bluuebunny/crossref_metadata_2025 huggingface dataset:
Empirical Evidence for Crystallization Sequences of DA Type White Dwarfs
Authors: S. Tapia S.
Published: July 2016

The determination of the distribution of white dwarfs in the HR diagram is marred by two observational difficulties: The recent discoveries of degenerate stars with unusual spectral characteristics and the controversy over the existence of crystallization sequences. Observationally, the origin of the controversy can be traced to the single band displayed on the MVvs. (b-y) diagram by several white dwarfs with accurate parallax (Graham 1972). The discrepancy between this single band and the two bands evident in the MVvs. (U-V) diagram (Eggen and Greenstein 1965) is far too great to be attributed to observational errors (Eggen 1969). Theoretically, the number of sequences in the HR diagram is directly related to the cooling properties of degenerate dwarfs, for which crystallization is expected on rather general grounds. On one hand, Van Horn (1968) considered a discontinuous transition to the solid phase with the release of latent heat and the addition of it to the total internal energy. Since the amount of latent heat depends upon the chemical composition, bright and faint crystallization sequences should be observed according to the different stages of evolution reached by the parent stars. On the other hand, Mestel and Ruderman (1967) proposed a gradual transition to the solid phase, and consequently the formation of a single cooling sequence. The purpose of this contribution is to report observational results indicating the existence of two crystallization sequences of DA type white dwarfs.
The Main Sequence of NGC 6231 and the Calibration of Absolute Magnitudes
Authors: Garrison R. F.
Published: July 2016

It is fitting to mark the Centennial of Henry Norris Russell's birth with a discussion of a new approach to the calibration of absolute magnitudes for MK spectral types. With the addition of the NGC 6231 main sequence down to A0, the material for the cluster fitting method using very carefully determined MK types is complete. The data will be published elsewhere (Garrison and Schild 1978).
Evidence for Non-Homogeneity in the Metal Abundances of Stars in Globular Clusters
Authors: Kraft Robert P.
Published: July 2016

Evidence for non-homogeneity in the metal abundances of giant stars in various globular clusters is reviewed. The nonhomogeneity is of two kinds: (1) differences in the value offrom star to star in the same cluster, for particular values of A, and (2) non-constancy of the clustermeanvalue ofas a function of A. Observational evidence for the existence of variations of both kinds is cited, and discussed for four “nucleosynthetic” groups of elements:viz., s-process, Fe-peak, α-process, and CNO. The rival hypotheses of core-envelope mixing and primordial abundance variations are examined in the light of the observations.
The Radii of RR Lyrae Stars
Authors: Balona L. A.
Published: July 2016

Balona (1977) has described a modification of the Wesselink technique of radius determination which takes into account the effects of observational errors using the Principle of Maximum Likelihood. This leads to a tighter period - radius relationship for Cepheids than obtained by the classical method and suggests that some of the problems associated with radii estimation of RR Lyraes may be due to the incorrect statistical treatment of the data. With this in mind, we have applied the Maximum Likelihood technique to well-observed RR Lyraes. Except for two stars, the data used were taken from the literature.
A Preliminary Color-Magnitude Diagram for the Ursa Minor Dwarf Galaxy
Authors: Schommer Robert A. , Olszewski Edward W. , Kunkel William E.
Published: July 2016

The Ursa Minor dwarf galaxy (RA = 15h08m.2, Dec = +67°18′ (1950)) was one of four dwarf ellipticals discovered by Wilson (1955) in a search of the Palomar Sky survey plates. The general properties of these galaxies resemble those of galactic globular clusters, linear size and density excepted (see Hodge, 1971, for a review). The characteristics of Ursa Minor are very similar to those of the Draco dwarf, for which a color magnitude diagram was published by Baade and Swope (1961). Van Agt (1967) published a study of the variable stars in Ursa Minor based on Baade's 200-inch plates.
The Hertzsprung-Russell Diagram of Metal-Poor Disk Stars
Authors: van den Bergh Sidney
Published: July 2016

A quarter of a century ago Keenan and Keller (1953) showed that the majority of high-velocity stars near the Sun outline a Hertzsprung-Russell diagram similar to that of old Population I. This result, which did not appear to fit into Baade's (1944) two-population model of the Galaxy was ignored (except by Roman 1965) for the next two decades. Striking confirmation of the results of Keenan and Keller was, however, obtained by Hartwick and Hesser (1972). Their work appears to show that high-velocity field stars with an ultraviolet excess (which measures Fe/H) of δ(U-B) ≃ +0m.11 lie on a red giant branch that is more than a magnitude fainter than the giant branch of the strong-lined globular cluster 47 Tuc for which δ(U-B) ≃ +0m.10. Furthermore Demarque and McClure (1977) show that the red giants in the old metal poor [δ(U-B) ≃ +0m.11] open cluster NGC 2420 are significantly fainter than are those in 47 Tuc. Calculations by these authors show that the observed differences between the giants in 47 Tuc and in NGC 2420 can be explained if either (1) 47 Tuc is richer in helium than NGC 2420 by ΔY ≃ 0.1 or (2) if 47 Tuc has a ten times lower value of Z(CNO) than does NGC 2420.
From Multicolor Photometric Indices to the HR Diagram
Authors: Straižys V.
Published: July 2016

The Vilnius photometric system permits one to determine photometrically temperatures and log g's or spectral types and MV's of stars in spite of the presence of interstellar reddening. The position of any normal star in the HR diagram can be determined by its direct calibration in five reddening-free quantities Q. The position of the star in the HR diagram corresponds to the point at which five Q-isolines intersect. This is the most direct way to find the position of the star in the HR diagram from photometry.
Evolution of Massive Stars Through Late Evolutionary Phases
Authors: Lamb Susan A.
Published: July 2016

The theoretical study of the evolution of massive stars has considerable relevance to many branches of observational astronomy. As an example, one may mention, first, the direct application of theoretical models in interpreting the observed properties of supergiants, and second, the use of calculations of the nucleosynthesis taking place in these stars, together with observed supergiant mass loss rates and supernova calculations, to estimate the rate and type of nucleosynthetic enrichment of the interstellar medium by supergiants.
Summary
Authors: Green Louis C.
Published: July 2016

The Symposium opened with a morning devoted to the accomplishments and character of Henry Norris Russell, as one of the two originators of the Hertzsprung-Russell diagram, on the hundredth anniversary of his birth. The papers presented at this session, together with some shorter remarks made at other times during the Symposium, are to appear in a separate volume asDudley Observatory Report. No. 13. Suffice it to say here that the picture which emerged was that of a fine man of enormous energy, prodigious memory, committed to his scientific work but with many interests, always polite and pleasant to those around him but somewhat remote.
Southern High-Velocity Stars
Authors: Augensen H.J. , Buscombe W.
Published: July 2016

Using the model of the Galaxy presented by Eggen, Lynden-Bell and Sandage (1962), plane galactic orbits have been calculated for 800 southern high-velocity stars which possess parallax, proper motion, and radial velocity data. The stars with trigonometric parallaxes were selected from Buscombe and Morris (1958), supplemented by more recent spectroscopic data. Photometric parallaxes from infrared color indices were used for bright red giants studied by Eggen (1970), and for red dwarfs for which Rodgers and Eggen (1974) determined radial velocities.
A B-Star High Luminosity Indicator
Authors: Furenlid I. , Sanders W.L.
Published: July 2016

In an effort to sort out BIa supergiants among B-stars for use in delineating spiral structure, a photometric discriminate has been sought in the following way. Wide slit 16Å/mm (flux) spectra were obtained of a sample of B stars over a suitable spectral and luminosity range. These spectra were digitized on the PDS Microdensitometer. Numerical filters of various widths were then slid along the spectra and numerous color-indices were formed and tested. An index ℓO= u + v − 1.9 (ℓ) plotted against cO, where ℓ is a 200Å halfwidth passband centered near 3840 Å and the other magnitudes are on the Strömgren 4-color system, succeeds in separating the Ia supergiants up to B1. For stars of spectral type B1 and earlier, confusion sets in and the separation is uncertain (although a fair percentage of success is also had for types B1 and B0). This luminosity discriminate is now in use for a large spiral structure program in which all known Be stars (and perhaps eventually all B stars) are being surveyed for Ia supergiants. Spectra for 2-dimensional classification are obtained for the Ia candidates.
Introductory Lecture
Authors: Rees Martin J.
Published: July 2016

It is now 22 years since quasars were discovered. When the ageing veterans of those pioneering investigations think back over two decades of boisterous debate, their reactions are probably rather mixed. Wonderment at the range and variety of novel phenomena revealed in all wavebands must be tinged with disappointment that we seem so slow in grasping what is really going on. Our understanding has advanced slowly, through many small steps — forward steps preponderating (fortunately) over backward ones.
Results from a faint QSO redshift survey
Authors: Shanks T. , Fong R. , Boyle B.J. , Peterson B.A.
Published: July 2016

We have used the FOCAP fibre optic coupler at the Anglo-Australian Telescope (AAT) to measure redshifts for a complete sample of ∼ 170 B ≤ 21m QSO's selected using the ultraviolet excess (UVX) criterion. We present preliminary estimates of the QSO luminosity function in discrete redshift ranges and show how these observations differentiate between models of QSO evolution. We have also investigated the clustering of QSOs in this complete sample by estimating the QSO 2-point correlation function and we use this to derive direct constraints on the homogeneity of the Universe at large scales.
About the QSOs contained in the Cerro el Roble Survey and the density of UVX-QSOs in the SGP field
Authors: Campusano Luis E.
Published: July 2016

A region containing the SGP, centered at α 00h 53m (1950) δ −28°03', is becoming a selected region for QSO research. Three lists of QSO candidates have been published for this field. One consists of candidates discovered visually on an objective prism plate, selected in a 25-deg2 area and with B(lim) ⋍ 20 mag (Clowes and Savage, 1983; the CS sample). The other list came from visual inspection of U and B plates (UVX stars), covering a region of 44-deg2 and with approximately the same limiting magnitude of the CS sample (Campusano and Torres, 1983; the CT sample). The third survey of QSO-candidates involved a machine selection of UVX stars (Shanks et al., 1983), whose published components correspond to two small areas of 1.6 and 8.2 deg2 with B(lim) = 19 mag (Boyle et al., 1985).
PKS 2005-489: A very bright BL Lac object in a nearby galaxy
Authors: Wall J V , Danziger I J , Pettini M , Warwick R S , Wamsteker W
Published: July 2016

The galaxy identified with the flat-spectrum radio source PKS 2005-489 has a bright stellar nucleus with V ⋍ 13 mag. Optical, UV and X-ray observations indicate variability and power-law continua in each of these wavebands, leading to the conclusion that PKS 2005-489 is one of the brightest BL Lac objects known.
Resolved imaging and spectroscopy of QSOs
Authors: Hickson Paul , Hutchings J. B.
Published: July 2016

We have obtained direct images and off-nuclear spectra for five QSOs having a wide range of radio, optical and X-ray luminosity. Four objects show absorption features identified with stars in a host galaxy, and off-nuclear changes in emission line wavelengths. All objects show off-nuclear changes in continuum coulour, and in emission line intensities and ratios. The radio loud objects have more luminous galaxies, strong and extended [OII] and [OIII], and UV-bright nuclei. They tend to have luminous nuclei, high nuclear to galaxy luminosity ratio, and blue host galaxies. This paper is a brief summary of results that will appear in more detail elsewhere.
CCD observations of galaxies with radio jets
Authors: Pérez-Fournon I. , Colina L. , Biermann P. , Marcaide J.M.
Published: July 2016

We present preliminary results of a CCD survey of nearby (z<0.1) northern galaxies which have well defined radio jets. Our main objectives are to: 1) detect - or put constraints to - the presence of optical jets in these galaxies, 2) obtain high dynamic range maps of known optical jets, and 3) make a detailed comparison of our results with those available from the radio maps.
Compact Radio Structure of Quasars
Authors: Porcas R.W.
Published: July 2016

Recent results concerning the compact radio structure of quasars are reviewed. Emphasis is placed on VLBI results from statistical studies, from detailed mapping and from multi-epoch monitoring of variable sources.
Results From X-Ray Satellites
Authors: Zamorani G.
Published: July 2016

One of the best studied results of the X-ray observations of Active Galactic Nuclei is the statistical correlation which has been observed between the X-ray and optical luminosities in these objects. In this paper I will review the present situation of the analysis of such correlation, focusing my attention on the large number of topics which are more or less directly linked to it.
The medium sensitivity survey and the X-ray selected quasar sample
Authors: Gioia Isabella M. , Maccacaro Tommaso , Schild Rudolph , Stocke John , Danziger John
Published: July 2016

We find that the inconsistencies discussed by many authors between the expected and observed number of X-ray selected quasars cannot be attributed to incompleteness of the Medium Sensitivity Survey (MSS). We are presently expanding the survey, this effort will produce a very large sample of X-ray selected quasars. Preliminary results are presented.
The X-ray jet in 3C 273
Authors: Harris D.E. , Stern C.P.
Published: July 2016

A subtraction technique is applied to the X-ray image of 3C 273 in order to determine the location and other properties of emission associated with the jet.
Studies of narrow emission lines in AGNs
Authors: Filippenko Alexei V.
Published: July 2016

Optical spectra having moderately high resolution (~ 2 — 5 Å) are being used to study the profiles of narrow emission lines in active galactic nuclei (AGNs). It is often found that forbidden lines associated with high critical densities for collisional deexcitation are the broadest. A good example is [O III] λ4363 [ne(crit) ≈ 3 × 107 cm−3], whose width can be more than twice that of [O III] λ5007 [ne(crit) ≈ 8 × 105 cm−3]. The tight correlation between line width and ne(crit) implies that a much larger range of densities (∼ 102 — 107 cm−3) must be present among clouds in the narrow-line region than was previously believed. At times there almost appears to be a continuity between the narrow- and broad-line regions. In some objects the dense, high-velocity clouds are optically thick to ionizing radiation, since they emit [O I] λ6300 as well as species of much higher ionization (such as [Ne V] λ3426). These results help eliminate several difficulties in photoionization models of LINERs. It may also be possible to use the observed line widths as probes of the gravitational potential in AGNs.
Photoionization models and low ionization lines in AGN
Authors: Joly M.
Published: July 2016

A two-component photoionization model where the high and the low ionization lines are allowed to arise from different kinds of clouds is explored. A spectral distribution of the incident radiation which tends to overestimate the X-ray flux around 3 keV is adopted in order to enhance the extent and heating of the excited HI region. It is concluded that the model is still unable to explain the observed ratio FeII/Hß.
FUV and optical spectrophotometry of X-ray selected Seyferts
Authors: Clarke J. T. , Bowyer S. , Grewing M.
Published: July 2016

Nearly simultaneous FUV and optical spectrophotometry of X-ray selected Seyfert galaxies has revealed an average Ly α/H β ratio of 22, a positive correlation between the ratio Ly α/H β and the width of the lines, and additional Ly α emission in the wings of one source which is not matched by emission in the Balmer line wings. However, we find no distinguishing features in the continuum emission from these X-ray selected objects compared with other samples. If the correlation between Ly α/H β and the width of the lines is found to apply to larger samples of Seyferts, it may be that our objects appear Ly α bright because they are also broad-lined compared with other samples.
Variability of emission lines in quasar spectra
Authors: Gondhalekar P M , O'Brien P , Wilson R
Published: July 2016

Analysis of ultraviolet spectra of quasars obtained with IUE indicate that the permitted emission lines in quasar spectra are variable. The upper limit for the delay between a change in the continuum and the consequential change in the emission lines is about 9 months. This rapid response of the permitted emission lines to changes in the continuum leads to a number of problems in understanding the nature of quasars.
The revived Penrose process can power the central engine in active galactic nuclei
Authors: Wagh Sanjay M. , Dadhich N.
Published: July 2016

Using the fact that the efficiency of the revived (Wagh et al 1985) Penrose process of energy extraction from black holes immersed in electromagnetic fields can be very high (Parthasarathy et al, 1986) we show that this process can comfortably power the ‘central engine’ in Active Galactic Nuclei. The microphysical Penrose process energized particles will be ultrarelativistic in the asymptotic frame. Hence the kinematical analysis of escaping photons by Piran and Shaham (1977) will be a good approximation to the kinematics of these particles. From this analysis one expects the energized particles to emerge within an angle∼ 40° above and below the equatorial plane. These energetic particles, which are collimated in the funnel of an accretion disk and further on by the magnetic field, then, form supersonic, relativistic, bilateral jets. The relativistic Y factor for such jets can be expected to be ∼ 2 since these ultrarelativistic particles will effectively mimick radiation in ‘dragging’ the matter already injected inside the funnel. Various implications of high energy extraction efficiency are illustrated.
Transport of radiation & energetic particles in accretion flows
Authors: Cowsik R. , Lee M.A.
Published: July 2016

The equations describing the transport of suprathermal charged particles and electromagnetic radiation across accretion flows onto compact objects are solved analytically, including the effect of shocks in the flows. These solutions indicate (a) accretion flows with shocks accelerate particles very efficiently upto ultra-relativistic energies. (b) the emergent spectra of electromagnetic radiation from such flows reproduce the observed spectra of quasars from the infrared to the hard X-ray region.
Constraints on the cosmological evolution of AGNs from X-ray data
Authors: Danese L. , Zotti G. De , Fasano G. , Franceschini A.
Published: July 2016

Both the soft (Maccacaro et al., 1982; Gioia et al., 1984; Giacconi et al., 1979; Griffiths et al., 1983) and the hard (Piccinotti et al., 1982) X-ray surveys provide crucial information on the evolution of AGNs in the X-ray band. Before combining the two data sets, however, the consistency of the two flux scales must be checked. To this end we have compared the soft (SX) and the hard (HX) X-ray luminosities of all powerful (log(SX)>43.5) AGNs for which both IPC and hard X-ray fluxes are available in the literature (lower luminosity objects frequently exhibit large intrinsic, luminosity dependent, absorbing columns which cannot be accurately accounted for). We find
 = 0.17±0.06,
to be compared with the expected value ≃0 for a typical X-ray energy index αX≃0.7. Thus, an average correction factor of ≃1.5 needs to be applied to the IPC fluxes to bring them into the hard X-ray flux scale.
BL Lacertae objects as an evolutionary population
Authors: Cavaliere A. , Giallongo E. , Vagnetti F.
Published: July 2016

If the BL Lac Objects are active nuclei with a beamed component that is dominant when directed at us, their observed luminosity function must comprise a flat faint branch: N(L)dL ∝ L1+1/pdL with p=4.5 (Urry and Shafer 1984). If this is flatter than the LF NP(L) of the parent objects at equal observed L, then we expect the counts of BL Lacs to flatten out in turn at fluxes quite higher than the counts of the parents, even when both populations evolve strongly and uniformly with comparable timescales (Cavaliere, Giallongo and Vagnetti 1985).
Quasar clustering around the Sculptor region
Authors: Kunth D. , Sargent W.L.W.
Published: July 2016

The Sculptor Region has been searched for quasar candidates: three IIIa-J objective prism plates from the UK Schmidt-telescope centred around the NGC55 and NGC300 galaxies have been used. 76 quasars have been found doubling the number of quasars previously known in this field. A test using Monte-Carlo simulations to reshuffle redshifts of the quasar sample shows that a simple eye examination of the simulated distributions produces as many quasar pairs or associations than in the original field. A further preliminary quantitative study using the autocorrelation function shows that quasar clustering is absent on any scale from 10 to 3500 Mpc (Ho=100).
Inflationary universe models and clustering of quasar red shifts
Authors: Sivaram C.
Published: July 2016

Recently it has been shown that many of the puzzling features of conventional cosmological models (such as the horizon and flatness problems) could be explained by invoking inflationary models of the early universe with an exponential expansion phase at very early epochs. These models have the added advantage that they are able to make a definite prediction about the present matter density in the universe, i.e. they require that the density be exactly equal to the closure density which in turn can be easily estimated from the Hubble constant now known to within a factor of two. Now if one goes back to an earlier idea that explored the possibility of unusual clustering of quasar redshifts around z = 2 or 3, we get an example of another cosmological model with a definite prediction for the present overall matter density. This is a modified version of the Eddington-Lemaitre type of model which naturally accommodates such features as a clustering of quasars at certain epochs. From these models one can get a prediction for the present matter density which would be an involved function of the Hubble constant and the redshifts at which such clustering occurs. It can be shown that if such clustering had occurred at any z, the present matter density predicted would be substantially smaller than the corresponding closure density. The conclusion is that any clustering of quasar redshifts is incompatiable with inflationary universe models, indirectly providing observational support for these new theories.
Large Distances, Hidden Mass and Fluctuations of the RELIC Radiation
Authors: Lukash V. N. , Novikov I. D.
Published: July 2016

The problem of determining the fundamental constants of the Universe - Ho, qo, Ω, Λ, hidden matter, and the primordial perturbation parameters is considered. The likelihood of finding new evidence for large-scale Δ T/T-fluctuations is discussed.
The Distribution of Bright Galaxies
Authors: Chincarini G. , Vettolani G.
Published: July 2016

Following a brief review of the early developments in the field, we discuss a few new advances in the distribution of bright galaxies which occured after the extensive review paper by Oort (1983) We show that the large scale structure, shells, filaments and/or sheets, may bias the determination of the velocity dispersion in clusters of galaxies and that the boundaries of the voids may often be biassed by the clusters and groups velocity dispersion.

Of interest are the very large structures selected on catalogs of clusters of galaxies. The “Local Structure” claimed by Tully seems to be somewhat flattened and about parallel to the plane of the Local Supercluster. If the structure is real the alignement is relevant in relation to the physical mechanisms at work at the time of formation. Noticeable progress has been done in the measurement of the large scale velocity field. Large scale motions may somewhat bias the study of the topology of the Universe.

Relevant work has be done on the shape of the boundaries of the voids and observational work is progressing to detect faint galaxies in voids and determine their charactestics. This is important also in relation to the theory of biassed galaxy formation. To better focus the observational problem and eventually related biasses, we give some statistics on dwarf galaxies in the Virgo cluster.
Large-Scale Structure: The Center for Astrophysics Redshift Survey
Authors: Geller Margaret J. , Huchra John P. , Lapparent Valérie de
Published: July 2016

Two slices of the Center for Astrophysics (CfA) redshift survey extension are now complete. The survey indicates that galaxies are distributed on the thin surfaces of “bubble-like” structures. The voids in the survey have diameters as large as 5,000 km s−1. These structures challenge theories for the formation of large-scale structure in the universe and suggest new approaches to several problems in the field.
The Galaxian Surface Density in the Nearby Universe
Authors: Balkowski C. , Chamaraux P. , Fontanelli P.
Published: July 2016

A simple study of the galaxian surface density maps of the nearby Universe, obtained from CGCG, MCG and ESO catalogues, has allowed to evidence 3 new large-scale structures. Analysis of the redshifts of the galaxies in the corresponding zones shows that two of them are probably real three-dimensional entities.
Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities
Authors: Bahcall Neta A.
Published: July 2016

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.
Large-Scale Distribution of Galaxies with Different Luminosities
Authors: Xia X. Y. , Deng Z. G. , Zhou Y. Y.
Published: July 2016

Analyses for complete samples of galaxies and clusters of galaxies showed that the two-point correlation function of galaxy-galaxy and cluster-cluster have form of power law with power indices about −1.8 (Peebles, 1980; Bahcall and Soneira, 1983). Because the completeness of a sample means that we have observed completely the objects brighter than a given apparent magnitude in certain sky region. But, we know that a complete sample will be lack of faint objects at distant region. If we attempt to avoid the influences of any non-intrinsic properties on the analysis, we have to use the samples which are complete in certain interval of absolute magnitude.
Evolution of Very Faint Field Galaxies and Quasars
Authors: Koo David C. , Kron Richard G.
Published: July 2016

This paper reports preliminary results of two long-term redshift surveys that are near completion. One consists of nearly 400 redshifts of field galaxies; the sample is faint enough (B ≲ 22) to test models of galaxy luminosity and color evolution (and possibly cosmology) and to search for the presence of very large-scale structures among distant field galaxies. The other consists of over 60 spectra of quasar candidates of similar faintness; the identifications and redshifts of bona-fide quasars provide strong constraints on the evolution and shape of the luminosity function of distant quasars. Almost all of the observations have been made with the 4m telescope at Kitt Peak National Observatory with the Cryogenic Camera in multiaperture mode. The spectral range covered 4500Å to 7500Å with 15Å FWHM resolution and 4Å per pixel; simultaneous exposures of an hour or two were made for about 10 objects within the 5 arcmin field of view.
Correlation of X-Ray and Infrared Emission of Radio-Quiet QSOs
Authors: Worrall D. M.
Published: July 2016

A correlation of the form , with γ = 0.83, is found between 2 keV monochromatic X-ray luminosity and 1.65 μm monochromatic infrared luminosity for a sample of optically selected radio-quiet QSOs. This is equivalent to an average 1.65 μm to 2 keV spectral index of αir/x = 1.28+0.05 log(lir/1031 ergs s−1 Hz−1). The ratio of X-ray to infrared luminosity decreases with increasing infrared luminosity in a manner similar to the relationship between X-ray and optical luminosity. The standard deviations of the distributions of data about the best-fit functions are comparable for the X-ray versus infrared and X-ray versus optical fits. Thus, contrary to a previous claim, the infrared luminosity is not better than the optical luminosity at predicting the X-ray emission from QSOs.
Counts of Optically Selected Quasars in the Magnitude Range 19<J<22
Authors: Zitelli V. , Marano B. , Zamorani G.
Published: July 2016

We present the current status of a survey of faint, optically selected quasars covering 0.7 square degrees. Candidates have been selected through multicolour search, grism spectroscopy, and, to some extent, variability analysis. Slit spectroscopy for almost all the high priority candidates brighter than J=20.84 yielded 22 confirmed quasars. In the magnitude range J=21–22 our results are in very good agreement with other existing surveys. The extension of the survey on an adjacent field is in progress.
A Complete Sample of Flat-Spectrum Radio Sources from the Parkes 2.7 GHz Survey
Authors: Savage A. , Chandler C.J. , Jauncey David L. , Batty Michael J. , White Graeme L. , Peterson B.A. , Peters W.L. , Gulkis S. , Condon J.J.
Published: July 2016

We describe our complete sample of flat-spectrum radio sources with fluxes >0.5 Jy selected from the Parkes 2700 MHz catalogue. The sample covers all right ascensions and declinations from +10° to −45°, but excluding the galactic plane (b < 10°), and contains some 400 sources.
An Exploration of Volume Test V/Vm Under Various Values of Deceleration Parameter qo
Authors: Gong(Kung) S. M. , Li H. J. , Xia C. L.
Published: July 2016

The problem of volume test, V/Vm, in zero pressure and matter dominated Friedmann universe model is explored under various values of deceleration parameter qo. The following conclusions are drawn. (i) For different values of qo, the change of V/Vm is sensitive at small values of z. Since values of V/Vm are very small at small values of z, this change exerts little effect on the average values of V/Vm. (ii) when values of z and zm are fixed for each member of a sample, large values of qo yield larger values of V/Vm, especially in the case of large z. (iii) For qo<1, the method of volume test is reliable. When qo>2, especially qo>3, this method has to be used with caution at large z.
Gravitational Lens Effects of Dark Matter of Milky Way
Authors: Xu C. M. , Wu X. J.
Published: July 2016

In this paper, dark matter of Milky Way is discussed as a transparent gravitational lens. The mass distribution of Milky Way is composed of spheroid, disk and dark matter (corona). The trajectory of light ray influnced by Milky Way has been calculated numerically. The deflecting angle to a extragalactic souce is changed with different observational direction and is about several seconds in maximum. The brightness amplification ratio Kv of extragalactic background radiation is also derived from the redistribution of intensity due to the gravitational lens effects of Milky Way, ΔKv/Kv is about 10−5 in maximum. Kv has been expanding to multipole with spherical harmonics by means of Kv distribution in celestial sphere. Dipole and qudrapole are about 3×10−6 and 7×10−6 respectively, which might be added to the observational data of microwave background radiation. A measurement method to pick out the gravitational lens effects from real cosmological anisotropy has been proposed. (ref. 8)
Observational Cosmology 1986: A summary of IAU Symposium No 124, Beijing, China
Authors: Longair M S
Published: July 2016

“This symposium marks the real beginning of observational cosmology”, Allan Sandage, 29 August 1986.

It is a pleasure to be invited to attempt to summarise the very intense work of the last 6 days. Virtually all aspects of contemporary observational cosmology have been described and debated and it is my task to try to put this wealth of new material into context. As in all such surveys, allowance must be made for personal bias - like everyone else, I am sure I am giving an unbiased view but you must judge for yourselves!
Kinematic Mapping of the Narrow Line Region of NGC4151
Authors: Kaiser M.E. , Bradley L.D. , Hutchings J.B. , Kraemer S.B. , Crenshaw D.M. , Ruiz J. , Weistrop D. , Nelson C. , Gull T.R.
Published: July 2016

We present HSTSpace Telescope Imaging Spectrograph (STIS) slitless spectroscopy of the NGC4151 narrow line region (NLR) as a probe of the kinematic stucture of the extended emission-line gas emanating from the nucleus. Using slitless spectroscopy at two roll angles (with a spatial resolution of 0.051 ″/pixel and a point source spectral resolution of 0.55 Å) augmented with narrow band images, we have mapped the velocity field of the NLR as defined by ˜60 discrete cloud structures in [OIII]. Flux measurements of [OII], Hβ, [OIII], [OI], and [SII] were made for individual cloud structures wherever possible.
Magnetohydrodynamic Origin of Jets from Accretion Disks
Authors: Lovelace R.V.E. , Ustyugova G.V. , Koldoba A.V.
Published: July 2016

A review is made of recent magnetohydrodynamic (MHD) theory and simulations of origin of jets from accretion disks. Many compact astrophysical objects emit powerful, highly-collimated, oppositely directed jets. Included are the extra galactic radio jets of active galaxies and quasars, and old compact stars in binaries, and emission line jets in young stellar objects. It is widely thought that these different jets arise from rotating, conducting accretion disks threaded by an ordered magnetic field. The twisting of the B field by the rotation of the disk drives the jets by magnetically extracting matter, angular momentum, and energy from the accretion disk. Two main regimes have been discussed theoretically, hydromagnetic winds which have a significant mass flux, and Poynting flux jets where the mass flux is negligible. Over the past several years, exciting new developments on models of jets have come from progress in MHD simulations which now allow the study of the origin -the acceleration and collimation - of jets from accretion disks. Simulation studies in the hydromagnetic wind regime indicate that the outflows are accelerated close to their region of origin whereas the collimation occurs at much larger distances.
The Emission Line Properties of the 3CR Radio Galaxies at Redshift One: Shocks, Evolution, and the Alignment Effect
Authors: Best Philip , Röttgering Huub , Longair Malcolm
Published: July 2016

The results of a deep spectroscopic campaign on powerful radio galaxies with redshifts z ˜ 1, to investigate in detail their emission line gas properties, are presented. Both the 2-dimensional velocity structure of the [OII] 3727 emission line and the ionisation state of the gas are found to be strongly dependent upon the linear size (age) of the radio source in a manner indicative of the emission line properties of small (young) radio sources being dominated by the passage of the radio source shocks. The consequences of this evolution throughout the few x107 year lifetime of the radio source are discussed, particularly with relation to the alignment of the UV–optical continuum emission of these objects along their radio axis, the nature of which shows similar evolution.
Origin of Blazar Activity
Authors: Romanova M. M.
Published: July 2016

Models of Blazars based on the propagation of finite discontinuities or fronts in the Poynting flux jet from the innermost regions of an accretion disk around a black hole are discussed. Such fronts may be responsible for short time–scale (from less than hours to days) flares in different wavebands from high frequency radioband to TeV, with delay in low radio frequencies as a result of synchrotron self-absorption. The cases of magnetic fields of one and opposite polarities across the front are investigated. We find that annihilation of magnetic field in the front leads to higher energy spectrum of leptons and possibility of strong TeV flares. Electron–positron pairs form in most cases as a result of interaction between numerous synchrotron photons and SSC photons, and constitute the majority species, compared with the ions at subparsec scales. Frequent weak outbursts may be responsible for flickering core radiation in all wavebands, while the stronger outbursts may be observed as short time–scale flares.
Broad Emission Lines in AGN: Phenomenology and Models
Authors: W. Sulentic Jack , Marziani Paolo , Calvani Massimo , Dultzin-Hacyan Deborah
Published: July 2016

We review the phenomenology of broad emission lines in AGN. We show that velocity displacements relative to the local rest frame of Hβ and CIVλ1549 are real. The most significant line displacement result involves a systematic blueshift for CIV, seen only in radio-quiet sources. We find some evidence that the amplitude of this displacement may correlate with source orientation. We show that disagreement between different studies of the CIV line properties is due to whether or not a narrow line component was subtracted. Finally, we consider evidence that optical and X-ray broad lines arise in an accretion disk. We show that the evidence for a disk origin is far from overwhelming for both Hβ and FeKα.
Bardeen-Petterson Effect and Broad HI Profiles of Seyferts
Authors: Bachev Rumen
Published: July 2016

A thin accretion disk could be not only the energy source of AGN but also the matter producing broad emission lines of Seyfert 1 type nuclei (Dumont & Collin-Souffrin, 1990 B). A possible mechanism for this is reprocessing of central hard X-ray radiation by the outer (at 102–5 RG, RG is the Schwarzschild radius), low-temperature regions of the disk. This mechanism is effective enough especially if the disk is a non-planar structure (a warped or twisted disk), when the outer parts could be directly seen from the centre. An accretion disk around a Kerr black hole could be twisted if the angular momentum of the accreting gas is initially not aligned with the rotation axis of the hole. Due to the differential Lense-Thirring precession of orbits around a Kerr black hole, a viscous disk is a steady but non-planar structure. This is the well-known Bardeen-Petterson effect (Bardeen & Petterson, 1975). Near the hole, at distances R>RBP, where RBP is the Bardeen-Petterson radius, the flow is aligned with the equatorial plane of the black hole, while at larger distances it is tilted to its initial orbital plane (Fig. 1).
Morphology and Photometry of the UV-Excess Galaxy Pair NGC 7770/7771
Authors: Ali G. B. , I. Osman A. M.
Published: July 2016

Morphology of the nuclear region of the component NGC 7770 indicates that it has a complicated structure in the B-band, while the V-band shows a double nuclear structure. The brightness and color of the nuclear condensations are given. Detailed photometric analysis of this component including luminosity profiles along major and minor scans as well as position angle and ellipticity curves is obtained. Integration and decomposition of the luminosity profiles are also performed. The color distribution and integrated color are also studied taking into account that the blue color together with the unusual color distribution are characteristics relevant to UV-excess galaxies. The integrated photometric parameters are also given.

The state of interaction between the components of the pair is also investigated. The peculiar features appearing in the isophotal maps, the truncation of the luminosity profile along the side of interaction and the unusual appearance of the structural profiles are discussed and considered as strong evidence for the real state of interaction between the components of the pair. A lower limit of the total orbital mass of the system is found to be Mt=1.36 × 1010 M⊙, and the total mass-to-luminosity ratio is f=0.63 f⊙.
First Ranked Galaxy Morphology and Morphological Content in Groups of Galaxies
Authors: Mahtessian A. P. , Movsessian V. H.
Published: July 2016

V. Ambartsumian (1956) has shown that the observable quantity of double and multiple galaxies much exceeds that expected, based on the assumption about dissociative balance. He has concluded that the members of double and multiple systems, as well as the clusters, could not arise independently of each other, and only then to be united in systems, by mutual capture. They should arise in common. Moreover, when in a group are large luminous central galaxies, the origin of the weak members of the group should be caused by activity of a nucleus of the central galaxy (Ambartsumian 1962). On the other hand, recently, there was widespread the opinion that the properties of central galaxies of groups and clusters are caused by interactions with environmental galaxies.
Ambartsumian's Greatest Insight - The Origin of Galaxies
Authors: Arp Halton
Published: July 2016

From simply looking at pictures of galaxies Ambartsumian realized that new galaxies were formed in ejections from old galaxies. In the ensuing 40 years, observations have supported in increasing detail his original insight. We can now empirically outline the development of compact objects emerging from the nuclei of active galaxies into young star forming galaxies and finally into aggregates of old stars.

The observations actually require galaxies to continually originate in a low particle mass plasma which has remarkably similar properties to the “superfluid” which Ambartsumian foresaw. He had the courage to present these conclusions to influential astronomers who still today reject any origin of galaxies other than in the Big Bang. In this most important subject of science, the nature of our universe, Ambartsumian's revolutionary insights are now increasingly vindicated by observation.
Ultrasoft Narrow-line Seyfert 1 Galaxies: An Extreme of Accretion onto Supermassive Black Holes
Authors: Brandt W. N.
Published: July 2016

X-ray studies of ultrasoft narrow-line Seyfert 1 galaxies are revealing surprising new phenomena that are expanding our understanding of Seyfert activity, and they may well allow us to observe the effects of high mass accretion rates onto supermassive black holes. I briefly review the basic properties of these galaxies, their importance in a general context, and the prospects for studying them further in the future.
Accreting Plasmas in Black Hole Magnetospheres
Authors: Takahashi M.
Published: July 2016

We present a fully relativistic study on the standing shock formation for magnetohydrodynamical plasmas in a stationary and axisymmetric black hole magnetosphere. We express all the postshock physical quantities in terms of the relativistic compression ratio. Then, the downstream state of a shocked plasma is determined by the upstream state of the accretion. We also discuss the dragging-effects of the rotating black hole on the shock conditions.
Magnetohydrodynamic Turbulence in Accretion Discs
Authors: Torkelsson U. , Brandenburg A. , Nordlund Å. , Stein R. F.
Published: July 2016

We present results from numerical simulations of magneto-hydrodynamic turbulence in accretion discs. Our simulations show that the turbulent stresses that drive the accretion are less stratified than the matter; thus, the surface layers are more strongly heated than the interior of the disc.
Electron Acceleration by Strong DC Electric Fields in Extragalactic Jets
Authors: Litvinenko Y. E.
Published: July 2016

Fast magnetic reconnection in extragalactic jets leads to electron acceleration by the DC electric field in the reconnecting current sheet. The maximum electron energy (γ > 106) and the acceleration time (< 106 s) are determined by the magnetic field dynamics in the sheet.
Collimation of Magnetically Driven Outflows from Accretion Disks
Authors: Kudoh T. , Matsumoto R. , Shibata K.
Published: July 2016

We performed 2.5-dimensional, nonsteady MHD numerical simulations to investigate the acceleration and collimation of magnetically driven outflows from accretion disks, including the accretion process itself, consistently. As an initial condition, we used a paraboloidal magnetic field line that is produced by electric current on the equatorial plane. We found that the outflow ejected from the accretion disk is collimated by the pinch effect of the toroidal component of the magnetic field that is produced by the rotation of the disk.
Numerical Simulations of the Precessing Jets of SS433
Authors: Müller E. , Brinkmann W.
Published: July 2016

The unique Galactic object SS433 contains the best-studied relativistic jets, and their physical parameters (velocity, temperature, density) are known to an astronomically unprecedented accuracy, i.e., to factors of order unity. The comparison of numerical simulations of these jets with observations provides deeper insight into the SS433/W50 system and is ideal for testing our understanding of the jet phenomenon in general.
Reacceleration of Relativistic Electrons by Turbulent Alfvén Waves in Radio Jets
Authors: Wang D.-Y. , Ma Y.
Published: July 2016

Relativistic electrons may be effectively accelerated by turbulent Alfvén waves in radio jets. The acceleration spectrum is a power law with the electron energy as high as γ ~ 106, but the spectrum index is ~ 1.2 in the condition of diffusion approximation, which is less than the observation value.
Symposium Summary and Concluding Remarks
Authors: Field G. B.
Published: July 2016

The symposium included invited papers, a panel discussion, and poster papers. In the following, I have summarized what to me were some of the more interesting parts of invited papers under the headings of trends, particle acceleration and heating, disks and jets, gamma-ray bursts, and other sources.
History, Strategy and Status of IAU Actions
Authors: Andersen J.
Published: July 2016

A brief account is given of how environmental challenges to astronomy have grown and diversified and how the IAU has addressed the problem. In the 1970s and '80s, appeals and Resolutions of increasing urgency were addressed to governments and other authorities. In the 1990s, interdisciplinary organisations such as ICSU and UNESCO were enlisted as allies. The present Symposium marks the beginning of a new phase, where direct collaboration with United Nations Member States is sought through the UN Committee on the Peaceful Uses of Outer Space.
International Action
Authors: McNally D.
Published: July 2016

The roles of the International Astronomical Union, the other ICSU Unions, UNESCO and the UN are reviewed in order to assess the way forward to resolve a unique situation - the impact of civilisation on the observational procedures of a particular science - astronomy. Action to create a modus vivendi to allow the continuance of vigorous astronomical science within a vibrant technological society is suggested.