bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress in Galaxy Redshift Surveys using FLAIR
Authors: Watson F. G. , Broadbent A. , Hale-Sutton D. , Shanks T. , Parker Q. A. , Oates A. P. 
Published: July 2016

AbstractAmong the most important stimuli for developing the FLAIR multi-object spectroscopy system on the 1.2-m UK Schmidt Telescope was its potential for carrying out large-scale redshift surveys of galaxies of intermediate magnitude (B <~ 17). During FLAIR’s lengthy development period, these objects provided the yardstick by which the system’s performance was measured, and a number of limited-area redshift surveys were carried out. We are now following these with a 1-in-3 survey over the 60 fields of the ROE/Durham Galaxy Catalogue to produce a redshift map of some 4000 galaxies out to a distance of ~ 300h−1 Mpc (where the parameter h is the Hubble constant expressed as a fraction of 100 kms−1 Mpc−1). In this paper we summarise the results from our redshift surveys to highlight the capabilities of FLAIR. We present a status report on the current large-scale survey, and show that the recently-introduced FLAIR II system will speed its progress considerably.
The Galactic Plane Radio Source G321.48 + 1.02: is it Extragalactic?
Authors: Caswell J. L. , Stewart R. T. 
Published: July 2016

Abstractstrong non-thermal radio sources at low galactic latitude may be young galactic supernova remnants or else distant extragalactic objects located in the direction of the galactic plane merely by chance. Here, we have imaged G321.48 + 1.02 with the Australia Telescope in order to distinguish between these alternatives for this source.
A Second Compact Radio Component Detected in the LMC HII Region N159
Authors: Hunt M. R. , Whiteoak J. B. 
Published: July 2016

AbstractThe Australia Telescope Compact Array has been used for observations, with arcsecond resolution, of the HII region N159 in the Large Magellanic Cloud. Images at 5 GHz reveal a second compact continuum component which has no obvious counterpart at optical and infrared wavelengths. Observations of HI 10α recombination-line emission, and HI and H2CO absorption, suggest that the object is a compact HII region embedded in a dense obscuring cloud on the edge of N159.
Reconstruction of the Annual Variation in Solar Radio Flux and the Catania Sunspot Area from Tree Ring-index Time Series
Authors: Murphy J. O. , Sampson H. , Veblen T. T. , Villalba R. 
Published: July 2016

AbstractFour tree ring-index site chronologies, representing standardised annual growth rates for spruce trees growing at high altitude sites in Colorado, have been employed as proxy data in a regression model for the annual variation of solar radio flux at 2800 MHz (F10·7) and the Catania sunspot area (Ac). These dendrochronological time series all exhibit significant power spectrum peaks at about 11 years and separately correlate with the annual values of Rz, F10·7 and Ac, as solar activity indicators. The two models constructed give the cyclic variation of F10·7 and Ac back to AD1673.
The Population I Core of the Galaxy
Authors: Allen David , Burton Michael 
Published: July 2016

Abstract We demonstrate the presence of a cluster of hot, population I stars at the very centre of the Galaxy, using the depth of the first overtone band of CO and the presence of emission in He I 2 ·058 μm and [Fell] 1·644μm to identify stars. The cluster is very compact and comprises at least several hundred stars. They lie close to the nonthermal radio source Sgr A* and dominate the luminosity and mass loss of the Galactic core. Their presence suggests that a starburst occurred at the Galactic centre.
Adaptive Optics at the Anglo-Australian Telescope
Authors: O’Byrne J. W. , Bryant J. J. , Minard R. A. , Fekete P. W. , Cram L. E. 
Published: July 2016

AbstractA consortium of Australian universities and the Anglo-Australian Observatory is currently implementing an adaptive optical system at the Anglo-Australian Telescope. This project aims to enhance the science output of the telescope and establish the utility of adaptive optics at the AAT site. The first stage of the project is a fast tip-tilt system, described here, to be installed in the west coudé room. Subsequent funding has been obtained to implement a second-stage, low-order deformable mirror system which is also outlined. Both phases will primarily serve the IRIS camera/spectrograph, since the maximum gains in image quality will occur in the infrared.
Dust Obscuration in the Universe
Authors: Masci F. J. , Webster R. L. 
Published: July 2016

AbstractA substantial population of red quasars has been discovered in a complete sample of flat-spectrum radio sources. Dust is the most likely cause of the reddening in this sample. The location of the dust is poorly known, but may either be in the line-of-sight to the quasar, or in the immediate quasar environment. In this paper we are interested in models where the dust is located in the line of sight to the quasar. We calculate the probability distribution of the optical depth in galactic dust as a function of source redshift, using a range of parameters which might describe real galaxies. We compare these results with those found for our sample of radio quasars. If the dust content is unevolving, then it is not possible to account for all the observed reddening in the quasar sample using these models. Our minimum dust model predicts that 15% of background quasars to z ~ 5 will have a line of sight within 5 kpc of a galaxy’s centre, and would therefore be reddened out of B-band flux-limited samples.
Instrumentation Plans at the AAO: 2dF and Beyond
Authors: Cannon Russell 
Published: July 2016

AbstractThis paper is based on a report given at the ASA Conference in July 1994, but takes account of subsequent developments up to the end of the year. The present state of the Two-degree Field (2dF) project for the AAT is reported. Good progress is being made on all fronts but some slippage has occurred, so that the instrument is now expected to begin astronomical observations only during the second half of 1995. An outline of other current and future instrumentation plans at the AAO is given.
A Hartmann Differential Image Motion Monitor (H-DIMM) for Atmospheric Turbulence Characterisation
Authors: Bally John , Theil David , Billawala Youssef , Potter Dan , Loewenstein R. F. , Mrozek Fred , Lloyd James P. 
Published: July 2016

AbstractWe describe the use of a multi-aperture Hartmann mask coupled to a slightly out-of-focus focal plane array imager to monitor atmospheric turbulence (‘seeing’) produced by refractive index fluctuations. The imager (a CCD) is located inside or outside the focal surface of the imaging system so that each sub-aperture of the Hartmann mask produces an image well separated from all of the other images produced by the mask. Since the depth of focus of the sub-apertures is an order of magnitude larger than that of the parent optical system, the individual images are still diffraction-limited. We obtain short (10 to 100 msec) exposures and monitor the position fluctuations of the images. Analysis of the position and intensity fluctuations of the images can be used to determine the atmospheric parameter r0, the wind direction and velocity, and, under some circumstances, the distance of the turbulent layer from the observing site.
A Study of the Stability Properties of Smooth Particle Hydrodynamics
Authors: Morris Joseph Peter 
Published: July 2016

AbstractWhen using a formulation of smooth particle hydrodynamics (SPH) which conserves momentum exactly the motion of the particles is observed to be unstable to negative stress. It is also found that under normal circumstances a lattice of SPH particles is potentially unstable to transverse waves. This paper is a summary of a detailed report (Morris 1994) investigating the nature of these and other instabilities in depth. Approaches which may be used to eliminate these instabilities are suggested. It is found that the stability properties of SPH in general improve as higher-order spline interpolants, approximating a Gaussian, are used as kernels.
Splitting of the Jupiter S Bursts
Authors: Ellis G. R. A. 
Published: July 2016

AbstractSpectrum analysis of video tapes of the Jupiter S bursts in the frequency range 8-24 MHz with a frequency resolution of 2 kHz and a time resolution of 0.5 ms has shown that many of the bursts with instantaneous bandwidths less than about 10 kHz and which appear single with lower resolution, are actually double in the frequency-time plane. The frequency interval between the two components varied from 6 kHz at 9 MHz to 10.5 kHz at 23 MHz, and the corresponding time intervals from 1.3 msec to 0.6 ms.
Outstanding Stellar Microwave Flares in 1986
Authors: Slee O. B. , Nelson G. J. , Stewart R. T. , Wright Alan E. , Jauncey David L. , Vaughan A. E. , Large M. I. , Bunton J. D. , Peters W. L. , Ryan S. G. 
Published: July 2016

AbstractWe describe bright microwave events that were first detected with the Parkes 64-m telescope at 8.4 or 22 GHz from six active-chromosphere stars. In some flares spectral data were obtained over a large frequency range from simultaneous measurements with the Parkes reflector (8.4 or 22 GHz), the Tidbinbilla interferometer (8.4 and 2.29 GHz), the Fleurs synthesis telescope (1.42 GHz) and the Molonglo Observatory synthesis telescope (0.843 GHz). Data on circular polarization were obtained from the Parkes observations at 8.4 GHz.The stars were in a wide variety of evolutionary states, ranging from a single pre-main-sequence star (HD 36705), two RS CVn binaries (HD 127535, HD 128171), an Algol (HD 132742) and two apparently single K giants (HD 32918 and HD 196818). Their high brightness temperatures, positive spectral indices and low polarization are consistent with optically thick gyrosynchrotron emission from mildly relativistic electrons with average energies 0.5 to 3 MeV gyrating in inhomogeneous magnetic fields of 5 to 100 G.
VLA Observations of NGC 5793
Authors: Whiteoak J. B. , Gardner F. F. 
Published: July 2016

AbstractThe edge-on spiral galaxy NGC 5793 has been observed at frequencies of 4860 and 14940 MHz with the Very Large Array. The corresponding half-intensity beamwidths in the final maps were 0.65 × 0.40 and 0.19 × 0.11 arcsec2. The maps show a continuum source close to the optical nucleus with dimensions of ≤0.01 and 0.04 arcsec in right ascension and declination. The average spectral index is –0.6.
On Solar Neutrinos and Chemically Inhomogeneous Solar Models
Authors: Robinson S. J. 
Published: July 2016

AbstractWork is in progress on the extension of a detailed stellar structure code to explore a suggested solution to the Solar Neutrino Problem where the Sun has a small (∼0.01M⊙) high-Z core on entry to the ZAMS. A basic premise of such models is that the core will burn itself out by solar age and the model acquire a neutrino luminosity in line with that observed. The work to date has involved the construction of a standard solar model and, currently, the development of inhomogeneous models with associated adjustments to the structure equations.
LYMAN : A New Window on the Universe
Authors: Dopita M.A. , Tuohy I.R. , Cropper M. , Hunstead R.W. , Lewis B. , Mathewson D.S. , Mitchell C.J. , Norris R.P. , O’Mara J. , Pettini M. , Roberts E.R. , Waterworth M.D. 
Published: July 2016

AbstractThis document is the final Phase A Science Report of the Australian LYMAN Science Working Group, and describes in detail the scientific objectives, technical feasibility, and engineering implementation of the LYMAN mission as developed in the Australian studies.
Optical and Infrared Observations of SN 1987A from Cerro Tololo
Authors: Terndrup D.M. , Elias J.H. , Gregory B. , Heathcote S.R. , Phillips M.M. , Suntzeff N.B. , Williams R.E. 
Published: July 2016

AbstractResults from optical and infrared observations of SN 1987A obtained at Cerro Tololo Inter-American Observatory since maximum light (100-400 days after core collapse) are reviewed.
Optical spectroscopy of SN 1987A
Authors: Hearnshaw J.B. , McIntyre V.J. 
Published: July 2016

AbstractMt John Observatory photographic spectra of SN 1987A have been obtained on 111 nights during the first year at resolutions of 1.1 Å (blue) and 1.6 Å (red). The early spectra are dominated by broad P Cygni profiles from neutral or singly ionised species. Ba absorption lines may be present. After six months nebular emission features emerged, including [OI] 630, 636 nm and two unidentified UV lines (367, 375 nm) in the previously dark region below 380 nm. Absorption line radial velocities show steep declines in the first month, but are almost constant or only slowly decline after 100 days. For the Hα absorption minimum the initial decline rate was 690 ± 70 km s−1d−1 and the initial velocity was −20.2±0.5 Mm s−1 (LMC frame). By 1988 Feb the slowest material in absorption was at −2.2 Mm s−1.The emission maxima of Hα and NaID show anomalous redshifts of about 1.0 Mm s−1. The [OI] lines show no such redshift. Recent [OI] and Hα spectra at higher resolution show ‘fine structure’ in the profiles, indicating inhomogeneity in the ejecta. Hβ, Hγ and Hδ (but not Hα) were all weaker or absent from 1987 late March to early May, but strong thereafter. From about 1987 Mar 18 to Apr 17 Hα showed a bump on the blue side of the emission at 647 nm and a double peak (658 and 668 nm). Absorption bumps in the Hα profile in early spectra (1987 Feb) may be due to circumstellar water vapour.
Late Evolution of SN 1987A
Authors: Chevalier Roger A. 
Published: July 2016

AbstractSN 1987A has illuminated a great diversity of astrophysical processes – from neutrino emission during core collapse to the structure of the interstellar medium on a scale of hundreds of parsecs. Here I cover the evolution of SN 1987A from the outside in; the topics are interstellar light echoes, circumstellar light echoes, circumstellar shock waves, late emission and structure of the ejecta, and the effects of a central neutron star.
Extensions to the Coupling Coefficient Calculations for Muon Telescopes
Authors: Baker C. P. , Duldig M. L. , Humble J. E. 
Published: July 2016

AbstractThe calculation of coupling coefficients for muon telescopes has previously used interpolation from a limited set of asymptotic directions of arrival of primary particles. Furthermore, these calculations have not incorporated curvature of the atmosphere and thus diverge from the true response at zenith angles greater than about 75 degrees. The necessary extensions to calculate coupling coefficients at arbitrary zenith angles are given, including an improved method of incorporating the asymptotic directions of the primary particles. It is shown, using this method, that certain coupling coefficients are highly sensitive to small changes in asymptotic directions for some telescope configurations.
Stellar Outflows and Jets
Authors: Zealey W. J. , Mundt R. , Ray T. P. , Sandell G. , Geballe T. , Taylor K. N. R. , Williams P. M. , Zinnecker H. 
Published: July 2016

AbstractWe present maps in the visible emission lines of [S II] and the infrared emission lines of H2, at 2.12μm, for several bipolar outflow complexes which exhibit jet structures. A comparison of the morphology of this infrared emission and that seen in visible emission lines shows both the visible and the H2 emission exhibit clumpy structure on similar scales. It appears that the brightest H2 emission occurs at the working surfaces of the jets. Virtually no H2 emission is associated with the jets themselves.Velocity profiles are presented for several objects and possible emission mechanisms are discussed.
Optical Aperture Synthesis with the Anglo-Australian Telescope
Authors: Bedding T. R. , Robertson J. G. 
Published: July 2016

AbstractWe propose to construct an optical interferometer to produce high resolution images by aperture synthesis. The interferometer, known as the Masked Aperture Pupil-Plane Interference Telescope (MAPPIT), will be mounted at the coudé focus of the Anglo-Australian Telescope. It will use a non-redundant aperture mask, together with closure phase methods developed for radio VLBI, to overcome the wavefront distortions which are introduced by atmospheric turbulence. By using the techniques of pupil-plane interferometry and wavelength dispersion, it is hoped that MAPPIT will have more sensitivity than many other interferometric imaging projects.
The Giant Radio Galaxy 0319-45 (MSH 03-43)
Authors: Jones P. A. 
Published: July 2016

AbstractThe extended radio source 0319-453 (MSH 03-43) was observed with the Molonglo Observatory Synthesis Telescope as part of a program to study a large sample of southern extragalactic radio sources. The low level structure showed a ridge pointing towards the nearby source 0317-456, which also showed low level structure. It is suggested that the two sources are the asymmetric lobes of a radio galaxy identified with the magnitude 15 peculiar dust-land galaxy AM 0319-452. The galaxy redshift of z = 0.0633 and the radio size of 25.6 arcmin give a projected size of 1.27 Mpc (H = 100 kms−1 Mpc−1). Thus it is one of the largest radio galaxies.
Short-Period Comet Production in Close Encounters with Jupiter
Authors: Olsson-Steel Duncan , Taaffe Lynne , Williams Simon 
Published: July 2016

AbstractA method for calculating the resultant probability distributions of orbital elements for a small body (a comet, asteroid or meteoroid) after a gravitational encounter with a planet is described. This technique incorporates the frequency of such encounters so that the chance of attaining a certain new orbit per unit time is derived. The use of this technique is then illustrated by considering the effect of Jupiter upon the orbits of near-parabolic comets with perihelia near that planet (q= 5.2 AU) and in the inner solar system (q= 1.0 AU), with prograde (i= 10°) and retrograde (i= 170°) paths. As indicated by previous authors the prograde comets are more easily captured into short-period (P< 20 yr) and intermediate-period (20<P<200 yr) orbits; however, in contradiction to most previous work but in agreement with the results of Stagg and Bailey (submitted toMon. Not. R. Astron. Soc.) it is found that the comets with smaller perihelia, rather than those with perihelia near Jupiter, have higher capture probabilities. This is apparently due to the fact that a small deflection only is needed to sufficiently decelerate a comet onto a smaller orbit if it makes a near-perpendicular crossing of Jupiter’s path, whereas a larger deflection (to achieve a large orbital change) is needed if the paths are near-parallel. With comparatively modest amounts of computer time this method may be used to calculate the relative capture probabilities as a function ofiandqfor all values of interest, and is thus a useful precursor to integrations following orbital evolution, since it indicates the most likely avenues whereby shorter-period comets are derived from the near-parabolic flux.
Coronal Loops in Solar Active Regions
Authors: Durrant C. J. , Brown S. F. 
Published: July 2016

AbstractWe discuss the appearance of solar active regions as seen in EUV line radiation in terms of a system of simple static coronal loop models. The loop models are based on those of Rosner et al. (1978) and may be understood in terms of the scaling laws introduced by these authors. We present here some generalized scaling laws which demonstrate that the global properties of loops in fixed length are insensitive to everything but the overall heating rate or the basal pressure. The model and scaling laws appear to describe hot loops (T< 106K) well. Empirically determined temperatures and densities in cooler loops are not in agreement with coronal loop models.We have computed a simple model of an active region using a dipole magnetic structure. The individual loop structures were calculated on the basis of the two different assumptions of constant basal pressure and of constant heating rate. This paper presents a preliminary discussion of the results and a comparison with observation.
Solar Radio Observations at 843 MHz
Authors: Gray A. D. , Campbell-Wilson D. , Large M. I. 
Published: July 2016

AbstractThe Molonglo Observatory Synthesis Telescope (MOST) has been used to observe the Sun with total-power fan-beams having a one-dimensional resolution of 41 arcsec at 843 MHz. The scans reveal clearly the rotation and evolution of the slowly-varying component as well as some burst activity. Low radio brightness features have also been identified, but the exact relationship between these features and coronal holes is, as yet, unclear. Several partial synthesis observations have been used to generate two-dimensional radioheliograms.
12.2 GHz Methanol Absorption towards Sgr A
Authors: Peng R. S. , Whiteoak J. B. 
Published: July 2016

AbstractLine absorption associated with the 12.2 GHz 20 − 3-1 transition of CH3OH has been mapped towards Sgr A with the Parkes 64-m radio telescope and a 2 arcmin beam. Two concentrations are present, both offset from the continuum peak, with velocities of 18 and 46 km s-1 and line-to-continuum ratios of 0.59 and 0.30. For the higher ratio the column density is almost 1017 cm-2. The concentrations may be associated with a molecular cloud which overlies Sgr A East but lies in part behind Sgr A West.
Two Models for the Radio Spectra of Stellar Flares
Authors: Beardwood R. J. , Melrose D. B. 
Published: July 2016

AbstractThere are two current models for the typical radio spectra of flare stars, which have a broad peak around a frequency typically 1 – 10 GHz. One model involves both optically thick and optically thin emission, with the turnover attributed to the source becoming self-absorbed. The other model involves only emission at optical depth unity, so that observing different frequencies corresponds to ‘seeing’ different regions in the source. The two models are reviewed, and new calculations for an inhomogeneous source presented.
A Technique for Reducing the Grating Lobes of the Molonglo Observatory Synthesis Telescope
Authors: Amy S. W. , Large M. I. 
Published: July 2016

AbstractThe grating ring response of the Molonglo Observatory Synthesis Telescope can be reduced by the installation of 60° phase switches into each of 176 signal paths of the antenna. A suitable voltage-controlled UHF phase switch has been designed and tested at 843 MHz. It consists of two varactor diodes in series with a microstrip. Although designed to provide only two phase states, the device works well as a continuous phase shifter with a coefficient of ∼3° per volt. Details of the design, performance and application to the radio telescope are given.
Hα and Hβ Imaging of the Planetary Nebula NGC 6302
Authors: Ashley Michael C. B. 
Published: July 2016

Abstract
NGC 6302 is one of the highest excitation planetary nebulae known. It has an obscured central star with a temperature estimated at 430,000 K. We present here CCD images in Hα and Hβ of NGC 6302, and interpret the differences between the images as being due to extinction caused by dust within the nebula. The dust appears to be concentrated in the core, as expected from infrared observations. There is no evidence of patchy foreground extinction, although there is a slight difference in the average extinction between the eastern and western lobes of the nebula. A comparison between the Hα image and a 5 GHz map gives a dust extinction of ΔAV~3.5 to the central star. The outer contours of the 5 GHz map are not in good agreement with the optical images, and further observations at this frequency would be useful.
RINGO: a Method of Determining Radio Source Positions
Authors: Wark Robin M. , Wright Alan E. 
Published: July 2016

AbstractWe report on a new method of determining radio source positions with the Parkes radio telescope. The method is appreciably quicker than, but has a comparable accuracy to, established methods such as orthogonal scanning. It has been particularly useful during 1989 in tracking theVoyager IIspacecraft as it approaches Neptune; a method of accurately pointing at the source of the radio signal was required without the signal degradation which is introduced by moving appreciably off source.