bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary Effects on Radial Pulsations of β–Cephei Stars
Authors: Jensen J. O.
Published: July 2016

During recent years it has become rather clear that the β-Cephei variables are in a hydrogen-buring stage of their evolution. The 8 (β-Cephei variables which have been found in the Scorpio-Centaurus association highlights this. The 6 of these variables for which Glaspey (1971) provides (β, (u – b)0) photometry all fall at the tip of the sequence in the Hertzsprung-Russell diagram. This indicates that (β-Cephei stars are in the final stages of core hydrogen burning. This is in good agreement with the position of the β-Cephei strip of Watson (1972) in the H-R diagram.
T.V. Type Systems in Astronomy
Authors: Disney M. J.
Published: July 2016

Over the past century the techniques and progress of optical astronomy have depended largely on the performance and limitations of the photographic plate. The sort of observations we can make, the faintest limits to which they have been carried and the design of telescopes and instruments have all been circumscribed by the available plates. Over the next decade we will see our emulsions gradually replaced for most applications by one or more of a variety of photo-electric imaging systems now under development.
Cosmic-Ray Energy Changes
Authors: Gleeson L. J. , Webb G. M.
Published: July 2016

The purpose of this paper is to provide a new expression for < ṗ > the average time-rate-of-change of momentum of cosmic-ray particles propagating in the interplanetary region. The expression derived replaces the previously used adiabatic deceleration formula and it is arrived at by a rearrangement and reinterpretation of the well known equation of transport for cosmic-rays. Thus, although we provide a new expression for < ṗ > we maintain the equation of transport and do not render invalid results for differential intensity and differential current density of cosmic-ray particles obtained by its solution (Jokipii 1971; Gleeson 1972).
Solutions of the Cosmic Ray Equation of Transport
Authors: Webb G. M. , Gleeson L. J.
Published: July 2016

In this paper we study the steady-state interplanetary propagation of solar cosmic-rays by means of analytic solutions of the equation of transport. The cosmic-rays are released monoenergetically from a fixed heliocentric radius and redistribute in energy as they propagate. Previous investigations by Goldstein et al. (1970), Urch and Gleeson (1971,1972), and Parker (1965, 1966), were either not general enough or used numerical solutions which could not deal with strictly monoenergetic initial injection nor maintain accuracy over a wide range of particle energies. We use the analytic solutions of Gleeson and Webb (1973) and show the energy changes, the redistribution in energy (or momentum) and the characteristics of the particle flow or streaming.
Synchrotron and Inverse Compton Processes in X-Ray Clusters of Galaxies
Authors: Vidal N.V.
Published: July 2016

The third UHURU catalogue of X-ray sources lists 64 sources at galactic latitudes higher than 20°, many of which have been identified with galaxies and clusters of galaxies. One of the best criteria for identifying a cluster of galaxies with an X-ray source is the extended nature of the X-ray source. Table I is a compilation of all clusters of galaxies known to be within the boundaries of X-ray error boxes. Not all have measured X-ray angular sizes (see column 3). Since the southern sky has been inspected too (Vidal 1975a), we believe that this list may represent a complete sample (down to the sensitivity of the UHURU satellite and the completeness of the Abell catalogue and the southern survey). Column 1 gives the optical identification, column 2 the 3U designation, column 3 the X-ray angular radius, column 4 the radio spectral index (see below), column 5 the redshift (corrected for galactic rotation) and column 6 the X-ray luminosities assuming the Hubble law. Numbers in parentheses give the references for the entries. When no such references are given, the data have been taken from Kellogg et al. (1973) and Bancall (1974).
22 GHz Observations with the Resurfaced Central 17 m of the Parkes Radio Telescope
Authors: Caswell J. L. , Batchelor R. A. , Goss W. M. , Haynes R. F. , Knowles S. H. , Wellington K. J. , Yabsley D. E. , Balister M.
Published: July 2016

At the centre of the Parkes 64—m radio telescope a region of diameter 17 m has recently been resurfaced to improve its efficiency at high frequencies. The first measurements using this section have been made at 22 GHz, in observations of both continuum sources and water tfapour masers. For these observations the receiver front-end used a mixer cooled in liquid nitrogen, followed by a 5 GHz cryogenic parametric amplifier as a second stage. The option of switching against an offset horn was available and the total system
noise temperature was ∽ 750 K.
Spectral-Line Observations of NGC 5128 at Centimetre Wavelengths
Authors: Gardner F. F. , Whiteoak J.B.
Published: July 2016

One of the unusual features of the lenticular galaxy NGC 5128 is the presence of HI absorption (Roberts 1970; Whiteoak and Gardner 1971) and H2CO absorption (Gardner and Whiteoak 1976) against the radio source located near the nucleus. Using the Parkes 64-m radio telescope we have made HI and H2CO observations with improved resolution, and have also detected OH absorption in this galaxy. For the OH and H2CO observations, the equipment and observing procedure have already been described (e.g. Whiteoak and Gardner 1973; Gardner and Whiteoak 1976); for the HI observations they will be described in a forthcoming paper (Whiteoak and Gardner, to be submitted to Aust. J. Phys.).
An Unidentified Emission Line at 7090 Å
Authors: Allen David A.
Published: July 2016

Symbiotic stars are at the same time perplexing and rewarding to study. Their spectra contain great numbers of emission lines due to atoms in a range of ionization states from neutral to coronal. The continua are weak and usually unobtrusive: the strongest lines may have equivalent widths of thousands of Angstroms. But the crowding of weak lines complicates their measurement and, often, their identification. Many symbiotic stars probably emit weak lines which currently defy identification, but which cannot be distinguished from their neighbours. It is, however, rather rare to find a strong unidentified emission line.
Pulsar Timing Observations at Tidbinbilla
Authors: Manchester R. N. , Goss W. M. , Newton Lynette M. , Hamilton P. A.
Published: July 2016

Pulse arrival time measurements allow the determination of accurate pulsar periods, period derivatives and, provided the data span is at least one year, precise pulsar positions. If observations are frequent and reasonably regular, irregularities in the period can also be investigated. To minimize the effect of possible variations in dispersion measure, it is important that these observations be made at a relatively high frequency, preferably above 1 GHz. To eliminate pulse shape variations due to variable ionospheric Faraday
rotation, the pulse total intensity or one of the circular polarizations must be recorded.
An Acousto-Optical Radio Spectrograph for Spectral Integration
Authors: Cole T. W. , Milne D. K.
Published: July 2016

From early experiments in 1966 (Cole 1968) the acousto-optical radio spectrograph has been developed at CSIRO to a sensitive, multi-channel spectral-line back-end. The principles of the instrument are described in detail elsewhere (Lambert 1962; Hecht 1977; Milne and Cole 1977). By means of a Bragg interaction between a laser beam and an ultrasonic beam derived from the radio signal, light is diffracted into an order whose light intensity distribution is accurately related to the power spectrum of the radio signal. In the earlier spectrographs the spectrum was recorded photographically (Cole 1973a, b; Hecht 1973) but this was limited to strong spectral features. To study weak spectral features a stable, linear system was needed with large dynamic range. The combination of an array of photodiodes and computer would be capable of observing these weak spectral features (Cole and Abies 1974). Development since 1974 has been a progressive identification of sources of thermal and mechanical instability and of excess noise in the spectrograph system.
Asymmetries in the Shells of Supernova Remnants — Evidence of Large-scale Gradients in the Surrounding Medium
Authors: Caswell J. L.
Published: July 2016

Most supernova remnants (SNRs) show a ring-shaped radio intensity distribution which is interpreted as the projection of an approximately spherical shell of emission. However, in many cases the ring is neither circular nor complete; in this empirical investigation a major factor responsible for asymmetry is identified and the implications of this discovery are explored.
Interpretation of Quasar Colours in the Near IR
Authors: Hyland A. R. , Schwarz M. P.
Published: July 2016

Over the past ten years, there has been considerable interest in the infrared continua of quasars, however few published colours exist in the literature. The only major compilation of infrared data out to 2.2 μ is that of Oke et al. (1970). The intrinsic faintness of the sources prevented the acquisition of significant high quality data. This situation is not expected to remain static for very long. The recent introduction of new high sensitivity InSb detectors has made it possible for a large number of sources to be measured, and published data is expected to increase significantly over the next few years.
Two of the most Metal-deficient Stars
Authors: Bessel M. S.
Published: July 2016

The metal content of stars (and galaxies) is of great interest as it relates to the theories of element formation, and through these to the history of our galaxy, the frequency of supernovae, the star formation rate and even the quasar rate. The kinematics and metallicity of stars have been correlated in a theory of formation of the galaxy by Eggen et al. (1962). Alternate theories (Unsold 1969) have also been proposed. Much work has gone into isolating individual metal deficient stars and determining their abundances, and also the abundances for stars in clusters.
Some Thoughts on Dyson Spheres
Authors: Suffern K. G.
Published: July 2016

According to Dyson (1960), Malthusian pressures may have led extra-terrestrial civilizations to utilize significant fractions of the energy output from their stars or the total amount of matter in their planetary systems in their search for living space. This would have been achieved by constructing from a large number of independently orbiting colonies, an artificial biosphere surrounding their star. Biospheres of this nature are known as Dyson spheres. If enough matter is available to construct an optically thick Dyson sphere the result of such astroengineering activity, as far as observations from the earth are concerned, would be a point source of infra-red radiation which peaks in the 10 micron range. If not enough matter is available to completely block the stars’ light the result would be anomalous infra-red emission accompanying the visible radiation (Dyson 1960).
Cyclotron Absorption in GD229?
Authors: Wickramasinghe D. T. , Martin Brian
Published: July 2016

The existence of a group of magnetic white dwarfs with mean surface fields of between ~5 × 106 G and ~2 × 1O7 G is now firmly established through the discovery of Zeeman structure in hydrogen and helium lines (Angel et al. 1974, Liebert et al. 1975, Wickramasinghe et al. 1977, Martin & Wickramasinghe 1978, Liebert et al. 1977). There is considerable evidence from polarimetric studies for even higher fields in some white dwarfs (Angel 1977). Most of these stars are cool and show nearly continuous spectra or weak unidentified absorption features. The possibility of cyclotron absorption in white dwarfs was first discussed in connection with the infrared polarisation spectrum of one of these stars, Grw + 70°8247 (Kemp 1970). More recently the polarised white dwarf GD229 was found to have a rich optical spectrum with a strong feature at λ4185, for which cyclotron absorption has been mentioned as a possible origin (Angel 1977, Greenstein & Boksenberg 1977), though without supporting computations. In this letter we use models to investigate this possibility further.
Atmospheric Shock Effects in Early B Stars
Authors: Stamford P. A. , Watson R. D.
Published: July 2016

Both radial and non-radial motions have been suggested at various stages to explain the observational peculiarities of the β Cephei variables. The non-radial possibility has been investigated most recently by Smith (1977) and Stamford and Watson (1977). We here examine the radial shock proposal by generating a series of isothermal radial shock models in suitable early B star atmospheres. Odgers (1955) has long advocated such a model in connection with the large amplitude variable BW Vul. The observations of Goldberg, Walker and Odgers (1976) clearly show a radial velocity ‘stillstand’ effect and line splitting in this star. We discuss our models in the context of these two phenomena.
On zero-point drift in astronomical photoelectric photometry
Authors: Kviz Z.
Published: July 2016

In variable star work, the frequent observations of comparison stars during a night often clearly indicate the presence of either changes in extinction or changes of zero point of the photometric system, or both effects simultaneously. In a magnitude — air mass plot, the graph is not linear, but is usually a loop. These loops are well known to observers but so far very little has been published about this problem. Young’s (1974) chapters are perhaps the only exception.
Observations of Galactic HII Regions with the Fleurs Synthesis Telescope
Authors: Retallack D. S.
Published: July 2016

The Fleurs Synthesis Telescope (FST) has been used to map a number of bright, southern galactic HII regions at 1415 MHz. Descriptions of the FST can be found in Christiansen (1973) and associated papers. For the observations reported here, both the east-west and the north-south arms of the cross were used resulting in beamshapes which are nearly circular with half-power widths of 50” arc. The maps have been “cleaned” using a standard process (Högbom 1974).
Possible Anisotropy of the Spatial Distribution of QSOs from the MC2 and MC3 Catalogues
Authors: Murdoch H. S.
Published: July 2016

The MC2 and MC3 catalogues cover two strips approximately 2° wide centred on declinations +11° and +16.5°. MC2 runs from 11h 28m to 01h 23m and MC3 from 13h 31m to 04h 11m (Sutton et al. 1974). Optical identifications up to 17h 00m have been’published (Hazard and Murdoch 1977) and identifications for the remainder exist in preliminary form (Hazard, Zotov and Murdoch, in preparation). Optical spectra are being obtained chiefly at Lick Observatory (Smith et al. 1977) and this programme is now approaching completion.
The Theory of Solar Radio Bursts: Can it be understood by the Non-Expert?
Authors: Melrose D. B.
Published: July 2016

The theory of solar radio bursts remains a mystery to most astronomers and astrophysicists. The reasons for this are not hard to identify. First, the solar radioastronomical data are unfamiliar. (The observational data on solar radio bursts is being reviewed separately at this meeting (McLean 1981).) The important features of this data involve frequency-time structures in dynamic spectra, and such features are absent in data on galactic and extra galactic objects. Even for pulsars the data are obtained at discrete frequencies, and the frequency-time structures are not of major importance. Second, the theory itself involves plasma physical concepts which are unfamiliar to most physicists and astronomers. These concepts include those of plasma instabilities, microturbulence, and of particle-wave and wave-wave interactions. Third, one must also admit that there is a prejudice amongst many astronomers against solar physics: the Sun is regarded as interesting only to the extent that it can teach us about other astronomical objects. I shall return to this third point later.
What Can Infrared Photometry Tell You?
Authors: Allen David A.
Published: July 2016

Historically, infrared instrumentation for astronomical research has been developed by individual groups largely for their own enjoyment. The commissioning of the AAO’s infrared photometer-spectrometer (IRPS) in late 1978 provided for the first time in Australia a common-user instrument. Since then it has attracted considerable interest and is now the second most popular instrument in use at the AAT.
The Molonglo Observatory Synthesis Telescope
Authors: Mills B. Y.
Published: July 2016

The Cross radiotelescope at the Molonglo Radio Observatory (Mills et al. 1963) came into full operation during 1967 and observations continued without interruption until 1978 when it was closed down for substantial modifications; these are now largely complete and observations have re-commenced. The decision to make some drastic changes was taken about seven years ago, although it had been evident right from the beginning that scientific returns from the Cross would drop sharply once the whole accessible sky had been surveyed. Indeed, the specifications for the original instrument were chosen to permit a subsequent conversion from 408 MHz to 1420 MHz with little extra expenditure on the reflector structure. Also, in 1972 a new form of circular polarized antenna was developed to provide a cheap mass-produced feed for 1420 MHz operation which could be easily phased and had good directional properties (Mills and Little 1972).
Some Features in the Spectra of Extragalactic Radio Sources
Authors: Slee O. B.
Published: July 2016

A recent analysis of the spectra of about 2000 sources in the Culgoora-3 list (Slee 1977) of radio sources (Slee et al. 1981) has revealed some interesting features which may be the result of source evolution. The Culgoora-3 spectra were obtained by combining the 80 and 160 MHz flux densities from the Culgoora radioheliograph with other published flux data between 10 and 10,000 MHz; this is probably the most accurate set of spectra yet derived for a large number of sources selected for observation in a reasonably consistent manner. In addition to fitting the log S-log v data for each source with a straight line (its slope is the usual definition of spectral index) Slee et al. also fitted second-degree and third-degree polynomials to search for curvature in the spectra.
Deep Photography of Radio Sources with the Cambridge CCD System
Authors: Mackay C. D. , Astili D. , Batty M. J. , Jauncey D. L. , Wright A. E. , Hunstead R. W. , Morton D. C. , Robertson J. G.
Published: July 2016

We present preliminary results from a programme designed to produce deep images of radio source fields drawn from the Parkes 2700 MHz and Molongolo 408 MHz catalogues using the charge-coupled-device (CCD) camera system built at the Institute of Astronomy, Cambridge. The programme is directed at a search both for faint extensions and nebulosity around radio QSOs and BL Lac objects and for faint objects in otherwise empty radio source fields; a detailed examination of the morphology of selected radio galaxies is also included.
Annular Synthesis Telescopes: A Novel Class of Multiple Beam Telescopes operating at MM-Wavelengths
Authors: Fourikis N.
Published: July 2016

Carbon monoxide (12CO) interstellar clouds are widely distributed while clouds of 13CO, HCN, CS and HCO+ are generally more compact. Additionally the molecular lines of the former species tend to be more intense than that of the latter. High resolution and high sensitivity maps of interesting interstellar clouds are, at present, time consuming when a single beam telescope is used. Multiple beam telescopes are therefore required to undertake these mapping tasks during the periods when the precipitable water vapour content of the atmosphere is low; for sites near sea level these periods can be short.
Populations and Mass Distributions in Spiral Galaxies
Authors: van der Kruit P. C.
Published: July 2016

The distribution of mass in a spiral galaxy is usually inferred from its rotation curve. The curve is most conveniently measured using part of its extreme population I such as HI or HII. This has a low velocity dispersion so that the observed tangential motion is in the absence of non-circular motions (van der Kruit and Allen 1978; Bosma 1981a, b) close to the circular velocity required to balance the gravitational force. The main difficulty is that for a detailed interpretation of the rotation curve one has to make assumptions on some general properties of the mass distribution, even though it is true that one can estimate the total mass within the last measured point to an accuracy of about a factor two. That of axial symmetry is only the simplest of assumptions. On the basis of the light distribution with a usually prominent disk component one often assumes that the mass distribution is also basically highly flattened.
Accuracy of the Anelastic Approximation in the Theory of Compressible Convection
Authors: Borght R. Van der , Fox P.
Published: July 2016

Theoretical investigations of non-linear convective motions quite often assume that either the Boussinesq or the anelastic approximations can be used.
Drifting Subpulses in Pulsars
Authors: Allen Michelle C. , Melrose D. B.
Published: July 2016

Individual pulses from a given pulsar can differ greatly in both shape and intensity, and are often made up of narrower ‘subpulses’, i.e. local emission peaks one tenth the width of the mean pulse. Properties such as shape, polarization and position of subpulses presumably reflect details of the emission processes and of the regions that produce the radiation.
Scattering of Radio Waves in the Solar Corona
Authors: Robinson R. D.
Published: July 2016

Radiation generated in the solar corona can be drastically altered by refraction and scattering as it escapes. This is especially true for sources having a frequency near the local plasma frequency, where the index of refraction approaches zero. Early investigations of the problem (e.g. Fokker 1965; Steinberg et al. 1971; Riddle 1972, 1974) have shown that the size, shape, location, intensity and time profile for the observed source can all be influenced.
CO Emission vs HI Self-Absorption
Authors: Peters William L. , Bash Frank N.
Published: July 2016

We present the initial results of a statistical comparison of CO emission and H I self-absorption in the galactic plane at large distances from the Sun. Evidence for self-absorption by cold atomic hydrogen (Ts < 60 K) over angular scales of 3 ´-20´ was reported by Baker and Burton (1979). They suggested that this hydrogen was associated with the molecular clouds of the ‘molecular ring’ located between 4 and 8 kpc from the galactic center (Burton and Gordon 1978). Burton, Lizst, and Baker (1978) did find a correspondence between CO emission and H I self-absorption; however, their observations were not extensive enough to prove that the correspondence was statistically significant or to test their prediction that all instances of H I self-absorption are accompanied by CO emission and thus associated with molecular clouds.
Microwave Holographic Surface Measurement of the Tidbinbilla 64-m Antenna
Authors: Rahmat-Samii Y. , Gulkis S. , Levy G.S. , Seidel B.L , Young L.E. , Batty Michael J. , Jauncey David L.
Published: July 2016

The ‘holographic’ technique for accurately measuring the surface figure of large reflector antennas, described by Bennet et al, (1976) and Scott and Ryle (1977), has many advantages over older conventional survey methods. These include high speed, low cost, and the absence of any need for additional complex mechanical or optical survey devices. In essence, the technique consists of measuring the complex far-field response of the antenna at a single frequency using a terrestrial, satellite-borne or celestial radiation source of small angular diameter. This two-dimensional pattern is then Fourier-transformed to yield the complex illumination function across the antenna aperture. Antenna surface deviations are manifested as phase fluctuations in this function. In practice, a second antenna is needed to provide a phase reference.
Sydney Observatory 1858-1983
Authors: Wood Harley
Published: July 2016

Astonomy in Sydney predates Sydney Observatory by some 70 years. Lt William Dawes arrived with the First Fleet and set up an observatory at a place now called Dawes Point at the foot of the present Observatory Hill. His instructions were to observe a comet predicted by the famous astronomer, Edmund Halley, to return about 1790.
Optical Spectra of Southern Molonglo Radio Sources — II
Authors: Murdoch H. S. , Hunstead R. W. , White Graeme L.
Published: July 2016

This is the second of a series of papers presenting detailed optical spectra for QSOs and strong-emission-line galaxies identified with radio sources from a selected area (−15° to −23° in declination) of the Molonglo Reference Catalogue (MRC: Large et al. 1981). The catalogue is complete to 1 Jy at 408 MHz although it contains many weaker sources. First results were reported by Hunstead et al. (1978, Paper I) and a summary was given by Hunstead (1979). Results have also been given by White et al. (1980) for spectra of QSOs identified with radio sources to a much deeper level of 88 mJy from a small strip within the larger selected area.
Absorption Lines in the Spectra of the QSO PKS 1448-232
Authors: Jian-sheng Chen , Morton Donald C. , Peterson Bruce A. , Wright Alan E. , Jauncey David L.
Published: July 2016

Savage et al. (1977) found that the radio source PKS 1448-232 coincided with a stellar object of about magnitude 16.4 having an ultraviolet excess. A low resolution spectrum obtained with the Anglo-Australian Telescope (AAT) confirmed this object as a QSO with zem = 2.22 and revealed many absorption lines short-ward of the La emission. Consequently this object was included in a programme of spectroscopy at intermediate resolution with the AAT to investigate QSO absorption lines. Savage et al. have given a finding chart with an optical position of 14h48m09s.3, −23°17′10″ (1950.0). The radio fluxes are 0.40 Jy at 2.7 GHz and 0.31 Jy at 5.0 GHz.
The Origin of Inner Rings in Barred Spiral Galaxies
Authors: Schwarz M. P.
Published: July 2016

A large number of barred spiral galaxies contain a ring-like structure surrounding the bar. This is known as an inner ring if the bar terminates at the ring. Structures which are not closed but which appear to be related phenomena are given the name pseudo-inner rings by de Vaucouleurs (1959).
The Plume Phenomenon in Barred Spirals
Authors: Buta R.
Published: July 2016

Barred spirals are well-known to include several ‘distinct components’ or morphological structures in the light distribution (Sandage 1961; de Vaucouleurs 1959; Kormendy 1979). In addition to the bar, spheroid, and disk components, one often observes ring-like enhancements at discrete relative positions within the disk. These inner rings (r), outer rings (R), and nuclear rings (nr) have been the subject of recent, fairly intensive observational (Buta 1984a; Kormendy J979; de Vaucouleurs and Buta 1980a,b; Athanassoula et al. 1982) and theoretical (Schwarz 1979,1981,1984a,b,c; Simkin, Su, and Schwarz 1980) research, and it now seems well-established that most rings are linked to dynamical resonances with the bar.
Alfvén Waves in Current-carrying Solar Magnetic Flux Tubes
Authors: Cramer N. F. , Donnelly I. J.
Published: July 2016

In theories of the heating of the solar corona a number of authors have recently considered the propagation and damping of fast and slow magnetohydrodynamic waves, in the form of surface waves localized on the interfaces of coronal flux tubes (Ionson 1978, Wentzel 1979, Roberts 1981, Cramer and Donnelly 1983). The damping of these waves occurs, in addition to a rather weak global damping due to viscous or resistive dissipation, by means of a localized absorption at a so-called ‘resonance’ in the density or magnetic field profile forming the flux tube. At such a resonance, the wave frequency is equal to the local value of the Alfven wave frequency, in the case of Alfven resonance absorption, or at the local slow mhd wave frequency, in the case of the ‘cusp’ or ‘compressive singularity’ resonance in a finite pressure plasma.
Cloud-Cloud Collisions
Authors: Lattanzio J. C. , Monaghan J. J. , Pongracic H. , Schwarz M. P.
Published: July 2016

The classical model of the interstellar medium consists of cool clouds (typical temperature 80 K, number density 20-40 cm-3) moving through a warmer interstellar medium (104 K, 0.15-0.3 cm-3) at a rms velocity of ~ 10 km s-1. More recent models have included the coronal gas (106 K) as part of this medium. We consider the collisions of these clouds in order to determine whether these collisions initiate star formation and/or change the state of the interstellar medium.
Observations of 115 GHz CO Emission Towards the Carina Nebula
Authors: Whiteoak J. B. , Otrupcek Robina E.
Published: July 2016

We have carried out a survey of the 115 GHz CO emission (J = 1→0 transition) towards the Carina nebula (NGC 3372) using the Epping 4 m radio telescope of the CSIRO Division of Radiophysics. Of all the molecules detected in the interstellar medium CO is perhaps the best tracer of molecular clouds. It is an abundant molecule (second only to H2) and its line emission at microwave frequencies occurs at relatively low excitation.
Fibre Optics at the UK Schmidt Telescope
Authors: Watson F. G. , Dawe J. A.
Published: July 2016

The four-fold advantage over a conventional 4 m reflector which naive information theory confers on the 1.2 m UK Schmidt telescope (Dawe and Watson 1982, Watson 1983) is only approachable in practice under certain rather specific conditions. These relate principally to the surface distribution on the sky of the object classes of interest, and the type of detection employed. Clearly, for general survey work with sky-limited photographic detection, the information advantage is high, but it can be demonstrated (Dawe and Watson 1983) that the relatively new technique of multi-object fibre-optics spectroscopy (eg Hill et al. 1980, 1982, Gray 1983, Lund and Enard 1983) with linear detectors offers very high potential in certain regimes of operation. In particular, the UK Schmidt telescope (UKST) equipped with 400 fibre channels has four times the effective light grasp (= number of fibres utilized × aperture) of a 4 m reflector (with a 1 deg field and equipped with any number of fibres) for target objects with surface densities between approximately 1 and 10 per square degree (Dawe and Watson 1983). Objects ranging from galactic variable stars to quasars lie within these limits, but of especial interest are galaxies, whose apparent luminosity function in this range of surface densities runs from magnitudes 15 to 17 (MacGillivray, private communication). Large-scale, medium accuracy (60 km s−1) redshift surveys of galaxies within this magnitude range promise to be extremely fruitful (Davis 1982) and are easily within the reach of the UKST fibre-coupled to a CCD spectrograph (Watson and Dawe 1984).
Speckle Observations with a Photon Counting Detector
Authors: Wood P. R.
Published: July 2016

A description of the production of astronomical speckles is given in terms of elementary physical principles. Using simple probability arguments, estimâtes are made of signal-to-noise requirements and magnitude limits for détection; data réduction techniques are discussed. A speckle System used on the AAT (Anglo-Australian Télescope) with the IPCS as detector is described.
The Relationship of the Fanaroff-Riley Classification of Extragalactic Radio Sources to Jet Physics
Authors: Bicknell G. V.
Published: July 2016

The Class I/Class II division of extragalactic radio sources by Fanaroff-Riley is a manifestation of important physical differences existing in radio sources.

It is proposed that the division essentially arises from the differing Mach numbers in Class I and Class II jets. The low Mach number, Class I jets are susceptible to turbulence, are decelerated by entrainment of the surrounding medium and maintain an anomalously high surface brightness as a result. The high Mach number, Class II jets are less turbulent and remain supersonic, produce high pressure shocks along their lengths and terminate via a strong shock against the IGM.

An analysis of the energy balance in both types of source reveals jet velocities of the order of 5-10,000 km s-1 for Class I jets and mildly relativistic velocities for Class II jets.

The important rôle of optical and X-ray observations in determining the gravitational field of pressure distribution in radio galaxies will be discussed with examples given of NGC1399 and IC4296.
Optical Counterparts of HEAO-1 X-ray Sources
Authors: Buckley D. A. H. , Tuohy I. R. , Remillard R. A.
Published: July 2016

We present preliminary results of a search for the optical counterparts of faint but energetic (1-13 keV) X-ray sources observed by the HEAO-1 satellite. The objects we have identified include Active Galactic Nuclei, Cataclysmic Variables, Be Binaries, and RS CVn Systems. A description is also given of the identification techniques and the X-ray database, which represents the most recent flux-limited all-sky survey of hard X-ray sources.
An Optlcal and Radio Investigation of the Active RS CVn Star HD 127535
Authors: Innis J. L. , Coates D. W. , Thompson K. , Nelson G. J. , Slee O. B. , Wright Alan E.
Published: July 2016

We present some preliminary results of an optical and radio study of the very active RS CVn binary HD 127535. Photometric measurements show the presence of a large amplitude wave which exhibits marked changes in shape and range on time scales as short as a few months. This photometric variation is almost certainly due to large cool starspots on the cooler, more luminous component. As part of a survey of southern active-chromosphere stars with the Parkes radio telescope, HD 127535 has been observed at 5, 8.4 and 22 GHz. No detection was made at 5 GHz, possibly because of confusion due to the angular proximity of the star to the galatic plane. However, it is one of the strongest sources detected in the 8.4 GHz survey, and is one of only two stars detected at 22 GHz. Photometry obtained two cycles before the 8.4 GHz observations suggest a possible correlation between the radio emission and the photometric wave, i.e. spot visibility, but more data are needed.
Ammonia in the Hot Galactic Centre Cloud G 1.6-0.025
Authors: Gardner F. F. , Whiteoak J. B. , Forster J. R. , Peters W. L. , Kuiper T. B. H.
Published: July 2016

As part of an extensive southern survey of interstellar NH3 with the Parkes 64-m radio telescope (with a beamwidth of 81 arcsec), the (1, 1), (2, 2), and (3, 3) transitions have been observed towards the galactic centre molecular cloud G1.6-0.025. The cloud has an overall size of 10 arcmin, and contains several concentrations with differing velocities. It has several features also observed in other galactic centre clouds, e.g. high optical depths and kinetic temperatures above 50 K.
The Role of Kinetic Boundary Conditions in Generating Type II Solutions for Rayleigh-Benard Convection
Authors: Murphy J. O. , Yannios N.
Published: July 2016

A new family of solutions for stationary convection (Murphy and Lopez 1984) has been established which exists within the astrophysical range of parameter values — large Rayleigh number and low Prandtl number. These single mode Type II solutions, which have a non-zero component of vertical vorticity, apparently do not exist at higher Prandtl numbers and are characterized by a lower vertical velocity and heat flux, when compared to the equivalent single mode Type I solutions for Rayleigh — Benard convection with zero vertical vorticity. In turn the vertical component of vorticity associated with Type II solutions is responsible for modifying the horizontal components of the velocity field to establish cyclonic or swirling type solutions within the hexagonal convection cell.
Radial Pulsations and Vibrational Stability of a Sequence of Two Zone Polytropic Stellar Models
Authors: Murphy J. O. , Fiedler R.
Published: July 2016

Characteristic frequencies of some modes of radial pulsations and their relative displacements have been determined for a sequence of composite polytropic stellar models having an inner zone of index n = 1 and an envelope n = 5. It is demonstrated that vibrational stability increases with the degree of central condensation of the individual two zone models.
A Method for the Study of Gas Dynamics in Galactic Potentials
Authors: Varnas S. R.
Published: July 2016

A particle method for the simulation of the global evolution of cold gas in galactic potentials is described. It incorporates an efficient artificial viscosity, based on the smoothed particle hydrodynamics approach, which conserves both linear and angular momenta and in the continuum limit is equivalent to a Navier-Stokes viscosity in a compressible gas. Parameters of this viscosity have been calibrated in such a way as to make a gas disk, embedded in an axisymmetric galactic potential and originally inclined to its equatorial plane, settle to the preferred plane on the time scale characterizing the differential precession. After a careful analysis of the previously published settling times we find that our results are consistent with Steiman-Cameron’s (1984) lower limits, and we argue that Simonson’s (1982) time scales have been seriously underestimated. We also demonstrate that two dimensional methods based on rigid rings do not model the evolution of a differentially precessing settling gas disk realistically and cannot be used to study the morphology of gas distribution.
A Novel Nolse-Adding Radiometer
Authors: Wright Alan E. , Nelson G. J. , Stewart R. T. , Slee O.B. , Murray J. D. , Cooke D. J. , Carrad G. J.
Published: July 2016

Very sensitive low-noise amplifiers designed to receive transmissions from spacecraft are not necessarily suitable receivers for radio astronomy. In the former case a good signalto- noise ratio is required so that high data rates can be achieved. In the latter the ratio of signal to noise power may be as low as 10-4 and the stability of receiver gain and that of ail sources of noise during long integration times become of equal importance.

This paper describes a novel solution to the problem, which allowed important astronomy to be performed while the ruby maser receivers belonging to the European Space Agency were installed on the Parkes radio telescope for an extended period of time.
The Astronomy Advisory Committee
Authors: Westfold K. C.
Published: July 2016

The present Astronomy Advisory Committee (AAC) was set up by the then Minister for Science and the Environment, Senator J. J. Webster, in July 1979 following a Government review of astronomical facilities carried out by an interdepartmental committee (IDC) in 1978-1979. The IDC was assisted by an expert sub-committee, whose report Review of Observatories (1978) has since been published. The AAC consists of a chairman and ten members drawn from the astronomical community in Australia. It is serviced by the Department of Science and the Environment.
On the F and M Type Solutions of the Lane-Emden Equation
Authors: Murphy J. O.
Published: July 2016

The traditional classification of solutions of the Lane-Emden equation

into E, F and M types is based on the value of the invariant quantity
Variable Sources at 408 MHz
Authors: McAdam W. B.
Published: July 2016

Flux density changes at low frequency in extragalactic sources were discovered in 1969 by Hunstead (1972a) and this low frequency variability has since been confirmed in the range 318 to 962 MHz at five other observatories. The changes are usually small and near the stability limit of most telescopes, but occasionally large changes ~ 30% are found. Many sources show changes at both low and high frequencies, but these appear uncorrelated even with delay lags of several years, and the likelihood of low frequency variability in a source cannot be predicted from high frequency behaviour. This paper reports statistics on the proportion of sources that showed changes of different amplitudes during a monitoring program with the Molonglo Cross in 1975/76.
Projection Effects and Radio Source Morphology
Authors: Reynolds J. E.
Published: July 2016

Since the discovery of the first ‘head-tail’ radio source (Ryle and Windram, 1968) extensive radio surveys of clusters of galaxies have revealed a surprisingly diverse range of source morphology. In additions to the familiar symmetric double-lobed shape, several other morphological types are now recognised; these are presumed to be due to interaction between the source and a relatively dense, hot plasma pervading rich clusters. In particular, rapid motion of a radio galaxy with respect to this inter-galactic medium appears to produce a ‘bent-double’ shape, or in more severe cases, a ‘double-tail’ or ‘head-tail’ shape. In such cases, the source no longer has the simple symmetry of ‘ordinary’ double structure and it is clear that the attitude of the source with respect to the line of sight may markedly affect what is observed. Results and details are given below of a simple computer code used to simulate the appearance of a hypothetical bent-double source seen in projection. It is emphasised that the model has been chosen as one that can represent in a simple way many of the observed morphological forms and is not based on any physical theory of radiation or emission processes.
Cross-Correlation Techniques for the determination of Galaxy Redshifts
Authors: Hunstead R. W.
Published: July 2016

Most of the galaxy redshifts currently available in the literature have been measured from photographic spectra and are generally based on subjective estimates of the position of the narrow absorption features. In using only the few prominent absorption lines, most of the light from the galaxy is discarded. With the advent of digital linear-response detectors it is possible to obtain accurate and objective redshifts by cross-correlating all or part of the galaxy spectrum with a template galaxy of known redshift (Tonry and Davis 1979, Kelton 1980 and references therein).
Associations between Galaxies and Bright Quasars
Authors: Drinkwater M. J. , Webster R. L. , Thomas P. A. , Millar D.
Published: July 2016

The results of a new imaging survey of 68 bright (mv < 18) high redshift (z > 0.7) quasars are presented. The distribution of celestial distances between the quasars and the nearest galaxy neighbours shows an excess at small separations (< 15 arcseconds) significant at the 99.96% level. The redshifts of these galaxies are not known, so two interpretations are possible. If the galaxies are in groups physically associated with the quasars then they must be significantly brighter (> 3 magnitudes) than normal M* galaxies at the present epoch. Alternatively, this may be the result of a bias caused by gravitational amplification of background quasars by compact lenses in the halos of the nearest neighbour (foreground) galaxies. Of the present sample, 25% of the quasars have extra galaxies. If this is caused by a gravitational lensing bias, then, allowing for incompleteness, the results imply that as many as 60% of bright quasars may be gravitationally lensed.
Synthesis 6 cm Images of 22 Strong Southern Radio Sources
Authors: Duncan R. A. , SproatS L. N.
Published: July 2016

We present 6 cm Australia Telescope images of 22 strong southern radio sources. At least one of these sources appears likely to be a gravitationally lensed mirage.
Radio Supernova 1987 A
Authors: Ball Lewis , Kirk J.G.
Published: July 2016

The reappearance of radio emission from SN 1987A is discussed. We propose a model involving synchrotron radiation from electrons which are accelerated when the expanding supernova shock wave runs into a density jump in the circumstellar material, and which then expand adiabatically.
Ring-width Variation in Sub-fossil Wood Samples as an Indicator of Short-term Solar Variability 2000 yr B.P.
Authors: Murphy J.O. , Palmer J.G.
Published: July 2016

Results from carbon 14 analysis of Bristle cone pine wood, using samples bounded by decade groups of annual rings, has established a significant long term solar periodicity of just over 200 years. Sites with large quantities of buried sub-fossil Kauri, Huon pine and Celery pine logs, which can provide data for a record possibly exceeding 20 000 years, have been identified in New Zealand and Tasmania. An initial study into periodicities, of possible solar origin, embedded in these ring-index time series can be justified on the basis that there are few other sources of annual proxy data, extending beyond the last 2000 years, that may reflect solar variability. Results from spectral analysis of a sub-fossil floating Celery pine chronology, which extends over 426 years, are considered. Carbon dating indicates that the Taupo volcanic eruption, which buried this forest, occurred about AD 177.
The Formation of Red Giants
Authors: Frost Cheryl , Lattanzio John C.
Published: July 2016

The astrophysical literature contains many discussions on exactly which changes in a star’s structure are responsible for the extremely large radii found after core hydrogen exhaustion. Different authors favour different mechanisms. Unfortunately none of the proposals are easily verified nor are they easily disproven. In this paper we examine the suggestion that it is the increased central mass concentration (i.e., the growth of the hydrogen exhausted core) which is the primary agent responsible for envelope growth.
Robert L. J. Ellery, his Life and Times
Authors: Gascoigne S.C.B.
Published: July 2016

To present-day astronomers the name of Robert Ellery, by which our newly established lectureship is to be known, means little. A century ago it was a different story. Ellery was then one of the most respected scientists in the country, a leading astronomer who had been director of the Melbourne Observatory since it was founded in 1853, and who had taken it to a prominent position in international astronomy. Besides this he was a man of parts who spread his talents widely. He was a founder and long-term president of the Royal Society of Victoria, treasurer of the University Council, chairman of the committee of the Alfred Hospital, Trustee of the Public Library, the Art Gallery and the Museum, and he was an active member, latterly commander, of the local Torpedo and Signal Corps, a coastal defence unit manned by citizen soldiers. Late in life he became the first president of the Beekeepers’ Club. He was elected to the Royal Society and awarded a CMG: all in all, a man of character and achievement.
Searching for Supernovae—Visually and Otherwise
Authors: Evans Rev. Robert
Published: July 2016

The main features of visual searching for supernovae in other galaxies by amateur astronomers are described, and an outline is given of the results which have been achieved so far by this method. A short comparison is made between visual searching and photographic searching. A more extensive comparison is then made between visual searching for supernovae in Australia, and the work of the Berkeley Automatic Supernova Search at Leuschner Observatory, since 1986. Among the conclusions is the claim that a competent visual observer could produce similar results to those produced by the Berkeley group if a telescope of similar aperture was used for a similar amount of observing time, and from a good observing site. Indeed, visual searching might possibly produce more results, and such a search would only cost a small fraction of what was spent on this automatic search. It would be a worthwhile project to conduct a visual search with a suitably designed 76-cm telescope, or a one metre telescope, over a period of a few years, to see if this conclusion could be supported in practice.