bluuebunny/crossref_metadata_2025 huggingface dataset:
The Second Cape Photographic Catalogue: CPC2
Authors: Murray C. A. , Penston M. J. , Zacharias N. , de Vegt Chr.
Published: July 2016

Between 1962 and 1972 the southern hemisphere has been covered by a 4-fold overlap pattern on 5820 plates, taken with a scale of 100 arcsec/mm and using a visual bandpass. More than 2 million pairs of x,y coordinates of the 2 exposures from 276259 stars have been measured at RGO with the GALAXY machine. The conventional plate adjustment, carried out at Hamburg Observatory, is now complete. About 150 000 primary stars will achieve a catalogue accuracy of about 0.06 arcsec at epoch of observation.

The rigorous FK4 and FK5 versions, using the SRS catalogue (C. Smith 1988), will be supplemented by preliminary new proper motions for those stars common with the SAOC. Finally, a rigorous block adjustment will be performed within the next year.
Third Preliminary Catalogue of Stars Observed With the Photoelectric Astrolabe
Authors: Lizhi Lu
Published: July 2016

On the basis of the data observed with the Photoelectric Astrolabe Mark II of the Beijing Astronomical Observatory during the period from 1982 to 1988, residuals of 355 fundamental stars and 2921 catalogue stars are reduced and analyzed. The relations between the residuals V and the magnitude M, and the spectral type S of FK5 stars are discussed. The position corrections (PACP3—FK5), Δα′s and Δδ′s, from the double passage of the stars are determined. There are 910 in Δα and 696 in Δδ. The mean precisions of Δα′s and Δδ′s are ±3.9 ms and ±0″.067, respectively. Under certain conditions 328 Δα′s and 12 Δδ′s from the observed single passage of the stars are determined. Finally systematic corrections of PACP3—FK5 are given.
The Electrodynamics of Neutrinos in Dispersive Media
Authors: Oraevsky V.N. , Semikoz V.B.
Published: July 2016

Neutrinos interacting with the vacuum of vector bosons and leptons possess important vacuum electromagnetic characteristics: viz., the anomalous magnetic moment Δμvacν and the mean-square radius of charge distribution 1/2. As a result, neutrinos, just like neutrons, may interact with an external magnetic field.
Large-Scale Flow Patterns in the Solar Atmosphere
Authors: Sivaraman K.R.
Published: July 2016

It is now well established (McIntosh 1979; Makarov and Sivaraman 1983) that the filament and filament channels seen in the H-alpha spectroheliograms (or filtergrams) can be used as reliable tracers for studying the time evolution of large-scale magnetic fields on the Sun. These features represent the neutral lines between the unipolar regions of opposite polarity. Comparison of the synoptic charts compiled from H-alpha pictures with those from full-disc magnetograms for the same period shows very good agreement and hence the former can be used with confidence for time evolution studies of large-scale unipolar regions for those periods when the magnetographs did not even exist. In this paper we shall present one of the results of our study (Makarov and Sivaraman 1983, 1989) on the migration of H-alpha filaments, namely, the existence of the meridional flow on the Sun. We shall extend it further to show the participation of this meridional flow in the solar cycle variation.
Interpretation of the “Third Harmonic” of the Solar Magnetic Cycle
Authors: Gokhale M.H. , Javaraiah J.
Published: July 2016

The peak at ˜ 3/22 y−1 seen for all odd-degree axisymmetric modes in the SHF analysis of ‘nominal magnetic field’ seems to be an artifact of some non-linearity between the field magnitude and the sunspot occurence probability.
Magnetohydrodynamics of Sunspots
Authors: Weiss N.O.
Published: July 2016

Recent numerical investigations of fully compressible nonlinear magnetoconvection have clarified the nature of convection in sunspot umbrae. In a shallow layer with a strong vertical magnetic field oscillations give way to travelling waves as the Rayleigh number is increased but in a deep stratified layer oscillatory behaviour only appears after secondary bifurcations. This behaviour leads to a model that explains the formation of umbral dots. Penumbral structure is more difficult to explain owing to the apparent presence of adjacent horizontal and inclined fields in dark and bright filaments. The inner penumbra lies above a transition zone where volume currents are needed to maintain an overall static equilibrium; instabilities in this region may be responsible for filamentary structure in the penumbra as well as for fine structure at the umbral-penumbral boundary.
Relaxed States of MHD Turbulence: Minimum Dissipation or Minimum Energy?
Authors: Montgomery David
Published: July 2016

Driven, dissipative MHD fluids often seem to undergo relaxation processes. After a turbulent formation phase, a geometrically simpler and less disordered configuration emerges. The best known example is the laboratory reversed-field pinch (RFP); similar field topologies have been proposed for solar prominences and astrophysical “flux ropes.” In a transient situation, the more rapid decay of kinetic and magnetic energy relative to magnetic helicity provides a mechanism for generating an MHD configuration with several similarities to observed RFP states. (This is the Taylor hypothesis, not unrelated to turbulent inverse magnetic cascades.) For the driven steady state, however, all quantities are supplied at the same time-averaged rate at which they are dissipated, by definition; nothing decays relative to anything else. Some other unifying principle, beyond “minimum energy” or “selective decay,” seems necessary to describe the results of driven, steady-state MHD computations. We have been attempting to adapt the principle of minimum energy dissipation rate to MHD. It is a 19th century principle that achieved some success in hydrodynamics and separately in dissipative electrodynamics.
Resonant absorption of Alfven Waves and the Associated Phenomenon of Magnetic Reconnection
Authors: Uberoi C.
Published: July 2016

The mathematical analysis of the Alfven Wave equation in inhomogeneous magnetic fields which explain the resonance absorption of Alfven surface waves near a resonant layer can also be used to show that magnetic reconnection process can arise near the zero frequency resonant layer driven by very low frequency Alfven surface waves. The associated phenomena of resonant absorption and magnetic reconnection in inhomogeneous plasmas can explain the recent obsrevations of intense magnetic activity in the long period geomagnetic micropulsations range, at magnetospheric cusp latitudes, during the time of occurence of flux transfer events.
Magnetic Reconnection on the Sun
Authors: Priest E R
Published: July 2016

Magnetic reconnection is a fundamental process in astrophysics which plays many different roles on the Sun. The classical theory of fast steady reconnection due to Sweet, Parker, Petschek and Sonnerup has been unified in a theory which possesses many new regimes that depend on the boundary conditions at large distances. For example, the flux pile-up regime possesses diverging flows, a long central diffusion region and a reconnection rate that is much larger than the Petschek value. Recent numerical experiments however, often possess three features that are not present in the earlier theoretical models, namely highly curved inflow field lines, separatrix jets and reversed current spikes, and so an attempt is described to include these features in a new theoretical model.

Several solar phenomena where reconnection is believed to be operating are described. Cancelling magnetic features in photospheric magnetograms are probably evidence of reconnection submergence. Most prominences are of inverse polarity and have upflows driven by reconnection below them. Coronal heating may well be due to reconnection in many small current sheets. In solar flares reconnection may be driven below an eruptiing active-region prominence and hence power the high-temperature flare loops and chromospheric ribbons.
The Role of Magnetic Reconnection in Flares and Prominence Eruptions
Authors: Forbes T.G.
Published: July 2016

Magnetic Reconnection is often invoked as the primary mechanism for driving a flare or a prominence eruption. Here I argue that a catastrophic loss of mechanical equilibrium, rather than reconnection, is probably the primary mechanism for driving these phenomena. However, reconnection is still essential in order for any significant amount of energy to be released. To illustrate this idea we present some recent results from an MHD simulation based on a catastrophe mechanism first proposed by Van Tend and Kuperus. In order for this mechanism to be effective a substantial amount of reconnection must occur within a few Alfvén-scale times. Such rapid reconnection is plausible since the loss of mechanical equilibrium can generate flows which drive the reconnection at a rapid rate.
Magnetic Shear and Flares
Authors: Venkatakrishnan P.
Published: July 2016

Magnetic tension posseses low values at regions of large magnetic “shear” on the polarity inversion line. The low tension allows for a non-force-free field that depends on the density of the medium. Instabilities which can modify the density may then possibly evolve into solar flares. Heuristic arguments are given to favour instability driven flare scenarios.
Coronal Loop Interaction
Authors: Smartt Raymond. N. , Zhang Zhenda
Published: July 2016

High–resolution images of post–flare loop systems in Fe XIV (5303Å) and FeX (6374Å) display transient enhancements at the projected intersections of some loops. The brightness of such enhancements gradually increases to a marked maximum and then fades with a typical lifetime of about thirty minutes. The maximum in the red line lags that of the green line by about ten minutes, while Hα reaches a maximum about ten minutes later, which gives a measure of the cooling time, and hence electron density. The observed phenomenon is interpreted as localized loop coalescence and partial magnetic reconnection, with the possibility of an increase in the current density, and heating of the plasma in the immediate vicinity of the X–point.
The Interaction of Cometary Plasma with Interplanetary Medium - A Post-Halley View
Authors: Prasad Debi
Published: July 2016

The strong interaction of cometary plasma with the interplanetary medium results the disconnection events and other features observed in plasma tail and the coma of comets. The understanding of these features provide direct probe of the heliospheric magnetic field. However the interpretation of these events is not without ambiguity, as revealed in the recent work with comet Halley. In this paper a review of the “Post-Halley era” developments of the cometary plasma physics is presented.
Observations of Energetic Electrons in Solar Flares
Authors: Lokanadham B.
Published: July 2016

A study of the simultaneous observations of solar flares in optical, radio and X-ray bands is important in understanding the process of energy release and particle acceleration in the explosive phenomena of solar flares. In order to determine the characteristics of such energetic electrons in solar flares, a total number of 50 two-ribbon flares have been carefully selected during the period 1979-89 having simultaneous observational data in the optical, X-ray and radio bands.
On Stochastic Dynamics of Protons in Solar Magnetic Loops
Authors: Senatorov V.N. , Tomozov V.M.
Published: July 2016

It is shown that stochastization of particles due to Alfven waves is accompanied by their effective acceleration in loop structures of solar magnetic fields.
Type III bursts traced from the solar surface to 1 AU
Authors: Leblanc Yolande , Jackson Bernard. V.
Published: July 2016

We trace type III radio bursts from the sun until they can be observed as in situ electrons at the ISEE-3 spacecraft. Our study extends over the period of operation of the electron experiment on ISEE-3 from August 1978 to November 1979. Our observations include data from solar flares, kilometric type III burst spectra from ISEE-3, and in situ measurements of low energy electrons from ISEE-3. By carefully restricting the data sets involved, we find a peak of 20° width in the number of flares associated with in situ electrons near 60° west solar longitude. This peak shows that the electron beams of type III bursts are not spread over a great range of longitudes as earlier studies indicate, but are fairly limited in spatial extent. However, even in that longitude range only 40% of type III-flare events are associated with in situ electrons.
The Sun at the VLA's Metric and Decimetric Wavelengths
Authors: White S. M. , Kundu M. R. , Gopalswamy N. , Schmahl E. J.
Published: July 2016

During September 1988 (International Solar Month) we observed the Sun with the Very Large Array on 4 days in the period Sep. 11-17. The VLA was in its most compact configuration, which is ideal for studying large-scale coronal structures. Here we summarize some preliminary results of the observations at 0.333 and 1.5 GHz. Despite the presence of numerous active regions the Sun was actually very quiet, with no flares during our observing, and this allowed us to make high-dynamic-range maps.
The Hyades Cluster Distance
Authors: Hanson Robert B.
Published: July 2016

This paper reviews recent astrometric progress in determining the Hyades cluster distance, emphasizing critical assessment of the precision and accuracy of the observations. Substantial improvement in the trigonometric parallaxes yields a mean Hyades distance modulus m - M = 3.25 ± 0.08 mag, nearly twice as precise as previous parallax results. New proper motions from three independent sources yield a mean distance modulus 3.31 ± 0.06 mag. The close agreement of the recent astrometric results suggests that the overall mean Hyades distance modulus 3.30 mag may be used with confidence in cosmic distance scale calibrations.
Open Cluster Analyses at KPNO
Authors: Crawford D. L.
Published: July 2016

For some years now, we have been slowly accumulating uvby, β data on numerous open clusters, with the various telescopes and photometers at KPNO. Analysis of the data, when combined with available UBV and MK data, has been done for most individual cluster stars. Such data and analyses have been published for most clusters and are in preparation for a few others.
Supplement 1 to the Second Edition of the Catalogue of Star Clusters and Assocations
Authors: Ruprecht J. , Balázs B.A. , White R. E.
Published: July 2016

The study of star clusters occupies a central place in the interaction between astronomical observation and theory. The extensive and exponentially growing literature concerning star clusters makes the Catalogue of Star Clusters and Associations (CSCA) an indispensable research tool.
Mass and Luminosity Function of the Pleiades
Authors: van Leeuwen Floor
Published: July 2016

From a proper motion survey by Pels and photometric measurement of selected stars it was found that the Pleiades cluster extends till at least 496 from the centre, corresponding to 10 pc at a distance of 125 pc. It turns out that the luminosity function of the Pleiades is a function of the distance to the centre, the proportion of faint stars increasing with this distance. Because of this, the luminosity function as it was determined before flattened towards fainter stars, whereas for the total field with a diameter of 20 pc one finds a luminosity function that is still increasing at the faint end. Flare star observations in the Pleiades field show that the increase amounts to at least a factor 20 in the mass range 2 to 0.4 M⊙. Accurate proper motions of stars in the projected central field show a dispersion of velocities in the cluster of 700 m/sec. This could indicate a total mass of the Pleiades cluster of the order of 2000 M⊙.
Formation of Open Clusters
Authors: Burki G.
Published: July 2016

A forming star progresses through several evolutionary stages which are marked by different observational signs that can be identified by different techniques. Stellar birth from interstellar matter occurs in dense, cold clouds of gas due to a local increase in the density and interstellar clouds composed of molecules and grains are the preferential place where star formation can be initiated. The observational indications of this prestellar stage are the emission of millimeter radio waves by the cloud's many molecules and the optical obscuration of the background field stars by the grains mixed with the molecular gas. When fragmentation and condensation mechanisms occur in a dense cloud, the gravitationally collapsing fragments cannot be directly observed at visible wavelengths, because their light is blocked by the dust grains which heat up and radiate in the infrared. Thus the various protostellar stages are essentially studied using infrared techniques. Evidently, the spectral energy distribution of the protostars depends on their evolutionary stage and, globally speaking, one can say that the maximum of the infrared emission moves towards the short infrared wavelengths as the protostar evolves. A tentative coherent stellar evolutionary scenario may be given for the radio and infrared sources directly connected with the star and cluster formation:
Dynamical Age Determination of Open Clusters
Authors: Buchholz M. , Schmidt-Kaler Th.
Published: July 2016

The radial mass distribution (obtained by counting stars in strips) of the real cluster is compared successively to the distribution functions of a simulated cluster of 100 stars, each of which corresponds to a certain dynamical age, Tdyn, The value of Tdyn, belonging to the function most similar to the observed one is taken to be the dynamical age of the cluster. The radius is given in units of R1/2 (sphere containing half of the total mass); this unit is nearly time-independent. The difference between the distribution functions is measured by the maximum Δmax of the Kolmogorov-Smirnov test which is free from assumptions on the form of the distributions. The minimum in the plot Δmax vs Tdyn, indicates the age of the cluster. It is then converted into an absolute age, Tabs (in years), by

The error due to the dynamical theory (limited number of distribution functions, etc.) is estimated at 12%, the error due to the uncertainty of diameter and mass of the cluster is about 30%. Unreliable results were obtained in case of strongly inhomogeneous reddening of the cluster. As an example, the plot of the test values for NGC 457 is given in Figure 1.
Anomalies in the uvbyβ Parameters of Young Open Clusters
Authors: Shobbrook R. R.
Published: July 2016

An investigation has been made of the Mv/co diagrams of six young galactic clusters - three in the north and three in the south, as listed on Figure 1. The uvbyß photometry of NGC 3293 is from unpublished observations of 42 stars by the author. From the Mv/co parameters of the ß Cep stars, which have evolved to the end of core hydrogen burning (Shobbrook 1978), the ages of Lac OB I, NGC 3293 and NGC 4755 were calculated using the models of Cogan to be 18, 10 and from 8.5 to 16 million years, respectively.
Photometry of the Lower Main Sequences of Nearby Clusters
Authors: Upgren A. R. , Weis E. W.
Published: July 2016

Photoelectric photometry in BVRI colors has been obtained at the Kitt Peak National Observatory of many stars in the regions of the Hyades, Praesepe and Coma star clusters which had no previous photometry. The stars were limited mostly to the lower main sequence. Their range is approximately 0.6 to 1.5 (and to 1.7 in the Hyades) in B-V and 0.25 to 0.85 (and to 1.3 in the Hyades) in R-I. Their ranges correspond from mid G through early M in spectral class. The purpose of this project is to detect and examine the main sequences of the nearest open clusters. It continues the results reported earlier in this program for the Hyades cluster [Upgren (1974), Upgren and Weis (1977)] and extends them to include Praesepe and Coma as well, by means of the new sensitive gallium-arsenide photocells which permit fainter stars to be observed with moderate sized telescopes, especially in the R and I bands.
Dynamics of Initial Binaries in Open Clusters
Authors: Aarseth S. J.
Published: July 2016

N-body calculations have shown that hard binaries play a dominant role in the evolution of small stellar systems. However, only one or two such binaries form by dynamical interactions and since the final components tend to be massive, their effect and observability in open clusters are limited to relatively short time-scales. In the present investigation we consider an initial population of binaries with physical evolution times exceeding the cluster age. These calculations may be applicable to a later phase when the heavier stars have suffered mass loss.
Globular Cluster Ages and Distances
Authors: Carney Bruce W.
Published: July 2016

Deblanketing vectors derived from subdwarf photometry and spectrophotometry are used to transform published UBV photometry of globular cluster main sequences into an effective temperature scale defined by model atmosphere surface fluxes. Conversion of apparent visual magnitudes into apparent bolometric magnitudes is accomplished using subdwarf bolometric corrections, which are functions of effective temperature and metallicity. The results do not depend on stellar evolution models.
The Binding-Energy Distribution of the Binaries in a Star Cluster
Authors: Retterer John M.
Published: July 2016

In order to study the development of the binding-energy distribution of hard binaries in a star cluster, solutions of the appropriate kinetic equation have been obtained, using the three-body encounter rates calculated by Heggie (1975). The binaries in a homogeneous, time-independent stellar medium are considered first. We calculate an analytical solution, of self-similar form, that can be applied to very hard binaries. Integrated forward in time from an initial state containing no hard binaries, a numerical solution of the kinetic equation rapidly approaches the equilibrium ‘Saha’ form of the energy distribution at small energies, while at high energies the numerical solution behaves like our analytical self-similar solution. The fluctuations in the distribution, due to the stochastic nature of binary creation and evolution, are analyzed. We calculate the rate of exchange encounters when stars of different masses are present; these rates are then combined with the other Heggie rates to find the binary distribution in a multi-mass environment. Next, the creation rate as a function of energy is obtained for the binaries that form in two-body, tidally dissipative encounters. This rate is combined with the three-body encounter rates to calculate how the energy distribution of the tidal binaries evolves. Finally, the binding-energy distribution of hard binaries is obtained in a more realistic inhomogeneous, time-dependent cluster model. Although the evolution of the cluster is governed primarily by the effects of two-body relaxation, the influence of the binaries on the cluster is considered as well. A detailed report of this study has been submitted to The Astronomical Journal.
Electronographic Photometry of Star Clusters in the Magellanic Clouds
Authors: Walker Merle F.
Published: July 2016

The high quantum efficiency, linear response, large dynamic range and large number of picture elements make the electronographic camera the most suitable of the presently available detector systems for the study of the colors and magnitudes of stars in the clusters associated with the Magellanic Clouds. Owing to the remoteness of these objects and the consequent small angular separation of the stars within them, the best method of determining electronographic magnitudes of the cluster stars is still that of measuring the star image profiles on one-dimensional scans made using a Joyce Loebl microdensitometer. While this technique does not utilize all of the information contained in the star image, it provides better correction for overlapping star images and variable background than is achieved with two dimensional methods that simulate observation through a focal-plane diaphragm. By this method, it has been possible to measure a star of B =23.8 on a 180 min exposure in 2.0 arcsec seeing taken with a Spectracon image converter on the 1.5 m Tololo reflector. The probable error of this measurement is ±0.12 mag, while the error due to photon statistics is ±0.06 mag. Thus, using electronographic cameras on larger telescopes and in good seeing, it should be possible to study the stellar content of the Magellanic Cloud clusters down to about the luminosity of the Sun. Further, current studies indicate that if a sufficient number of electronographic magnitudes are determined in a cluster, these can then be used to set up calibration curves as a function of radial distance from the cluster center, permitting photographic photometry of a large number of stars to be carried out, free of the usual limitations imposed by the effects of the unresolved background light of the cluster on the photographic measures. Using this technique, cluster observations can be carried out effectively using a small-field electronographic camera such as the Spectracon, which may be much smaller and less expensive than the large-field electronographic cameras, and thus more practical to use at distant observing sites.
Chemical Properties of Individual Globular Clusters
Authors: Cohen Judith G.
Published: July 2016

Rapid improvements in instrumentation over the past few years have made the spectroscopic study of individual globular cluster giants feasable. Three years ago I began a program of high dispersion abundance analyses of such stars to provide a calibration for the many photometric systems used to rank globular clusters in metallicity. The results for four clusters (M92, M15, M13, and M3) of low and intermediate metallicity have already appeared (Cohen, 1978, 1979), and additional detailed analyses of stars in M5 and M13 (Pilachowski, Wallerstein and Leep, 1979) will soon be available. Ignoring the elements C, N, and O, to which we shall return later, these detailed abundance analyses yielded few great surprises; perhaps the metallicity scale that had previously been used was too high by about 0.2 dex, and also it became clear that M3 was a very metal poor cluster. However, the calibration of the metal rich globulars beyond the simple ranking level of Mould, Struthman, and McElroy (1979) had not been attempted.
Calcium Abundance in the RR Lyrae Stars in NGC 3201 and M 5
Authors: Cacciari C. , Freeman K. C.
Published: July 2016

The assumption that individual globular clusters formed from chemically homogeneous protosystems, which seems to be valid for some clusters, is clearly not valid in others, e.g., ω Cen and M22 (see Freeman and Rodgers 1975, Hesser, Hartwick and McClure 1976, Butler, Dickens and Epps 1978 and references quoted therein). One indicator of chemical inhomogeneity is the width of the cluster giant branch in the C-M diagram, because the B-V colors for the cool giants are sensitive to heavy element abundance. NGC 3201 and M 5 show narrow giant branches (Lee 1977, Arp 1962) and so are not expected to show large star-to-star heavy element differences.
Proper Motion Studies of Globular Clusters
Authors: Cudworth Kyle M.
Published: July 2016

Yerkes refractor plates of M3, M5, M13, M15, and M92 have yielded proper motions for a few hundred stars in each cluster with typical standard errors cent−1. Membership probabilities have been derived, leading to color-magnitude diagrams essentially free of field star contamination.
Infrared Photometry of Globular Cluster Giant Stars: Some Recent Results
Authors: Frogel Jay A.
Published: July 2016

This talk will briefly summarize some recent results based on infrared observations of giant stars in globular clusters. The program is being carried out jointly with Eric Persson and Judith Cohen of the Hale Observatories.
Dynamical Theory of Collisionless Relaxation
Authors: Severne G. , Luwel M.
Published: July 2016

In his classical paper on violent relaxation, Lynden-Bell (1967) gave convincing but qualitative arguments for the approach of collisionless systems towards a stationary state and, applying the methods of equilibrium statistical mechanics to a coarse-grained description of the system, derived the equilibrium distribution attained. Here we report on a dynamical derivation of Lynden-Bell equilibrium, proceeding from the coarse-graining of the collisionless Boltzmann equation.
Axial Ratios, Orientations, and Center Coordinates of Galactic Globular Clusters
Authors: White R. E. , Shawl S. J.
Published: July 2016

A program to determine the axial ratios and major axis orientations for a sample of 120 galactic globular star clusters was begun by us recently. The sample was selected from the clusters listed by Kukarkin and which can be seen on the glass copies of the blue-emulsion plates of the Palomar Observatory Sky Survey and on the B-series film copies of the European Southern Observatory Sky Survey. Out of the major program will come axial-ratios of the elliptical isodensity contours for each cluster, as well as the orientations of the major axes of the elliptical contours, and an accurate position for the center of each of the clusters in the sample. The probable errors of the central coordinates will be on the order of ±1 arcsec or better.
The Electric Fields in Nonneutral Beam Models of Pulsar Magnetospheres
Authors: Smith Dean F. , Muth Lorant A. , Arons Jonathan
Published: July 2016

The electric fields in the polar cap region of the magnetosphere of a pairless orthogonal rotator are being calculated using a modified Poisson's equation which takes explicit account of the effect of the displacement current on the potential Φ. This is the first step in a program to determine how return currents are formed in these models and the resulting global current flow patterns. The potential is being calculated from 0.1 RL to 3 RL, where RL is the light cylinder radius, using known results for ⊘ at 0.1 RL with an inner last closed magnetic field line corresponding to that of a point dipole. Considerable difficulty is being encountered because of the mixed nature of the equation and the irregular boundaries. Possible methods of overcoming these difficulties are indicated.
e+e− Annihilation in Strong Magnetic Fields
Authors: Wunner G. , Herold H. , Ruder H.
Published: July 2016

The possible existence of electron-positron plasmas in the magnetosphere of neutron stars gives rise to the question in which way the e+e− annihilation process is modified by the strong magnetic fields prevailing there. On the basis of a correct quantum mechanical treatment of the two-body problem in an external magnetic field we have calculated lifetimes of the ground state as well as of excited states of bound e+e− pairs (positronium). We find that the 1γ decay remains strictly forbidden, whereas the 2γ process is strongly enhanced with respect to the field-free case.
Radio Observational Constraints on Pulsar Emission Mechanisms
Authors: Cordes J. M.
Published: July 2016

A discussion is made of those observations that place constraints on the pulsar emission mechanism and its location in the pulsar magnetosphere. After reviewing the salient features of pulsar radiation, a number of issues are confronted, including (1) whether coherence is broadband or narrowband and, accordingly, (2) whether the emission frequency is mapped into radius and/or magnetic polar angle; and (3) whether pulse structure (micropulses and subpulses) represents angular or temporal structure. It is proposed that pulse nulling, mode changing, and quantized drift rates for subpulses are related to discrete states of the particle flow in polar cap models.
Pulsar Electrodynamics: Production of Fast Particles
Authors: da Costa A.A.
Published: July 2016

The three-dimensional structure of a pulsar magnetosphere is hard to calculate. Instead we start with a two-dimensional model (Kahn, 1971). It consists of a vacuum electromagnetic field generated by a line of rotating dipoles, from −∞ to +∞, perpendicular to the rotation axis. This field resembles that in the equatorial plane of a rotating dipole aligned perpendicular to its rotation axis. In both cases the electric field E is perpendicular to the magnetic induction B.
Simultaneous Multi-Frequency Pulsar Observations
Authors: Thorne David J.
Published: July 2016

To investigate the frequency dependence of single pulse properties it is necessary to make simultaneous multi-frequency observations. This is because although some of the investigations are of a statistical nature, these should be carried out on the same pulses at the different frequencies. Further, detailed study of pulse shape, time of arrival and spectra can only be carried out on simultaneous data.
On X-ray Pulsar Radiation Mechanisms
Authors: Zheleznyakov V. V.
Published: July 2016

In this report we shall discuss the origin of radiation from the neutron star component of X-ray binary systems whose spectra contain cyclotron lines (Her X-1 and 4U0115+63). A relevant model of the polar region of a neutron star is presented in Figure 1. According to this model the observed X-rays (continuum + cyclotron lines) are generated in the dense plasma atmosphere of a star (in its hot spot heated by accreting matter). The problem of heating the neutron star atmosphere due to accretion has been earlier investigated by Zeldovich and Shakura (1969). Cyclotron lines are formed similarly to the Fraunhofer spectrum of ordinary stars and are absorption lines. For objects such as Her X-1 and 4U0115+63 the cyclotron emission and absorption in the extended accreting column with an inhomogeneous magnetic field should be unessential. Otherwise the accreting column will produce an X-ray continuum devoid of any line type features.
Masses of Neutron Stars in X-ray Binary Systems
Authors: Kelley R. L. , Rappaport S.
Published: July 2016

The masses of 6 neutron stars have now been established through studies of binary X-ray and radio pulsars. All of the masses are found to be consistent with, but not necessarily constrained to, the range 1.2–1.6 M⊙. In this talk we discuss the methods and assumptions used in determining the masses of neutron stars in binary X-ray pulsar systems. For other recent reviews of this subject, the reader is referred to Bahcall (1978), Rappaport and Joss (1981), and references therein. Neutron-star parameters may also be obtained from studies of X-ray bursts that result from thermonuclear flashes near the surface of an accreting neutron star (see Joss 1980 and references therein), which we will not discuss here.
Evolution of Close Binaries and the Formation of Pulsars
Authors: van den Heuvel E.P.J.
Published: July 2016

The various ways in which compact objects (neutron stars and black holes) can be formed in interacting binary systems are outlined. It is argued that most of the remnants of massive stars (M1 ≳ 10 M⊙) will be runaway pulsars, with space velocities ≳ 100 km/s, i.e.:

(i)

semi-conservatively evolving massive close binaries (~ 1/3 of all massive stars) after the first SN explosion consist of a massive star and a neutron star; subsequently, after a stage of common-envelope evolution and spiral-in most of these systems are disrupted in the second SN, producing two runaway pulsars, one young and one old.

(ii)

highly non-conservatively evolving systems (with initial mass ratio q0 ≲ 0.5 and binary periods up to several decades; ≳ 1/3 of all massive stars) will spiral-in during the first phase of mass transfer and are disrupted in the first SN explosion, producing one young runaway pulsar, together with a runaway star of low or moderate mass.
Asymmetries in the Galactic Distribution of Pulsars
Authors: Harding Alice K.
Published: July 2016

The distribution of pulsars in galactocentric radius and z distance has been determined for opposite halves of the Galaxy, using data on 328 pulsars from three surveys. The distributions in galactocentric radius are found to be significantly different at positive and negative longitudes, although both show strong peaks between 5 and 6 kpc. There is also some indication that pulsars are located preferentially along spiral arms. Distributions in the z component of dispersion measure above and below the galactic plane also show asymmetry, with higher dispersion occurring at negative z. This may imply the existence of a narrow (~ 100 pc), high electron density layer below the plane of the Sun in the inner galaxy.
15. Cooling of White Dwarfs
Authors: van Horn H. M.
Published: July 2016

A knowledge of the precise relationship between the age and luminosity of a white dwarf can in principle be used to determine the compositions of the white dwarfs in galactic clusters. To this end the assumptions in Mestel's theory of white dwarf cooling are critically reviewed, and the results of recent work aimed at relaxing these restrictions are briefly summarized. It is concluded that on the basis of current knowledge an accuracy of the order of 10 or 20% in the age-luminosity relation should be attainable.
17. On the Origin of White Dwarfs
Authors: Paczyński B.
Published: July 2016

Model evolutionary calculations have been made for population I stars (X = 0.7, Z = 0.03) with masses of 0.8, 1.5, 3, 5, 7, 10, and 15 M⊙ (Paczyński, 1970). Neutrino losses were taken into account. All the models were evolved up to the red supergiant phase with the hydrogen and helium burning shell sources. In this phase of evolution the hydrogen rich envelopes of 0.8, 1.5, and 3 M⊙ stars became dynamically unstable due to the large depth of the hydrogen and helium ionization zones. It was assumed that almost entire envelopes were lost as a result of that instability. The degenerate carbon-oxygen cores of 0.6, 0.8, and 1.2 M⊙ were left with the hydrogen rich envelopes of a small mass. Almost all the hydrogen that was left was subsequently burnt in the shell source. Finally, the hydrogen and helium burning shell sources disappeared as the nuclear fuel was exhausted. The models were cooling down to the white dwarf phase and they had a small amount of hydrogen left close to their surfaces. It is estimated that population I stars with masses up to 3.5 M⊙ may produce white dwarfs with masses up to 1.37 M⊙. The hydrogen rich envelopes that were lost as a result of dynamical instability could form planetary nebulae with masses up to 2 M⊙. Further details are published in the paper referred to above.
New Determination of the Polar Motion from 1890 to 1969
Authors: Fedorov E. P. , Rorsun A. A. , Major S. P. , Panchenko N. T. , Tarady V. K. , Yatskiv Ya. A.
Published: July 2016

To obtain the coordinates of the Earth's pole almost all series of systematic latitude observations that continued for more than two years have been utilized. They are listed in Table I which comprises 92 series of observation at 72 observatories.

Computation was made by the following stages. As initial data we used normal values of latitude φ1, φ2, ……. φn, i.e. the means of instantaneous latitudes over successive intervals of time. These values were smoothed using Whittaker's numerical method which is capable of giving the most probable curve of latitude variation. The smoothed values φ′ satisfy the following condition
where
hi is a measure of precision, λ2 an arbitrary number by means of which the degree of smoothing is set, and Δ3 designates the third difference of φ′. Whittaker's method was applied in different modifications according to whether or not the normal values of φ′i had an equal weight and were given at equidistant moments of time.

For the origin of the system of coordinates we adopted the mean pole of the epoch of observation. Because of this the data given in Table II represent only the periodic part of the polar motion in the region of frequency from 0.77 to 2 cycles per year. In this connection the sequence of φ′ was subjected to filtration in order to eliminate variation of the mean latitude.

Coordinates of the pole were computed in two approximations. First, it was assumed that all the series are of the same accuracy and so they were taken with an equal weight.

The polar coordinates obtained on this assumption are denoted by x1, y1 and shown in the second and third columns of Table II. The divergences of the smoothed values φ′i from the latitudes computed with x1, y1 were denoted by zκi where the index κ designates the number of a series. Then for the second approximation each series of observation was taken with the weight inversely proportional to the mean value of for this series. The polar coordinates obtained in the second approximation are denoted by x2, y2 and given in the last two columns of Table II.

The full paper with the tables will be published by the Ukrainian Academy of Sciences as a separate book.
The Variation of Latitude
Authors: Jeffreys Harold
Published: July 2016

The 14-monthly variation of the Earth's axis is a free oscillation, and like others it is damped, and must be maintained by some irregular disturbance. In addition there are complications from the annual variation and observational error. The method adopted is first to analyse the data from 1899 to 1967 over 7-yr intervals, to eliminate the free period as well as possible and leave a mean value of the annual terms. The mean displacements fluctuated considerably. With a unit 0·001″ l(=x) ranged from – 15 to + 53, m(= – y) from the start to 1947 from – 41 to + 3, in both cases quite irregularly, but m reached – 164 in 1955–61 and has reached – 225 in 1962–8. The apparent standard errors are mostly about 6. This behaviour is inconsistent with any hypothesis of a uniform rate of drift in either the pole or the observatories. A smooth formula for interpolating the means was adopted; this and the mean annual terms were subtracted, and the remainder was analysed for harmonic terms of 14-month period. Drift of phase gave a correction to this trial period. A model on Yule's lines was used to estimate the parameters in a disturbed system. The remaining observational error over 14-month intervals turned out to be very small. The final period was 433·15 ± 2·23 mean solar days. The damping factor e–k in 14 months gave k = 0·05 ± 0·034, suggesting a time of relaxation between 14 and 73 yr, with a most probable value of 23 yr.
Non-Periodic Latitude Variations and the Secular Motion of the Earth's Pole
Authors: Fedorov E. P. , Korsun A. A. , Mironov N. T.
Published: July 2016

The phenomenon known as the secular polar motion is, in essence, a relative displacement of the mean pole of the epoch of observation and the Conventional International Origin (CIO). The latter is attached to the zeniths of the five international latitude stations. If the zeniths were fixed relative to one another, or, in the terminology of A. Danjon, formed an invariable constellation, then the CIO could be considered as fixed with respect to such a constellation. But this is not the case: displacements of zeniths with respect to one another do occur. The question is how large they are.
Secular and Long-Term Variations of the Polar Motion
Authors: Proverbio E. , Carta F. , Mazzoleni F.
Published: July 2016

An analysis on the secular motion of the pole has been carried out utilising the latitude observations of the ILS stations reduced to the ØII(i) system (Proverbio et al., 1969).

The existence of long periodic terms in the polar motion as found out by Markowitz (1960) was confirmed.

The secular displacement of the polar motion calculated abstracting from long period terms results 0″.00294 for year along the meridian 65°.6 W.

A probable drift of continental blocks with average Northward rate of 1–2 cm/year for Eurasia and 1 cm/year for North America has been suggested. The possible drift emphasized for Japan is on the contrary of 1 cm/year southwards.
Comparison of the Coordinates of the Pole as Obtained by Classical Astrometry (IPMS, BIH) and as Obtained by Doppler Measurements on Artificial Satellites (Dahlgren Polar Monitoring Service)
Authors: Feissel M. , Guinot B. , Taton N.
Published: July 2016

Before combining the coordinates of the pole obtained by the Dahlgren Polar Monitoring Service (DPMS) with those of the Bureau International de l'Heure (BIH) we investigated the systematic differences between the two series and their relative weights.
The ATS-F/NIMBUS-E Tracking Experiment
Authors: von Bun F. O.
Published: July 2016

In this paper the objective of the ATS-F/NIMBUS-E Tracking Experiment, the first of such kind, is presented. Specifically, this experiment has a two-fold purpose: First, to gain experience in the practical use of satellite-to-satellite range and range rate data for very accurate orbit determination (this was its original intent); and second, to evaluate the real usefulness of such a technique for geodetic studies despite the fact that the 1000 km NIMBUS orbit is not ideally suited for such a purpose.

The accuracies of the tracking systems of the satellite-to-satellite and satellite-to-ground link (ATS-F to the Rosman, N.C. ground station) will be ~ 0.035 cm/s in range rate and ~ 1 m in range – utilizing a 10 s integration time. With these values one obtains, based upon performed error analyses, orbit height errors in the order of 0.1 to 0.3 m for the near earth orbiting NIMBUS spacecraft. This experiment will therefore hopefully prove to be a significant first step for future Earth applications spacecraft carrying altimeters systems for measuring ocean height variations.

In addition, laser corner reflectors placed on board the ATS-F will make a total independent position determination of this spacecraft to approximately 15 m to 30 m possible, assuming that the location errors of four laser tracking stations used to determine the orbit are about 3 m or 5 m in each component respectively, with laser ranging system noise errors of 1.2 m and bias errors of 0.15 m. A small position error of the ATS-F, the ‘orbiting tracking station’ is essential in order to make full usage of the small satellite-to-satellite tracking errors mentioned.

For purpose of geodetic studies, one of the final goals, range rate variations of 0.1 cm/s or less corresponding to surface gravity anomaly of 20 mgal or less (over a half-width of 100 km on the Earth surface), will have to be measured during a time interval of approximately, say, 30–60 s. These values are within the range of the planned tracking systems accuracies for ATS-F and NIMBUS-E.
Polar Motion from the Tracking of Close Earth Satellites
Authors: Lambeck Kurt
Published: July 2016

The methods of using close earth satellites for determining the motion of the Earth's axis of rotation are discussed. Particular emphasis is given to the possibility of using laser range observations. Typical error sources in orbit computations are discussed and their influence on the resulting pole positions estimated. Within a few years pole coordinates with an accuracy of about 20 cm and with a resolution of 1 day or even 12 hr can be routinely expected.
Pole Position Studied with Artificial Earth Satellites
Authors: Gaposchkin E. M.
Published: July 2016

Long-arc orbit computation of highest accuracy can provide pole positions. Optical Baker-Nunn and laser range observations of several satellites are combined. The accuracy of the pole position is comparable to that of the mean satellite-tracking station coordinates (±5 m) when sufficient tracking data are available. Exploitation of the technique requires more accurate tracking data.
On the Determination of Anomalous Refraction out of Astrometrical Measurements in the Zenith Zone
Authors: Teleki G. , Ševarlić B.
Published: July 2016

The method is given for the analysis of the anomalous refraction in the zenith zone. Connected with this the observations of the same zenith stars in the meridian and the prime vertical are used. The moment of passage through the eastern and western part of the prime vertical is registered, while the difference of zenith distances in the meridian passage is measured – always in two instrument position.

The method practically eliminates coordinate errors influences of observed stars. For the succesful employment of this method, we must use the high quality instruments and, especially, correct apparatuses for the carreful determination of the inclinations of instrumental parts.