bluuebunny/crossref_metadata_2025 huggingface dataset:
Taurus – A Wide Field Imaging Fabry-Perot Spectrometer
Authors: Atherton P. D. , Taylor K.
Published: June 2019

TAURUS, an imaging Fabry-Perot system, was developed as a collaborative project by the Royal Greenwich Observatory and Imperial College London and is capable of obtaining seeing-limited velocity field information over a 9 arcminute field on a 4 m telescope. At the detector (the IPCS) the image of the source is modified by the fringe pattern of the capacitatively stabilized servo-controlled Fabry-Perot. As the Fabry-Perot is scanned, this fringe pattern tracks radially across the field and each pixel of the detector maps out a spectral line profile within the bandpass of the “blocking” interference filter. At each F-P spacing a picture (Typically 256 × 256 pixels) is recorded on computer disk. 100 pictures make up a complete scan, covering for example 1,200 km sec−1 free spectral range (this range in practice depends on the particular etalon). In this manner a 3 D data cube of the field is built up where (X, Y, Z) are typically (256 pixels, 256 pixels, 100 steps).
Molecular Clouds in the Galactic Nucleus
Authors: Cohen R. J. , Dent W. R. F.
Published: June 2019

The galactic nucleus contains the largest concentration of dense molecular clouds in the Galaxy. A new survey of the region has been carried out recently at Jodrell Bank in the 1667 and 1665 MHz lines of OH (Cohen 1981). The OH lines appear primarily in absorption against the galactic continuum background. The survey reveals many new clouds within the previously known nuclear concentration, and also a more extensive outer distribution of clouds extending to projected distances of ±1 kpc from the centre. The outer part of the distribution is tilted with respect to the galactic plane, reaching z-distances of −200 pc at positive longitudes and +200 pc at negative longitudes. The same tilt or warp has been seen in the high-velocity HI “nuclear disk”.
Gas at Large Radii
Authors: Sancisi R.
Published: June 2019

A considerable fraction of the neutral hydrogen in spiral galaxies is generally found at large radii and beyond the optical image. This outlying gas either forms an extension of the stellar disk and of the inner HI layer, or, is concentrated in a ring. It shows well ordered motion around the galaxy, although the plane of the orbits is generally inclined with respect to the inner disk. The study of this gas is important for at least three reasons: i) although it represents only a very small fraction of the total mass it can be used as a tracer of the kinematics to determine the total mass and the mass distribution of the system, ii) it contributes to the galactic cross-sections needed to explain QSO absorption lines, iii) its physical and chemical properties may throw some light on the formation of galactic disks and their evolution.
M82 - Tilt and Warp of its Principal Plane
Authors: Notni P. , Bronkalla W.
Published: June 2019

The main plane of a late type galaxy is best determined by its population I components : young stars, gas and dust. In the case of M82 the determination of its principal plane is complicated by its very irregular appearance and the presence of scattered light. We have used three-colour UBV-photometry of this galaxy to determine the stellar population, using the extinction- free parameter Q = (U-B) − 0.65(B-V), and the extinction AB = 4 ((B-V) − (B-V)oo; (B-V)oo being the intrinsic colour of the population, taken, e.g. from population synthesis calculations. Corrections for scattered light were made using the degree of polarization as well as the excess ultraviolet light (see Notni and Bronkalla, 1983; Notni et al., 1981 for details).
Groups of Galaxies and the Missing Mass Problem
Authors: Appleton P. N. , Davies R. D.
Published: June 2019

The existence of a massive dark component to the matter distribution of galaxies (the ‘missing mass’) is inferred from the now overwhelming evidence for flat rotation curves in galaxies. However observational data on the linear extent of such a dark component and its total mass contribution is usually restricted by the limited radial distance to which rotation curves of individual galaxies can be measured (typically < 100 kpc). The magnitude of the mass contained within a larger radius around a galaxy can in principal be inferred by studying the kinematics of small groups of galaxies and making assumptions about their dynamical stability (see Faber and Gallagher, 1979, for review). However, one of the major difficulties in such studies is the question of group membership. The inclusion of disrelated foreground or background galaxies into a dynamical calculation of mass obtained for example via the Virial Theorem, can lead to spurious results. The effects of varying membership criteria on the dynamical properties of groups is well illustrated by the work of Huchra and Geller (1982).
Quasi-Stationary Spiral Structure in Galaxies
Authors: Lin C. C.
Published: June 2019

The hypothesis of quasi-stationary spiral structure in galaxies was explicitly formulated in the early 1960's in papers of Bertil Lindblad and of Lin and Shu. It asserts that the grand design observed in spiral galaxies may be described by the superposition (and interaction) of a small number of spiral modes. (See Lin and Bertin, 1981 for a fairly extensive review of the theory.) We wish to re-affirm the correctness of this hypothesis in the present contribution. Early numerical experiments by P.O. Lindblad and by Miller, Prendergast and Quirk demonstrated that spiral structures occur naturally in certain models of stellar systems, although it was difficult to control the morphological types of galaxies simulated. We are now able to simulate galaxies of various morphological types in a controllable manner. Numerical fluid-dynamical codes developed by Pannatoni (1979) and improved by Haass (1982) have been used to calculate normal modes of various spiral types (Haass, Bertin, and Lin 1982) in the morphological classification of Hubble, Sandage, and de Vaucoulers. Furthermore, the processes that govern the maintenance and the excitation of these modes simulating both normal spirals and barred spirals, can be understood by using analytical theories which are closely related to the local dispersion relationship, as Bertin will describe in his paper at this conference. Understanding these mechanisms enables us to choose the parameters and the distribution functions in our models more properly in order to exhibit the desired characteristics in the computed modes. Such an approach also has important implications on observational studies. Much of the previous work on comparison between theory and observations in normal spirals used only the short trailing waves. A mode must consist of at least two waves propagating in opposite directions. It has been found that, at least in normal spiral modes, the long wave branch provides essentially only a modulation of the amplitude along the short wave branch, which accurately describes the phase. Previous calculations are thereby justified. [These points were not adequately covered in the previous paper reviewing theory of spiral modes.]
Model Calculations on the Large Scale Distribution of Bubbles in Galaxies
Authors: Feitzinger J. V. , Seiden P. E.
Published: June 2019

One main characteristic of the ionized and neutral component of the interstellar medium in galaxies is the appearance of shells and bubbles in all sizes up to 1 kpc diameter (Hodge, 1974; Heiles, 1979). Between different galaxy types differences in size and radial distribution of these bubbles are observed as a function of galaxy type. The stochastic selfpropagating star formation model is able to simulate such distributions on a global galactic scale.
Hi-Shells in M31
Authors: Brinks E. , Bajaja E.
Published: June 2019

Close inspection of the channel maps which make up the high resolution M31 HI-data set (Brinks, this volume) resulted in finding numerous shell structures and bubble-like regions. To avoid any bias in the interpretation we shall call holes, in the course of this contribution, all those structures where we find a deficiency of neutral gas. Some of the holes can be identified directly in a total surface density map of M31, but due to blending of the various velocity components, e.g. the warp, holes tend to loose contrast. Therefore the best way to search for the holes is by inspection of the full resolution channel maps (δα x δδ x δV = 24″ x 36″ x 8.2 km s−1).
Spectral Analysis of the Luminosity Distribution of Seven Galaxies in the Virgo Cluster
Authors: Iye Masanori
Published: June 2019

An objective method involving a Fourier analysis is applied to seven galaxies for measuring the strength of spiral and bar components.
Large Scale Magnetohydrodynamical Considerations in Spiral Galaxies
Authors: Battaner E. , Sánchez-Saavedra M. L.
Published: June 2019

A magnetohydrodynamical result is deduced, which could contribute to our understanding of spiral and ring structures in galaxies. The usual expressions for the continuity, momentum and induction equations are adopted for the gas of a galaxy, and the following simplifying hypotesis are made : a) Steady state conditions, b) Axisymmetry, c) A velocity field given by (π=0, θ=θ(r), Z=0) for the interstellar gas (where π,θ and Z are the radial, azimuthal and vertical to the galactic plane components and r is the distance from the galactic center). Then, the direction of magnetic field must be azimuthal and the plasma distribution is compatible with ring structures.
Magnetic Fields and Spiral Structure
Authors: Beck R.
Published: June 2019

Interstellar magnetic fields are known to be a constraint for star formation, but their influence on the formation of spiral structures and the evolution of galaxies is generally neglected. Structure, strength and degree of uniformity of interstellar magnetic fields can be determined by measuring the linearly polarised radio continuum emission at several frequencies (e.g. Beck, 1982). Results for 7 galaxies observed until now with the Effelsberg and Westerbork radio telescopes are given in the table. The Milky Way is also included for comparison.
Spiral Structure: Density Waves or Material Arms?
Authors: Clube S. V. M.
Published: June 2019

Recent studies (Frenk and White 1980, 1982) of the (x, y, z) and (Π, θ) distributions of the Galactic globular cluster population have given Ro = 6.8±0.8 kpc and Π = 51±26 kms−1 for the inner halo. The observations leading to these solutions are well illustrated by the ρ vs. x plot in figure 1 (Clube and Watson (CW), 1979) for the globulars with the best determined data within |l|, |b| < 20°. The independently determined Ro value clearly divides the distribution in such a way that most of the objects on the nearside of the G.C. approach the Sun while those on the farside recede, the probability that this arrangement arises by chance from a “stationary” distribution being ~ 0.002.
Disk Stability
Authors: Sellwood J. A.
Published: June 2019

What has prevented the formation of a strong bar in the majority of disc galaxies? No truly satisfactory answer has yet been given to this question and the difficulty remains a major obstacle to our understanding of the dynamics of these systems. In this review, I will discuss the implications of recent studies of this problem.
Ordered and Semi-Ergodic Motions in Barred Galaxies
Authors: Athanassoula E. , Bienaymé O. , Martinet L. , Pfenniger D.
Published: June 2019

A preliminary step towards the construction of self-consistent models for barred galaxies consists in understanding the stellar orbital behaviour in a given axisymmetrical + bar-like potential and, in particular, the influence of various parameters characterizing the bar on the different kinds of possible motions. To do this we undertook a systematic study of the main periodic and quasi-periodic orbits in a two-component mass model: An axisymmetrical part characterized by a rotation curve V(r) = Vo (r/ro)1-δ and a prolate bar-like perturbation whose density distribution is ρ = ρo (1-(x2+z2)/b2-y2/a2)2(a>b). This rather realistic choice for the bar is in agreement with the available photometric data and has several advantages, i.e. all cos(mθ) terms are included and the physical parameters such as the length of the bar a or its eccentricity e are explicitly included in the formulae. The ratio of bar to disk mass measured up to the outer Lindblad Resonance (ε) and the angular velocity (ωs) are also free parameters.
Hydrodynamical Models of Offcentered Barred Spirals
Authors: Colin J. , Athanassoula E.
Published: June 2019

We have studied the flow of gas in barred spirals in which the centers of the bar and the disk do not coincide. This is often observed in late type galaxies like the L.M.C., NGC 1313, NGC 4618 etc…
Rotational Velocities and Central Velocity Dispersions for a Sample of SO Galaxies
Authors: Dressler Alan
Published: June 2019

The following discussion is based on a paper of the same title co-authored with Allan Sandage in the January 1, 1983 Astrophysical Journal.
Three-Dimensional Orbits in Triaxial Galaxies
Authors: Martinet Louis , de Zeeuw Tim
Published: June 2019

Many elliptical galaxies may be slowly rotating, moderately triaxial systems. Their dynamics are probably characteristic of a 1:1:1-resonance between the frequencies of oscillation along the three principal axes.
New Phenomena in Triaxial Stellar Systems
Authors: Magnenat P. , Martinet L.
Published: June 2019

For a number of years the Geneva Observatory stellar dynamics group has undertaken numerical investigations of stellar orbital behaviour in conservative dynamical systems with three degrees of freedom. Compared to results for 3-D axisymmetrical models (2 degrees of freedom), this work displayed the advent of several new phenomena which may appear in rotating or non-rotating stellar systems with three unequal axes (ellipticals, bulges, bars). Some of these phenomena deserve particular attention.
Sensitive Search for HI in E and SO galaxies
Authors: Thonnard Norbert
Published: June 2019

Do elliptical and SO galaxies in which type I supernovae (SNI) were detected contain more gas than those without SNI detections? Thirteen E and SO galaxies in the Virgo and Pegasus I clusters, seven with SNI detections and six without, were mapped well beyond the optical image at the 21-cm neutral hydrogen line. No HI was detected. In Virgo, the upper limit to MMI/LB is between 0.0005 and 0.0024.
Observational Evidence for Mergers
Authors: Schweizer Francois
Published: June 2019

Theory has long suggested that dynamical friction between colliding galaxies must lead to mergers. The problem for observers has been to find which galaxies are mergers. I shall first review the available evidence for mergers in various kinds of galaxies, then propose a tentative classification scheme for mergers, and finally discuss mergers in giant ellipticals and their relation to the evolution and perhaps even the formation of ellipticals.
Taurus Observations of the Emission-Line Velocity Field of Centaurus A (NGC 5128)
Authors: Taylor Keith , Atherton Paul D.
Published: June 2019

Using TAURUS – an Imaging Fabry Perot system in conjunction with the IPCS on the AAT, we have studied the velocity field of the Ha emission line at a spatial resolution of 1.7″ over the dark lane structure of Centaurus A. The derived velocity field is quite symmetrical and strongly suggests that the emission line material is orbiting the elliptical component, as a warped disc.
On the Formation and Dynamics of Shells around Elliptical Galaxies
Authors: Quinn P. J.
Published: June 2019

Sharp shell-like structures around elliptical galaxies can be modelled by the phase wrapping of a cold disk of stars in the fixed potential of a massive elliptical galaxy. Such structures can then be used as probes of the potential field of ellipticals and a diagnostic of the merger event.
Dynamics of Globular Cluster Systems
Authors: Freeman K. C.
Published: June 2019

In the Milky Way, the globular clusters are all very old, and we are accustomed to think of them as the oldest objects in the Galaxy. The clusters cover a wide range of chemical abundance, from near solar down to about [Fe/H] ⋍ −2.3. However there are field stars with abundances significantly lower than −2.3 (eg Bond, 1980); this implies that the clusters formed during the active phase of chemical enrichment, with cluster formation beginning at a time when the enrichment processes were already well under way.
Is the Hubble Type of a Disk System Essentially Determined by one Parameter: Total Mass?
Authors: Tully R. Brent
Published: June 2019

The contentious title of this discourse was chosen to draw attention to some ideas expressed in a recent publication by Tully, Mould, and Aaronson (1982, hereafter TMA). Two important correlations were discussed in that article. One of those was a correlation between the colors and the intrinsic luminosities or magnitudes of spiral galaxies. The other was a relationship between the color and total mass of disk systems. It is now reasonably accepted that there is also a tight connection between luminosity and total mass.
The Manifold of Elliptical Galaxies
Authors: Brosche P. , Lentes F.-Th.
Published: June 2019

The significant number of dimensions of the manifold is two. Notwithstanding the contamination of the second dimension by projection effects, there are arguments for an intrinsic variation.
Recent Observations of Cassiopeia A
Authors: Kamper K. W. , van den Bergh S.
Published: June 2019

During the last few years radio and x-ray astronomers have produced high-resolution imagery of the remnant of Cas A. Since the most recent published optical photographs of Cas A date back to 1975 (Kamper and van den Bergh 1976 a, b) it seemed worthwhile to present new optical results based on plates obtained with the 5-m Hale telescope in 1976, 1977 and 1980. A photograph taken in 1980 is shown in Fig. 1.
Very High Resolution Calculations of Very Young Supernova Remnants
Authors: Jones Eric M. , Smith Barham W.
Published: June 2019

After the supernova shock wave has swepted up about 8–10 stellar masses of interstellar material, the SNR structure is well described by blast wave theory (eg. Sedov 1959, Chevalier 1977). In fact, both numerical calculations of the early phases (Jones, Smith, and Straka 1981) and small scale, laboratory simulations (Wilke 1982) show transition to blast wave at 8–10 masses. While the late stages have been well understood for some time, the early stages have only been crudely modeled until very recently.
X-ray Emission from Supernova Remnants in a Cloudy Medium
Authors: McKee Christopher F.
Published: June 2019

Young SNRs expand to much larger radii in a cloudy ISM than in a homogeneous medium, and they can have large variations in the pressure. The collision between supernova ejecta and an ambient cloud can result in an expanding high pressure region (a “secondary blast wave”). Observations of MSH 15–52 can be accounted for in this manner. X-ray emission from both young and older SNRs can provide an important probe for inferring the structure of the ISM.
Non-Equilibrium Ionization X-ray Emission from Supernova Remnants
Authors: Shull J. Michael
Published: June 2019

X-ray spectra of young supernova remnants (SNR's) are perhaps the most spectacular examples of hot, line-emitting astrophysical plasmas. Heated to temperatures of 1 to 10 keV and enriched with the heavy element products of stellar nucleosynthesis, the plasma inside these SNR's emits prodigiously in lines of 0, Ne, Mg, Si, S, Ar, Ca, and Fe. Theoretical models of this emission provide measures of the plasma temperature and density, elemental abundances, and the degree of approach to ionization equilibrium. Thus, astrophysicists are offered the opportunity to test their understanding of the supernova explosion, its interaction with the interstellar medium, and the nucleo-synthetic processes which enrich our galaxy with heavy elements.
Spherization of the Remnants of Asymmetrical SN Explosions in a Uniform Medium
Authors: Bisnovatyi-Kogan G. S. , Blinnikov S. I.
Published: June 2019

The “snow-plough” approximation is applied to the problem of the propagation of the shock wave from a nonsymmetrical supernova explosion in a uniform medium. The spherization of the shape of the remnant is obtained. The results are in good agreement with the observed properties of Cas A.
Particle Acceleration and Radio Emission of the Supernovae Remnants at Different Stages of their Evolution
Authors: Fedorenko V. N.
Published: June 2019

In this Paper, I consider physical processes, governing relativistic electrons in SNRs.

a)

SNRs at the age t > 102 yr. I argue that the shock wave acceleration faces some difficulties. Then I show that the temporal evolution of the SNRs radio emission can be accounted for without involving the acceleration.

b)

SNRs at the age t < 102 yr. I associate the lack of radio emission at this stage (Brown and Marscher, 1978) with the weakness of the magnetic field.

c)

I infer that the most efficient particle acceleration and radio emission of the SNRs should occur at the stage t ~ 102 yr.
The Evolution of Supernova Remnants as Radio Sources
Authors: Cowsik R. , Sarkar S.
Published: June 2019

The acceleration of relativistic electrons by hydromagnetic turbulence in shell-type supernova remnants (SNRs) is examined within the framework of previous studies of their structural evolution through interaction with the interstellar medium. The predicted evolution of the synchrotron radio emission by the electrons is in agreement with a wide variety of observations.
Optical Properties of Supernova Remnants
Authors: Danziger I. J.
Published: June 2019

Over the past decade there has been an increasing tempo of detailed optical and UV spectroscopy of SNR leading to comparisons with prevailing models of radiative shocks.
Spectrophotometry of the Optical Emission from RCW103
Authors: Ruiz Maria Teresa
Published: June 2019

Spectra for five different positions in RCW103 were obtained with the 1.5m and 4m telescopes of CTIO equiped with a SIT Vidicon detector.

From the observed Hα/Hβ ratio we found a variation of about 1.5 magnitudes in reddening for different filaments. The minimum value of Av found was 4.4 magnitudes implying a distance of 6.5 kpc.

Temperatures of about 105 K and densities of 70 cm−3 were found. Nitrogen is overabundant at least by a factor 3.
Non-Equilibrium Ionization in Puppis A
Authors: Winkler P. F. , Canizares C. R. , Bromley B. C.
Published: June 2019

High resolution X-ray spectroscopy of the brightest knot of emission in the Puppis A supernova remnant shows that it is made up of ionizing plasma, far from equilibrium. Flux measurements in several X-ray lines enable us to determine the non-equilibrium conditions: electron temperature, ion populations, and time since the knot was heated by the supernova shock. Imaging and spectroscopic data from the Einstein Observatory together suggest that this knot is a cloud of density about 10 cm−3 which has recently been shocked to a temperature 7 × 106 K. Radio and optical data on the region appear consistent with this picture.
Einstein Observations of the SNRs IC443, W44 and W49B
Authors: Watson M.G. , Willingale R. , Pye J. P. , Rolf D. P. , Wood N. , Thomas N. , Seward F. D.
Published: June 2019

We present soft x-ray observations made with the Einstein Observatory Imaging Proportional Counter (IPC) of IC443, W44 and W49B (for details of the observatory and instruments see Giacconi et al. 1979). The x-ray emission from IC443 and W44 is clearly concentrated within the interior of the remnant with little or no evidence for a limb-brightened shell. Significant spectral differences are found across the x-ray images in both remnants which are interpreted as being due to a combination of differential absorption by molecular clouds and intrinsic spatial temperature variations. The distant remnant W49B is only just resolved in the IPC observations, but additional observations with the High Resolution Imager (HRI) indicate a similar “infilled” morphology to IC443 and W44.
High Resolution X-ray Images of Puppis a and IC 443
Authors: Petre R. , Canizares C. R. , Winkler P. F. , Seward F. D. , Willingale R. , Rolf D. , Woods N.
Published: June 2019

We present soft X-ray photomosaic images of two supernova remnants, Puppis A and IC 443, constructed from a series of exposures by the Einstein imaging instruments. The complex morphologies displayed in these images reflect the interaction between “middle-aged” supernova remnants and various components of the interstellar medium. Surface brightness variations across Puppis A suggest that inhomogeneities on scales from 0.2 to 30 pc are present in the interstellar medium, while the structure of IC 443 is apparently dominated by the interaction between the remnant and a giant molecular cloud.
The Radio Morphology and Possible Nature of 3C 58
Authors: Er Ma , Strom Richard G.
Published: June 2019

Observations have been made of the supernova remnant 3C 58 with the Westerbork Synthesis Radio Telescope at 6 and 49 cm. These measurements provide us with greater resolution and sensitivity than that attained with previously published data. The 49 cm map has been used for comparison with an existing 21 cm one (Wilson and Weiler, 1976) to obtain information on the spectral index, rotation measure and depolarization. The 6 cm map is valuable both for its greater resolution, and for comparing with an observation made with the same instrument eight years previously. The total intensity distribution is shown in Figure 1.
CTB80: Cosmic Collision?
Authors: Salter C. J. , Mantovani F. , Tomasi P.
Published: June 2019

High resolution maps of the Galactic radio source CTB80 at three different frequencies are presented. A new interpretation in terms of a cosmic collision between two SNRs of different age is suggested.

CTB80 is one of the most mystifying Galactic Objects yet discovered and has recently attracted considerable attention from X-ray, optical and radio astronomers (see for example: Becker et al. (1981), Angerhofer et al. (1980, 1981), Velusamy et al. (1976), van den Bergh (1980).

The present observations of the radio continuum emission of the extended feature at 408 MHz, 1720 MHz and 4750 MHz and the linearly polarized emission at 1720 MHz and 4750 MHz (Figs 1,2,3) throw new light on the morphological, spectral and polarization properties of the whole source.
Supernova Remnants with Central Pulsars
Authors: Seward Frederick D.
Published: June 2019

The recent discovery of a central pulsing X-ray source makes MSH 15–52 the third SNR to contain a radio pulsar surrounded by diffuse X-ray emission. The pulsar periods are all increasing with time and the consequent loss of rotational kinetic energy is enough, in each remnant, to power a synchrotron nebula with the observed luminosity and volume.

After a review of the properties of the Crab Nebula it will be shown that both Vela X and MSH 15–52 have the same relationship between central pulsar and diffuse emission. Using empirical rules derived from these SNR, it is demonstrated that other plerionic remnants have similar characteristics. Two accretion-powered central sources can be distinguished from radio pulsars in SNR by the relatively high X-ray luminosity of the central source compared to that of possible synchrotron diffuse emission.
The Pulsation Period and Possible Orbit of 1E2259+586
Authors: Fahlman G. G. , Gregory P. C.
Published: June 2019

The currently known characteristics of the unique x-ray pulsar 1E2259+586 are briefly reviewed. The results from a recently completed analysis of the x-ray photon arrival times recorded by the Einstein Observatory are presented. The pulsar light curve has changed shape between two epochs separated by six months. The true pulse period is 6.978632 sec, double the previously reported value. In addition, there is evidence for orbital motion with a period close to 2300 sec. Some implications of this orbit are briefly discussed.
X-rays from Radio Pulsars: The Portable Supernova Remnants
Authors: Helfand David J.
Published: June 2019

Neutron stars are the longest-lived remnants of supernova explosions. As a reservoir of thermal energy remaining from the explosion and generated by frictional coupling between core and crust, as a storehouse of magnetic and rotational kinetic energy which allows the star to act as a high energy particle accelerator, and as the source of a deep gravitational potential which can generate heat from infalling matter, neutron stars remain capable of producing high energy radiation for a Hubble time. We review here the results of an extensive survey of supernova remnants and radio pulsars with the imaging instruments on board the Einstein Observatory and discuss the implications of these results for pulsar physics and for the origin and evolution of galactic neutron stars.
X-ray and Gamma-ray Radiation from the Switched-off Radiopulsars
Authors: Tsygan A. I.
Published: June 2019

It is shown that pulsars that have ceased to generate electron-positron pairs (switched-off radiopulsars) may be the sources of X-ray and γ-ray radiation. The magnetic dipole radiation from these rotating neutron stars is transformed near the “light radius” into hard radiation by the plasma that is created due to ionization of interstellar neutral hydrogen.
Chemical Abundances in the Interstellar Medium of Galaxies from Spectrophotometry of Supernova Remnants
Authors: D'Odorico S. , Dopita M.
Published: June 2019

In the recent past supernova remnants (SNR) have been identified in external galaxies as far as 5 Mpc. These galaxies are: M 33(12), M 31(12), NGC 6822(1), IC 1613(1), NGC 2403(2), NGC 300 (2), NGC 4449(1), where the numbers of SNR confirmed by optical spectroscopy are given in parenthesis. Data for objects in the Magellanic Clouds are discussed extensively elsewhere in this volume.
Luminous Supernova Remnant Candidates in M82 and The Physical Properties of The Variable Radio Source 41.9+58
Authors: Kronberg P. P. , Biermann P.
Published: June 2019

Large numbers (∼30) of supernova remnant candidates have been revealed in new VLA maps of the inner 600 pc of M82 with subarcsecond resolution. The flux density decrease of the bright source 41.9+58 in the M82 nuclear region is found to be occurring with an approximately constant spectral index of −0.9 at ν≳3 GHz, and the low frequency turnover has moved from ∼700 MHz in 1974–1975 to <400 MHz in 1979–81.

A model of 41.9+58 is proposed in which it is, at least initially confined by its own hot (∼108K) pre-SN ejecta, and its relativistic particles are accelerated by a pulsar at its centre.
Automated Quasar Detection
Authors: Clowes Roger G. , Cooke John A. , Beard Steven M.
Published: June 2019

The existing spectral searches for quasars have increased the number of quasars known very substantially but have not contributed proportionately to an understanding of the collective properties because of the selection effects. To fully exploit the spectral searches we have developed the technique of automated quasar detection (AQD) using objective-prism plates from the UK Schmidt Telescope, the COSMOS measuring machine at the Royal Observatory Edinburgh, and the STARLINK nodes at Durham and Edinburgh.
QSO Redshift Limit and Periodicity in a Fib Universe
Authors: Barnothy Jeno M. , Barnothy Madeleine F.
Published: June 2019

The FIB cosmology was conceived half a century ago, to explain the origin and spectrum of the ultrahigh energy cosmic ray particles we observed in deep mines. It succeeded in explaining quantitatively the 3°K microwave background radiation (IAU Symposium No. 44), the redshift periodicity (PASP 1976), and the cutoff of QSO's beyond z=3.5 (AAS 1982).
Near Infrared Photometry of Faint Radio Galaxies
Authors: Windhorst Rogier A. , Leiden Sterrewacht , Puschell Jeffrey J. , Thuan Trinh X.
Published: June 2019

This paper describes the first results of systematic near IR photometry of radio galaxies in the Leiden Berkeley Deep Survey. The LBDS contains ∼ 400 radio sources with S1.4 GHz ≥ 0.22 mJy (for details see van der Laan et al., this symposium), 50% of which have reliable optical identifications on deep multicolor KPNO 4m plates, being mainly faint blue radio galaxies (Windhorst et al., 1982). The aim of the present IR photometry program is to study their IR properties and to obtain clues as to the nature of these faint blue radio galaxies, which may be either ellipticals, possibly with recent star formation, or spirals with exceptionally high radio power. The additional optical-IR color baseline will help to solve these questions.
Near Infrared and Radio Observations of Distant Galaxies
Authors: Laing R. A. , Owen F. N. , Puschell J. J.
Published: June 2019

This paper is concerned with the distant radio galaxies in a sample of bright sources selected at 178 MHz by Laing, Riley & Longair (1982). This sample is 96% complete for sources with θ < 10′ and the bias of the 3CR catalogue against sources of large angular size has also been reduced. Deep optical searches have located many candidate identifications, but the probability of a chance coincidence with an unrelated object is appreciable, especially in the faintest cases, unless the area to be searched is small. We have therefore mapped the sources with candidate identifications having V > 20, using the VLA at a wavelength of 6 cm (Laing, Owen & Puschell, in preparation), in order to search for radio cores. We have so far located cores in 16/23 sources and set 5σ upper limits of 0.6 mJy for the remainder. None of the cores had been detected previously. In all cases, the cores coincide with optical objects, although one source (3C 340) had been misidentified. Several ambiguities have now been resolved.
A Redshift Survey of Very Faint (B≤22.5) Field Galaxies, Radio Sources, and Quasars
Authors: Koo David C.
Published: June 2019

As part of a three year program to study the evolution of galaxies, quasars, and radio sources (in collaborations with R. Kron and R. Windhorst), we will use over 30 nights on the KPNO 4-m CCD Cryogenic Camera System, in the multi-aperture mode, to measure the redshifts of several hundred very faint objects. These will be selected from four fields (SA68 00h+15; Lynx 08h+45; SA57 13h+30; Herc 17h+50); for each we possess 4-m plates in four bandpasses (limits: U≃23, B≃24, V≃23, I≃21) as well as Westerbork interferometer maps to 1 mJy at 21cm (a 50cm survey is in progress). Galaxies are selected randomly by their apparent red magnitudes as measured with a PDS; quasar candidates to B≈22.5 by stellar objects which lie apart from Galactic stars in the multi-color diagram; and radio sources by their positional coincidence with optical images (∼50% of the 300 radio sources are identified). To date, 10 nights have produced spectra of ∼250 field galaxies, ∼20 radio sources, and ∼40 quasar candidates.
Distortion of the Microwave Background by Dust from Population III
Authors: Rowan-Robinson Michael
Published: June 2019

Population III has been invoked to explain the missing mass in the haloes of galaxies, the first heavy elements in our Galaxy and even to explain the whole microwave background. However there are alternative explanations for each of these phenomena. The most compelling evidence for the existence of a pregalactic generation of objects is the observed distortion of the microwave background in the millimetre range, which can be explained as radiation from Population III objects absorbed and re-emitted by dust grains. If the distortion is confirmed, we can probably conclude that the density fluctuations in the early universe were isothermal and that no neutrino can have a mass in the astrophysically interesting range 1–100 eV.
Measurement of the 3 K Cosmic Background Noise in the Far Infrared
Authors: Dall'oglio G. , de Bernardis P. , Masi S. , Melchiorri F.
Published: June 2019

Quantum fluctuations of the cosmic background have been measured in the 900 to 2000 micron range (H.P.B.W.) by means of a balloon-borne correlator operating between 5 and 150 Hz. Preliminary results indicate an upper limit √ ≤ 2.1 × 10−17 watt/(cm2 srad Hz)1/2, corresponding to the noise of a blackbody at a temperature T ≤ 3.1 K at 1σ.
Characteristic Size of Superclusters
Authors: Kalinkov M.
Published: June 2019

A new processing of the surface distribution of clusters from the catalogues of Abell and Zwicky has been carried out for an area of 2000 square degrees around the NGP. Four statistical tests (M. Kalinkov, I. Kuneva, 1980, C.R. Acad. Bulg. Sci., 33, 1305) are applied to search apparent characteristic sizes. Assuming a mean distance R = 440 h−1 Mpc (Ho = 100 h km s−1 Mpc−1) to Abell clusters, a characteristic size Q = 52 Mpc for superclusters has been obtained. For Distance Group 5 (R = 400 Mpc) and for Distrance Group 6 (R = 530 Mpc), we have Q = 48 Mpc and Q = 40 Mpc, respectively. For Zwicky D clusters (R = 390 Mpc, assuming a uniform distribution in the volume from 300 to 450 Mpc, Q = 55 Mpc and for ED clusters R ≈ 650 Mpc), Q = 46 Mpc. Therefore, the mean characteristic size of superclusters is 50 h−1 Mpc. There is an exception, however, for VD clusters (R = 540 Mpc) for which Q ≈ 100 h−1 Mpc.
Properties of Galaxies in Low Density Regions
Authors: Brosch N.
Published: June 2019

Isolated galaxies seem to have more nuclear activity and less disk activity than nonisolated objects. This is interpreted as an expression of the mass-profile in their halos.

The discovery of voids in the three-dimensional distribution of galaxies has rapidly been followed by claims that in at least one such void some objects, like Markarian and emission-line galaxies, are present. Why are only active galaxies found in these voids? Should we also expect the opposite to be true, namely that active galaxies ought to be found more often in voids, or in regions of the Universe with lower-than-average density? There are indications that this seems to be the case, as Gisler (1978) found that emission-line galaxies, Markarians and possibly Seyferts avoid environments of dense clusters. Differences between “field” and “cluster” populations are probably due more to the enhanced local density of galaxies than to the nature of the overall environment.
Infall of Galaxies into the Virgo Cluster
Authors: Shaya E. , Tully R. Brent
Published: June 2019

There are a subtantial number of galaxies in the Virgo southern extention just beyond the Virgo Cluster which are blueshifted with respect to the cluster and a lesser number of galaxies slightly nearer than the Virgo Cluster which are redshifted with respect to the cluster. These galaxies must be falling into the cluster. We are able to model the observed infall motions by following the collapse of spherical shells with the Friedmann equations in a closed universe. A family of mass-age solutions provide satisfactory fits to the observations.
The Perseus Supercluster
Authors: Giovanelli Riccardo
Published: June 2019

In analyzing the distribution of galaxies of a sample projected on the plane of the sky, the magnitude of a surface density enhancement produced by a clumpy structure depends on the size and magnitude of the volume density enhancement, and the depth of the sample. If the sample is too deep, or the line of sight size or volume overdensity of the clump too small, the surface enhancement may be too shallow to discern against the fore- and background objects. The Catalogue of Galaxies and Clusters of Galaxies (CGCG: Zwicky et al. 1960–68) provides a representative sample of the local universe (cz ≤ 15000 km s−1) and, in hindsight, possibly the one available that best enhances the inhomogeneities that appear to characterize the large scale structure of the universe. Using maps of the surface density distribution of galaxies from the CGCG, of which figure 1 is an example, Martha Haynes, Guido Chincarini and I have selected a number of filamentary structures discernable and undertaken a 21 cm redshift survey of large regions enclosing them, with the telescopes of 305 m at Arecibo and 92 m at NRAO-Green Bank. Here I shall discuss our current results from a large area extending from Pegasus to Ursa Major, which engulfs the well known Perseus supercluster (Einasto et al. 1980; Gregory et al. 1981).
Unseen Mass
Authors: Rees Martin J.
Published: June 2019

The arguments for “unseen mass”, and the evidence on its distribution, are still somewhat controversial as far as the details are concerned.
Absorption Structure in the BL LAC Object 0215+015 at 20 KM S−1 Resolution
Authors: Hunstead R. W. , Murdoch H.S. , Pettini M. , Blades J. C.
Published: June 2019

The origin of the narrow metal absorption lines in the spectra of QSOs remains uncertain despite the large amount of high-quality data obtained at high resolution over the past decade. Recently, statistical tests of a uniform sample of C IV absorption systems have shown that their redshift distribution is consistent with the view that these lines arise in randomly distributed intervening galaxies in a Friedmann Universe (Young, Sargent and Boksenberg 1982, hereafter YSB). In a complementary approach we consider in detail the physical properties of the absorbing material in cases of particular interest. We have chosen the high-redshift BL Lac object 0215+015 (Blades et al. 1982, hereafter BHMP) for detailed spectroscopic study because it is currently in a bright phase (V ∼ 14.5–16.5) and because it has several strong absorption systems with differing ionization structure. From our medium-resolution spectra of 0215+015 (BHMP) it appears that the density of C IV systems per unit redshift in this object is somewhat higher than, but not inconsistent with, the average density in the YSB sample.
Nature of ‘Unseen’ Galactic Envelopes
Authors: McCrea W. H.
Published: June 2019

It is suggested that unseen matter in a galactic envelope or in a group of galaxies may consist of substellar bodies originating as the first permanent ‘stars’ in the formation of a very massive galaxy according to a model previously proposed by the author.
Monte-Carlo Simulations of the Distribution of Faint Galaxies
Authors: MacGillivray H.T. , Dodd R. J.
Published: June 2019

Simulations of static (non-evolving) fields of galaxies are carried out by means of a Monte-Carlo computer technique which models all physical effects acting on the light from distant galaxies, from emission at the source up to the final detection and measurement on the photographic plate by means of a high-speed measuring machine. Parameters for the model galaxies are computed in order to match the main types of measurement made on astronomical photographs (e.g. image centroids, isophotal magnitudes and colours, orientations and shapes).
Possible Contraction of the Members of the Binary Pulsar PSR 1913+16 and its Astrophysical Consequences
Authors: Spyrou N.
Published: June 2019

It is proposed that the small difference between the observed and the theoretically predicted decrease of the orbital period of the Binary Pulsar PSR 1913+16 is not due to the insufficiency of the quadrupole formula and can be attributed to a mass-energy loss due to the contraction of the binary's members. Assuming that the pair's primary is a typical, noncontracting pulsar, is in favour of a slowly contracting, neutron-star companion, thus limiting the member's radii to at most 25 km and 28 km, respectively. The primary's computed total absolute luminosity is in excellent agreement with the observed upper limit of its X-ray and optical luminosities. Moreover, the companion's slow contraction rate implies that its present total absolute luminosity presents a maximum at wavelengths characteristic of X-rays. Finally, it suggests that if the energy-loss remains constant, the duration of the contraction phase will be of the order of 108 y and the final radius about 25 km.
Particle Phase Transitions can Prevent an Initial Cosmological Singularity
Authors: Bludman S. A.
Published: June 2019

The present universe has small vacuum energy density (cosmological constant) and small spatial curvature. Therefore, before symmetry breaking, it had to have huge positive vacuum energy density, significant curvature, and low entropy. Because the energy positivity condition was not then satisfied, there need not have been an initial singularity (Hot Big Bang). If the universe is spatially open or the initial entropy high enough, then before the elementary particle phase transition, it was indeed an inflecting universe with an initial singularity. But if the universe is spatially closed and of low initial entropy, it needed to be a curvature-dominated bouncing universe, with a minimum size and maximum temperature (Tepid Little Bang). The closure of the present universe will therefore determine whether or not there was an initial singularity.
Inflationary Universe, Primordial Sound Waves and Galaxy Formation
Authors: Lukash V. N. , Novikov I. D.
Published: June 2019

At present cosmology experiences a qualitatively new state of its development. Up to now cosmological theory successfully extrapolated to the past the Universe we observe now. This extrapolation was reliable up to the temperatures T ∼1010K. The endeavors to advance nearer to the singularity imply that even cardinally new hypotheses in the elementary particle physics (e.g. Hagerdorn's hypothesis) brought about the relatively insignificant variations in cosmology—the Universe expansion rate obeyed the power law as before, the main features of the cosmological model (homogeneity, singularity, the existence of horizone, etc.) remained unchanged.
Physics of the Bi-Partition of the Universe
Authors: Schatzman Evry
Published: June 2019

Using already tested physics of matter-antimatter interaction, an attempt is made of a check of the bi-partition model of the Universe of Fliche, Souriau and Triay (1982b). No inconsistency is found.
The Integrated Spectra of Star Clusters and the History of the Magellanic Clouds
Authors: Searle Leonard
Published: June 2019

This paper reviews the attempts that have been made to derive the ages and compositions of star clusters from studies of their integrated light. It discusses what can be learned by such methods regarding the history of the Magellanic Clouds. Finally, it reviews what is known about the age-spread and abundance-range in the cluster-systems of other galaxies and considers the history of the Magellanic Clouds in this context.
Metallicities of Young Populous Clusters in the Magellanic Clouds
Authors: Nelles B. , Richtler T.
Published: June 2019

We present metallicities for the young LMC clusters NGC 1818, 1866 2157, 2136 and 2214. This sample is increased by taking over additional values from literature, so for NGC 1850, 1994, 2004, 2100 from the list of Hodge (1981). The intention is to compare these values with metallicities found in a field population of comparable age. Such a population may be represented by bright Cepheids, for which metallicities based on Washington photometry (Harris 1983) are available. The only young SMC cluster, for which we could estimate a metallicity, is NGC 330. Therefore, a comparison with SMC Cepheids, whose metallicities are also quoted by Harris (1981), can lead to uncertain statements only, until further observations of young SMC clusters will have been made.
Period Changes of RR Lyrae Stars in the LMC Globular Cluster NGC 2257
Authors: Nemec James M. , Liller Martha H. , Hesser James E.
Published: June 2019

The period changes of RR Lyrae stars can be compared with models of horizontal branch stars as a means of investigating the physical properties of the stars themselves, and of the stellar systems in which they are found (Smith and Sandage 1981). The present study is the first in which period change rates of extragalactic RR Lyraes have been estimated.
The Electronographic Color-Magnitude Diagram of Hodge 11
Authors: Andersen J. , Blecha A. , Walker M. F.
Published: June 2019

A program of electronographic photometry of star clusters in the Magellanic Clouds is being carried out using the McMullan camera on the Danish 1.5-m telescope at La Silla. The observations are being reduced using the Geneva microdensitometer and data reduction programs. Results are shown for the LMC cluster Hodge 11 (=SL 868), based on measurements of two exposures in both yellow and blue-light, each three hours in length, recorded on Ilford L4 emulsion.