authors: Meurer G. R. , Stathakis R. A. , Spyromilio J. , Cannon R. D.
Published: July 2016

This paper presents a brief discussion of the AAT data on SN 1987A and its archive.
Balloon X-ray Astronomical Observations: a China-Japan Collaborative Transoceanic Flight
Authors: Hang Heng-Rong , Zang Zhi-Yun , Liu Shan-Zhao , Ma Gui-Qing , Gong I-Zhong , Yamagami Takamasa , Nakagawa Michio
Published: July 2016

A China-Japan X-ray balloon flight took place in 1988 August. Preliminary results are presented for the energy spectrum of Cyg X-1.