bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic Observations of BF Cygni
Authors: Huang C. C. , Chen L. 
Published: July 2016

AbstractSpectroscopic observations of BF Cygni performed at the Haute-Provence Observatory in 1981 August, October and November are presented. The spectrum of BF Cyg was dominated by strong emission lines of H I, He I, [O III] and [Ne III]. Emission lines of He II and N III were weak. The spectrum of the star displayed dramatic variations during our observations. The intensities of Balmer lines, Balmer continuum and He I lines clearly increased from August to October, while the lines of [Ne III] and [O III] showed inverse variability.
Misidentified OH/IR Stars
Authors: Lewis B. M. , Hekkert P. te Lintel 
Published: July 2016

AbstractPlots of periods against (25μm – 12μm) colour of OH/IR stars suggest that four IRAS sources, that have been associated with known OH/IR stars, either provide anomalous identifications, or are weak rather than regular variables. It is argued here that only one of these cases is an association error. OH15.7+0.8 and OH37.1–0.8 are the new proto–planetary nebula candidates.
Ecliptical Orthogonal Motion and Perihelion Distribution of the AAA Asteroids
Authors: Siregar Suryadi 
Published: July 2016

AbstractThis paper briefly discusses the Aten, Apollo and Amor asteroid types (collectively referred to as AAAs), their perihelion distribution and orthogonal motion. There are 90 objects in these classes: 6 Atens, 46 Amors and 38 Apollos. The maximum distance to the ecliptic plane of each class follows an exponential function.
A Numerical Simulation for the Cooling Process of the Solar Flare Loop
Authors: Gan W. Q. , Fang C. , Zhang H. Q. 
Published: July 2016

Extended abstractWe have simulated numerically the hydrodynamic cooling process after the maximum phase of a solar flare with improvements on the chromospheric radiative loss and the resolution of the transition region, together with the introduction of the mechanism of chromospheric heating by coronal soft X-rays. The main results are as follows:
1.At the early stage of the gradual phase, thermal conduction maintains chromospheric evaporation, but with the cooling of the atmosphere, chromosphere evaporation decreases gradually.2.In most of the gradual phase, the velocity is smaller than 40km s−1 in the corona and 4km s−1 in the chromosphere.3.From the middle stage of the gradual phase, the coronal atmosphere appears to have a quasi-periodic oscillation. The period is about two minutes, and the amplitude of velocity is within ±20km s−1.4.The transition region continues to move downward at first and then changes very slowly for quite a long time. The upward motion of the transition region takes place only at the latest stage, when the atmosphere cools below the quiet-Sun case.5.In contrast to the changes of temperature, the density of the corona does not seem to vary until the violent descent of coronal material takes place at the end of the gradual phase.6.The coronal part cools mainly by thermal conduction, while the chromospheric part cools by radiative loss. With our initial model, it takes about 25 minutes for cooling from the maximum phase to nearly the quiet-Sun case.7.The soft X-ray heating of the chromosphere seems to be of negligible importance in our calculations, but if the coronal density is greater than 1011 cm−3 at the maximum phase of the flare, the soft X-ray heating may play some role in the gradual phase.8.At the latest stage of the gradual phase, the atmosphere remains dense and at low temperature. As a further consequence, it would evolve into a post-flare loop.
CCD Observations from the Centre of a City: Use in Astronomical Education
Authors: Lomb N. R. 
Published: July 2016

AbstractOne of the two main telescopes at Sydney Observatory is a computer-controlled 35.6-cm Celestron. It is used with a television-type system. There is an integrating CCD camera available as well as an ordinary TV camera for bright objects. The images from the cameras can be shown in the Observatory’s lecture room. They are first put through an image processor which allows constant enhancement, spatial filtering and the recording of images for use on cloudy nights. Preliminary results are encouraging, and show the value of the system, even in Sydney’s highly light-polluted sky.
Survey of Quasars over Large Areas
Authors: He Xiang-Tao 
Published: July 2016

AbstractThe survey techniques for finding quasars in large areas of sky have developed rapidly in recent years. One can search for quasars in all wavelengths. The area of sky surveyed may be more than 1000 square degrees. The average density of quasar candidates down to magnitude 20 is about 20 per square degree. Therefore, more than 20 000 quasar candidates are waiting for further observation. The total number of confirmed quasars is currently about 5000. This paper gives a discussion of some of the physical properties of quasars, such as space distribution, luminosity function, clustering and redshift limit.
Heavy Element Abundances in the Magellanic Clouds
Authors: Russell Stephen C. 
Published: July 2016

AbstractThis paper presents a brief discussion of the apparent underdepletion of the heavy neutron-capture elements (elements heavier than Ba), compared with Fe in the Magellanic Clouds. The s-process appears to have been only effective in forming elements in the light neutron-capture group (Sr, Y, Zr) in the Magellanic Clouds, but to have much reduced effectiveness in forming the heavy neutron-capture group. The abundances of the elements heavier than Ba have a distribution that indicates that they were produced by the r-process alone.
Cosmic Ray Positron Production by Gamma Ray Interactions on Starlight
Authors: Mastichiadis A. , Protheroe R. J. , Stephens S. A. 
Published: July 2016

AbstractWe examine the production of cosmic ray positrons by photon-photon pair production of high-energy γ-rays on starlight photons. We start by calculating the production rate as a function of positron energy and distance from the Sun resulting from interactions with sunlight. The results are generalized to production on other types of star. We calculate the average production rate per unit volume averaged over the local region of the galaxy, and we estimate the contribution to the observed intensity from this process.
The Galactic Magnetic Field from Pulsar Rotation Measures
Authors: Costa M. E. , Hamilton P. A. , McCulloch P. M. 
Published: July 2016

AbstractPulsar rotation measures have been used to investigate the structure of the local Galactic magnetic field. The Galactic field is found to be concentrated in the spiral arms and hence to be a spiral field. From the pulsars within 2kpc of the Sun, the field in the local spiral feature was modelled with Gaussian profiles in altitude and azimuth. In this model the field has a peak strength of 4.3 ± 0.2 μGauss directed towards Galactic longitude l = 73°±6°.
Collimation and Dissipation of Pulsar Winds
Authors: Chiueh Tzihong 
Published: July 2016

AbstractA nearly stationary pulsar wind is shown to be always collimating along the direction of rotation. It follows that the conventional picture of the equatorial pulsar wind can occur only in a highly time-dependent manner, which, if true, may account for the observed time variation within a single pulse. Furthermore, a mechanism, via excitation of magnetosolitons, is proposed for explaining the continuous generation of energetic electrons, which yield the observed radio emission in the Type II supernova remnants. Fully relativistic analyses will be presented to substantiate these claims.
Barrel-like Supernova Remnants
Authors: Bisnovatyi-Kogan G. S. , Lozinskaya T. A. , Silich S. A. 
Published: July 2016

AbstractThe origin of cylindrically symmetric supernova remnants (SNR) is discussed. The results of numerical simulations of the two best examples of barrel-like SNRs, SN 1006 and G296.5+10.0, are presented.
Spectroscopic Observations of Emission-line Stars
Authors: Kogure T. , Ogua K. , Nakano M. , Yoshida S. 
Published: July 2016

AbstractIn this paper we present the results of spectroscopic observations for 34 emission-line stars (ELSs) in the Orion belt region, which were detected in an extensive survery. Spectral classification and the intensities of Hα and Hβ emission have revealed that the observed ELSs are probably T-Tauri type stars.
Cold HI Gas in the Chamaeleon I Dark Cloud Region
Authors: Sato F. , Whiteoak J. B. , Otrupcek R. E. , Shimizu M. 
Published: July 2016

AbstractWe have detected a large cold HI cloud consisting of several fragments in the region south of the Chamaeleon I dark cloud. The cold HI cloud is shown to be a future site of star formation.
Cold HI Gas in the M17SW Giant Molecular Cloud
Authors: Sato F. , Whiteoak J. B. , Otrupcek R. E. , Tokushige T. 
Published: July 2016

AbstractThe cold HI cloud in the region of the M17SW giant molecular cloud comprises three major fragments with a mean size of ~ 30 pc. Their overall distribution is rather similar to that of CO gas, but one of the fragments does not seem to have a molecular counterpart. It is shown that such a cloud is also a future site of star formation.
Near Infrared Mapping of Jets and Outflow Cavities Associated with Young Stellar Objects
Authors: Zealey W.J. , Suters M.G. , Randall P.R. 
Published: July 2016

AbstractOur current understanding of Herbig-Haro objects and their relationship with outflows and Pre-Main-Sequence objects is limited. Although the general mechanism of outflows is understood, the detailed questions concerning the outflowing material’s origin and the collimation mechanisms remain largely unanswered. The role of multi-waveband observations (visible, infrared and radio) is vital to our understanding of the shock dynamics of outflows.This paper discusses high spatial resolution near infrared maps of three outflow complexes, HH34, HH46/HH47 and HH54, made using the Anglo Australian Observatory’s infrared camera, IRIS. For the first time molecular hydrogen emission is observed associated with the edges of outflow cavities. In the cases of HH46/47 and to a lesser extent HH34 molecular emission is seen coincident with highly collimated jets feeding the outflow cavities.
Radio Jets and UHE Gamma-ray Emission in Cyg X-3
Authors: Manchanda R.K. , Waldron L.E. , Sood R.K. 
Published: July 2016

AbstractThe low-mass X-ray binary source Cyg X–3 has been extensively observed from radio to ultra-high-energy (UHE) gamma-ray energies (i.e., energies >1015eV). In the radio, Cyg X–3 exhibits intense non-thermal outbursts (flares) and a double-sided relativistic jet morphology. Interestingly, at energies above 1 TeV (1012eV), the gamma-ray emission is highly variable and possibly correlated with the radio outbursts. This emission results primarily from the radiative decay of π°-mesons generated in inelastic collisions between relativistic nuclei (predominantly protons) and the surrounding matter. The observed flux of UHE gamma-rays from Cyg X–3 implies that Cyg X–3 is a localised accelerator of such particles.We propose a model of Cyg X–3 wherein particles expelled by the source are accelerated by Shockwaves in the relativistically expanding jets. Intense flaring episodes then lead to time variations in the ambient particle flux which account for the observed features at UHE energies.
Automated Optical Identifications of Radio Sources
Authors: Unewisse A.M. , Hunstead R.W. , Piestrzynski B. 
Published: July 2016

AbstractThis paper evaluates the COSMOS database as a tool for large-scale automated optical identification programs. Firstly, we explore the limitations inherent in the database by a study of regions centred on clusters of galaxies. We then perform an automated search in the database for a sample of previously measured optical objects and compare the properties of corresponding objects. Finally, we describe a set of new plotting routines in AIPS (Astronomical Image Processing System) designed to plot COSMOS-derived ellipses and, optionally, magnitudes onto radio images.
Modelling the Galactic Centre Snake
Authors: Nicholls Jennifer , Gray A.D. 
Published: July 2016

AbstractHigh resolution imaging at radio frequencies has revealed several long, filamentary, non-thermal sources in the Galactic Centre region. One of these, known as the Snake, is unique in that it lies outside the Galactic Centre Lobe, and has two kinks along its length, one of which appears to be associated with a small, resolved source. For this work the Snake is assumed to be embedded in a region where both the magnetic field and the particle energy spectrum are uniform. The Snake is then modelled as an enhancement over the background of the particle energy spectrum. Some preliminary results from this model are presented here.
Magnetic Fields and Disks in Star-forming Regions
Authors: Wright C.M. , Aitken D.K. , Smith C.H. , Roche P.F. 
Published: July 2016

AbstractThe star-formation process is an outstanding and largely unsolved problem in astrophysics. The role of magnetic fields is unclear but is widely considered to be important at all stages of protostellar evolution, from cloud collapse to ZAMS. For example, in some hydromagnetic models, the field may assist in removing angular momentum, thereby driving accretion and perhaps bipolar outflows.Spectropolarimetry between 8 and 13μm provides information on the direction of the transverse component of a magnetic field through the alignment of dust grains. We present results of 8–13μm spectropolarimetric observations of a number of bipolar molecular outflow sources, and compare the field directions observed with the axes of the outflows and putative disk-like structures observed to be associated with some of the objects. There is a strong correlation, though so far with limited statistics, between the magnetic field and disk orientations. We compare our results with magnetic field configurations predicted by current models for hydromagnetically driven winds from the disks around Young Stellar Objects (YSOs). Our results appear to argue against the Pudritz and Norman model and instead seem to support the Uchida and Shibata model.
Model Atmospheres and the Teff Scale for M Dwarfs
Authors: Brett John M. , Plez Bertrand 
Published: July 2016

AbstractThe Teff (effective temperature) scale for M dwarfs is very uncertain. One method which can be used to establish this scale is to compare observed spectra to synthetic ones derived from appropriate model atmospheres. With this method the adequacy of the model atmosphere is of great importance and simple models can give incorrect results. Alternatively if the Teff scale is known with some accuracy then this comparison is a good test of the adequacy of the models. We have computed some new and preliminary model atmospheres for late type dwarfs which accurately treat the line opacity with the opacity sampling technique and employ laboratory values for the transition strengths of molecular bands. With the above two considerations in mind we compare the fluxes of these models to observed fluxes of late K and early M dwarfs. This preliminary analysis indicates a discrepancy with the currently accepted Teff scale for early M dwarfs with the models suggesting values some 200 K hotter.
The Effect of Magnetic Field Strength on the Oscillatory Characteristics of Multimode Magnetoconvection
Authors: Murphy J.O. , Lopez J.M. , Dyt C.P. 
Published: July 2016

AbstractThe effect of varying magnetic field strength on the frequency of oscillatory motions for cellular multimode magnetoconvection has been investigated. In addition the influence of the thermal, viscous and magnetic diffusivities have been taken into account and the range of preferred horizontal scales established. The relationship between the period of oscillation and the magnetic field strength is determined.
First Test Data from the CANGAROO Project for Stereo Čerenkov Imaging
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. , Fujii H. , Kabe S. , Watase Y. , Fujimoto M. , Hara T. , Hayashida N. , Kifune T. , Teshima M. , Kakimoto F. , Ogio S. , Tanimori T. , Yoshikoshi T. , Mizumoto Y. , Suda T. , Matsubara Y. , Muraki Y. 
Published: July 2016

AbstractThe CANGAROO project incorporates two Čerenkov imaging telescopes at Woomera to obtain stereo images of very high-energy gamma-ray (and cosmic-ray) showers. The first stereo observations, with one imaging system, were made in March 1992, and preliminary stereo imaging observations began in July 1992. This paper describes the stereo imaging technique, the sources under investigation, and the indications from the first data sets.
Cosmic Ray Isotropy at Energies Above 1018 eV
Authors: Smith A.G.K. , Clay R.W. 
Published: July 2016

AbstractStudies have been made of the extent to which extragalactic cosmic rays observed at the earth would be deviated by the galactic magnetic field. The distribution of these deviations is presented as a function of observed direction for two field models. Also using these two models, possible extragalactic directions are derived for the cosmic rays detected by the SUGAR giant air shower array as a basis of a possible technique for searching for extragalactic cosmic ray sources.
Structure in the Radio Remnant of Supernova 1987A
Authors: Staveley-Smith L. , Manchester R.N. , Kesteven M.J. , Tzioumis A.K. , Reynolds J.E.R. 
Published: July 2016

AbstractThe radio emission associated with SN 1987A appears to be synchrotron emission resulting from the acceleration of electrons at the interface between the outward moving shock wave and clumps of circumstellar material. The Australia Telescope Compact Array is now able to resolve this region, which has dimensions of ~ arcsec, revealing a slight (10%) asphericity in the distribution of the low density gas within the [OIII] circumstellar ring. Assuming that the radio emission arises from a region just behind the shock front, we deduce a mean radial expansion velocity, from 1987 to 1992, of 29 200 kms. First observed contact of the shock with the [OIII] circumstellar ring could occur as early as mid-1993, depending on the deceleration in the intervening gas. This will probably be closely followed by shock-excited optical lines, a strong X-ray outburst and a further increase in the radio emission.
On the Existence of DA, F White Dwarfs
Authors: Bessell M.S. 
Published: July 2016

AbstractThe ideas and work presented in this paper date almost entirely from 1977 when the original paper was submitted. The referee suggested that we check out several other strong northern candidates before publication, but upon resubmission several years later the editor noted that as it was now accepted that DA,F white dwarfs did not exist there was little point in publishing the paper. In view of the fact that our preprint was the main stimulus for this status change and reference to this work remains ‘1977 unpublished’, we would like the paper to be published and thus complete the historical record.Observations of some of the stars considered by Weidemann as the most likely DA,F candidates are discussed together with theoretical computations of white dwarfs and subdwarfs. The reddest stars BPM 23251 and G 82–23 are shown to be K subdwarfs and L 532–81 (EG62) is a DA white dwarf. It is suggested that the DA,F stars, if they exist at all, are extremely rare and that the metal abundance of the DA sequence may be less than 10–74 of the solar abundance.
A Medium Rigidity Muon Experiment for the South Pole Station
Authors: Duldig M. L. , Jacklyn R. M. , Pomerantz M. A. 
Published: July 2016

AbstractA proposal for a medium rigidity muon telescope system to be installed at the U.S. South Pole Station for observations of time variations of cosmic ray intensity is at present being prepared by Professor Pomerantz, Director of the Bartol Research Foundation, University of Delaware and Drs Jacklyn and Duldig of the Cosmic Ray Section, Antarctic Division, Department of Science. A novel approach to medium energy cosmic ray observations viewing in equatorial to mid-latitude directions is described. The absorber depth required for the proposed 50-1000 GV rigidity range would be achieved by locating the telescope system at a depth of approximately 7 metres water equivalent (MWE) in the ice and viewing at high zenith angles. Optimization techniques used in the telescope design are presented together with the unique advantages of the location. Justification for the experiment and comparison with important observatories in this rigidity range are also discussed.
The Australia Telescope — Current Status
Authors: Forster J . R. 
Published: July 2016

AbstractThe design of the Australia Telescope is discussed, particularly in reference to the compact array, the frequency ranges of operation, the field of view, dynamic range, polarization, bandwidth, correlators, time resolution and flexibility. Site preparation at Culgoora, antenna design, reflector panel construction, feed horns, receivers an cryogenics, and computing are receiving full attention.
Gamma-Ray Astronomy at the Highest Energies
Authors: Protheroe R.J. 
Published: July 2016

AbstractIn 1983 ultra high energy γ-rays were detected from Cygnus X-3. This was of particular interest since it is the first identifiable source of cosmic rays. Since then, there has been an explosion of interest in the field with more than twenty air shower arrays planned or being used to search for γ-rays at energies above 1014 eV. Observational techniques for both very high energy and ultra high energy γ-ray astronomy are described and existing and proposed experiments reviewed with particular reference to their geographical locations. The results obtained so far are summarised together with some of the models proposed to explain them.
The Giotto Radio Science Experiment at Parkes
Authors: Hall P. J . 
Published: July 2016

AbstractOn 14 March 1986 the European Space Agency’s Giotto spacecraft passed within 600 km of the nucleus of Halley’s comet. During the encounter a radio science experiment was conducted with the aim of determining the total amount of cometary material which impacted the probe. In this paper the theory and implementation of the experiment are discussed and a summary of experimental results is given.
A Nonlinear Bifurcation in Cellular Convection Theory
Authors: Yannios N. , Lopez J. M. , Murphy J. O. 
Published: July 2016

AbstractTime dependent solutions of the nonlinear modal equations for cellular convection in a fluid layer heated below have demonstrated the existence of a nonlinear bifurcation which leads to a stable regime with reduced heat flux and vertical velocities. This new state is brought about by the growth, to a significant level, of the vertical component of vorticity after an initial quasi-steady state has been established. The growth rate mechanism has been investigated analytically and compared with the numerical results. These vorticity modified solutions exhibit favourable features Which could be established in the solar convection zone.
Development of the Buckland Park Cosmic Ray Air Shower Array for Ultra High Energy Gamma Ray Astronomy
Authors: Ciampa D. , Clay R. W. , Corani C. L. , Edwards P. G. , Patterson J. R. 
Published: July 2016

AbstractThe Buckland Park air shower array is being developed particularly for use as an ultra-high-energy gamma ray astronomy telescope. The properties of this instrument are described with an emphasis on improvements being made to its angular resolution. Some early data are presented to illustrate the way in which the data obtained will be used.