bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Thermal Source with Strong 1612 MHz OH Emission
Authors: Robinson B. J. , Goss W. M. , Manchester R. N. 
Published: July 2016

During 1968 we have found at Parkes several types of emission in the lines of the 18 cm quadruplet of the ground-state OH molecule. This note describes a strong source of 1612 MHz emission near galactic longitude 331°.OH emission was originally detected in the vicinity of HII regions, and a search of a large number of HII regions showed that about a third had associated OH emission. This type of emission is usually strongest at 1665 MHz, and is also seen at 1667 MHz and weakly on one of the satellite lines.
A New Redistribution Function Applied to Radiative Transfer
Authors: Argyros J. D. 
Published: July 2016

A redistribution function R(x, x′)dx dx′ is defined as the probability that a photon with frequency between x and x + dx will be absorbed by an elemental atmosphere which then emits another photon the frequency of which lies in the range from x′ to x′ + ax′. The frequencies x and x′ are measured from the central frequency νo of the spectral line in units of the Doppler width Δ The particular functional form taken by R(x, x′) in this discussion will be given bywhere α represents the broadening of the spectral line in units of the Doppler width while the function H(o, z) is defined bythe Voigt function. The function defined by means of equation (1) is one of that class of redistribution functions which combines natural and Doppler broadening. Therefore, it should be expected that any results obtained using this particular redistribution function will exhibit certain features characteristic of this type of scattering.
Low Frequency Maps of the Galaxy
Authors: Cane H.V. 
Published: July 2016

This paper is a preliminary report on the sky mapping being undertaken at the University of Tasmania using the Llanherne low frequency array. (Ellis 1972).The observations are facilitated by the use of an on-line PDP-8 computer and the beam steering system described by Whitham (1975). In summary, a scanning system is used in which the computer is programmed to steer the telescope beam to a number of declinations with a time interval between settings such that a scan takes 5 minutes. Usually a scan of 12 declinations is chosen. Calibration levels obtained each hour and recorded on magnetic tape permit gain changes to be accounted for when the data is analysed from the tape.
The RS CVn Type Star PZ Tel
Authors: Innis J. L. , Coates D. W. , Thompson K. 
Published: July 2016

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

AbstractTechniques in QED (quantum electrodynamics) have been developed previously (see for example Melrose and Parle 1983) allowing one to treat electron-photon and photon-photon interactions exactly in the magnetized vacuum and allowing one to include the effects of a medium. These techniques are extended to include particle-particle interactions. Exact cross-sections for electron-electron collisions are derived and compared with known expressions. Such calculations have application in studies of the formation and transfer of radiation in the atmospheres surrounding neutron stars.
NGC 4945-A Galaxy with a Nucleus Full of Surprises
Authors: Whiteoak J. B. 
Published: July 2016

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

AbstractTwo hundred and seventeen HI profiles at positions approximately 1 ° apart in the bridge region between the Small and Large Magellanic Clouds have been observed with a 15’ arc beam. Diagrams of all the profiles, lists of column densities and average radial velocities are given, together with details of the extensive Gaussian analysis needed to account for the components.It is shown that the bridge region is most complex. (a) Two radial velocity groups, +214 and +238 km s-1, represent the actual HI bridge between the two galaxies, (b) Three other components, at mean radial velocities of +155, +177 and +195 km s-1 are seen to be integral parts of the SMC, stretching east to R. A. ~ 04h. (c) A further three components in groups at mean radial velocities +253, +272 and +293 km s-1 appear to be extensions of HI from the main body of the LMC.Nine sets of five closely spaced observations in the lower Magellanic Stream and in the bridge region at high sensitivity supply further information about the region.
The Variation of Lithium Equivalent Width in Active Cool Stars
Authors: Robinson R. D. , Thompson K. , Innis J. L. 
Published: July 2016

AbstractIn an attempt to determine whether the lithium Une at 6707 Å cornes mainly from the quiet photosphere or from the cooler spots on spotted active stars we have measured Une équivalent widths due to Li and also due to Cal at 6717 Å at various rotation phases on three fast rotating stars, AB Doradus, PZ Telescopium and V 1005 Orionis. The results for AB Dor and PZ Tel show there might be some small rotational modulation which can be linked to the best estimate of the spot position from the available photometry. This moduation is less than that expected on the basis of Giampapa’s work on sunspot spectra. The Li and Cal line equivalent widths were found to anticorrelate.
The CANGAROO Project: Very High Energy Gamma-ray Astronomy at Woomera
Authors: Edwards P.G. , Gregory A.G. , Patterson J.R. , Roberts M.D. , Rowell G.P. , Smith N.I. , Thornton G.J. , Wild N.R. , Ebisuzaki S. , Fujii H. , Kabe S. , Watase Y. , Fujimoto M. , Hara T. , Hayashida N. , Kifune T. , Ohno Y. , Teshima M. , Kakimoto F. , Ogio S. , Tanimori T. , Kobayakawa K. , Mizumoto Y. , Oda H. , Suda T. , Masaike A. , Matsubara Y. , Muraki Y. 
Published: July 2016

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

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

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

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

AbstractThe technique of aperture synthesis is well developed in radio astronomy. When applied to the optical regime, aperture synthesis allows one to partially overcome the blurring effects of the atmosphere and increase the angular resolution of large telescopes to the diffraction limit. MAPPIT (Masked APerture-Plane Interference Telescope) is a multi-element interferometer which operates at the coude focus of the 3.9 m Anglo-Australian Telescope. This instrument has recently been reconfigured to operate in a dispersed mode so that simultaneous observations in a band of wavelengths are possible. We will discuss this instrument’s new mode and present observations of the double star δ Sco and an angular diameter of the previously unresolved red giant β Gru.
s-Process Nucleosynthesis on the Asymptotic Giant Branch
Authors: Lattanzio John C. 
Published: July 2016

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

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

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

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

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

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

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

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

AbstractWe present near-infrared spectroscopic observations over the wavelength range 0·9 to 2·5 μm of the AM Herculis system BL Hyi. During these observations, broad and resolvable cyclotron emission harmonics were visible near 1·25, 1·60 and 2·20 μm. We have interpreted these features as arising from a cyclotron emission region located near the white dwarf’s polar cap of magnetic field strength Bp = 23 MG.
The North–South Anisotropy and the Radial Density Gradient of Galactic Cosmic Rays at 1 AU
Authors: Hall D. L. , Duldig M. L. , Humble J. E. 
Published: July 2016

AbstractThe radial density gradient (Gr) of Galactic cosmic rays in the ecliptic plane points outward from the Sun. This indicates an increasing density of cosmic ray particles beyond the Earth’s orbit. Due to this gradient and the direction of the Sun’s interplanetary magnetic field (IMF) above and below the IMF wavy neutral sheet, there exists an anisotropic flow of cosmic ray particles approximately perpendicular to the ecliptic plane (i.e. in the direction parallel to BIMF × Gr). This effect is called the north–south anisotropy (ξNS) and manifests as a diurnal variation in sidereal time in the particle intensity recorded by a cosmic ray detector. By analysing the yearly averaged sidereal diurnal variation recorded by five neutron monitors and six muon telescopes from 1957 to 1990, we have deduced probable values of the average rigidity spectrum and magnitude of ξNS. Furthermore, we have used determined yearly amplitudes of ξNS to infer the magnitude of Gr for particles with rigidities in excess of 10 GV.
MHD Turbulence in an Accretion Disk
Authors: Hawley John F. , Balbus Steven A. 
Published: July 2016

AbstractA long-standing problem in the theory of astrophysical accretion disks has been to determine the nature of the stress that transports orbital angular momentum outward. The discovery of a local MHD instability is strong evidence that transport occurs through turbulent Maxwell and Reynolds stresses. Using numerical simulations, we have demonstrated that a weak seed magnetic field in an accretion disk shear flow is unstable and leads to sustained MHD turbulence at dynamically important levels.
Quiescent Non-thermal Radio Emission from Stellar Systems
Authors: Storey Michelle C. , Hewitt R. G. 
Published: July 2016

AbstractNon-thermal radio emission has been detected from dMe stars, RS CVn binaries and W T Tauri stars. Polarisation and intensity measurements of the quiescent (i.e. non-flaring) emission indicate that the emission is gyrosynchrotron emission from mildly relativistic electrons spiralling in a magnetic field. A three-dimensional dipole magnetic field model for the stellar field is presented and the quiescent gyrosynchrotron emission from such a model is calculated and compared with observations. The model can account for many phenomenological features of quiescent emission. Quantitative comparisons of model results with observations indicate that the electron distribution in the emission region may be a magnetic mirroring distribution.
Infrared Surveys from Antarctica
Authors: Bailey Jeremy 
Published: July 2016

AbstractThe very low background observed from Antarctica in a window from about 2·25 to 2·45 μm can be exploited as a way of making deep near-IR surveys over wide areas of sky. Imaging surveys using the entire window can cover large areas of sky to limits of around K = 20, and can be used to study galaxy evolution and to search for high-redshift quasars, dust-obscured quasars and brown dwarfs. It is also possible to make spectroscopic surveys in this window. The window includes molecular hydrogen emission and CO absorption in galactic sources, and can also be used to search for emission lines such as Hα in high-redshift star-forming galaxies.
The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)
Authors: Balm Simon P. 
Published: July 2016

AbstractThe Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) is a highly automated 1·7 m diameter telescope aimed at exploiting the superb submillimetre skies of the Antarctic Plateau for astronomy and aeronomy studies. It was recently installed at the Amundsen-Scott South Pole Station during the 1994/95 Austral season and is currently undergoing its first winter-over of operation. In this paper we briefly outline the capabilities of the instrument and describe some recent achievements culminating in the telescope’s first observations of the South Polar submillimetre sky.
An Instrument Devoted to the Study of mm/sub-mm Galactic Emission at Dome C
Authors: Dall’Oglio G. , Miriametro A. , Morgante G. , Pizzo L. , Valenziano L. 
Published: July 2016

AbstractAn experiment has been developed in order to map the submillimetre Galactic emission at four different wavelengths between 400 μm and 2 mm at an angular scale of 1°. A binocular telescope system has been realised by means of two off-axis wobbling parabolic mirrors, each one coupled to a two-channel 3He photometer. A first run of observations from Dome C is planned for the Antarctic summer 1995–96.
Preliminary Radio Continuum Maps of Three Spiral Galaxies
Authors: Mazzolini Margaret , Webster Rachel 
Published: July 2016

AbstractThe Australia Telescope Compact Array has been used in two 6 km configurations to make 12 hour observations of the radio continuum structure of three spiral galaxies at 1380 MHz and 2378 MHz. Radio maps of NGC 1792, 6300 and 1097 are presented here, as part of a survey to find examples of anomalous radio structures in spiral galaxies.
Shock Acceleration in Hot Spots
Authors: Pope M. H. , Ball Lewis , Melrose D. B. 
Published: July 2016

AbstractA simple model is presented for electron acceleration in extragalactic radio sources with two hot spots. The effect of diffusive shock acceleration by multiple shocks is calculated numerically, with adiabatic and synchrotron losses included. It is found for the sources 3C 20 and 3C 268·4 that a consistent set of model parameters exists which reproduce the observations. The model fails to reproduce the observations for the source 3C 196.
Research Programs at the Carter Observatory: An Overview
Authors: Dodd R. J. , Orchiston W. 
Published: July 2016

AbstractAn outline is given of the main research programs currently in progress at the Carter Observatory. These include: the establishment of a set of standard star magnitudes and colours in the Vilnius seven-colour photometric system; the study of galactic and extragalactic star clusters using Vilnius and broadband photometries; binary stars and the development of APTs; and the history of Australasian astronomy. The role of Carter Observatory Honorary Research Associates is described and mention is made of the joint New Zealand/Japan program to observe gravitational microlensing effects, discover variable stars and patrol selected clusters of galaxies for supernovae.