bluuebunny/crossref_metadata_2025 huggingface dataset:
Bessellian Spectral Analysis of Interplanetary Scintillation
Authors: Ward B. D. , Blesing R. G. , Dennison P. A.
Published: July 2016

It is now well established that observations of interplanetary scintillation from a single station can yield useful information on the angular structure of radio sources, and on the propagation of large-scale disturbances through the interplanetary medium. However, when it is required to obtain detailed information on the plasma properties single station observations suffer from the disadvantage that, in general, it is not possible to measure the velocity and scale of the irregularities independently. For example, a change in the width of the observed temporal power spectrum of the scintillations might be caused by either a change in velocity, or a change in scale, or a combination of both.
The Effect of Rotation on Thermal Convection
Authors: Murphy J. O. , Van Der Borght R.
Published: July 2016

An investigation into the influence of rotation on thermal convection has some applicability in the study of the solar convection zone. Of particular interest is the effect of rotation on the total heat transport and the cell size for maximum heat transport at high Rayleigh number, which is estimated to be as high as 1020 for the Sun.
A Search for the Optical Counterpart of Centaurus X-3
Authors: Peterson B. A.
Published: July 2016

Centaurus X-3 was first observed by Chodil et al. in the energy range 2-9.5 Kev in 1967. Subsequent observations by Cooke and Pounds in the energy range 1-12 Kev snowed that the source was variable. Periodic X-ray pulses from Centaurus X-3 in the energy range 1-20 Kev have been discovered by Giacconi et al. They found that 70% of the X-ray energy was emitted in a pulse during 30% of a cycle. The length of the cycle is about 4.84 sec, but it was found to change by ~0.1% in a few days and by ~1% in three months. The X-ray data locate the source at 11h21.8m -60°25.8′ (1950) with an error of ±5′ arc.
Astronomers’ Facilities on the 150-Inch Anglo-Australian Telescope
Authors: Gillingham P. R.
Published: July 2016

The organization of the Anglo-Australian Telescope Project and the major features of the telescope design have been reported previously so only a brief description of the design aspects most relevant to the potential user will be given here.
The 100 cm Optical Telescope Instrumentation
Authors: Waterworth M. G.
Published: July 2016

An optical astronomical facility is being established near Hobart where the emphasis is being placed upon spectroscopy. A 40 cm telescope and Coudé spectrograph is already operational, and the 100 cm instrument will be operational by mid-1973. In this paper discussion is restricted to the 100 cm instrumentation.
Spectroscopy Using a 16-Inch Telescope
Authors: Castley J. C.
Published: July 2016

The 16-inch telescope on Canopus Hill (Tasmania) has been equipped with a Coudé spectrograph.
Variation in the Polarization Across Bends in the Spectra of Self-Absorbed Synchrotron Sources
Authors: Melrose D. B.
Published: July 2016

The accepted interpretation of the low frequency turnovers in the spectra of many extragalactic radio sources is that they are due to the effects of synchrotron self-absorption, i.e. to the source becoming optically thick. It has been shown that the signs of the degrees of both linear and circular polarization for a homogeneous source at frequencies where it is optically thick are opposite to those at frequencies where it is optically thin.
Anomalies in the Low-Frequency Radio Spectra of Some Bright Galaxies
Authors: Slee O. B.
Published: July 2016

During 1971/72 the radioheliograph at Culgoora, N.S.W. was used to observe 30 bright galaxies at 80 MHz.
Collapsed Objects and Galactic X-Ray Sources
Authors: Peterson B. A.
Published: July 2016

The observation of the X-ray sky from balloons, rockets, and satellites has led to the discovery of more than 100 X-ray sources. Optical and radio identifications have been made for about a dozen of these. A few X-ray sources are of extra-galactic origin, but the majority are objects in the Galaxy.
Very Long Baseline Interferometry in the Southern Hemisphere
Authors: Robertson D. S. , Gubbay J. S. , Legg A. T.
Published: July 2016

Phase coherent interferometers with intercontinental baselines became possible because of the development of stable frequency standards. With sufficiently stable frequency standards, no connection is necessary between the two ends of an interferometer. The first VLBI experiments were conducted by a group at the University of Florida who used an intensity interferometer with independent tape recorders for observations of Jupiter. Later, they changed to a coherent system using crystal-controlled oscillators. Since then, several interferometer systems have been developed. A Canadian group developed a system using video tape recorders at each end of the interferometer. They recorded the data in analogue form and managed to bring the two tapes together and to synchronize them to an accuracy of better than a microsecond. After synchronization, the outputs were combined and fringes extracted. Their system has a bandwidth of about 4 MHz. No-one else has attempted a wide-band analogue system.
Black Holes and X-ray Binaries
Authors: Vidal N. V. , Wickramasinghe D. T. , Bessell M. S.
Published: July 2016

Zeldovich and Guseynov suggested that neutron stars and collapsed stars (‘Black holes’) may be found as highly evolved companions of single lined spectroscopic binaries. They pointed out that the detection of X-rays or γ-rays from such a system would constitute positive evidence for the highly evolved nature of the companion. Trimble and Thorne searched through the catalogue of orbital elements of spectroscopic binaries (Batten) and found a few systems which were single line spectroscopic binaries with companions of mass M2 ≥ (1.4 M⊙, M1), where M1 is the primary mass. None of these has, however been identified with an X-ray source and other explanations such as multiple systems could not be ruled out. The alternative procedure, namely the identification of galactic X-ray sources with spectroscopic binaries is clearly more rewarding from the view point of searching for black holes and neutron stars. In particular, a high mass secondary which could be identified with a black hole is more likely to be discovered as a companion of an X-ray binary with a massive primary such as a blue supergiant.
Absorbtion of Radio Waves in the Gum Nebula
Authors: Cane H. V.
Published: July 2016

Free-free absorption by thermal electrons attenuates low frequency radio waves and such absorption will indicate the presence of ionized hydrogen. The Gum Nebula contains bright H-alpha emission regions and therefore it is not surprising that the region appears as an area of low brightness on low frequency continuum maps.
Some Applications of Model Atmospheres
Authors: Bessell M. S.
Published: July 2016

In the five years since the last invited paper on model stellar atmosphere applications there have been many significant advances made on all fronts. The five aspects which I will cover in this paper are:

(1) the results of white dwarf model atmosphere investigations;

(2) the results of the inclusion of non LTE phenomena in the atmosphere computations of hot (T > 15,000 K) stars;

(3) the probable understanding of the cause of peculiar abundance patterns in the Ap and Bp and Am stars;

(4) the advances in theory and observations of cool star atmospheres; and

(5) the use of synthetic spectra and colours.
Thioformaldehyde Clouds in the Direction of Sgr B2
Authors: Fourikis N. , Sinclair M. W.
Published: July 2016

Preliminary mapping of the thioformaldehyde distribution in the direction of Sgr B2 followed the detection of the 211←212 transition of interstellar thioformaldehyde by Sinclair et al. (1973). Observations were made with the Parkes 64-m telescope in conjunction with a 9 cm parametric amplifier.
Amplification and Absorption of the 9 cm2Π, J = ½ A-Doublet Lines of Interstellar CH
Authors: Gardner F. F. , Robinson B. J.
Published: July 2016

Following the detection of the 9 cm ground-state triplet of CH by Rydbeck et al. (1973), preliminary observations at the CH frequencies were made with the Parkes 64-m telescope (beamwidth ∼6′ arc) in December 1973 and January 1974. We have detected the CH lines in many galactic HII regions and in the direction of the galactic centre.
A Scattering Hypothesis for Type V Solar Radio Bursts
Authors: Melrose D. B.
Published: July 2016

The purpose of this paper is to advance an alternative hypothesis for the underlying distinction between solar radio bursts of spectral type V and ‘inverted U’ bursts, and to explore its implications.
Convective Instability of Hydrogen-Burning Shells in β–Cephei Stars
Authors: Borght R. Van der
Published: July 2016

It appears that the relative number of β–Cephei variables among the early B stars is comparable to the fraction of the evolutionary lifetime spent in the secondary contraction and early shell-burning phases (Lesh and Aizenman 1973a) and it may therefore be of some interest to investigate possible instability mechanisms associated with hydrogen shell-burning in stars within the mass range of 10 to 15 M⊙ (Lesh and Aizenman 1973b).
The Dwarf Nova EX Hydrae
Authors: Watson R. D. , Rayner P. T.
Published: July 2016

The object EX Hya is a dwarf nova with a binary period of 98.3 min (Mumford 1964, 1967). Warner (1972, 1973a) has observed two complete cycles of this star with a photoelectric time resolution of 5 sec. These observations suggested that EX Hya can be understood in terms of the model proposed by Warner and Nather (1971) in their discussion of U Gem. In this model, a white dwarf primary of a semi-detached binary system is surrounded by a disk of gas formed from matter transfered from the secondary, which is a cool dwarf star filling its Roche lobe.
A Simple Houghton Camera
Authors: Rumsey N. J.
Published: July 2016

The Schmidt camera is conceptually elegant and has a remarkable performance, but it suffers from several practical disadvantages. Two of these concern us here. First, there are very few craftsmen who are competent to make the aspheric correcting plate of the Schmidt camera compared with the number of those competent to make spherical surfaces of high quality.
Nitrogen Sensitizing of Photographic Plates
Authors: Mckinlay J. , Peterson B. A.
Published: July 2016

Several methods are available for sensitizing photographic plates, each with its own disadvantage. Pre-flashing greatly increases the plate background and is useful only for enhancing the plate’s response to light levels near the plate’s threshold. Baking and (or) evacuating enhance the plate’s response at all light levels and leave a slightly higher background. Unfortunately all of these methods produce plates with a short shelf life after sensitization.
High Speed Photometry at Mt Stromlo Observatory
Authors: Peterson B. A.
Published: July 2016

Important observations of X-ray sources and searches for the optical counterparts of X-ray and radio pulsars require a capability of detecting and analysing light variations with a time scale of milliseconds. X-ray sources in binary star systems are expected to be collapsed objects – neutron stars or black holes (Peterson 1973) – and are expected to produce light variations. In the case of a neutron star, pulses with the same period as the rotation period of the neutron star would be produced, and such have been observed from Cen X-3 (schreier et al. 1972) in the X-ray, and from Her X-1 (Middleditch and Nelson 1973) and the Crab Nebula pulsar (Cocke et al. 1969) in the X-ray optical.
The Colouring of White Noise
Authors: Kalnajs A. J. , Peterson B. A.
Published: July 2016

The Mount Stromio optical pulsar detection equipment is built around a commercial two-track tape recorder: one track records timing pulses, and the other the pulses from a photomultiplier (Peterson 1974). Because of the modest frequency range of the recorder, it has been necessary to introduce a scaler between the recorder and photomultiplier in order to cope with bright sources.
Active Phenomena in the Solar Atmosphere
Authors: Pikel’ner S.B.
Published: July 2016

This paper gives a short description and interpretation of some solar magneto-hydrodynamical and plasma phenomena, based mainly on work by the writer and his collaborators (for an extended review see Kaplan et al. 1974).

The magnetic field is considered as the main factor responsible for a number of manifestations of solar activity. At the photospheric level active regions are displayed as plages, i.e., bright areas, seen near the limb. This means that the temperature gradient in plages is smaller than in the undisturbed photosphere. The decrease in gradient is a result of an increase of convective transport of energy.
Hardware and Software for the Llanherne Low Frequency Sky Surveys
Authors: Whitham P.S.
Published: July 2016

Since 1971, the Llanherne low frequency radio telescope (Ellis 1972) has been used to conduct surveys of the sky at several decametric wavelengths. Prior to 1974, only pen recordings on paper chart for one declination at each of the wavelengths were obtained each night and all the work to produce the final sky maps was to have been done by hand. However in 1974, a general purpose digital minicomputer (a Digital Equipment Corporation PDP 8/E) has considerably increased the research capabilities of the telescope. In the continuum sky surveys profiles at several different declinations are now obtained each night. In addition all the information gathered in an observing session is written onto magnetic tape which is later analysed on the University of Tasmania’s computer (an Elliot-503) thus providing the possibility of removing much of the tedious manual work in preparing the final sky maps. This paper describes the system developed by the author which is used by Cane (1975) to obtain the profiles from which the sky maps are being compiled.
Long Term Variations in Jupiter’s 11 cm Radio Emission
Authors: McCulloch P.M.
Published: July 2016

During the past twelve years five series of observations have been made of the polarization of Jupiter’s radio emission at a wavelength of 11 cm. This data shows characteristics which have been stable over a period of years as well as some unexplained variations. The observations were made during one complete orbital period of Jupiter and hence were obtained over the full range of values of DE, the angle between Jupiter’s rotational axis and the plane of the sky. These are summarized in Table 1. The 1967 observations have been reported previously (Komesaroff and McCulloch 1967) and the 1963 data is from Roberts and Komesaroff (1965).
Evaluation of an Eclipsing Variable Minimum with an HP Desk Calculator and Plotter
Authors: Kvíz Z.
Published: July 2016

A program has been designed for Hewlett-Packard 9100 A Calculator connected by a 9102A Buffer to a 9101 A Extended Memory, a 9120 A Printer and 9125 Plotter. The program evaluates and plots one-night photoelectric measurements in 3 colours of a short period eclipsing variable and detects the exact time of the minimum. The program may take a maximum of 24 observations either of a comparison star or of the variable in each colour but it could easily be modified for a maximum of 36 observations in two colours or seventy two observations in one colour. The usual alternating succession of the type CVCVC… is supposed but up to three successive measurements both of the comparison star and of the variable is possible, e.g. CVCCCVCVCVVVCVC…
A Nitrogen Rich OB Supergiant in the Large Magellanic Cloud
Authors: Hyland A.R. , Bessell M.S.
Published: July 2016

Recent spectroscopic investigations of OB stars by Walborn (1970,1971a) have revealed the existence of OB stars with anomalous nitrogen and carbon spectra. In particular, two groups of stars were identified — those with strong nitrogen features and accompanying weak carbon-oxygen blends (called ON stars), and those with weak nitrogen features and strong carbon features (called OC stars). These groups bear a striking resemblance to the WN, WC dichotomy exhibited by the Wolf Rayet stars and is suggestive that a common process may be responsible for both phenomena.
Globular Cluster Winds
Authors: Faulkner D.J. , Freeman K.C.
Published: July 2016

Current evolutionary theory indicates that evolving stars in globular clusters arrive on the horizontal branch with ~30% less mass than they had on the main sequence. If, as seems likely, this mass loss results from the outflow of unprocessed material at the stellar surface during the giant stage, and if the ejected mass were retained within the cluster between successive sweeps through the galactic plane (~108 yr), sufficient hydrogen (100-2000 M⊙ should accumulate for detection. Radio searches, however, have failed to find evidence for either neutral or ionized gas. The hydrogen mass upper limits obtained by various workers are: Hills and Klein (1973) ionized H, 3.8 cm, <20-200 M⊙; Knapp, Rose and Kerr (1973) neutral H, 21 cm, <1-20 M⊙; Conklin and Kimble (1974) neutral H, 21 cm, <0.7-1.4 M⊙.

We have extended the search into the optical region and have also calculated time-independent gas flow models to try to resolve this anomaly.
Distribution of Elliptical Galaxies in the Virgo Cluster
Authors: Lewis B. M. , Gibb R.G.
Published: July 2016

Both Holmberg (1961) and de Vaucouleurs (1963, 1973) found a significant difference between the mean velocities of the different morphological types in the Virgo cluster of galaxies. To check on any dependence of this result upon spatial distribution, Lewis (1975) plotted the position of every object in the compilation of de Vaucouleurs (1961) as a function of its type. Figure 1 is the resulting plot for the elliptical galaxies, which appear to lie within two well-defined and well-separated groups. The principal parameters of these groups are listed in Table I. Arp (1967) briefly noted the linear form of the northern group centred on NGC 4486. This paper examines the evidence for the physical existence of these groups.
A Centaurus A : Spectra of the Optical Filament
Authors: Peterson B.A. , Dickens R.J. , Cannon R.D.
Published: July 2016

The radio source, Cen A, is large and complex with many peaks in the brightness distribution over an area about 4 x 10 degrees. The peculiar elliptical galaxy NGC 5128 lies between the two strong inner radio brightness peaks and is centred on a weaker central radio source. This radio source is in the centre of the dust lane which divides the galaxy and may be related to the infrared, X-ray and γ-ray sources.
Interplanetary Scintillation and Flare — Produced Disturbances
Authors: Ward B.D.
Published: July 2016

Determination of the large-scale structure of flare-produced disturbances requires either multiple spacecraft observations or an ensemble averaging of single spacecraft observations of a number of events. There is currently some confusion in the results of studies of shock normals derived from spacecraft data. Chao and Lepping (1974) suggest that the average shock shape near 1 AU is essentially spherical while Bavassano et al. (1973) suggest that the disturbance corresponds closely to the shapes predicted in the numerical simulations of de Young and Hundhausen (1971).
The Magellanic Stream
Authors: Mathewson D.S.
Published: July 2016

I shall briefly outline some observational aspects of the Magellanic Stream before discussing the pros and cons of the two conflicting theories of its origin: a) that the Stream was pulled out of the Clouds by tidal forces produced by a close encounter with our Galaxy and b) that the gas clouds of the Stream are primordial and in the same orbit as the
Magellanic Clouds.
Southern Standards for the CMT1 T2 System
Authors: Bessell M. S. , Williams S. L.
Published: July 2016

The K giants are the brightest stars in clusters of both intermediate (∽ 108 years) and old (∽ 109-10 years) age. They have strong metal lines and strong bands of CN and CH in the optical spectrum, and are the logical objects in which to measure the metal abundance of such stellar systems and trace the evolution of heavy elements in the universe.
Gravitational Lens Effect of a Moving Black Hole
Authors: Kvíz Z.
Published: July 2016

The deflection of the light rays of a distant star by the gravitational field of a nearby star was first derived independently by Link (1936) and Einstein (1936). It was shown by Link (1936,1937) that the light of a distant star is not only deflected forming two separate images of the distant star, but also the brightness of the distant star (in both
images) is affected.
Hyperfine Polarization Structure of Jupiter’s Radio Bursts
Authors: Whitham P. S.
Published: July 2016

Observations of Jupiter’s decametric radio burst have established that above 20 MHz more than 90% of the emission is elliptically polarized in the RH sense, but below this frequency the proportion of the LH polarization increases (Sherrill 1965) until at 10 MHz nearly 40% of the emission is LH polarized (Dowden 1963). The best time and frequency resolutions so far obtained when examining the polarization of the spectra of Jupiter’s bursts have been 10 ms and 50 kHz respectively (Gordon and Warwick 1967, Riihimaa 1975). To study the fine structure of Jupiter’s emission as observed by the linearly polarized Llanherne low frequency radio telescope (Ellis 1972), spectrum analysers with resolutions in the ranges 0.3 — 1 msec and 2–10 kHz have been used (Ellis 1973a, 1973b, 1974, 1975). A new telescope at Llanherne, which is capable of detecting the RH and LH circular components of incident radiation, is being used in conjunction with these analysers to yield information of the hyperfine polarization structure of Jupiter’s decametric radio emission. This paper is a preliminary report of this investigation.
The Centred Multipole and Other Representations of Jupiter’s Magnetic Field
Authors: Komesaroff M. M.
Published: July 2016

The fact that Jupiter’s inner magnetosphere is not axially symmetric was originally demonstrated by ground-based radio measurements. Departures from symmetry are evident in the pattern of bursts occurring at decametre wavelengths and also in the characteristics of the polarized synchrotron emission observed at decimetre wavelengths. Direct measurements of Jupiter’s magnetic field, made from the Pioneer space probes, also indicate departures from an axially symmetric configuration.
Radial Velocity Structure in OH and H2O Masers
Authors: Knowles S. H.
Published: July 2016

Since the discovery of highly masering OH emission, and later of H2O masers, there has been little progress made in understanding their geometry and structure. Although both OH and H2O spectra are highly complex, no one has been able to ‘decode’ the information from the many individual features. Knowles and Batchelor (1976) have recently suggested that many water vapour spectra have a symmetrical character, with one or more pairs of features equally spaced in radial velocity about a central axis. It is here proposed that a similar symmetry exists in HH-region OH masers as well as main-line OH stars such as VY CMa. We also demonstrate that features at close to the same radial velocity are often present in several different OH and H2O transitions and probably come from the same masering cloud. From this widely applicable empirical observational model we then make a few simple deductions about the possible geometry of such masering regions.
Detection of the J = 1->0 Transition of Cyanodiacetylene in Sgr B2
Authors: Brooks J. W. , McGee R. X. , Newton Lynette M.
Published: July 2016

In November 1975 workers at the Herzberg Institute for Astrophysics in Canada (Avery et al. 1976) discovered cyanodiacetylene in Sgr B2. This molecule is the heaviest yet detected in interstellar space, having a molecular weight of 75 amu, and is the longest linear molecule known.
HI Absorption in NGC 4945
Authors: Whiteoak J. B. , Gardner F. F.
Published: July 2016

NGC 4945 is a ninth-magnitude southern galaxy orientated almost edge-on to the line-of-sight. De Vaucouleurs and de Vaucouleurs (1964) list its classification as SB(s)cd and its optical dimensions as 17’ x 3’ arc. It is of particular interest because 18 cm OH and 6 cm H2CO absorption has been detected (Whiteoak and Gardner 1973; Gardner and Whiteoak 1974) in molecular clouds in this galaxy which overlie the small-diameter radio source located near the nucleus. In reporting the detection of the OH absorption we suggested that the HI profile in the direction of the nucleus was affected by HI absorption. In this paper we describe a study of the HI distribution which substantiates this conclusion.
Spectra and Absorption of Low Frequency Galactic Background Radiation
Authors: Cane H. V.
Published: July 2016

Surveys of the Galaxy at five frequencies in the range 2 to 20 MHz have been made using the Llanherne low frequency array (Ellis, 1972). The data has been assembled into maps covering the area 320° < £ < 30° and -25° < b < 22° and these are presented in rectangular galactic co-ordinates. Galactic radio spectra in various directions have been obtained, combining the new data with seven earlier galactic continuum surveys. The details of all the surveys used are given in Table I. A new 4.7 MHz map has been plotted from the profiles presented by Ellis and Hamilton (1966).
Radio Spectra and Optical Identification of Sources from the MC2and MC3 Catalogues
Authors: Murdoch H. S.
Published: July 2016

I will summarize briefly some results obtained from further studies of the Molonglo catalogues MC2 and MC3, centred approximately at declinations +11° and +16° respectively (Sutton et al. 1974).
The Search for Variable Sources at 408 MHz
Authors: McAdam W. B.
Published: July 2016

It has been known for about 5 years that the flux densities at 408 MHz of some sources change over time scales of a few months, but discovery of these variable sources has been largely accidental during the intensity calibration of various observing programs at Molonglo. This paper describes some results from systematic observation of 254 sources over a 12 month period, through which we hope to better understand the telescope performance, find more identifications in the southern sky, and recognise variable sources. An improved calibration will be applied to digital data from Molonglo observations since 1967 (both surveys and individual source observations), now stored on magnetic tape.
Convection in Stars
Authors: van der Borght R.
Published: July 2016

It is likely that in most stars certain layers, either in the interior or outer regions, will be unstable against convection and the study of energy transport by convection has raised considerable interest since the early days of this century when Karl Schwarzschild derived his criterion for deciding whether a certain region is in convective or radiative equilibrium.
Reduction of the Baseline Ripple on Spectra Recorded with the Parkes Radio Telescope
Authors: Padman R.
Published: July 2016

One of the factors determining system sensitivity in radio astronomy measurements of microwave emission and absorption spectra is the flatness of the spectrometer response in the absence of any spectral features. Ripple appears as a quasi-sinusoidal variation of this baseline and occurs whenever two or more components of the same signal reach the receiver by different paths and interfere.
The Tidbinbilla Interferometer
Authors: Batty M. J. , Jauncey D. L. , Gulkis S. , Yerbury M. J.
Published: July 2016

The reliable detection and identification of weak, small-diameter radio sources require an instrument with both high sensitivity and high positional accuracy.
The Natural Wave Modes in a Pulsar Magnetosphere
Authors: Melrose D. B. , Stoneham R. J.
Published: July 2016

Our purpose in this paper is to explore the properties of the natural wave modes of a relativistically streaming electron-positron gas and to apply the results to the interpretation of the polarization characteristics of pulsar radio emission.
The Magellanic Stream: the Turbulent Wake of the Magellanic Clouds in the Halo of the Galaxy
Authors: Mathewson D. S. , Schwarz M. P. , Murray J. D.
Published: July 2016

New observations of the Magellanic Stream were made in December 1976 with the 64-m radio telescope at the Parkes Observatory of CSIRO. The ridges of H I emission of the Stream were traced from near its tip at ℓ = 90°, b = -40° to the Magellanic Clouds. This was the first time that the total length of the Stream was observed with the one system (only possible from the southern hemisphere) and with high spatial (15’ of arc) and velocity (4 km s-1) resolution. The results of this survey are presented in Figures 1 and 2 and the main features are listed below.
Formation Times for Rich Clusters of Galaxies
Authors: Lewis B. M.
Published: July 2016

Rich clusters of galaxies are a common feature of the large-scale structure of the Universe. Those studied so far, show striking regularities with

(a)

a smooth radial gradient of number density.

(b)

’isothermal’ distributions, which according to Bahcall (1975) have a scatter of only ±15% in the size of their characteristic core radii.

(c)

their limiting structural diameters are ~50 Mpc (cf. Abell, 1975), if they are identified with superclusters.

(d)

the magnitude of the velocity dispersion about their centres is generally 600-1000 km s-1, and the velocities are cpnsistent with a gaussian distribution (Yahil and Vidal, 1976; also Faber and Dressier, 1976).

(e)

The extreme velocities are generally within ±3000 km s-1, and for Coma are ∼2400 km s-1 (Tifft and Gregory, 1976).

(f)

elliptical galaxies tend to predominate near the centre, spirals in the surrounding loose groups.
Solar X-ray Emission and Metre-Wave Radio Bursts
Authors: Duncan R. A.
Published: July 2016

Soft X-ray photographs of the Sun taken from the manned Skylab satellite (Vaiana et al. 1973) gave, not the earliest, but perhaps the most graphic evidence that the solar corona is patchy. During the Skylab mission (May 1973 to February 1974), the solar corona as usually envisaged covered only 80% of the Sun (Bohlin 1977). The areas lacking a ‘dense’ corona are called coronal holes (Withbroe al. 1971; Waldmeier 1975).
The Role of Grain Motions in Star Formation
Authors: KrautSChneider M. J.
Published: July 2016

A number of authors (Reddish, 1968, 1969, Reddish and Wickramasinghe 1969) have stressed the importance for star formation of the role of condensation of H2, onto solid grains inside the cool dark regions of a large interstellar cloud. However, although the thermodynamic consequences of the existence of grains have been extensively studied, the dynamical implications have received little attention. Solid grains of course do not possess a thermal pressure as their gaseous counterpart does, neither do they directly experience the magnetic fields which thread the ions and electrons of the gas cloud. The grains therefore, as soon as they are formed, are free to fall toward their common centre of mass, relatively unrestricted by the constraints on the gas cloud.
Formation of the Satellite Systems of the Major Planets
Authors: Prentice A. J. R.
Published: July 2016

It is well known that the satellite systems of the major planets Jupiter, Saturn and Uranus share many of the same regular features that can be seen in the planetary system of the Sun. The inner satellite orbits are nearly circular and lie in the plane defined by the axis of rotation of the central body. Again the distances Rn of the regular satellites, numbered inwards to the centre n = 0, 1, 2, …, form a nearly geometric sequence

Rn/Rn + 1 ≌ constant,

similar to the Titius-Bode law of planetary distances. These facts suggest that the same cosmogonic process must have been responsible for the origin of both types of systems.
Observations of High Brightness Temperatures in Moving Type IV Solar Radio Bursts
Authors: Stewart R. T. , Duncan R. A. , Suzuki S. , Nelson G. J.
Published: July 2016

It has generally been accepted that moving type IV bursts are generated as synchrotron radiation from energetic electrons high in the solar corona (Boischot and Denisse 1957). At 80 MHz the peak brightness temperature is usually ~ 108 K and the radiation becomes highly circularly polarized as the burst decays. This has led several authors (Kai 1969; Dulk 1970, 1973; Schmahl 1972; Robinson 1974, 1977; Nelson 1977) to the conclusion that the radiation comes from mildly relativistic (~ 100 keV) electrons and occurs at low harmonics of the gyro-frequency (gyro-synchrotron radiation). We present evidence of moving type IV bursts at 43, 80 and 160 MHz with brightness temperatures of ~ 109 K, and one at 43 MHz as high as 1010 K. The number (~ 1033) of energetic (≥ 1 MeV) electrons which is required in order to explain such high brightness temperatures by incoherent gyro-synchrotron emission is very large and near the upper limit for the number of fast electrons accelerated in the second phase of a solar flare. If amplification takes place a smaller number of electrons with energies ~ 100 keV would be required.
Radio Observations of a Massive, Slow-Moving Ejection of Coronal Material
Authors: Sheridan K. V. , Jackson B. V. , McLean D. J. , Dulk G. A.
Published: July 2016

Studies of coronal transients observed in white-light (Gosling et al., 1976) have shown that fast-moving events (≤ 400 km s-1) are closely associated with flares and with type II and IV radio bursts while slow-moving events are not. We now report the first detection of the radio counterpart of a slow-moving transient. The event of 1974 January 21 is shown to be visible on maps of the quiet Sun made at a frequency of 80 MHz.
On the Origin of Modulation Lanes in the Dynamic Spectra of Jupiter’s Decametric Radiation
Authors: Zheleznyakov V. V. , Shaposhnikov V. E.
Published: July 2016

In this paper, two models for the origin of modulation lanes in Jovian radiation are discussed. The results of calculations of dynamic spectra due to the Cotton-Mouton effect in Jupiter’s plasma envelope and due to modulation of the frequency spectrum in the source are reproduced. The characteristics of the theoretical spectra are then described. This offers the possibility of solving the problem of modulation lanes by comparison of observed Jovian dynamic spectra with the theoretical ones.
Solar Activity in the Corona
Authors: McLean D. J.
Published: July 2016

When I began my studies of solar radio astronomy, Dr J. L. Pawsey, who then led the radio astronomy group in the Division of Radiophysics, CSIRO, explained to me that the internal structure of the Sun was ‘well understood’, thanks to a lack of conflicting observational data, but that for the observable layers of the Sun, the photosphere, chromosphere and corona, a great many mysteries remained. I am sure that he would have been amused by the recent discovery that there are not enough neutrons coming from the core of the Sun. I shall devote most of my talk to matters about which we are fairly certain, but often I will only be able to give part of the story because the details have not yet emerged from the wealth of solar mysteries.
A Radial Shock Model for BWVUL
Authors: Stamford P. A. , Watson R. D.
Published: July 2016

The proposal that the complex spectral line changes seen in the large amplitude β Cephei variable BW Vul resulted from a shock effect, driven by an underlying radial pulsation, was first made by Odgers (1955). Stamford and Watson (1978) examined some suitable atmospheric models for this star, which were driven by a hard subphotospheric piston under an isothermal assumption. These models displayed strong shock development and had some encouraging similarities with the BW Vul phenomenon. However, particularly because of the use of a hard piston, they were not very physically realistic. Here we discuss the results of a more sophisticated approach to this modelling problem. This modelling problem is of specific current importance because Odell’s (1981) recent observations of a variable polarization in BW Vul have renewed the debate over possible nonradial pulsations in this star. Since nonlinear effects are clearly substantial in BW Vul, it is evident that the implications of these on the observed spectral line changes should be carefully examined on a radial pulsation hypothesis, before turning to the complexities of nonlinear nonradial profile modelling.
The Absence of 1584 MHz Maser Emission from 18OH
Authors: Caswell J. L. , Haynes R. F.
Published: July 2016

In the terrestrial environment the abundance ratio of 18O to the common oxygen isotope 16O is about 1 in 490. Measurements of hydroxyl absorption in the interstellar medium show that 18OH as well as 16OH can be detected towards Sgr A and Sgr B2 (Gardner et al. 1970; Wilson and Barrett 1970; Williams and Gardner 1981); in these two galactic centre regions the 18OH isotopic species has an abundance relative to 16OH of about 1 in 220, somewhat greater than the terrestrial ratio of 18O to 16O.
Gas and Dust in CrA
Authors: Taylor K. N. R. , Llewellyn R. , Payne P. , Vaile R. A. , Sakellis S.
Published: July 2016

Coronae Austrinae is one of the few star formation areas lying well away from the galactic plane (l = 360°, b = −17°) and is visible predominantly from the Southern Hemisphere.
A Harmonic Analysis Solution to the Parkes Spectrometer Baseline Ripple
Authors: Williams D. R.
Published: July 2016

The arrangement whereby the front end of a radio astronomical receiver is located at the focal plane of a paraboloidal telescope causes the incoming waves to be reflected between focal plane and vertex. The result is a sometimes simple, sometimes complex wave pattern on the output of an associated spectrometer and is known as baseline ripple.
The Morphology and Surface Brightness of Extragalactic Jets
Authors: Bicknell G. V.
Published: July 2016

Radio maps of extragalactic radio sources made with the Westerbork, Cambridge and V.L.A. synthesis telescopes have revealed collimated jets extending from the cores to the radio lobes (see Miley 1980 for a review). These observations have provided outstanding support for ‘beam models’ of extragalactic radio sources (Scheuer 1974, Blandford and Rees 1974). Two crucial pieces of information to emerge from high resolution observations are the behaviours of jet full width half maximum (FWHM) and surface brightness with angular distance from the core. Such data have for instance been provided by Formalont et al. (1980) and Bridle et al. (1981) for the jets in 3C-31 and by Willis et al. (1981) and Bridle (1981) for the jets in NGC 315. An important point is that the relationship between jet surface brightness and FWHM is not in general as predicted by simple magnetohydrodynamic models (Bridle 1981).
A Convective Model of Solar Granulation
Authors: Borght R. Van der , Fox P.
Published: July 2016

Some years ago the full non-linear equations, within the one mode approximation, describing finite amplitude convection in a compressive medium with polytropic structure were derived (Van der Borght 1977). It is the purpose of the present paper to report on the numerical integrations of these equations and to show how these can be used to construct a convective model of granulation. In this way one may gain some insight into the structure of the outer layers of the Sun.
An Investigation of Fragmentation in Collapsing Magnetic Gas Clouds
Authors: Phillips G. J.
Published: July 2016

In recent years, a large amount of work has been directed towards understanding the process of star formation. However, despite these efforts, there still remain areas largely unexplored, where theories are only justified by approximate qualitative arguments rather than fully three dimensional calculations.
A New Method for Computing the Gravitational Force in Particle Simulations
Authors: Monaghan J. J.
Published: July 2016

A standard procedure for the simulation of galaxies is to replace the ∼ 1011 stars by ∼ 104 particles. These particles are assumed to have equal mass and their distribution in space produces a mass density ϱ which mimics the average mass density of the stars. From the mass density of the particles the gravitational forces between the particles can be computed. In the literature two methods have been used to compute these forces.
Spectroscopic Studies of the Stellar Population in Baade’s Window
Authors: Ruelas-Mayorga R. A. , Hyland A. R.
Published: July 2016

Baade (1963) pointed out three regions of low obscuration in the general direction of the galactic centre, wherein a stellar population assumed to be characteristic of the galactic bulge could be studied.
1981-82 Observations of the Beat Cepheid U Trianguli Australis
Authors: Faulkner D. J. , Shobbrook R. R.
Published: July 2016

The nature and cause of the double-mode (DM) pulsation in beat Cepheid variable stars is still a matter of considerable uncertainty. Recently, evidence has been accumulating that the relative energy of the two modes in any particular star may be a slowly varying function of time. For TU Cas, Hodson, Stellingwerf and Cox (1979) have found that the first overtone amplitude has been decreasing over a 67 year timebase, while the present authors (Faulkner and Shobbrook 1979) have reported an increase in overtone energy in U TrA over 20 years. Observational details of the form of the mode energy changes may be helpful in obtaining a better understanding of these stars (see Shobbrook and Faulkner 1982). Our present observations of U TrA have been obtained to investigate its energy changes more fully.
Grain Sedimentation and the Old Open Clusters NGC2420 and NGC2506
Authors: Lattanzio J.
Published: July 2016

Star formation is believed to occur in interstellar clouds consisting of both gas and grains. Under the gravitational influence of such a cloud the constituent dust grains sediment toward the centre, and both calculations and implications of this sedimentation have been published by many authors (McCrea and Williams 1965; Horedt 1973, 1976; Prentice 1976; Krautschneider 1977; Flannery and Krook 1978; and others). Two main results from these calculations warrant our attention. Firstly, the timescale for appreciable sedimentation Ts ≃ 107 -108 years, which is consistent with age estimates of many clouds (Harrison 1978, Blitz and Shu 1980). Secondly, the sedimentation proceeds more rapidly for larger grains. This leads to an increase of mean grain size toward the centre of the cloud.
The Stellar Population in the SMC Region N76B
Authors: Seal P. , Hyland A.R.
Published: July 2016

The Magellanic Clouds are the nearest major extragalactic objects to the Milky Way. The study of young giants or supergiants in the Clouds enables us to obtain information regarding the birth rates and evolution of young massive stars in those systems, free from biases inherent in similar studies in the Galaxy. Although the Magellanic Clouds have been studied by an extremely large number of research workers at optical wavelengths, it is only recently that significant infrared observations have also been undertaken (e.g., Glass 1979, McGregor and Hyland 1981, Cohen et al. 1982). Cool supergiants in the SMC have been studied optically by Humphreys (1979). She found that most are very metal deficient, and should be classified spectroscopically as M0.
HCO+ in NGC 6334
Authors: Batchelor R. A. , Robinson B. J. , McCulloch M. G.
Published: July 2016

In this paper we present maps showing the distribution of HCO+ (J= 1→0 transition at 89.18855 GHz) in the direction of NGC 6334 as a function of radial velocity, lhe observations were carried out in May-June 1979 as part of a larger program of HCO+ observations (Batchelor et al. 1980, 1981) using the Epping 4-m millimetre-wave radio telescope.
Nebula Tides and Gap Formation
Authors: Hourigan K. , Schwarz M. P.
Published: July 2016

An intriguing problem in cosmogony concerns the ability of a planetoid embedded in a nebula disc to clear a gap around its orbit. The application of density wave theory to this problem has demonstrated that a significant exchange of angular momentum can take place between a planetoid and a disc (Goldreich and Tremaine 1980). The torque exerted by the disc on the planetoid can result in orbital drifting of the latter, which may play an important role in the aggregation process (Hourigan and Ward 1983). In fact, in the absence of significant deformation of the nebula, the radial orbital drift rate of a planetoid increases with planetoid mass. In this case, it would be expected that only one or two planetoids would sweep out the nebula, a situation not compatible with present observations. The orbital drift resulting from the generation of density waves therefore requires a limiting mechanism.
Structural and Thermal Icy Satellite Models: Preliminary Results
Authors: Thomas P. J.
Published: July 2016

The satellites of the outer solar system appear to be composed principally of water ice and silicates, with the presence of ammonia and methane hydrates (Lewis 1971). Although these bodies are small (with radii typically < 1000 km) they can exhibit very active evolutionary histories, due to the low melting point of water ice.
Fragmentation of Gas Clouds
Authors: Monaghan J. J. , Lattanzio J. C.
Published: July 2016

A common test for hydrodynamic calculations is the Boss and Bodenheimer (1979, 1981, hereafter BB) problem in which an isothermal, spherical cloud of 1 M⊙ is given a cos (2Φ) density perturbation and the ensuing evolution studied.
Carbon Abundances in Planetary Nebulae in the Galactic Bulge
Authors: Webster B. Louise
Published: July 2016

The galactic nuclear bulge is a well defined population, but it is one that is relatively difficult to study in detail because its members never stray into the solar vicinity and they are both distant and obscured. Mould (1982) has summarized much of our knowledge of the masses and composition of stars in the bulge. The red giants resemble those in metal-rich old open clusters and the late M giants are either younger than galactic globular clusters or super-metal-rich or both. Whitford and Rich (1983) have demonstrated the existence of K-giants that are super-metal-rich in iron and Wood and Bessell (1983) have interpreted the properties of a sample of long period variables in the bulge as those of a young, super-metal-rich population.
The Distribution of H2CO Absorption Towards W33
Authors: Gardner F. F. , Whiteoak J. B. , Otrupcek Robina E.
Published: July 2016

There is a difference of opinion as to whether W33, an HII-region/molecular-cloud complex of size about 15′ arc centred near l = 12°.8, b = -0°.2 is a single object or a chance line-of-sight alignment of two complexes at completely different distances.
A Search for OH Emission from Symbiotic Stars
Authors: Norris R. P. , Allen David A. , Haynes R. F. , Wright Alan E.
Published: July 2016

A sensitive search has been made for OH maser emission from a sample of 16 symbiotic stars. This sample has been selected on the basis of infrared optical depth and variability, so that the stars within it have circumstellar shells similar to those seen in the well-known OH/IR and OH/Mira stars. There were no significant detections, except for one unassociated background source, and we conclude that the presence of a hot binary companion inhibits any possible OH maser action.
The FST-A 20 arc second Synthesis Telescope
Authors: Jones I. G. , Watkinson A. , Egau P. C. , Percival T. M. , Skellern D. J. , Graves G. R.
Published: July 2016

The baseline of East-West array of the Fleurs Synthesis Telescope (FST) has been extended from 786 metres to 1585 metres by the addition of two 13.7 metre dishes. A digital receiver has been built to accommodate the extra delay and correlation requirements, low noise FET preamplifiers have been installed on the large antennas, and a software package has been developed for processing observation data on a VAX 11/780. The FST is now capable of producing accurate wide field maps at 1415 MHz with a resolution of 20 arc seconds and a sensitivity of several milliJansky.