bluuebunny/crossref_metadata_2025 huggingface dataset:
Sunspot changes following proton flares
Authors: Sawyer Constance
Published: July 2016

Although the area of some sunspot groups declines suddenly after a flare that produces energetic protons, other groups show a delayed or gradual decline, or continue to grow for several days after the flare. The mean area of sunspot groups that produced flares with polar-cap absorption declines gradually and continuously, beginning within a day after the flare.
Homology of solar radio events
Authors: Fokker A. D.
Published: July 2016

Successive flares within the same centre of activity sometimes produce radio events that are remarkably similar. The occurrence of such homologous radio events is commonly restricted to periods of less than 48 hours.

Typical for certain centres of activity is their tendency to give rise to impulsive microwave bursts. Such bursts may occur repeatedly during a period of more than a week. The distributions of the lengths of periods during which series of homologous bursts and of impulsive microwave bursts occur are compared.
Satellite observations of solar radio bursts
Authors: Stone R. G. , Malitson H. H. , Alexander J. K. , Somerlock C. R.
Published: July 2016

The second Advanced Technology Satellite (ATS-II) carries a radio-astronomy experiment designed to perform radio-noise measurements in the range 0·5 to 3·0 MHz from above the terrestrial ionosphere. The spacecraft was launched into an 11000-km apogee, 180-km perigee orbit on April 6, 1967, and since there was considerable solar activity in the ensuing months it is possible to present a preliminary description of the kind of solar observations this experiment will provide.
Comparison of 8-mm solar radio features with local magnetic fields and chromospheric features
Authors: Efanov V. , Moiseev I. , Severny A.
Published: July 2016

The new big 22-m radio-telescope of Crimean Observatory shown on Figure 1 appeared to be of very good quality: for radio emission at λ = 8 mm the antenna beam is 1′.6, the efficiency ≅0·4, and the error of automatic pointing (guiding) does not exceed ±20″. A Dicke type radiometer was used as receiver possessing a sensitivity ≃2°K at the time constant τ = 1 sec, and pass-band ~30 MHz. The error in the contrast determination does not exceed ±0·5% of the level nearly corresponding to that of the quiet Sun. The scanning of the solar image is made in right ascension with velocity 0·5 sec in sec of time, the distance between successive scans in δ being 1′.5. An example of a single scan is shown in Figure 2, where the scan through Jupiter (for the determination of antenna beam) is also presented (for description see Moiseev, 1968).
The Kitt Peak Magnetograph. IV: 40-Channel Probe and the Detection of Weak Photospheric Fields
Authors: Livingston W. , Harvey J.
Published: July 2016

The 40-channel magnetograph is described. Special attention is given to details of the fiber-optic probe which dissects the Fraunhofer line image and provides for a choice of spectral and spatial resolution. Examples of magnetograms taken with the instrument are shown. Maps of quiet areas, made with long integration times to achieve a noise of 0.4 G, yet with 5 arc-sec resolution, indicate the presence everywhere of a minimum background field of average strength 2–3 G.
Sacramento Peak Magnetograph
Authors: Dunn Richard B.
Published: July 2016

The Sac Peak magnetograph (DZA) has been modified from Evans' original scheme so that it measures the displacement of the right and left hand circularly polarized lines separately. The computer reduction calculates the Zeeman and radial velocity signals. A grating servo system has been added to correct for slow temperature drifts in the spectrograph. A paper-tape reader controls the raster scan and the formatting of data on to magnetic tape.
A New Completely Digitized Filter Magnetograph
Authors: Brueckner G. E.
Published: July 2016

The optics and electronics of a new filter magnetograph will be described. The instrument uses a Zeiss 0.13 Å birefringent filter to isolate magnetic sensitive lines. All four Stokes parameters can be measured. A Westinghouse SEC vidicon WX 30 654 serves as the detector. The data are completely digitized and transmitted in real time into a Univac 1108 computer.
Spectra-Spectroheliograph Observations
Authors: Title Alan M. , Andelin John P.
Published: July 2016

This paper describes a photographic technique for recording solar spectra. The technique, which we call spectra-spectroheliography, requires the same amount of observing time as conventional spectroheliography but yields much more information. Data reduction techniques have been developed to use this information for the construction of spectroheliograms and other contour maps. Parameters investigated by this method include the vector magnetic field, line-of-sight velocity, continuum intensity, and line strength. Results indicate (1) good correlation between bright regions in spectroheliograms and small vertical magnetic fields; (2) poorer correlation between larger magnetic fields and bright regions; (3) a feature in the continuum resembling a pore but having no vertical magnetic field; and (4) a gradient in the vertical magnetic field of 12 kG/arc s.
The Time Dependence of Magnetic, Velocity, and Intensity Fields in the Solar Atmosphere
Authors: Sheeley Neil R.
Published: July 2016

Spectroheliogram movies of magnetic, velocity, and intensity fields have been obtained in a wide variety of spectral lines. The time resolution was typically 10–30 s. Some of the lines used were: CN λ 3883; CaI λ 6103; FeI λ 4071; FeI λ 5434; FeII λ 4924; CaII λ 3934; CaII λ 8542.
Hα Structures and Small-Scale Magnetic Field Configurations
Authors: Smith Sara F.
Published: July 2016

Magnetic field observations made utilizing a 1/7 Å birefringent filter for the FeI line at 5324 Å resolve magnetic field features comparable in scale to the Hα fine structure. Without exception, low lying filaments in the center of the disk coincide with boundaries of polarity change in the line of sight component of the magnetic field. Small filaments can be identified on a scale comparable to the Hα fibril structures. The arch filament systems are associated with areas of mixed polarity. ‘Satellite spots’ may sometimes be identified as small localized enhancements of magnetic field of both polarities around the perimeter of a sunspot.
Magnetic Field Spectroheliograms from the San Fernando Observatory
Authors: Vrabec Dale
Published: July 2016

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.
Five-Minute Oscillations in the Solar Magnetic Field
Authors: Tanenbaum Andrew S. , Wilcox John M. , Howard Robert
Published: July 2016

Evidence for the existence of 5 min oscillations in the photospheric and low chromospheric magnetic fields is presented, their properties discussed, and a possible production mechanism suggested.
Sunspot Magnetic Fields and High Energy Electrons in Flares
Authors: Takakura Tatsuo
Published: July 2016

A balloon observation of an impulsive hard X-ray burst on September 27, 1969 showed the size of the source to be one arc minute or less. It was remarkably smaller than the associated Hα flare with a size of 3 arc min.

The efficient acceleration of electrons and the trigger of the flares are suggested to be attributed to a large scale electric potential field caused by a gas motion near the photosphere. The primary cause of the onset of flares would be the acceleration of electrons. The electrons excite plasma waves which make the conductivity lower by several orders, so that the electromagnetic energy I2L stored before the onset of the flare would be suddenly converted into the heat due to the ohmic loss.
Magnetic Fields in the Lower Corona Associated with the Expanding Limb Burst On March 30th 1969 Inferred from the Microwave High-Resolution Observations
Authors: Énomé Shinzo , Tanaka Haruo
Published: July 2016

An expansion of the source of a great solar microwave burst was observed a little beyond the west limb on March 30, 1969. This expansion is interpreted in terms of diffusion of energetic electrons in a turbulent magnetic field in the flare region. The height of the source is estimated to have been 104 km.
An Attempt to Associate Observed Photospheric Motions with the Magnetic Field Structure and Flare Occurrence in an Active Region
Authors: Martres M. J. , Soru-Escaut I. , Rayrole J.
Published: July 2016

We have tried to find empirical evidence for the role of photospheric motions in the building up of the flare productive magnetic patterns in Active Regions.

The bright Hα faculae are associated with V∥ structures different from a classical Evershed flow and particularly ‘anomalous’ in the regions and periods of high flare occurrence. The flares observed occurred at ‘crossings’ of the lines V∥ = 0(V ≠ 0) and H∥ = 0 and at places where V∥ = 0 showed abrupt changes of direction. It is suggested that these anomalous V∥ structures are evidence of vortex motions.
Observation of Solar Flare Type Processes in the Laboratory
Authors: Bostick W. H. , Nardi V. , Grunberger L. , Prior W.
Published: July 2016

A filamentary magnetic structure is produced on the plasma current sheath of a coaxial accelerator operated with deuterium. Space and time analysis of X-ray, neutron and visible-light emission indicates that the magnetic energy of the filaments is transferred to the plasma during a process of decay of the filaments. X-ray photographs show very localized regions (diameter <0.5 mm) of strong emission. Some of these regions are also located where the plasma is not subject to a maximum of compression. Similar bright spots (Hβ) are observed by 5 ns image converter photographs. The detailed analytical description of the self-consistent fields is deduced. The localized regions of strong emission may well correspond with the explosive onset of an instability at a point on a filament (single filament decay) or at a point where two filaments with opposite fields coalesce with magnetic field annihilation. The similarities with solar flares are considered.
Anisotropy of Electric Conductivity and Dissipation of Magnetic Fields
Authors: Kopecký M. , Kopecký V.
Published: July 2016

The Joule dissipation of magnetic fields in the highest photosphere and spot layers can be considerably accelerated by the anisotropy of electric conductivity.
Large Scale Solar Magnetic Fields and Their Consequences
Authors: Newkirk Gordon
Published: July 2016

The general properties of large scale solar magnetic fields are reviewed. In order of size these are: (1) Active region, generally bipolar fields with a lifetime of about two solar rotations. These are characterized by fields of several hundred G and display differential rotation similar to that found for the photosphere. (2) UM regions which appear to be the remnants of active region fields dispersed by the action of supergranulation convection and distorted by differential rotation. These are characterized by fields of a few tens of gauss and have lifetimes of several solar rotations. (3) The polar fields which are built up over the solar cycle by the preferential migration of a given polarity towards the poles. The poloidal fields are of a few gauss in magnitude and reverse sign in about 22 yr. (4) The large scale sector fields. These appear closely related to the interplanetary sector structure, cover tens of degrees in longitude, and stretch across the equator with the same polarity. This pattern endures for periods of up to a year or more, is not distorted by differential rotation, and has a rotation period of about 27 days. The presence of these long enduring sector fields may be related to the phenomenon of active solar longitudes. The consequences of large scale fields are examined with particular emphasis on the effects displayed by the corona. Calculated magnetic field patterns in the corona are compared with the density structure of the corona with the conclusion that: (1) Small scale structures in the corona, such as rays, arches, and loops, reflect the shape of the field and appear as magnetic tubes of force preferentially filled with more coronal plasma than the background. (2) Coronal density enhancements appear over plages where the field strength and presumably the mechanical energy transport into the corona are higher than normal. (3) Coronal streamers form above the ‘neutral line’ between extended UM regions of opposite polarity. The role played by coronal magnetic fields in transient events is also discussed. Some examples are: (1) The location of Proton Flares in open, diverging configurations of the field. (2) The expulsion of ‘magnetic bottles’ into the interplanetary medium by solar flares. (3) The relation of Type IV radio bursts to the ambient field configuration. (4) The guiding of Type II burst exciters by the ambient magnetic field. (5) The magnetic connection between widely separated active regions which display correlated radio bursts.
The Polar Fields and Time Fluctuations of the General Magnetic Field of the Sun
Authors: Severny A. B.
Published: July 2016

In an attempt to summarize the present knowledge on the general magnetic field (gmf) of the Sun we pointed out the fine structure and the statistical nature of the gmf as one of its most important properties. The dipole-like behaviour of the mean polar field strengths is combined sometimes (since 1964) with a bias of the S-polarity flux for both poles. Highly uneven distribution of gmf with latitude and longitude, the disappearance of gmf at the South pole for months, and short period, almost synchronous at both poles, variations in the sign of gmf are pointed out. The fluctuations with time of the mean magnetic field of the Sun seen as a star (as well as mf at different latitudes) shows periodicity connected with the rotation of the Sun and very close agreement with the fluctuations of the interplanetary field (sector structure). The effect of faster rotation of N-polarities as compared with S-polarities as well as the bias of mean solar as well as interplanetary S-polarity fields are also pointed out. The possibility of short time-scale (hours) intrinsic changes in the local pattern of gmf is demonstrated.
Dynamo Theory of the Sun's General Magnetic Field on the Basis of a Mean-Field Magnetohydrodynamics
Authors: Krause F. , Rädler K.-H.
Published: July 2016

An outline of the mean-field magnetohydrodynamics suggested and developed by M. Steenbeck and the authors and its application to the dynamo theory of the solar cycle is presented. Four basic requirements are formulated which have to be satisfied by any dynamo model which claims to explain the solar cycle. The models investigated allow conclusions about the differential rotation. In this connection Leighton's work is criticized.
Dynamics of Superclusters as the Most Powerful Test for Theories of Galaxy Formation
Authors: Ozernoy L. M.
Published: July 2016

Analysis of Brown's (1964, 1968) data on the orientation of galaxies inside superclusters confirms his conclusion that the directions of the major axes of the galaxies are significantly correlated. For a number of superclusters, the minor axes are found to be oriented along the direction of the flattening of the supercluster as a whole. By analogy with the Local Supercluster where the same phenomenon is associated presumably with the rotation established by de Vaucouleurs (1959), one may conclude that, in general, superclusters rotate. It is shown that rotation on scales as large as these cannot be explained by tidal or by any local effects, and must have a primeval nature analogous to the 3 K microwave background. Rotation on such scales contradicts the standard idea of galaxy formation from density fluctuations but favours the concept of primeval whirls which gave rise to pregalactic density inhomogeneities.
Recent Westerbork Observations of Head-Tail Galaxies
Authors: Miley G. K. , Van Der Laan H. , Wellington K. J.
Published: July 2016

Some recent observations of head-tail galaxies are presented. The properties of these objects are reviewed and are shown to be consistent with the radio trail hypothesis.
Interpretation of Observations of Spiral Structure in Terms of the Density Wave Theory
Authors: Lindblad Per Olof
Published: July 2016

A review is given of recent theoretical and observational work on the density wave theory of spiral structure. Emphasis is put on the kinematic picture, and the question whether modern observations reveal the existence of density waves is discussed.
Status of Molecular Opacities of Interest in the Modeling of a Proto-Solar Nebula
Authors: Huebner W. F. , Fullerton L. W.
Published: July 2016

The report centers on general procedures applicable to the calculation of constitutive properties (equation of state and opacity) of media that serve as models for the solar nebula during planet formation and for the atmospheres of some planets. Specifically considered are the equilibrium compositions of a mixture of atoms, molecules, and their ionic species in the gaseous phase, condensation into grains with refractory cores and mantles of volatile compounds, and the ‘optical’ properties of the grain-gas medium. A summary of available and still needed basic (input) data and some currently available results are presented.
Modern Research in High Resolution Infrared Spectroscopy and its Importance to Planetary Physics
Authors: Rao K. Narahari
Published: July 2016

The scope of research in the field of high resolution infrared spectroscopy has expanded in numerous directions in recent years. Investigations of high resolution molecular spectra performed under controlled conditions in the laboratory are of significance to planetary studies because of the high resolution which one can achieve at the present time in the spectra of planets. In making use of laboratory data it is important to develop a proper perspective; due to technological advances the quality of experimental results has improved continuously during the past two decades, and, therefore, one has to exercise proper judgement when combining information from different laboratories. Somewhat detailed discussions are presented for the spectra of CO and CO2 to illustrate what modern measurements are capable of accomplishing. In the case of CO2, the extensive measurements of Courtoy and Herzberg done in the early 50's are not summarized in this paper because they are all consolidated in three previous publications. On the other hand, more recent measurements on CO2 are scattered in several publications and, therefore, an attempt has been made to collect them together in this article. This is not a comprehensive review paper but it is intended to provide only a glimpse into the expanding frontiers of research in high resolution infrared spectroscopy.
First Results of the Soviet-Polish Space Experiment ‘Intercosmos-Kopernik 500’
Authors: Hanasz J. , Aksenov V. I. , Komrakov G. P.
Published: July 2016

The report contains a short description of the first Soviet-Polish space experiment, which has been accomplished aboard the ‘Intercosmos-Kopernik 500’ satellite, launched to commemorate the 500 anniversary of Copernicus birth. The purpose of the experiment is to observe sporadic radio emissions generated in the coronal and interplanetary medium at hectometric wave-length range and to measure parameters of the ionospheric plasma by means of the low- and high-frequency impedance probes. The idea of the experiments is presented together with the brief description of the measuring equipment and data recorded. First results of the space observations are shown. The correlation between electron density of the ambient plasma, ion-sheath capacitance of the aerial, and the upper hybrid frequency can be seen.
Ground-Based Observations of Mars and Venus Water Vapor during 1972 and 1973
Authors: Barker E. S.
Published: July 2016

The Venus water vapor line at 8197.71 Å has been monitored at several positions on the disk of Venus and at phase angles between 22° and 91°. Variations in the abundance have been found with both position and time. The total two-way transmission has varied from less than 5 to 77 μ of water vapor. Comparisons will be made between the water vapor abundances, presence of UV features, and the CO2 abundances determined from near simultaneous observations of CO2 bands at the same positions on the disk of Venus.

The amount of Martian atmospheric water vapor has been monitored during the past two years at McDonald Observatory using the échelle coudé scanner of the 272 cm reflector. Two periods of the Martian year have been monitored. The first period was during and after the great 1971 dust storm (L8 = 280° to 20° or summer in the southern hemisphere). The results obtained will be compared to the Mariner 9 IRIS and Mars 3 observations made during the same period.

During the second period (L8 = 124° to 266°) observations were made to follow the seasonal latitudinal and diurnal changes in the water vapor abundance in the Martian atmosphere. The water vapor abundance declines from a maximum of 20–35 μm at L8 = 125° to the 5–15 μm level at L8 = 180°. Then it remained relatively constant until L8 = 250° when the increase to 20–25 μm occurred in the southern latitudes. Studies of the latitudinal and diurnal water vapor distributions indicate the location of maximum and minimum abundances for this season are positively correlated with surface temperature variations.
New Infrared Spectra of the Jovian Planets: Study of Jupiter and Saturn in the 3v3 Methane Band by Fourier Transform Spectroscopy
Authors: De Bergh C. , Combes M. , Encrenaz Th. , Lecacheux J. , Vion M. , Maillard J. P.
Published: July 2016

High resolution spectra of Jupiter and Saturn were obtained with a Fourier Transform Michelson interferometer. A comparison of the observed spectra, after elimination of the solar and terrestrial contributions to absorption, with synthetic profiles for the reflecting layer model has permitted new determinations of the Lorentz half-width, the methane abundance, the rotational temperature and the pressure at the level of formation of the methane lines for both Jupiter and Saturn.
Jupiter's Microwave Spectrum: Implications for the Upper Atmosphere
Authors: Gulkis S. , Klein M. J. , Poynter R. L.
Published: July 2016

It is shown through the use of weighting functions that Jupiter's brightness temperature in the wavelength range 0.8–1.5 cm contains information on the thermal structure and abundance of ammonia in and above the tropopause in Jupiter's atmosphere. We present new data of Jupiter's brightness temperature in this wavelength range, and compare the results with theoretical spectra. The pressure in the Jovian atmosphere is estimated from these data to be 0.48 atm at 130K.
Results of the Beta Scorpii Occultation by Jupiter on May 13, 1971
Authors: Vapillon L.
Published: July 2016

The aim of this paper is to present results of temperature and density profiles of the upper atmosphere of Jupiter as deduced from observation of the occultation of β Sco on May 13, 1971.

The occultation light curve of β Sco is shown. The analysis of data is based on the Abelian integral inversion. Jovian refractivity profiles and typical temperature and density profiles are also shown.

The extent of the atmospheric zone where results are significant is discussed.

It is shown that no valid information about the thermosphere has been obtained.
La rotation, la cartographie et la photometrie des satellites de Jupiter
Authors: Dollfus Audouin , Murray John B.
Published: July 2016

The four Galilean satellites of Jupiter have been observed frequently during the past 20 years with the high resolution telescopes of Pic-du-Midi. Reliable features are seen and photographed at their surface. They have been mapped on planispheres. Their identification proves that the rotation period is synchronous with the revolution for each satellite, with an axis not significantly departing from the normal to the orbital plane. The transits of satellites in front of the limb-darkened Jupiter disk provide a technique for accurate contrast and albedo determinations of the features observed. For Callisto, the albedos at 5° phase angle range from 0.19 to 0.09 with a contrast 0.5, indicating a lunar type surface, despite the low density involving a different internal structure. For Europa, the albedos are very high, between 0.73 and 0.52, with low contrasts of 0.3, readily explainable by a snow or frost deposit, the spectroscopic evidence indicating water. For Ganymedes, the very high contrasts reach 0.7, and albedos span from 0.50 to 0.15; patches of snow on Callisto-type terrains are suggested. Io has very high albedos of 0.83 for the equatorial zone to 0.46 for the two darkened poles; the yellow color and absence of H2O bands in the spectrum indicate a special surface composition.
Some remarks on multiple galaxies
Authors: Ambartsumian V. A.
Published: July 2016

Within each cluster of galaxies, the ratio of the number of multiple galaxies to the number of single galaxies is much higher than the ratio calculated under the assumption of statistical equilibrium. This fact leads, without any supplementary assumption, to the conclusion that the components of any given multiple galaxy have a common origin. In this respect the multiple galaxies are similar to the multiple stars of our stellar system.
The space distribution of middle- and late-type super-giants in the region of the galactic system near the sun
Authors: Bidelman William P.
Published: July 2016

This paper is concerned with the space distribution in our own Galaxy of the most luminous stars of spectral types A5 and later which have been classified on the basis of low-dispersion slit spectrograms. Seventy stars of luminosity classes Ia and Iab on the Morgan–Keenan system are considered, of which the majority have been previously noted as of high luminosity at the Yerkes, Harvard, Mount Wilson, and Warner and Swasey Observatories. The Cepheid variables have not been considered.
Spiral structure and the rotation of galaxies
Authors: Vorontsov-Velyaminov B. A.
Published: July 2016

There is no general agreement about either the location or the direction of winding of the spiral arms in our Galaxy. Since the measurement of the distances of gaseous nebulae is based on their association with hot stars, the locations of arms based on these objects are not independent.
The Observational Evidence for an Intercloud Medium
Authors: Radhakrishnan V.
Published: July 2016

The 21-cm evidence for an intercloud medium is reviewed. The observations include the sky distribution and velocity structure of 21-cm emission profiles, self-absorption features in emission profiles, and absorption profiles in the directions of discrete sources. It is concluded that the intercloud medium in the solar neighbourhood has a temperature between 103 and 104 K, a column density of ~1.4 × 1020 cosec |b| atoms cm-2, and a brightness temperature of ~4.4 cosec |b| K wherever the line of sight does not intersect optically thick cold concentrations.
Extended Oh Emission at 1720 Mhz
Authors: Goss W. M. , Johansson L. E. B. , Elldér J. , Höglund B. , Nguyen-Q-Rieu  , Winnberg A.
Published: July 2016

Low-velocity OH emission lines at 1720 MHz have been investigated in the direction of W41, W43, W51, and 3C 353. The emission lines in the directions of W43 and W51 show no detectable circular polarization and are about 27 and 32 arcmin in size, respectively. The inferred peak brightness temperatures are 0.6 K for W43 and 2.0 K for W51. This emission may be similar to the nonthermal 1720-MHz emission in dust clouds.
Absorption Characteristics of Dust in the Lyman Continuum Region
Authors: Mezger P. G. , Churchwell E. B. , Smith L. F.
Published: July 2016

The absorption cross-sections of dust grains in the Lyman continuum region are calculated based on integrated spectra of OB star clusters and observed values of the IR excess radiation from H ii regions.
Spectrum of Galactic Background Radiation
Authors: Shakeshaft J. R.
Published: July 2016

New measurements of the galactic background radiation between 151 and 1407 MHz have been made by Sironi and by Webster. The radio spectrum shows a bend at ~ 315 MHz in Bridle's Region I and ~ 100 MHz in Region II, implying magnetic fields of 7.6 µG and 2.4 µG, respectively.
New Results on Supernova Remnants
Authors: Shklovskii I. S.
Published: July 2016

Estimates of the masses and energies of the supernova explosions that resulted in the Cygnus Loop and similar remnants are revised downward on the basis of recent soft X-ray observations.
Infrared and X-Ray Variability of Cyg X-3
Authors: Wynn-Williams C. G.
Published: July 2016

The 2.2 µm flux from the infrared counterpart of Cygnus X-3 has been found to vary in phase with the X-ray flux with a 4.8 h period. The infrared observations imply a radius ~ 1 R⊙ for the X-ray object and do not favor models involving a compact object such as a neutron star or a black hole.
21-cm Line Studies of the Galactic Center Region
Authors: Simonson S. Christian
Published: July 2016

Features of the 21-cm line radiation that have often been attributed to the galactic center or to activity there include, near the equator, the ‘3-kpc arm’, the ‘expanding arms’ at +70 and + 135 km s+1, and the ‘nuclear disk’, and, away from the equator, features observed by Cugnon, by Shane, by van der Kruit, and by Sanders, Wrixon, and Penzias, among others. Models of the features in the equatorial plane are discussed on the basis of the form of the Tb(l, V) contours that they generate. Both explosions in the nucleus and resonance with a spiral wave have been suggested as the cause of the 3-kpc arm and related features. Some of the models put limits on the mass distribution, particularly the amount of condensed mass at the center. Higher-latitude features have been less thoroughly modeled, but explosions in the nucleus and resonant orbits have also been suggested for their origins.
Kinematics of Molecules at the Galactic Centre
Authors: Robinson B. J.
Published: July 2016

Dense gas clouds containing OH, CO, NH3 and H2CO are found in the inner part of the H1 nuclear disk. The molecular spectral lines allow direct observations of the kinematics of the gas near the galactic centre. Strong absorption of the thermal continuum sources by OH and H2CO shows that much of the gas on the near side of the centre can be located in a massive ‘ring’ expanding at 130 km s-1 which may have originated close to the nucleus about 106yr ago. Observations of CO emission from beyond the centre show that the far side of the ‘ring’ is expanding at a lower velocity, less than 90 km s-1. Observations of CO and NH3 emission with positive velocities for l < 360° are needed to establish whether the ‘ring’ is a continuous structure.

OH and H2CO are also observed to be falling towards the centre. There is no agreement as to the location of this infalling matter.

The nuclear regions of the Galaxy are compared with those of NGC 253, particularly in regard to expansional velocities, IR and radio emission, and OH absorption.
The Galactic Centre
Authors: Oort J. H.
Published: July 2016

The phenomena displayed by the interstellar medium in the galactic centre are considered. The asymmetries shown by the features between 1 and 3 kpc from the centre together with the presence of material lying out of the galactic plane favour the expulsion hypothesis for their origin. The nuclear disk shows a perturbation which might have resulted from such expulsion. The dense molecular clouds in the disk may well be considered as the most direct evidence that matter is expelled from the nucleus and that this occurs at a high rate. The +50 km s-1 feature in the direction of Sgr A may be the most recently expelled body of molecular gas. New observations of the central radio source, Sgr A, have revealed details on a very small scale, and the infrared core also shows a complicated structure. Probably a number of individual concentrations of gas and dust are present. While the position of the actual nucleus seems now to have been defined to within a few arcseconds, no indication has yet been found concerning its nature nor concerning the mechanism that enables it to expel the vast expanding masses of gas observed in the central region.
Some Aspects of Galactic Structure Derived from the Berkeley Low Latitude Survey of Neutral Hydrogen
Authors: Weaver Harold
Published: July 2016

The principal problem in the study of spiral structure is to reduce the data to a small enough number of pictures or numbers that can be easily comprehended. A new map has been produced, based on circular rotation, but the high probability of large radial motions makes it likely than any picture of spiral structure derived on current theories will be in error. New computer pictures have made it possible to see the structure of the outer arm, which has many cloud-like structures lying above it on one side, some reaching heights of more than 1 kpc. Some very weak extended features in the outer regions are described, and examples of holes and jets are discussed.
The Radio Spectrum Across Three Tailed Radio Galaxies
Authors: Andernach H.
Published: July 2016

Multifrequency observations with large single dishes are the ideal tool to examine the variation of the shape of the radio spectrum across extended extragalactic radio sources. Three complex low luminosity sources with angular extent 20′ < θ < 30′ have been mapped with the 100-m telescope of the MPIfR at frequencies 2.7, 4.9 and 10.7 GHz (HPBW = 4!4, 2!6 and 1!2 resp.). To extend the frequency range we used published low frequency maps for the spectral comparison, too. Thus at least four maps with angular resolution ≦ 4!4 were available for each source. All maps were (if necessary) corrected for sidelobes, then cleaned from obvious background sources and finally smoothed to the same beam of 4!4 HPBW. To look for spectral curvature a spectrum of the form In S = a1 + a2 In ν + a3 (In ν)2 was fitted to the brightness data for each sampling point of the map. We chose two parameters to characterize the spectral shape. The first is the mean spectral index, , defined as the slope of the fit curve at the geometric mean of the lowest and highest observing frequency. As a measure of the spectral curvature we derived the change of spectral index, Δα, along the fit curve between the lowest and highest observing frequency, i.e. Δα positive for a concave (= flattening) spectrum and vice versa. In the following the results are briefly summarized (see Andernach, 1981, for details).
Time Dependent Energy Supply in Radio Sources and Morphology of Radio Lobes
Authors: Christiansen W. A. , Pacholczyk A. G. , Scott John S.
Published: July 2016

The fact that radio jets, which are often one-sided, are nevertheless associated with extended lobes of nearly equal luminosity indicates when analyzed in detail (1) that the energy supply by the nuclear engine to the lobes is strongly time-dependent. Time dependent ejection from the nucleus of a parent galaxy produces low density channels which are ploughed in the background medium by the passage of intermittently ejected radio emitting plasmons (2), (3), (4) and (5). An analysis of the dynamics of radio emitting plasmons in such channels leads to unique morphological features consistent with observations of both narrow jets (resulting from splashback or reflections from the channel ends) and conical lobes (resulting from slower hydrodynamic deceleration).
Extended Structure in High-Redshift Radio Sources
Authors: Duffett-Smith P. J. , Purvis A.
Published: July 2016

We have compared measurements of several hundred 3C and 4C radio sources at large redshifts to investigate how radio-source structure changes over a factor of 5–10 in luminosity. Our results show that for z ≳ 0.6:

(i)

most sources (both 3C and 4C) have hotspots about 3.5 kpc in size (Ho = 50 km s−1 Mpc−1, Ω = 1);

(ii)

lower-luminosity sources (bottom of 4C) have less-extended outer lobes.
Extended Emission Lines in Radio Galaxies
Authors: Fosbury R A E
Published: July 2016

In whatever physical state the gas is found, observations of the interstellar medium in elliptical galaxies are of considerable interest. This is particularly true in the case of radio galaxies where we believe that the gas is an indespensable part of the cause of nuclear activity and plays a role in the origin and the evolution of the radio galaxy phenomenon. In a few cases we are fortunate to find some of the gas to be ionized with a temperature of about 104 K where optical spectroscopy allows us to deduce something about the excitation/ionization mechanism, about its chemical composition and about its state of motion. Here I wish to summarize observations of three Southern radio galaxies which show optical emission lines from regions tens of kiloparsecs in extent.
Emission Lines: Sign of a New Energy Source?
Authors: De Young David S.
Published: July 2016

In addition to the occurrence of emission line regions coexistent with extended radio sources which have been discussed at this Symposium, this phenomenon has been observed earlier in 3C277.3 (Miley et al. 1981) and in Centaurus A (Graham and Price 1981). This gas has been detected only in the Fanaroff and Riley “Class I” radio sources. Data concerning this class of object suggest that outflow from the nucleus is proceeding at transonic or subsonic speeds and this correlation has led to the suggestion (De Young 1981) that the origin of the emission line gas arises from entrainment of the interstellar medium into the ejected material.
Optical Inverse Compton Emission in Extragalactic Radio Sources
Authors: Okoye S. E. , Obinabo O.
Published: July 2016

In this contribution the reported detection by Saslaw, Tyson and Crane (1978) of weak optical emission in the lobes of three 3C sources — 3C 265, 3C 285 and 3C 390.3 — is reappraised in the framework of three optical emission mechanisms — synchrotron (SYN), synchrotron inverse Compton (SIC) and blackbody inverse Compton (BIC). This effort has been motivated partly by the knowledge that the contribution to the synchrotron inverse Compton emission in a radio source component is likely to become significant for very compact and bright radio components (see e.g. Okoye 1972), and partly by the recent availability of high resolution radio frequency structural data on the sources in question. Another incentive arose from the demands of a separate investigation into high energy particles interactions in radio sources (reported by Okoye and Okeke in this volume) involving very high energy protons thus making it necessary to ascertain whether such highly energetic particles exist in radio source components.
Kiloparsec Scale Structure in High Luminosity Radio Sources Observed with MTRLI
Authors: Wilkinson Peter N.
Published: July 2016

The new Jodrell Bank Multi-Telescope-Radio-Link Interferometer system (MTRLI) began operating in January 1980 with four telescopes and with its full complement of six telescopes in December 19 80. The location of the telescopes and the baseline lengths (in km) thus obtained are shown in Fig. 1. However, before describing some of the exciting new results it has yielded on high luminosity radio sources it is important to outline the capabilities of the instrument since the maps are produced in a rather different way to those from conventional synthesis instruments.
A Suggested Classification and Explanation for Hotspots in Some Powerful Radio Sources
Authors: Kronberg P. P. , Jones T. W.
Published: July 2016

High resolution (1′→0′.1) maps of the outer complexes of some “well formed” powerful radio sources suggest that we can now distinguish two physically distinct types of outer hotspots. We denote them as type “A” and “B” and describe them as follows: Type A hotspots, illustrated in Figure 1, occur at the outer leading edge, and have a cusp-like, or otherwise elongated shape. This strongly suggests that their shape and energy density are determined by the ram-pressure interaction between the end of a beam or momentum flux “pipeline”, and the ambient i.g.m. Magnetic fields appear well-ordered along the cusp (Laing, 1981). The surface brightness of well-resolved Type A hotspots leads to a velocity of advance (Va) which is typically 103→104 (ρ−1ig-27)km/s (ignoring the ion energy).
Hot-Spots in Luminous Extragalactic Radio Sources
Authors: Laing R. A.
Published: July 2016

Compact hot-spots in luminous extragalactic radio sources are often double on the scale of a few kpc (Laing 1981a). Examples are shown in Figures 1–3; the maps were made with the A and B configurations of the VLA. The general features are as follows:

(a)

It is usually possible to recognize a compact, “active” subcomponent within a radio lobe. This has a size of <1 kpc and may only contain a small fraction of the total flux of the hot-spot. It need not be at the leading edge.

(b)

More diffuse regions are often grossly offset from the source axis (e.g. 3C 196). In some cases, there is apparent inversion symmetry about the optical identification.

(c)

The characteristic morphology of a diffuse subcomponent is best illustrated by the eastern hot-spot of 3C 20, which is limb-brightened, with a circumferential magnetic field. The bright edge is on the side furthest away from the compact subcomponent.

(d)

The polarization structure in the diffuse subcomponents, like that in most extended radio lobes, can be explained if the magnetic field has been sheared so as to be tangential to the surface, but is otherwise random (Laing 1980; 1981b).

(e)

The most obvious explanation for the multiple structure is that the compact subcomponents represent the points of impact on the surrounding gas of twin beams from the associated galactic nucleus; if these alter their direction, then diffuse remnants may be formed. This idea would be consistent with the inversion symmetry seen, for example, in 3C 196.

(f)

A problem with this model is posed by the detailed morphology of the diffuse subcomponents: why should the bright limb be opposite the compact subcomponent, rather than at the leading edge of the source? An alternative picture, in which the diffuse subcomponents are formed by material escaping from the active regions, should also be considered.
The Radio Jet of 3C273
Authors: Conway R. G.
Published: July 2016

Most radio sources are two-sided, like Cygnus A. A minority, however, are one-sided, and the first-known and brightest example is 3C273 (see Fig. 1), a high-luminosity QSO, showing ‘super-luminal’ proper motions in the core. The explanation of such one-sided sources may follow one of two lines (and it seems that both schools of thought are represented at the present meeting): on the one hand, the ejection of material from the central object may truly be one-sided, while on the other hand the ejection may be two-sided but at a relativistic speed, so that the receding half is hidden by Doppler beaming.
Westerbork Observations of Low Luminosity Radio Sources
Authors: Parma P.
Published: July 2016

The two radio galaxies 0326+39 and 1321+31 are both part of a complete sample of low luminosity radio galaxies which was obtained by identifying B2 radio sources with galaxies from the Zwicky Catalogue. Both sources have a very symmetrical double jet, like many other sources of the sample (Ekers et al. 1981a).
Particle Acceleration in Radio Sources with Internal Turbulence
Authors: Eilek J. A. , Henriksen R. N.
Published: July 2016

Many extended radio sources seem to need in situ regeneration of the relativistic electrons. MHD turbulence generated by surface instabilities has been suggested as the reacceleration mechanism. However, Eilek (1981) has shown that short wavelength MHD waves, which are the most effective particle accelerators, are strongly damped in radio sources. This results in the turbulent region being confined to a thin layer on the edge of the source, so that particles accelerated here must propagate into the radio source if this reacceleration mechanism is to account for the internal synchrotron luminosity. Most likely the particles diffuse across tangled field lines; using numerical modelling of the turbulence, Eilek showed that the particles propagate only a small distance (10 pc–1 kpc) in from the edge. This predicts that larger sources should appear limb brightened; but such limb brightening is rare. If short wavelength MHD waves are indeed the source of reacceleration, they must be generated internally.
Spectral Shapes of Compact Extragalactic Radio Sources
Authors: Spangler Steven R.
Published: July 2016

Possible mechanisms for producing the observed broad radio spectra of compact extragalactic radio sources are discussed. The explanations considered are: (a) superposition of the spectra of sub-components, (b) inhomogeneous synchrotron sources, and (c) synchrotron radiation from “non-standard” energetic electron spectra. These three models have been compared with results of spectral and VLBI observations. These comparisons indicate: (1) if the “superposition” hypothesis is correct, then the subcomponents themselves must be inhomogeneous synchrotron sources, (2) there is apparently no general inhomogeneous synchrotron source which characterizes compact extra-galactic sources, and (3) many compact sources have spectra which resemble synchrotron radiation from a relativistic Maxwellian electron spectrum, but the inferred electron energies and magnetic fields have a wide range of values. VLBI observations of a selected sample of sources generally favor a single component model, but cannot distinguish between models (b) and (c).
Depolarization of Extragalactic Radio Sources
Authors: Inoue M. , Tabara H.
Published: July 2016

In the last decade correlations of the depolarization parameter λd with several parameters, i.e., the radio luminosity L, redshift z, and source size D have been investigated by several authors, where λd is the wavelength at which the percentage polarization drops to its half maximum. Kronberg ET AL. (1972) first pointed out that λd decreases with increasing z, while Morris and Tabara (1973) showed that λd increases with L and suggested that the depolarization is due to the internal Faraday rotation within radio sources. Conway ET AL.(1974), on the other hand, suggested that the λd-(1+z) relation is primary. Recently, Cohen (1979) showed that the λd-z relation may be the remnant of the physically meaningful relation λd-L, though the former is statistically real.
The Optical Polarization of QSOs
Authors: Moore Richard L.
Published: July 2016

Recent optical polarization studies indicate that there are two distinct types of QSOs — “normal” QSOs with P ≲ 1%, and highly polarized QSOs (HPQs) with P > 3%. The HPQs are very similar to BL Lac objects, yet still share some properties of normal QSO's (e.g. strong emission lines). Our results generally support the relativistic beaming model for QSOs; however, certain key predictions of this model are not observed.