bluuebunny/crossref_metadata_2025 huggingface dataset:
The Photometric Properties of the Ap Stars
Authors: Hauck B.
Published: July 2016

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).
The Ultraviolet Spectrum Variations of Alpha Andromedae
Authors: Rakos K.D.
Published: July 2016

The manganese star α Andromedae shows variations in its special lines. The intensity and the radial velocity variations of certain lines can be described with the oblique dipole rotator model for magnetic stars.
Positioning with the Global Positioning System
Authors: Goad Clyde C.
Published: July 2016

This year (1980) the U. S. Department of Defense has scheduled to have in operation six satellites of the Global Positioning System (GPS), which will provide timing and three dimensional position recovery potential to North America during certain segments of a day. By the mid-eighties, continuous timing and three dimensional recovery from 18 GPS satellites are planned. Although the GPS is designed for fast position recovery to the 10-meter level, extended data collection periods could yield subdecimeter relative positioning on a routine basis.
Relationship between Terrestrial and Satellite Doppler Systems
Authors: Lachapelle Gérard , Kouba Jan
Published: July 2016

Classical horizontal geodetic networks are commonly combined with space observations, mostly satellite Doppler, in order to optimize the accuracy of geodetic control points and, thus, satisfy as many types of users as possible. Since satellite Doppler observations refer to a fully defined three-dimensional reference system and terrestrial observations, through the presence of Laplace stations (astronomical longitude and azimuth), contribute also to the pole and longitude orientations, it is imperative to ensure the highest possible degree of compatibility between the astronomical and satellite Doppler systems to maintain optimization of the accuracy of control points. Since gravity and geopotential (in the form of spherical harmonics) data are usually combined to evaluate geoid undulations and deflections of the vertical which are in turn used to reduce terrestrial angular and range observations, it is equally imperative to ensure that the satellite Doppler system and that of the geopotential solution are truly geocentric and thus compatible with the gravity data which should refer to a single equipotential surface. In order to estimate the degree of compatibility in terms of longitude orientation between satellite Doppler and geodetic astronomical systems as realized by current observations, astrogeodetic (based on CIO pole, BIH longitudes, and NWL9D satellite Doppler system) and gravimetric deflections of the vertical were compared at several hundred stations of the Canadian geodetic framework and U.S. transcontinental traverse. It was found that, when using the U.S. data subset only, incompatibility between the zero geodetic meridian plane of the NWL9D system and the zero astronomic meridian plane of the BIH was of the order of 08, which is in good agreement with previous results. However, inter-comparisons between various North American subsets revealed inconsistencies between areas of up to 08 (between Canadian and U.S. geodetic astronomical longitude observations). These results are based on the assumption that gravimetric deflections are bias free. The geocentricity of the NWL9D system with respect to other systems such as the Goddard Earth Models and SAO Standard Earths is also analyzed by comparing satellite Doppler derived geoid undulations with GEM and SAO SE undulations. An incompatibility of 4 m in Z (axis) exists between the origin of the NWL9D system and that of the other systems.
The Reference Frames and a Transformation of the Spherical Functions
Authors: Shkodrov V. G.
Published: July 2016

The use of spherical functions in dynamical problems is very common. As a rule, they arise in perturbing functions. It is well known that passing from one reference frame to another is accompanied by a double transformation of the perturbation function. That is why problems lose their simplicity and elegance. The problem of two solid bodies is a typical example in this respect.

In the present paper the questions connected with the transformation of the spherical functions when passing from one reference frame to another frame are considered. Traditional functions are generally unsuitable as they introduce a series of difficulties in the problems. That is why complex spherical functions are used. The transformation of spherical functions due to rotation of the coordinate frame is made by means of the Wigner’s functions. When translating the frame the Clebsch-Gordon’s coefficients are used.
Combined Space Geodetic and Geophysical Measurements for Studies of Crustal Movement in Scandinavia
Authors: Anderson Allen Joel
Published: July 2016

Scandinavia rests upon one of the most stable crustal platforms on the Earth, the Baltic shield. None the less the study of crustal movement is of great importance. Inparticular studies of vertical movement induced by post glacial rebound have been carried out for over 100 years. These have been accomplished usinq water level variations, and more recently in this century using precise levelinq methods. The uplift measurements of Fennoscandia has led to a clearer understanding about the rheology of the crust and upoer mantle of the Earth.
The Application of Faint Minor Planet Dynamics to the Problems of Improving the Fundamental Reference System
Authors: Hemenway P. D. , Duncombe R. L.
Published: July 2016

The underlying method of forming the adopted Fundamental Reference System is the compilation of observations referred to some (independent) well defined coordinate systems. If the observations themselves are used to define the independent coordinate system, they may be used to help establish the Fundamental System. If the observations are differential, they may be used to refer star positions to the Fundamental System and/or smooth systematic irregularities within the Fundamental System.
Comments on Conventional Terrestrial and Quasi-Inertial Reference Systems
Authors: Kovalevsky Jean , Mueller Ivan I.
Published: July 2016

After commenting on certain definitions related to both the terrestrial and celestial (quasi-inertial reference systems (CTS and CIS) to clarify terminology, the geodynamic requirements for such systems are reviewed. This is followed by a discussion of certain problematic aspects of the two systems. The article concludes with a list of required actions aimed to assure that the reference system issue is resolved early. The list is proposed for the joint IAG/IAU working group to be established in accordance with the Colloquium resolution printed elsewhere in this volume.
Fragmentation in Rotating Isothermal Protostellar Clouds
Authors: Bodenheimer P. , Tohline J. E. , Black D. C.
Published: July 2016

In this paper we report briefly the results of an extensive set of 3-D hydrodynamic calculations that have been performed during the past two and one-half years to investigate the susceptibility of rotating clouds to gravitational fragmentation. Because of the immensity of parameter space and the expense of computations, we have chosen to restrict this investigation to strictly isothermal collapse sequences. Isothermality is, fortunately, a fairly accurate description of the optically thin phases of collapse of protostellar clouds: a one solar mass, Jeans unstable interstellar cloud, having a temperature of 10 K and density ~ 106 particles/cm3, for example, will collapse isothermally through about 6 orders of magnitude in density before heating up significantly (Gerola and Glassgold, 1978). The assumption also applies to protogalactic clouds (Silk, 1977). The results, therefore, should add specifically to our understanding of the dynamics of the earliest phases in a protostellar (or protogalactic) cloud’s evolution. A much more complete discussion of these calculations can be found in Bodenheimer, Tohline and Black (1980), hereafter referred to as BTB.
A Wave Model for Dwarf Novae
Authors: Sparks Warren M. , Kutter G. Siegfried
Published: July 2016

The rapid coherent oscillation during a dwarf nova outburst is attributed to an accretion-driven wave going around the white dwarf component of the binary system. The increase and decrease in the period of this oscillation is due to the change in the velocity of the wave as it is first being driven and then damped. Qualitatively, a large number of observations can be explained with such a model. The beginnings of a mathematical representation of this model are developed.
Rotational and Tidal Perturbations of Nonradial Oscillations In a Polytropic Star
Authors: Saio Hideyuki
Published: July 2016

The degeneracy of frequencies of nonradial oscillations is resolved in the presence of rotation. As observed in an inertial frame the frequency of a nonradial oscillation in a uniformly rotating star is given as
α-Stability Analysis of Hydromagnetic Instabilities in Stars with Toroidal Magnetic Fields
Authors: Goossens M. , Biront D.
Published: July 2016

α-stability analysis is used to investigate the adiabatic stability of a star containing an axisymmetric toroidal magnetic field. Necessary and sufficient conditions for α-stability are derived. Special attention is devoted to the typical hydromagnetic instabilities that can be introduced by a weak toroidal magnetic field in a star that is stably stratified in the absence of any magnetic field. An expression for the maximum growth rate of instability is derived and the basic properties of the displacement fields associated with the instabilities are indicated.
The Origin of Uranus: Compositional Considerations
Authors: Podolak M.
Published: July 2016

Several cosmogonic theories are examined for their ability to explain the details of Uranus’ composition as inferred from observations and interior models. Suggestions are made as to how future work may enable us to decide among competing scenarios.
A fast method to retrieve data from a large star catalogue file
Authors: Schuetz A.
Published: July 2016

A method optimized for the access from a large catalogue of stars lying in a given cap of the celestial sphere is described. The performances of the method applied to the SAO catalogue are presented.
The system Spora
Authors: Lavrov S.
Published: July 2016

“SPORA” is an abbreviation for “Software Package Oriented to Research in Astronomy” (in Russian – “Specializirowannoie Programmnoie Obespechniie Rabot po Astronomii”).

The system is designed for the wide range for users who are not inclined to call themselves computer programmers. We assume that most of them only wish to state their problems as simply as possible – just to say which information they have and what they want to get. On the other hand some of these users have rich programming experience and they are fond of using sophisticated languages, like PL/1 or ALGOL 68, and writing complicated programs.
Fundamental Data For FK4/FK4Sup Stars
Authors: Jahreiss H.
Published: July 2016

The stars in the FK4- and FK4Sup-Catalogue are supplied with visual magnitudes and spectral types essentially on the basis of the Henry Draper Catalogue. There are several good arguments, to compile additional astrometric, photometric and spectroscopic data for these stars. Not only to detect astrometric effects, which can produce errors in the fundamental system, like magnitude equation, colour equation, and foreshorthening effect. For the last one distances and radial velocities have to be known. But also to study the kinematics of the FK4/FK4Sup stars, in profiting from their high precision in proper motion.
Catalogue of planetary nebulae and their nuclei
Authors: Acker A. , Marcout J.
Published: July 2016

Since the catalogue by Perek and Kohoutek (PK) has been printed in 1967, numerous observations and theoretical studies have been made, and new planetary nebulae (NP) have been discovered, in addition to the 1036 PN indexed by PK. We have compiled a bibliographic index from 1965, covering about 80 papers per year; a catalogue of 1455 PN and a bibliographic index have been established (Acker, Marcout, Ochsenbein, 1981).

Now, two important catalogues are being compiled which result from the joint work of the Observatories of Strasbourg, Bordeaux, Marseille, the Laboratory of Astronomy of Montpellier, and the Observatory of Haute Provence.
The Canada-France-Hawaii Telescope
Authors: Bely Pierre Y. , Lelièvre Gérard
Published: July 2016

Visiting astronomers have now used the CFH telescope for 18 months in the prime focus and coudé configurations. Many observers have reported very good image quality and high resolution plates have already been obtained. The general concepts and technical details of the telescope and observatory are discussed. The focal plane instrumentation includes more than 25 instruments and detectors, and these are also discussed.
Un Spectrographe a Reseau Aspherique pour Telescope f/4
Authors: Lemaître G.
Published: July 2016

Aspheric diffraction gratings have been produced by the elastic relaxation method. These gratings lead to more efficient spectrograph mounting arrangements since, for a wide field instrument of fast aperture ratio, a smaller number of optical surfaces are required. The UV-PRIM spectrograph is the first instrument of this type to have been constructed.
High Resolution Imagery and Slitless Spectroscopy at the Prime Focus of the CFH Telescope
Authors: Fouéré J.C. , Lelièvre G. , Lemonier J.P. , Odgers G.J. , Richardson E.H. , Salmon D.S.
Published: July 2016

Direct photographic work over a large field (1°) at the prime focus of the classical Canada-France-Hawaii 3.6m telescope has been achieved with a very good image quality (less than 0.5” FWHM). The basic characteristics of the Wide-Field Corrector are presented. Our Wynne Corrector was in fact redesigned to have the last optical surface flat so that a transmission grating could be replicated thereon. This arrangement with only three optical elements locates the gratings at a maximum distance from the focal surface resulting in improved resolution over a one degree field. The C.F.H.T. grating-plus-lens, or “grens” has a brightness limit which is fainter than the Palomar Sky Survey.
Experiments with Silicon Array Detectors in the RGO Coude Spectrograph
Authors: Harmer C.F.W. , Harmer Dianne L.
Published: July 2016

Two detector systems, recently developed at the Royal Greenwich Observatory, have undergone tests on the coude spectrograph of the 30-inch telescope at Herstmonceux. The first is an intensified Reticon system, used in a photon counting mode; the second is a directly illuminated, cooled CID.
The origin of comets among the accreting outer planets
Authors: Greenberg Richard
Published: July 2016

The hypothesis of formation of comets as an accompaniment to formation of Uranus and Neptune from icy planetesimals is attractive for several reasons, but has suffered from long-standing problems regarding formation of the planets themselves. The history of this problem is reviewed, and recent results are described that may help solve it. Numerical simulations of planet growth show that when the system of planetesimals is no longer artificially constrained to a power-law size distribution, growth of planets may occur in reasonable time. An adeguate number of comet-sized bodies to populate the Oort cloud is not produced as collisional debris during the planet-building process. Rather, the comets are probably a remnant of the original planetesimal “building blocks” from which the planets grew.
Dynamical evolution of the Oort cloud
Authors: Weissman Paul R.
Published: July 2016

New studies of the dynamical evolution of cometary orbits in the Oort cloud are made using a revised version of Weissman’s (1982) Monte Carlo simulation model, which more accurately mimics the perturbation of comets by the giant planets. It is shown that perturbations by Saturn provide a substantial barrier to the diffusion of cometary perihelia into the inner solar system; Jupiter also. Perturbations by Uranus and Neptune are rarely great enough to remove comets from the Oort cloud, but do serve to scatter the comets in the cloud in 1/a. The new model gives a population of 1.8 to 2.1 × 1012comets for the present-day Oort cloud, and a mass of 7 to 8 earth masses. Perturbation of the Oort cloud by giant molecular clouds in the galaxy is discussed, as is evidence for a massive “inner Oort cloud” internal to the observed one. The possibility of an unseen solar companion orbiting in the Oort cloud and causing periodic comet showers is shown to be dynamically plausible but unlikely based on the observed cratering rate on the earth and moon.
The formation and evolution of meteor streams
Authors: Williams I.P.
Published: July 2016

The physical processes which may affect the evolution of meteor streams are discussed and a review is then given of the work carried out to date on the evolution of meteor streams. It is clear that they evolve principally due to the effect of planetary perturbations and radiation pressure. The formation of streams from the breakup of a comet is also discussed. All the evidence, including the recent, discovery of 1983TB points to the correctness of this hypothesis.
First results of the integration of motion of short-period comets over 800 years
Authors: Carusi A. , Kresák L. , Perozzi E. , Valsecchi G.B.
Published: July 2016

All the known short-period comets have been followed by numerical integration over a time span of 821 years, from 1585 to 2406. A preliminary survey of the results of these integrations has shown some interesting features, which become recognizable thanks to the length of the time interval covered, not negligible if compared with the typical evolutionary time scale of comets moving in short-period orbits. Interesting phenomena that have been recognized include: (1) captures from, or ejections into, very elongated ellipses, with perihelia of the parking orbits close to the orbit of Jupiter and aphelia within or beyond the region of outer planets; (2) passages of comets from the control of Saturn to that of Jupiter; (3) orbital evolutions controlled mainly by Saturn; (4) librations of comets around low-order resonances; (5) repeated close approaches of comets to Jupiter, often with the comet being captured as a temporary satellite; (6) an almost perfect coincidence of two comet orbits just before a close approach to Jupiter, suggesting their genetic relationship.
A study of the pre-discovery motion of the two asteroids 1983 SA and 1983 XF
Authors: Benest Daniel , Bien Reinhold , Rickman Hans
Published: July 2016

Our investigation demonstrates that the asteroidal objects 1983 SA and 1983 XF can be considered as temporary visitors of the 4/3 and 2/1 resonance with Jupiter, respectively. Evidence is given that both objects are first rank candidates for a cometary origin. The case of 1983 SA is remarkable in so far as (279) Thule is up to now the only known asteroidal 4/3 librator.
Balloon Observation of the F-Corona at the 1983 Total Solar Eclipse
Authors: Isobe S. , Tanabe H. , Hirayama T. , Koma Y. , Soegijo J. , Baba N.
Published: July 2016

A balloon observation of the F-corona in visual and infrared regions was carried out by Japanese and Indonesian teams at the total solar eclipse on June 11, 1983, in Java, Indonesia. For the visual observation, a SIT television camera, with 4 interference filters (5300Å, 6000Å, 7200Å and 8000Å) and a 45°-step rotating polarizer, was used. The camera measured brightness distributions in a sky area of 5°×5° centered at the eclipsed sun at each polarizer position for each filter. In this paper, a part of results, which are the brightness and polarization distributions in a half area of the 6000Å picture, is shown.
The LDEF Interplanetary Dust Experiment
Authors: Singer S.F. , Stanley J.E. , Kassel P.
Published: July 2016

The Long Duration Exposure Facility was launched for the first time on April 6, 1984 by the NASA space shuttle Challenger. An array of solid-state detectors record the arrival time and approximate direction of an impacting particle. Two levels of detector sensitivity provide an indication of particle energy and mass. The active area is nearly 1 m2. We therefore expect count rates of about 30 per day over an exposure time of about a year. The orbit of the particle cannot be obtained, except statistically. We know the orientation of the detector, the position of LDEF in earth orbit, and the position of the earth in relation to other celestial bodies. From this information we can extract essential orbit information.

An earlier flight on the Explorer 46 satellite gave first evidence of the existence of submicron-sized particles, mostly associated with fresh meteor streams. We hope to obtain more precise data and estimate lifetimes in interplanetary space.

To study the fate and origin of IP (interplanetary) dust, we measure various kinds of time variations. Among the most interesting is the secular variation, i.e., the flux in various meteor streams, as a function of the passage of a comet.

One of the challenging problems will be to distinguish IP dust from man-made space debris. The separation will depend on knowing something of the orbits of debris. Probably more important will be the chemical analysis of the particles. The two types of information are in a sense complementary.
Observation of High 3He/4He Ratio in Ocean Sediments — Evidence for Extraterrestrial Material Contamination
Authors: Ozima M. , Takayanagi M. , Zashu S. , Amari S.
Published: July 2016

Occurrence of anomalously high 3He/4He ratio (> 5 × 10−5) is rather common in the Pacific deep sea sediment. The 3He/4He ratio correlates well with the 3He content, whereas the 3He content shows approximate inverse relation with the sedimentation rate. Input of stratospheric dust of about 1 ppm or less which corresponds to about 2000 ton/y fallout rate can explain the above observation.
Laboratory Investigations and Optical Properties of Grains
Authors: Zerull R.H.
Published: July 2016

A survey on different techniques of scattering measurements is given. Typical results are presented. Efficiency and limits of theoretical methods available are shortly summarized. Special emphasis is given to the demands on future laboratory experiments needed for the interpretation of polarization and colour effects produced by interplanetary and cometary dust.
Electrostatic Charge of Interplanetary Dust Grains: New Results
Authors: Lamy P.L. , Lefevre J. , Millet J. , Lafon J.P.
Published: July 2016

A continuing program aimed at improving the determination of the charge of interplanetary as well as cosmic grains is presented. Recent data have been combined to generate two high-resolution solar spectra corresponding to the maximum & minimum of activity. The energy distribution of photoelectrons emitted by quartz grains under solar irradiation is calculated using the new laboratory measurements of Quemerais et al. (this volume). Finally, the method of Lafon, Millet and Lamy (Astron. Astrophys., 95,295, 1981) is used to find the electrostatic potential of these grains.
Secondary Emission from Interplanetary Dust Grains
Authors: Millet J.M. , Lafon J.P.
Published: July 2016

Secondary emission can play an important role in the charging of dust grains. This process is very sensitive to their size and to the physical properties of the solid. It is particulary important in the case of insulators in which an intense electric field is present at the surface and can accelerate the excited electrons.

As a consequence, the secondary emission yield δ does not depend on the energy of primaries and multiple solutions of the potential due to the usual non-monotonic form of δ versus the energy of primaries disappear.
Effect of Two Types of Non-Maxwellian Electron Distributions on Temperature Spectroscopic Diagnostics
Authors: Möller C. , Lamoureux M.
Published: July 2016

Continuum emission due to bremsstrahlung and direct radiative recombination is studied in two types of fusion-plasmas with non-Maxwellian electron distributions. The calculated emissivity coefficients Jω(hω) are shown to depart from the Maxwellian ones. The main consequence of the modification of the spectrum is to invalidate the usual electron temperature diagnostic which consits in equating dlnjω(hω)/d(hω) to l/kTe.

Case I corresponds to the critical density region of a laser-produced plasma ( Langdon 1980, Mora and Yahi 1982 ). The distribution function is cm exp (-v/vo,m)m with m=5 for all values of the incident electron velocity v. Case II corresponds to very steep temperature gradients for which the spacial scale of the transport region is larger than the gradient scale itself (Albritton 1983, Luciani et al. 1984, Campbell 1984). On the higher temperature side of the heat front, the tail of the distribution is depleted with respect to the Maxwellian one. At a particular distance from it, this tail can be roughly described by the above analytical function but with m=3.
VUV High Resolutton Absorption Spectra Obtained with Synchrotron Light, and Interpretations
Authors: Baig A.M. , Connerade J.P. , Garton W.R.S. , Hormes J. , Mayhew C. , Noldeke G. , Sommer K.
Published: July 2016

For over ten years an expanding collaborative programme of experimental work on the absorption spectra of neutral atomic and simpler molecular gases and vapours, and on similar species “matrix-isolated” in rare-gase solids, has been in progress. The experimental work has centered on use of background continua from the 0.5 and 2.6 GeV synchrotrons in Bonn, - high resolution work being based mainly on the smaller machine. The instrumentation includes - most significantly for the work reported here - a 3-metre Eagle-style vacuum spectrograph equipped with “holographic” gratings of 5,000 – 6,000 1/mm spacing, and usable over the range 200 – 2,000Å.
Atomic Calculations for the Highly Ionized Iron Ions Produced in Solar Flares
Authors: Mason H.E. , Bhatia A.K.
Published: July 2016

The XUY (90–150 Å) and X-ray (10–25 Å) spectra of solar flares are rich in lines from the highly ionized iron ions. Atomic data have been calculated for Fe XVIII (Bhatia, unpublished), Fe XIX (Loulergue et al., 1984, Bhatia and Mason, 1984), Fe XX (Mason and Bhatia, 1980, 1983), Fe XXI (Mason et al., 1979), Fe XXII (Mason and Storey, 1980), Fe XXIII (Bhatia and Mason, 1981), Fe XXIV (Hayes, 1979). The University College London computer package was used. This consists of an atomic structure code (SUPERSTRUCTURE, Eissner et al., 1974); a ‘distorted wave’ electron scattering program (COLLDW, Eissner and Seaton, 1972); a ‘Bethe’ approximation electron scattering program (Burgess and Shoerey, unpublished); a program for obtaining electron collision strength in pair coupling from R matrices in LS coupling (JAJOM, Saraph, 1972); a proton scattering program (Bely and Faucher, 1970) and a program for obtaining level populations and intensity ratios.
Atomic Data in Astrophysics
Authors: Bochkarev N.G.
Published: July 2016

A short review of the atomic and molecular data which are necessary for astrophysics researches is presented. A list of atomic data is described which was chosen by first Soviet colloquiuun on atomic data in astrophysics.
Recombination Lasers in the XUV Spectral Region
Authors: Pert G.J.
Published: July 2016

In a conventional laser operating in the near ultra-violet, optical or infra-red spectral bands the photon energies, not exceeding lOeV, are closely matched to the electronic or molecular energy levels of neutral and weakly ionised atoms. Consequently typical photon energies (~ eV), and transition lifetimes (~ ns) closely match the characteristics of fast electrical circuitry feeding a weakly ionised discharge which may be used to pump either directly or indirectly the laser medium.

In a X-ray laser operating at about 10Å, photon energies are about 1 keV, and lifetimes about 10−14s (l0fs). In consequence the power required to pump the laser must be expected to increase rapidly as the wavelength decreases. The gain per unit length is given by:

where ζ is the line shape factor, A the spontaneous transition probability, λ the wavelength, and Δν the width of the line, and (n2,g2) and (n3,g3) the population density and statistical weight of the lower and upper laser states respectively. The total power loss per unit area, p, of the medium must exceed that emitted by spontaneous decay of the laser transition.
XUV Spectra of Ag XVII - Ag XXI and Cd XVIII - Cd XXII from Laser Produced Plasmas
Authors: Khan M.A. , Al-Juwair H.A. , Tallents G.J.
Published: July 2016

The spectra of highly ionized Ag and Cd in the region 20–200 Å excited in laser produced plasmas were recorded and analyzed. The spectral lines identified correspond to Ag XVII - Ag XXI and Cd XVIII -Cd XXII involving transitions of the type 3dk n1 – 3dk nl' and 3dk – 3dk−l nl" where k = 9,10; n = 4,5,6; 1 = s,p,d,f; 1' = s,p,d,f,g, and 1" = p,f.

The experimental work was carried out at the Australian National University Research School of Physical Sciences. The Nd=glass laser system delivered pulsed powers of the order of 1015W/cm2 onto flat metalic targets placed in a vacuum. The target could be positioned accurately in the focal plane of the input lens. The spectra were recorded photographically on Kodak SC5 plates with a 2-m grazing incidence spectrograph (Hilger & Watts E-580) employing a 600 lines/mm grating at 88.157° incidence. A maximum of three laser pulses gave the desired plate exposure while a single shot exposure from a pure carbon target plasma provided the reference points for wavelength calibration. The well-known Lyman spectra of CVI and CV appeared strong and could be clearly identified upto their 5th order. The wavelengths of some strong lines of Ag XIX and Cd XX previously measured (1) were used as secondary wavelength standards and a best fit was then made with the wavelengths computed from the dispersion equation of the grating. The accuracy of the measured wavelengths was within 0.02A° and better than 0.005A° at points closer to the reference lines.
Novae and Accretion Disc Evolution
Authors: Bath G.T.
Published: July 2016

At outburst the classical nova generates an extended optically-thick wind driven by radiation pressure in the continuum. At maximum light the optical luminosity is close to the Eddington-limit. The subsequent decline illustrates the interaction between radiation and matter in a wind which gradually thins as the mass loss rate falls at an approximately constant Eddington-limit luminosity. As the wind thins so the effective photosphere shrinks back into the underlying binary, and an increasing fraction of the radiation is emitted at ultraviolet wavelengths. Model atmosphere computations show how the increasing flux of ultraviolet photons is associated with the shell becoming more and more ionized through radiative ionization. Attempts to study the internal structure of the wind confirm that the luminosity must be close to the Eddington limit and must be expelled from close to the white dwarf surface. It is generally agreed that the outbursts are caused by runaway nuclear burning of accreted material at the white dwarf surface, but it is possible that some events of the classical nova type may be caused by runaway accretion at a super-critical rate.

In dwarf novae very different behaviour is evident. The outbursts are located within the accretion disc and are generated either by mass-transfer bursts due to dynamical instability of the Roche-lobe filling star, or by an instability within the disc itself. In either case the eruption behaviour is due to an enhanced accretion flux through the accretion disc. One important aspect of the radiation hydrodynamics is the luminosity generated by impact of the mass-transfer stream with the accretion disc and penetration by the stream within the disc. Attempts at examining this penetration region are described and results compared with observed behaviour of disc evolution through the course of an outburst. The possibility that disc instabilities will not propogate in realistic discs which deviate from axial symmetry is considered.
Observations of Galactic and Extragalactic Jets
Authors: Perley R.A.
Published: July 2016

Since nearly all discrete radio sources of astronomical interest are of insufficient angular extent for their detailed structural properties to be accessible to single-dish radio telescopes, radio interferometry must be employed to gain information on the morphologies of these objects. Recently constructed imaging interferometer arrays which employ the technique of Fourier synthesis, particularly MERLIN and the VLA (Very Large Array), and the more recent VLBI arrays, have given unprecedented imaging capabilities, with the result that our knowledge, and hence perceptions, of discrete radio sources have vastly changed over the last few years. An equally important parallel development has been image processing algorithms. These have vastly improved the quality of information produced by these arrays, so that an instrument such as the VLA can now produce images with speed and quality exceeding original design specifications by factors of 100 to 1000.
Diverse Structures, Same Science
Authors: Wentzel Donat G.
Published: July 2016

This is truly an international gathering, as befits the IAU. We have a wide range of educational backgrounds. Most of us hope to adapt each others’ ideas to suit our own needs. That adaption will be much easier if we appreciate each others’ individual circumstances, and especially if we know something about each others’ different educational systems. To ease the exchange of information, I shall outline two very different educational schemes. I shall call them the “traditional” and the “U.S.” system. I suspect that about half of us will identify more closely with the traditional system, and half with the U.S. system.
Graduate Astronomy Studies at The University of São Paulo, Brazil
Authors: Maciel Walter J.
Published: July 2016

The University of São Paulo (USP), founded in 1934, is the largest university in Brazil, having about 50,000 students and 5,000 teachers/researchers distributed among 33 institutes and 184 departments.

Astronomical work was already developed at the older São Paulo Observatory (founded 1912), which was later attached to the university. The observatory has been renamed as Instituto Astronômico e Geofisico (IAG), and presently houses the departments of Astronomy, Geophysics, and Meteorology. Graduate astronomy courses, intended to provide Master (M.Sc.) and Doctor (D.Sc.) degrees, started in 1973.
Workshop for Teachers of Introductory Astronomy
Authors: Mumford George S.
Published: July 2016

As interest in astronomy develops through missions to Mars, SETI, and heaven-only-knows-what earth-shaking new discoveries in the future, demand for astronomy courses at all levels will increase. Without adequate numbers of professional astronomers to teach them, persons from other fields will be thrown into the breech. Already a significant number of college students in the United States are receiving instruction from persons not trained in astronomy. I suspect that this is currently true world-wide, especially as physicists who adopt our field for their research on neutrinos or cosmic strings are assigned or volunteer to teach elementary courses.
Comparative Methods for Teaching an Astronomical Topic
Authors: Isobe Syuzo
Published: July 2016

Astronomy has greatly progressed in this decade. The number of people who are interested in astronomical phenomena is certainly increasing as the number of IAU members increases. These people are divided into several categories, depending on their degrees of interests. For Japan, these are as follows:

The situation is changed when some such special event, such as a return of Halley’s comet, occurs. We can say that our present target in teaching astronomy is to increase the number of people in each category except the last one.
The Personal Computer for Teaching Astronomy
Authors: Andreoni R. , Forti G. , Ranfagni P.
Published: July 2016

The two interactive software packages, which we called ASTRONOMIA 1 and ASTRONOMIA 2 (in the following Al and A2) and developed for a personal computer under MS-DOS, are primarily intended to be used in junior-high and high schools as tools for teaching astronomy. With the help of these programs and using the sky as a laboratory, the teacher can explain the most difficult parts of the astronomical geography: time and coordinates. Very few schools in Italy own the necessary educational tools such as a small planetarium, a sidereal clock, an oriented celestial sphere, etc.

We tried to exploit the capability of a personal computer to visualize and to present the results of a calculation as diagrams and tables. A limited interaction permitted by the programs allows the user to compare the results with other computations.
Informative Slide Sets in Astronomy
Authors: Fraknoi Andrew , Harrington Sherwood
Published: July 2016

In astronomy, perhaps more than any other science, the cliché is true: A picture can be worth a thousand words. Unfortunately, with the illustrations in some astronomical textbooks, a picture can sometimes require a thousand words. And for beginning or inexperienced instructors, the worst thing can be that a picture may deserve a thousand words, but the instructor has only 50 words at his or her disposal.

Even for experienced instructors, unless the image happens to be in one’s own area of expertise, it can sometimes be difficult to appreciate or convey the full significance of a modern deep-sky photo, radiograph, or satellite multicolor composite image.
Public Misconceptions about Astronomy
Authors: Acker A. , Pecker J.-C.
Published: July 2016

The Chinese proverb quoted above means more or less the same thing that our Rabelais did in the middle of the Renaissance, when his famous Gargantua made the statement: “well built brains are to be preferred to overfed brains.”

Indeed, when facing the fallacies that invade our modern life, and when facing the very quickly changing world in which we evolve, it seems that the only weapon we can give is a critical approach to science and life. We feel that anyone can assess at least the likelihood of any alleged fact, or, if he cannot, that he should be able to recognize openly his inability to do so.

Now let us consider the common fallacies of modern times. And you will excuse me if I come back several times to the same motto, from my old Rabelaisian education....
Teaching Astronomy at Keio Senior High School, Japan
Authors: Tsubota Yukimasa
Published: July 2016

The major problem in teaching astronomy in our senior high schools has to do with the nature of the Japanese educational system. The typical science curriculum consists of physics, chemistry, biology, earth science, and general science I & II. The Japanese Ministry of Education allows General Science I to fulfill the minimum high-school graduation requirement in science. General Science I covers the basics of earth science. Astronomy has been taught as a part of General Science I and Earth Science.

Many Japanese high schools do not offer earth science because it is not covered in the college entrance exams (Table l). Moreover, teachers usually spend many hours with the students memorizing the basics of earth science rather than allowing some time in the laboratory.
A Project of Astronomy Teaching in the Secondar Schools
Authors: Nikolov N.S. , Stefanova T.
Published: July 2016

At present, astronomical teaching in the Bulgarian secondary schools is incorporated in the subject of physics. This situation dates from about 10 years ago. Before that, astronomy was a separate school subject with 15 to 30 hours in the last (10th) year of school. Now a new reform aroused by the rapid social and economic progress is in operation. During the course of the reform, one not very definitive decision was taken by the Ministry of Education to again separate astronomy, with about 30 hours in the 11th year of a school system which now has 12 years. In connection with this reform, the Ministry asked the Department of Astronomy at Sofia University to work out a project for developing a didactic system for teaching astronomy in the secondary schools. The elements of the system are: alternative variants for the curriculum and the respective textbooks; advisable teaching methods with the appropriate didactic means (diagrams, models, slides, films, etc.);computer programs to demonstrate astronomical objects and phenomena and for pupil computer dialogues, including means for controlling the knowledge level.
Strategies for Presenting Astronomy to the Public
Authors: Sweitzer James S.
Published: July 2016

Imagine an American trying to explain a triple play to someone who understands English poorly and who has never seen a baseball diamond, much less a game. Yet this is the sort of challenge astronomy educators face every day both in the classroom and in more informal settings.

In a college classroom, the professor has some time to teach students the language of science and astronomy. As the students gain proficiency, they can then comprehend increasingly complex concepts. Through repeated classroom exposure and study, eventually most students learn the basics of astronomy.
Teaching Astronomy at School in a Planetarium
Authors: Duval M.F. , Bardin D.
Published: July 2016

In some countries, such as the U.S.A., there are quite a lot of major planetariums and an enormous number of small fixed-operating planetariums. In France, the situation is not as good. There are only three planetariums with domes in excess of 15 meters across, six with diameters between six and nine meters, and ten transportable ones. For these last — five EX3s, three Starlabs and two of personal design — the inflatable domes are between four and five meters in diameter, providing a dedicated astronomy teaching facility significantly large to accommodate a typical class.
Innovative Astronomy Education Programs for Developing Countries
Authors: Sidharth B.G.
Published: July 2016

It is desirable that planetariums in developing countries should make the maximum and most efficient use of the planetarium infrastructure and facilities to cover as much ground as possible in the popularization and dissemination of astronomy. After all, the number of planetariums in developing countries necessarily has to be small, and so specialization in specific disciplines or fields becomes a luxury. In India, for example, there are about ten planetariums, and another five or six will come into operation in the next few years. But these planetariums have to cater to a large population. In the U.S.A., which has a fraction of India’s population, on the other hand, there are hundreds of planetariums. The following suggestions are based on successfully implemented projects at the B.M. Birla Planetarium, Hyderabad.

A golden rule for planetarium programs anywhere, and certainly in developing countries, is to start a planetarium sky show or activity with a local flair. For example, the local names of stars and constellations, local myths, local astronomers or, more specifically, topics like the history of astronomy in the region should be highlighted.
Algols as Limits on Binary Evolution Scenarios
Authors: Hjellming M.S.
Published: July 2016

Evolutionary scenarios must account for Algol binaries surviving their first phase of mass transfer. The outcome of this phase is dependent upon the rapidity of the initial mass transfer, which can be estimated by calculating the radial reponse of potential progenitors to mass loss. Limits on the donor’s evolutionary state, and its companion mass, can be placed on systems which would transfer mass on a thermal or dynamical timescale. Slower mass transfer rates are necessary for the successful transition to an Algol. Considering 1.5 and 5.0 M⊙ models, the former succeed in case A and Br systems, while the latter can do so only in case A systems. To evolve into an Algol binary, all systems seem to require initial mass ratios near one.
The Masses and the Radii of the Components of U Cep
Authors: Heintze J.R.W. , van Gent R.H.
Published: July 2016

This system needs no introduction after the publications of Batten (1974) and of Hall (1975). According to Plavec (1983) the spectral type of the primary is B8 V.

Tomkin (1981) obtained simultaneously the radial velocities of the primary (≡ RV1) and the secondary (≡ RV2) of U Cep in the near-infra red, which resulted in the following parameters (in km/s):

From the slope of the RVCZ around ϕ= 0, he finds:

The (M/M⊙ ; R/R⊙ ) values as published by Tomkin are (4.2; 2.7) for the primary and (2.6; 4.9) for the secondary.
The Evolution of Binary Stars into Contact States
Authors: Hilditch R W
Published: July 2016

Good-quality empirical results on 62 short-period binary stars recently summarised by Hilditch & Bell (1987) and Hilditch, King & McFarlane (1988) are discussed in terms of evolutionary paths from detached to semi-detached and contact states. These data suggest two evolutionary paths to the contact binaries - from detached systems directly into contact to form initially shallow-contact systems, and via case A mass transfer to semi-detached states, thence to contact systems. These empirical results support previous arguments based on evolutionary models and less detailed observational data.

Concern is expressed about the paucity of high-quality spectroscopic data, particularly for low-mass systems displaying EB-type light curves and the resultant limitations on analyses of those light curves. Such systems provide tests of evolution into contact for the first time, or of broken-contact phases for WUMa-type binaries. The crucial importance of long-term monitoring (decades) of times of minima as indicators of mass transfer rates amongst these interacting binaries is also noted.
Who is Who in Algol-Land ? - Part II -
Authors: Packet W. , De Greve J.P.
Published: July 2016

In part I (De Greve and Packet) we have investigated the occurrence of reversed phases of mass-transfer during Case A evolution in close binaries. If the initial period of a system is shorter than 1 - 2 days (Early Case A) the reversed phase starts before core hydrogen exhaustion of the gainer (part I). This type of evolution is characterized by at least two phases of slow mass-transfer.

We have computed the evolution of four Early Case A systems with initial masses of the loser equal to 3 Mo and 5 Mo. These four systems start mass-exchange when Xc of the primary has decreased to 0.525 (75% of its initial value). They all experience two phases of slow mass-transfer.

We find that both phases have about the same duration for all systems. The mass ratios are clearly distinct, being closer to unity during the first phase. In the Hertzsprung-Russell, mass-radius and mass-luminosity diagrams both components remain close to the main-sequence band during slow mass-transfer. Evolution as an Algol is ended when both components overflow their outer critical surface after a second reversal of the mass-transfer.

Observed Algol systems evolving in Early Case A are scarce. A search thruogh the catalogue by Giuricin et al. gives us the following candidates: X Tri, SX Aur and V Pup. Based on their mass ratios, SX Aur can tentatively be assigned to the first phase of slow mass transfer and X Tri to the second phase. For V Pup (which is more massive) this choice can not be made with certainty.