bluuebunny/crossref_metadata_2025 huggingface dataset:
The Structure and Evolution of Massive Stars
Authors: Chiosi C.
Published: July 2016

This review is restricted to the most recent studies of the structure of stars in the approximate range from 10 to 100 M⊙, during the core H- and He-burning phases. Other recent major reviews on this subject are by Dallaporta (1971), Massevich and Tutukov (1974) and Iben (1974). The lower limit was chosen to be just above the transition from degeneracy to non-degeneracy in the core at carbon ignition (Schwarzschild and Härm 1958). The upper limit is very uncertain. The canonical value of about 60 M⊙for Pop I composition was set by Schwarzschild and Harm (1959), using linear pulsation theory. More recent non-linear dynamical calculations lift the limit above 100 M⊙, and also show that mass loss by vibrational instability occurs at such a rate that stars in the range from 100 to 200 M⊙can survive for a time comparable to the total main sequence lifetime (Appenzeller 1970a, b, Ziebarth 1970, Talbot 1971a,b and Papaloizou and Taylor 1974).
Fundamental Parameters and the Helium Content of Eclipsing Spectroscopic Binaries
Authors: Jørgensen H.E.
Published: July 2016

Today we know accurate masses, radii, surface gravities and luminosities or effective temperatures of a very small number of stars. There are several reasons for deriving accurate parameters of stars. I shall mention only four problems:

(i)

checking stellar evolution calculations, particularly calculations of isochrones, using binaries,

(ii)

derivation of helium content in stars of different age,

(iii)

checking log g derived from photometry and stellar atmosphere calculations,

(iv)

determination of accurate positions in the HR diagram to get an independent check on calibrations of photometric systems.
Quasar Surveys
Authors: Smith M. G.
Published: July 2016

A review is given of progress in surveys for quasars at frequencies from radio to x-ray. Radio results show evidence for a decline in the radio luminosity function for flat-spectrum radio sources at redshifts z > 2. The IRAS survey is uncovering hitherto unknown dusty Seyfert galaxies. Optical surveys, which yield the largest number of QSOs per square degree, may suffer from selection effects which depend on intrinsic luminosity, redshift, and spectral evolution - particularly above redshift 2. Below redshifts of about 2.3, the optical magnitude-redshift plane is being filled in to the point where the evolution of the luminosity function can be seen directly. The statistics of quasar pair separations provide the best evidence so far for quasar clustering.

The existence of many potentially significant selection effects means that a multi-frequency approach to quasar surveys is likely to prove essential to an understanding of the evolutionary behaviour of the quasar population as a whole.
Ultraviolet excess quasar candidates in large fields: a status report concerning the NGC 450 area
Authors: Gosset E. , Surdej J. , Swings J.P.
Published: July 2016

New results are presented based on several statistical analyses of a 25 square degree field around NGC450. They include the detection of a clustering on a small scale (⋍ 10 arcminutes) and possible large scale inhomogeneities.
Compact continuum emission from violently variable quasars and BL Lacertae objects
Authors: Bregman Joel N.
Published: July 2016

A dozen BL Lacertae objects and violently variable quasars were observed repeatedly during the last six years by obtaining simultaneous measurements from the radio through X-ray region. The relationship between the radio-millimeter, infrared-ultraviolet, and X-ray regions are determined from single epoch spectra and variability measurements. The structure of the emitting regions and the emission mechanisms are discussed. The results of this program are summarized.
Physical interpretations from quasar light curves — 3c273
Authors: Smith Harlan J. , Angione Ronald J.
Published: July 2016

Light curves of quasars give information on time scales (hence limits on size of principal luminous source), and on phase of variation (hence evidence bearing on the distance of surrounding regions or shells).
Evolution of the compact radio source 3C 345
Authors: Biretta J. , Cohen M. , Moore R.
Published: July 2016

The quasar 3C 345 is recognized as a strong, variable, superluminal radio source, an optically violent variable, and a weak X-ray source. We present results of VLBI monitoring between 1979 and 1984 at 2.3, 5.0, 10.7, and 22.2 GHz using antennas of the U.S. and European VLBI Networks. These results are interpreted in terms of a relativistic jet model (Biretta 1985; Biretta et al. 1986).
New superluminal quasars
Authors: Pearson T. J. , Barthel P. D. , Readhead A. C. S. , Lawrence C. R.
Published: July 2016

Since 1977 we have been engaged on a project to survey the milliarcsecond structure and internal motions of a complete, unbiased sample of 65 radio sources (Pearson and Readhead 1984). One of the goals of the project was to discover more superluminal sources and find out how common they are. The sample contains three established superluminal sources (3C 179, 3C 345, and BL Lacertae); so far we have discovered three new superluminal quasars (0850+581, 1642+690, and 1928+738), and a fourth (3C 216) that may be superluminal. Thus at least six out of the 65 sources are superluminal, and we expect to find more as our observations proceed.
Monitoring of BL Lac objects at 327 MHz
Authors: Vats Hari Om , Degaonkar S.S. , Manoharan P.K. , Ananthakrishnan S.
Published: July 2016

The variable BL Lac objects OJ 287 and B2 (1308+326) have been observed using the Ooty Synthesis Radio Telescope (OSRT) at 327 MHz. Preliminary analysis of one of them, namely OJ 287 indicates that flux variations of ∼ 20% on a time scale of few hours to few days could be present, but this needs to be confirmed by a larger data base.
PKS 0812+020: a quasar interacting with its environment
Authors: Ghigo F. , Rudnick L. , Wehinger P. , Wyckoff S. , Spinrad H. , Johnston K.
Published: July 2016

Slit spectra have shown optical emission line gas in the vicinity of the radio jet and the north radio lobe of PKS 0812+020. Velocities up to −1000 km/s with respect to the central quasar are seen in the north lobe. The [OII] emission strength becomes comparable to the [OIII] near the north lobe, as would be expected from acceleration by shocks. We suggest this acceleration occurs by interaction with the radio-emitting jet.
WSRT observations of core-dominated radio sources
Authors: Bruyn A.G. de , Schilizzi R.T.
Published: July 2016

A few years ago we presented evidence for large scale radio structures around most superluminal radio sources (Schilizzi and de Bruyn, 1983). The extended emission is relatively faint and, in at least two cases (3C120 and 30345), exhibits a rather complex morphology. Although the sample was small, the conclusion seemed inescapable that the largest angular sizes (LAS) of the superluminals do not permit a large deprojection factor due to foreshortening, without making these sources exceptionally large intrinsically. That is to say, they would be exceptional within the context of the unified scheme (US) which interprets superluminal sources as favourably oriented, strongly beamed, core components of classical double radio sources. To save the US, we concluded that the ejection axes of these sources must undergo a large (≥ 30°) change of direction in the period between the creation of the outer and inner emission regions. Superluminality would then be a temporary phase (although possibly recurrent) in the lifespan of a large fraction of the parent population of classical doubles.
High resolution VLA observations of core-dominated quasars
Authors: O'Dea C.P. , Barvainis R. , Challis P.
Published: July 2016

We selected 16 core-dominated sources based on two criteria. (1) They have a core-jet VLBI morphology. (2) Previous observations at lower resolution indicated that there was extended structure on scales of ≥1″. The sources were observed in the A configuration of the VLA at 6 and 2 cm with typical resolutions of ∼0.″45 and ∼0.″15 respectively. Contour plots of total intensity with E vectors superposed (length proportional to fractional polarization) of four sources with jets are shown in Figure 1.
X-ray bursting activity in the BL Lacertae object PKS 2155-304
Authors: Maccagni D. , Chiappetti L. , Maraschi L. , Molteni D. , Morini M. , Tanzi E.G. , Treves A. , Wolter A.
Published: July 2016

The bright BL Lac object PKS 2155-304 (mv=13; z=0.117) was observed with EXOSAT at five epochs (1983 Oct. 31, Nov. 30, 1984 Nov. 6, 7 and 11), for a total of about 30 hours of exposure time. Here we present data and results obtained with the Low Energy (LE) telescopes, in the band 0.05–2. keV, and with the Medium Energy (ME) argon proportional counters in the range 1.–6. keV.
Broad Absorption Line QSOs
Authors: Turnshek David A.
Published: July 2016

Observational constraints on models for broad absorption line (BAL) QSOs are discussed. The picture which emerges is one in which the broad absorption line region (BALR) contributes to the broad emission line region (ELR) as a high ionization component. Depending on QSO luminosity, the limits on the distance of the BALR from the central source are 1–1000 pc. A highly metal enriched and disk-like geometry for the region is indicated. The similarity between the absorption in some radio quiet BAL QSOs and the associated complexes of absorption in some radio loud QSOs may indicate that the BALR outflow can affect the region surrounding a QSO out to distances in excess of several hundred kpc.
Black Hole Models of Quasars
Authors: Blandford R. D.
Published: July 2016

Observations of active galactic nuclei are interpreted in terms of a theoretical model involving accretion onto a massive black hole. Optical quasars and Seyfert galaxies are associated with holes accreting near the Eddington rate and radio galaxies with sub-critical accretion. It is argued that magnetic fields are largely responsible for extracting energy and angular momentum from black holes and disks. Recent studies of electron-positron pair plasmas and their possible role in establishing the emergent X-ray spectrum are reviewed. The main evolutionary properties of active galactic nuclei can be interpreted in terms of a simple model in which black holes accrete gas at a rate dictated by the rate of gas supply which decreases with cosmic time. It may be worth searching for eclipsing binary black holes in lower power Seyferts.
Variability and Instabilities of Accretion Disks
Authors: Abramowicz M.A. , Lasota J.P. , Xu C.
Published: July 2016

In the Seyfert galaxy NGC 1566 and quasars 3C 345, 3C 446 long term (∼ 103 days) variations have been observed. We propose to explain them as a limit cycle behaviour, similar to that well studied in the case of dwarf novae outbursts. The key element of our analysis is the relationship between the accretion rate · and the surface density Σ.
Accretion disk flares
Authors: Sturrock P. A. , Yang W.
Published: July 2016

Flare activity on the sun may be attributed to the distortion of coronal magnetic field caused primarily by vortical (Shearing) photospheric motion. If an accretion disk is permeated by a magnetic field, the strong differential rotation of the disk will lead to similar stressing of the magnetosphere, and one may expect similar flare activity to occur. It is likely that the density of plasma in the maganetosphere is sufficiently large that the “frozen flux” condition is satisfied, and sufficiently small that the magnetic field will be substantially in the force-free state.
Complete quasar samples and comparative cosmology
Authors: Segal I. E.
Published: July 2016

Comprehensive testing of alternative cosmologies on the basis of complete samples of discrete sources is described. Application is made to the comparison of the Friedman and chronometric cosmologies (denoted C1 and C2) using quasar samples. C2 predicts the results of analyses predicated on C1 that represent evolution in the C1 framework, but is itself nonevolutionary, nonparametric, and consistent with observation.
On the concentration of high redshift quasars in the region of m33
Authors: Kapahi Vijay K.
Published: July 2016

We have investigated the strong concentration of high redshift radio quasars in a large area of the sky near M33 reported by Arp. Selection effects appear to be important in determining the significance of the inhomogeneity.
Gravitational Lenses: Observations
Authors: Burke Bernard F.
Published: July 2016

The gravitational lens phenomenon is shown to be not uncommon. A search is now underway to find a larger number of examples, using the VLA to search for candidates, following up with optical observations to establish equality of redshifts in the images. Most of the present lensing examples exhibit anomalous behavior that is most easily understood as evidence for large quantities of intervening non-luminous matter.
Gas in cosmic voids
Authors: Gondhalekar P M , Brosch N
Published: July 2016

Absorption lines at the redshifts of cosmic voids in Perseus-Pisces and Böotes have been detected in the ultraviolet spectra of background quasars. The detection of Si IV and C IV lines besides Ly α suggests chemical enrichment of gas in the voids. Additional observations of three sight-lines through the void in the Böotes suggests that the gas in the void is clumped in large clouds.
High Sensitivity Observations of the Microwave Background Radiation
Authors: Davies R.D. , Lasenby A.N.
Published: July 2016

Angular fluctuations in the cosmic microwave background radiation are indicators of the seed structure at recombination (z ≅ 1000) which subsequently evolves into the present-day Universe (z = 0). Such measurements provide stringent tests of the cosmological theories of universal evolution and have implications for allowed values of the density and composition of matter in the Universe.
Spatial Distribution of Galaxies: Biased Galaxy Formation, Supercluster-Void Topology, and Isolated Galaxies
Authors: Einasto Jaan , Saar Enn
Published: July 2016

To study distribution of galaxies and voids, the rectangular box under study is divided into cubic cells, and mean density of particles in cells is derived. For any density level cells can be divided into ‘filled’ or ‘empty’ ones if their density is higher or lower than a threshold density. The length and volume of the largest connected system, as well as the number of systems of connected cells are derived for observed, model and random samples. The comparison of results demonstrates that galaxy formation is biased, supercluster-void topology is sponge-like in a wide threshold density interval, and that there are no isolated galaxies in voids.
The Void Probability Function as a Statistical Indicator
Authors: Lachièze-Rey Marc , Maurogordato Sophie
Published: July 2016

Recent results concerning the galaxy distribution at scales < 100 h−1 Mpc (Ho = 100 h kms−1 Mpc−1) show a number of characteristics which cannot be described by conventional statistical models. Correlation functions, for instance, can in no way give account of the presence of voids of the cellular (or spongy) appearance of the local galaxy distribution (M. Geller, this conference). There is clearly a need for new kinds of statistical models and statistical indicators.
The Distribution of Faint Galaxies
Authors: Ellis Richard
Published: July 2016

Faint galaxy data are reviewed in the context of standard evolutionary models and our understanding of the statistical properties of galaxy populations. The differences in number magnitude counts from group to group can largely be understood via fluctuations induced by large scale clustering. However count slopes still present convincing arguments for an extra component of faint blue galaxies beyond B ∼21. Colours provide an useful tool in estimating redshift distributions but the uncertainties are large for the bluest galaxies of interest. However, new faint object redshift surveys are now underway and promise to determine definitively the nature of this extra component. We discuss preliminary results from one of these surveys. Neither distant luminous galaxies nor intrinsically faint nearby galaxies appear to be very numerous to B = 21.5. Many of the galaxies with 0.2 < z < 0.4 show spectral signatures of prominent star-formation. If such objects are somehow related to the excess counts, the traditional redshift-dependent evolutionary theory may require revision.
The Sponge-Like Topology of Large Scale Structure in the Universe
Authors: Gott J. Richard
Published: July 2016

We describe and apply a quantitative measure of the topology of large scale structure: the genus of density contours in a smoothed density distribution. For random phase (gaussian) density fields, the mean genus per unit volume exhibits a universal dependence on threshold density, with a normalizing factor that can be calculated from the power spectrum. The topology of the observational sample is consistent with the random phase, cold dark matter model.
Search for Proto-Clusters at Meter Wavelengths
Authors: Swarup G. , Subrahmanyan R.
Published: July 2016

Although current models of galaxy formation differ widely, it seems likely that just prior to their formation, a significant fraction of the matter in the Universe was in the form of neutral hydrogen (HI) clouds at redshifts z greater than about 3, beyond which the quasar density decreases rapidly. In this paper we have taken a semi-empirical approach for estimating values of measurable parameters for a variety of scale sizes and masses expected in the epoch prior to galaxy formation and have compared these with the results of searches made so far.
Spectroscopy of QSOs from the Texas Radio Survey
Authors: Wills D. , Wills Beverley J.
Published: July 2016

We report briefly on our optical spectroscopy of QSOs from the radio survey in progress at the University of Texas Radio Astronomy Observatory (UTRAO). The radio survey, under the direction of Dr J. N. Douglas, covers declinations north of −36 degrees, in strips that are 9 degrees wide in declination. Preliminary results for the strip centered at +18 degrees have been published (Douglas et al. 1980) and other strips are currently being prepared for publication. The complete catalogue will list 1 arcsec positions and some structure information for about 75,000 sources stronger than about 250 mJy at 365 MHz. Optical identifications are made from the Palomar Observatory Sky Survey plates using an interactive laser measuring machine (Ghigo 1977), and the accuracy of the radio source positions allows the identifications to be made regardless of the colours of the objects. Optical spectroscopy of a sample of about 300 QSO candidates brighter than 19 mag, drawn from the +36, +18 and −12 degree strips, is being carried out at McDonald Observatory using an Intensified Dissector Scanner at the cassegrain focus of the 2.7m reflector. Two image-tube and dissector chains are available, together covering the range 3200–8500 A; a typical spectrum takes 1 hour to obtain, with wavelength resolution of 10 A over a total range of 3000 A.
Complete Samples of Variable Quasars
Authors: Hawkins M.R.S.
Published: July 2016

The merits of selecting samples of quasars for statistical analysis on the basis of optical variability is discussed. Samples selected this way are essentially uncontaminated by spurious objects, and contain no serious redshift biasses. A preliminary sample from a long term survey suggests a timescale of variation for quasars of about four years, and indicates a fall off in numbers at around B = 20.
A VLA Gravitational Lens Survey
Authors: Hewitt J. N. , Turner E. L. , Burke B. F. , Lawrence C. R. , Bennett C. L. , Langston G. I. , Gunn J. E.
Published: July 2016

Gravitational lens surveys are of cosmological interest because they provide a way to measure the gravitational field of both luminous and dark matter. Many of the other methods used to detect the presence of dark matter, such as studies of galaxy rotation curves and cluster dynamics, require that there be luminous objects in the gravitational field that act as tracers of the mass. This may introduce a selection effect. In constrast, in studies of gravitational lenses, the beacon we observe can be far (at distances of order one thousand Mpc) from the gravitational field. In this paper we describe a VLA survey designed to detect gravitational lensing on sub-arc second and arc second scales. We also present a preliminary result of the radio data: we find that the density of matter in the form of a uniform, comoving number density of 1011 to 1012M⊙ compact objects, luminous or dark, must be substantially less than the critical density.
1146+111B,C: A Giant Gravitational Lens?
Authors: Turner E.L.
Published: July 2016

The history and current observational status of the giant gravitational lens candidate 1146+111B,C are reviewed. In the absence of any new positive evidence and in the presence of reported differences in the UV and IR spectra of B and C, the lens hypothesis is clearly much weaker than previously. Nevertheless, given the substantial similarity of the spectra over a broad range of wavelengths, discrepancies among various spectroscopic observations of C, and the possibility of spectral variability plus large differential time delays, the data do not yet support any definite conclusion as to the nature of 1146+111B,C.
On the Nature of Radio Emission of AGNs: Spectra, Milli-arcsecond Structure and Polarization
Authors: Kovalev Yu.A. , Kovalev Y.Y.
Published: July 2016

The main observational properties of AGNs at centimeter-decimeter wavelengths –- spectra, variability on various time scales, polarization and milli-arcsecond maps –- are in agreement with calculations in a jet model with a strong quasi radial magnetic field. Typical spectra and VLBI structures can be explained by a simple case of a straight line jet, unlike the degree of the linear polarization. Curved jets in the model allow decreasing the polarization to observational values as well.
Surface Photometry of Barred AGN Arakelian 564
Authors: Petrov G. , Slavcheva L. , Bachev R. , Mihov B.
Published: July 2016

The Seyfert 1.5 galaxy Akn564 [1] is a well known X-ray active galactic nucleus (AGN) included in our list of selected barred AGN. The galaxy was observed during the August 1996 season at the 2-m RCC telescope of the Astronomical Observatory “Rozhen” of the Bulgarian Academy of Sciences. ST-6 with standard Schott V, R, I filters were used. MIDAS'96 package was used for the data reduction with teh Richter's expansion for the surface photometry [2]. Most of the basic data for the galaxy are shown in the Table 1 below.
Spectrophotometry of Selected AGN Seyfert Galaxy AKN 564
Authors: Slavcheva L.S. , Mihov B.M. , Petrov G.T. , Bachev R.S.
Published: July 2016

Akn 564 (α1950 = 22h40m18.3s, δ1950 = 29°27′47″) is a Sy1.5G SBb type galaxy. According to Zwicky (1966) it has a photographic magnitude mp = 14.4 and a redshift of 0.025. The spectra of the galaxy were obtained at the 2.6-m telescope of the Crimean Astrophysical Observatory with a spectrograph having a dispersion of 100 A mm−1. They were processed with the help of SPEC and LONG packages integrated in MIDAS. As a result of the spectrophotometry we obtain the fluxes at λλ 4363, 4959, 5007 A: I(4363), I(4959), I(5007). The spectrum of the galaxy in λλ 4000–7000 is shown in Figure 1. We use the relation of the fluxes of those narrow forbidden emission lines:

sensitive at a greater extent to the electron temperature Te than to the electron density ne. The value of R = 74.3 we got, having a typical value of ne = 5×105 cm−3 for the NLR (Narrow Line Region), leads to the estimation of a typical temperature of Te = 104 K.
On the QSO Content of the First Byurakan Survey and the Completeness of the Palomar Green Survey
Authors: Véron P. , Mickaelian A.M. , Gonçalves A.C. , Véron-Cetty M.P.
Published: July 2016

The second part of the First Byurakan Survey is aimed at detecting all bright (B < 16.5) UV-excess starlike objects in a large area of the sky. By comparison with major X-ray and radio surveys we tentatively identified as QSOs 11 FBS objects. We made spectroscopic observations of nine of them. We found six new QSOs bringing the total number of known QSOs in this survey to 42.

By comparison with the Palomar Green (PG) QSO survey, we found that the completeness of this last survey is of the order of 70% rather than 30–50% as suggested by several authors.
2.5–11.6 μ Spectrophotometry and Imaging of AGNs
Authors: Clavel J. , Schulz B. , Altieri B. , Barr P. , Claes P. , Heras A. , Leech K. , Metcalfe L. , Salama A.
Published: July 2016

We present low resolution spectrophotometric and imaging ISO observations of a sample of 58 AGN's over the 2.5–11.6 μ range. The data strongly support unification schemes and set new constraints on models of the molecular torus.
Investigation of a New Sample of IRAS Galaxies
Authors: Mickaelian A.M. , Hakopian S. A. , Balayan S. K.
Published: July 2016

A new sample of some 900 faint IRAS galaxies will be constructed after optical identifications of all IRAS point sources from PSC and FSC in an area with 1500 deg2 at high galactic latitudes. The identifications are being made on the basis of FBS low-dispersion spectra, DSS images and infrared colours. Some 320 IRAS sources have been identified and 180 galaxies have been found. Spectral observations of these objects revealed new AGN and luminous infrared galaxies.
Photometric Monitoring of Selected Quasars: The Highly Luminous Quasar HS 1946+7658
Authors: Mihov B.M. , Bachev R.S. , Strigachev A.A. , Slavcheva L.S. , Petrov G.T.
Published: July 2016

We present and discuss Johnson – Cousins V and R photometry of the highly luminous quasar HS 1946+7658 (z = 3.051). We found no evidence for strong variability during one year of monitoring.
Hidden Quasars in Ultraluminous Infrared Galaxies
Authors: Tran H. D. , Brotherton M. S. , Stanford S. A. , Breugel W. van
Published: July 2016

Many ultraluminous infrared galaxies (ULIRGs) are powered by quasars hidden in the center, but many are also powered by starbursts. A simply diagnostic diagram is proposed that can identify obscured quasars in ULIRGs by their high-ionization emission lines ([O III]λ5007/Hβ ≳ 5), and “warm” IR color (f25/f60≳ 0.25).
Black Hole Masses and Unification of Seyferts
Authors: Bachev R. , Petrov G. T. , Slavcheva L. , Mihov B.
Published: July 2016

The most commonly invoked power source of Active Galactic Nuclei (AGN) is accretion of galactic gas (probably through a disk) onto a supermassive black hole in the center of the nucleus (Rees 1984). As is well known, a black hole is completely defined by its mass and angular momentum. The unification scheme of active galaxies assumes that two known Seyfert types (Sy1 and Sy2) are not intrinsically different, i. e. their black hole masses, accretion rates and the whole internal structures are identical (Antonucci 1993) and observed differences are due just to a different orientation to the observer of the axisymmetrical central structure (central engine, BLR and thick torus, shadowing broad lines from some directions).
Compact Nuclei of Galaxies and Sources of Their Energy
Authors: Grigoryan L.Sh. , Sahakian G.S.
Published: July 2016

A model of compact nuclei of galaxies as spherically-symmetric star clusters is proposed. A concept of the equation of state for star clusters in statistical equilibrium is introduced (galactic nuclei are systems in statistical equilibrium if their age is of the order of the age of the Universe). It is shown that a statistically equilibrium star cluster is described by the equation of state of a polytrope P = aρ3, and with its help the main parameters of compact nuclei of galaxies are calculated. The formula M = 2.524GR5/a for mass M and radius R of the cluster is derived.
Quark-Hadron Hybrid Stars as Remnants of Supernovae Explosions
Authors: Poghosyan Gevorg S.
Published: July 2016

It is expected that at explosion of Supernovae the mechanism of producing a shock wave is based on subatomic interactions, and the remnant of the supernovae explosion can be a hybrid quark-hadron star. Since the temperature in the centre of collapsing stars reaches of order T = 6 − 8 · 1010K and density electrons from the top of the Fermi sea can be captured and convert protons into neutrons via e− + p → n + ve. The capture of electrons results in a neutronization burst (V.S. Imshennik 1988). Core collapse of the progenitor star becomes essentially a free fall with a time scale . When the central density of the core reaches supernuclear densities the repulsive QCD forces becomes essential. This can bring about manifestations of quark-hadron phase transitions (A. Dar 1997). After the explosion, from the remaining matter is probably formed a hybrid star.
Rapid Variations in the Broad Hβ Profile of the Radio Galaxy 3C 390.3
Authors: Asatrian N. S. , Khachikian E. Ye. , Notni P.
Published: July 2016

We report on rapid variations of the Hβ profile shape in 3C 390.3 over a period of one hour and discuss the implications for the velocity field of the BLR.
Are There Quasars at Non-Cosmological Distances?
Authors: Harutyunian Haik A.
Published: July 2016

In Dravskikh & Dravskikh (1996) the results of a statistical analysis of quasar luminosity as a function of redshift, if it is assumed to be cosmological, are given (see Fig.1). Three quasar samples were analyzed separately:

•

quasars with absorption lines;

•

quasars associated with galaxies or association-quasars not having absorption lines (from Burbidge et al. 1996);

•

other quasars not included in the first two groups.
The Next Generation of High-energy Astrophysics Observatories
Authors: Holt S. S.
Published: July 2016

The sky will soon be populated with a fleet of new X- and gamma-ray satellites with extraordinary capabilities. This paper is meant to introduce these new missions,Chandra, XMM, and Astro-E, which will provide a large fraction of our high energy “space observatory” functionality for the next decade.
X-ray Emission Characteristics of Pulsars
Authors: Becker W.
Published: July 2016

Recent X-ray observatories such as ROSAT, ASCA, RXTE, BeppoSAX, and Chandra have achieved important progress in neutron star and pulsar astronomy. The identification of Geminga as a rotation-powered pulsar, the discovery of X-ray emission from millisecond pulsars, and the identification of cooling neutron stars are only a few of the fascinating results. In the following, I will give a brief review on the X-ray emission properties of rotation-powered pulsars and their wind nebulae.
The Constellation X-ray Mission
Authors: White N. E. , Tananbaum H.
Published: July 2016

The Constellation-X mission is a large collecting-area X-ray facility emphasizing observations at high spectral resolution (E/ΔE ~ 300–3000) while covering a broad energy band (0.25–40 keV). By increasing the telescope aperture and utilizing efficient spectrometers, the mission will achieve a factor of 100 increased sensitivity over current high-resolution X-ray spectroscopy missions. The use of focusing optics across the 10–40 keV band will provide a similar factor of 100 increased sensitivity in this band. When observations commence in ~ 2008, Constellation-X will address many pressing questions concerning the extremes of gravity and the evolution of the Universe.
Jets from Compact Objects
Authors: Spruit H. C.
Published: July 2016

Some topics in the theory of jets are reviewed. These include jet precession, unconfined jets, the origin of knots, the internal shock model as a unifying theme from protostellar jets to gamma-ray bursts, relations between the Blandford-Znajek and MHD disk-wind models, and jet collimation in magnetic acceleration models.
Gamma-rays from Solar Flares
Authors: Ramaty R. , Mandzhavidze N.
Published: July 2016

Gamma-ray emission is the most direct diagnostic of energetic ions and relativistic electrons in solar flares. Analysis of solar flare gamma-ray data has shown: (i) ion acceleration is a major consequence of flare energy release, as the total flare energy in accelerated particles appears to be equipartitioned between ≳ 1 MeV/nucleon ions and ≳ 20 keV electrons, and amounts to an important fraction of the total energy release; (ii) there are flares for which over 50% of the energy is in a particles and heavier ions; (iii) in both impulsive and gradual flares, the particles that interact at the Sun and produce gamma rays are essentially always accelerated by the same mechanism that operates in impulsive flares, probably stochastic acceleration through gyroresonant wave particle interaction; and (iv) gamma-ray spectroscopy can provide new information on solar abundances, for example the site of the FIP-bias onset and the photospheric 3He abundance. We propose a new technique for the investigation of mass motion and mixing in the solar atmosphere: the observations of gamma-ray lines from long-term radioactivity produced by flare accelerated particles.
Interaction of Gravitationally Contracting Gas Having Angular Momentum with Magnetic Field, and the Acceleration and Collimation of Astrophysical Jets
Authors: Uchida Y. , Nakamura M. , Miyagoshi T. , Kobayashi T. , Mukawa T. , Hirose S.
Published: July 2016

In the present paper, we stress the importance of the magnetic field in the problem of acceleration and collimation of astrophysical jets, and discuss our proposed generic picture for such “central gravitator + jets + lobes” systems and inherent interpretations of the various observational characteristics of such systems: Mechanisms are proposed for (1) the enhanced liberation of gravitational energy at the central object, (2) the transfer of a part of the liberated energy along the large-scale magnetic field by large-amplitude, torsional Alfvén wave trains that form collimated jets (we call this a sweeping pinch process), (3) the dumping of the transferred energy at the end of the jets when they impinge on the denser region outside the border of the “cavity” from which the mass contracted to the central condensation (central gravitator + accretion disk, as well as the larger-scale condensation surrounding them), and (4) the formation of wiggled jets and lobes as helical kinks and the tucked-up magnetic field produced in the sweeping pinch process, respectively.
The Magnetic Fields of the Universe and Their Origin
Authors: Colgate S. A. , Li H.
Published: July 2016

Recent rotation-measure observations of a dozen or so galaxyclusters have revealed a surprisingly large number of magnetic fields whose estimated energy and flux are, on average, ~ 1058 ergs and ~ 1041 G cm2, respectively. These quantities are so much larger than any coherent sums of individual galaxies within the cluster that an efficient galactic dynamo is required. We associate these fields with single AGNs within the cluster and, therefore, with all galaxies during their AGN phase. Only the central, massive black hole (BH) has the necessary binding energy, ~ 1061 ergs. Only the accretion disk during the BH formation has the winding number, ~ 1011 turns, necessary to make the gain and magnetic flux. We present a model of a BH accretion-disk dynamo that might create these magnetic fields, where the helicity of the α-Ω dynamo is driven by star-disk collisions. The back reaction of the saturated dynamo forms a force-free field helix that carries the energy and flux of the dynamo and redistributes them within the clusters.
Jets from Black Hole Magnetospheres
Authors: Shibata K. , Koide S. , Kudoh T. , Aoki S.
Published: July 2016

Recent general-relativistic MHD simulations of jets ejected from black-hole magnetospheres (for both Schwarzschild and Kerr holes) have revealed that (1) strong shock waves are formed in the accretion flow inside 3rs, (2) jets show two-layered shell structure consisting of a gas-pressure driven jet and a magnetically driven jet, the former being accelerated from a high-pressure region heated by strong shocks, and (3) in the case of a Kerr hole, magnetically driven jets are produced from the ergosphere by the effect of frame dragging.
Particle Acceleration at Astrophysical Shocks
Authors: Achterberg A.
Published: July 2016

The acceleration of particles in the vicinity of astrophysical shocks has become the main paradigm in astrophysics for the production of superthermal and relativistic particles. In this review, I consider the basic theory of shock acceleration and the open questions.
Hard X-ray Spectrum of the Above-the-Looptop Source in Impulsive Solar Flares
Authors: Masuda S.
Published: July 2016

Extended Abstract

The Hard X-ray Telescope (HXT: Kosugi et al. 1991) onboard Yohkoh has observed that, in impulsive solar flares, a hard X-ray source is located above the apex of a soft X-ray flaring loop, in addition to double footpoint sources (Masuda et al. 1994, 1995). This observation suggests that flare energy-release, probably magnetic reconnection, takes place not in the soft X-ray loop but above the loop. It is important to derive the hard X-ray spectrum of the above-the-looptop source accurately in order to understand how electrons are energized there. The above-the-looptop source was most clearly observed during the 13 January 1992 flare. However, the count rate, especially in the H-band (53–93 keV), is too small to synthesize high-quality images and to derive an accurate spectrum.
High-energy Radiation from a Model of Quasars, AGNs, and the Galactic Center with Magnetic Monopoles
Authors: Peng Q.-H.
Published: July 2016

The structural parameters of the supermassive object at the Galactic Center and its high-energy radiation are estimated according to observations in near-infrared radiation, under the model of a supermassive object with magnetic monopoles.
Candidates for Optical Counterpart in the Field of PSR 1821–24 in M28
Authors: Sutaria F. K.
Published: July 2016

The 3-ms, X-ray pulsar RX J1824.2-2R52P has been identified at the 2-σ level as a possible X-ray counterpart of the radio pulsar PSR 1821-24. The present work uses archival HST data for M28 to set upper limits on the optical V-band magnitude of PSR 1821–24 / RX J1824.2-2R452P. The optical limit extends the multiwavelength observations for this source and would provide constraints for theoretical models of pulsar emission.
Statistical Properties of Magnetic Separators in Model Active Regions
Authors: Welsch B. T. , Longcope D. W.
Published: July 2016

“Transient brightenings” (or “microflares”) regularly deposit 1027 ergs of energy in the solar corona, and account for perhaps 20% of the active corona's power (Shimizu 1995). We assume these events correspond to episodes of magnetic reconnection along magnetic separators in the solar corona. Using the techniques of magnetic charge topology, we model active region fields as arising from normally distributed collections of “magnetic charges”, point-like sources/sinks of flux (or field lines). Here, we present statistically determined separator (X-ray loop) lengths, derived from first principles. We are in the process of statistical calculations of heating rates due to reconnection events along many separators.
Numerical Simulations of Solar Flares
Authors: Yokoyama T. , Shibata K.
Published: July 2016

We study reconnection and chromospheric evaporation in flares using a numerical code including nonlinear, anisotropic heat conduction (Yokoyama & Shibata 1998). The two-dimensional, nonlinear, time-dependent, resistive, compressible MHD equations are solved. The evolution from the rise phase to (the early part of) the decay phase of a solar flare is qualitatively reproduced in this simulation. Based on the results, we obtained a relationship between the flare temperature and the coronal magnetic field strength. We assume that the energy input to a loop balances with the conductive cooling rate, that the temperature at the loop apex is TA ≍ (2QL2/κ0)2/7, where Q is the volumetric heating rate, that L is the half-length of the loop, and that the Spitzer thermal conductivity constant is κ0 = 10−6 CGS. In our simulations, the heating mechanism is magnetic reconnection, so the heating rate is described as Q = B2/(4π) · Vin/L · l/sin Θ, where B is the coronal magnetic field strength, Vin is the inflow velocity (≍ 0.1 VA from our result and also from Petschek's theory), and Θ is the angle between the slow-mode MHD shock and the loop and is approximately given by sin Θ ≍ Vin/VA. By manipulating the equations, we find
where ρ is the mass density of the corona. The simulation results show very good agreement with this scaling law.
Summary of Posters on Solar Physics
Authors: Aschwanden M. J.
Published: July 2016

Five posters in the group of solar physics have been presented at this meeting on “Highly Energetic Physical Processes and Mechanisms for Emissions from Astrophysical Plasmas”. Four of these posters were dealing with aspects of solar flares, the most energetic processes observed in the solar corona, while one poster dealt with active regions. Although the most energetic particles in solar flares (E < 108 eV) do not compete with the most energetic cosmic rays (E > 1018.5 eV) observed in the rest of the universe, similar particle-acceleration mechanisms (electric fields, stochastic acceleration, shocks) are investigated for both phenomena. On the other hand, some highly efficient acceleration mechanisms operating in astrophysical plasmas (e.g., E x B drift in rapidly rotating B-fields on pulsars) are definitely not applicable to solar flares. However, a common theme in both astrophysical and solar acceleration processes is the role of magnetic reconnection, which was also the subject in one or the other form in all of the five presented solar posters. The joint venture of astrophysical and solar participants of this workshop contributed therefore nicely to a cross-fertilization of these common physical themes in both disciplines.
Solar Flares, the Solar Corona, and Solar Physics
Authors: Parker E. N.
Published: July 2016

The Sun serves as the local physics laboratory for studying the suprathermal activity phenomena of stars. Scrutiny of the Sun has led to the discovery of a host of previously unknown physical effects, largely within the classical physics of Newton and Maxwell, but including quantum mechanics and lepton physics as well.
Neutron Star Powered Accelerators
Authors: Ruderman M.
Published: July 2016

Neutron stars can be the underlying source of energetic particle acceleration in several ways. The huge gravitational-collapse energy released in their birth, or the violent fusion at the end of the life of a neutron-star binary, is the energy source for an accelerator in the surrounding medium far from the star. This would be the case for: (a) cosmic rays from supernova explosions with neutron-star remnants; (b) energetic radiation from “plerions” around young neutron stars (e.g., the Crab Nebula, see Pacini 2000); and (c) “afterglow” and γ-rays of cosmic Gamma-Ray Burst (GRB) sources with possible neutron-star central engines. Particles can also be energetically accelerated if a neutron star's gravitational pull sustains an accretion disk fed by a companion. Examples are accretion-powered X-ray pulsars and low-mass X-ray binaries. A third family of “neutron-star powered” accelerators consists of those which do not depend on the surrounding environment. These are the accelerators which must exist in the magnetospheres of many solitary, spinning-down, magnetized neutron stars (“spinsters”) when they are observed as radio pulsars or γ-ray pulsars. (There are probably ~ 103dead radio pulsars for each one in our Galaxy that is still active; the ratio for γ-ray pulsars may well exceed 105.)
Does the Magnetodynamic Model for the Formation of AGN Jets Survive New Findings of High-energy Phenomena near the Central Objects?
Authors: Uchida Y.
Published: July 2016

Here, we argue that, despite all-new findings of phenomena with very large Lorentz factors, the importance of the magnetodynamic process accelerating and collimating AGN jets should not be affected because there exists evidence in the features of the jets and tails at large distances indicating that the wiggles of the jet structure are likely to be due to a magnetic, helical kink instability. These systematic features require too much energy and coherence of the driving process to be produced locally and axe most naturally produced by a magnetic effect coming from the powerful central engine. This indicates that the major effect producing the jets, and the lobes with hotspots at the tips of the jets, is likely to be the Poynting flux carried by torsional Alfvén wave trains plus the re-accelerated high-energy particles in them. The very large Lorentz-factor phenomena should not hinder the transfer of these magnetic effects and are likely to be byproducts of the basic magnetodynamic process, and not the reverse.
Light Pollution: How High-Performance Luminaires Can Reduce It
Authors: Remande Christian
Published: July 2016

In 1984 the International Commission on Lighting (CIE) set up a Technical Committee TC 4.21 to study interference by artificial light in astronomical observation. The resulting document “Guidelines for minimizing sky glow” (CIE No. 126) complements previous CIE documents from 1978 and the joint CIE-IAU (International Astronomical Union) publication of 1984. In this paper, we demonstrate how high performance luminaires based on more global and pertinent criteria can significantly reduce sky glow.
The Artificial Sky Brightness in Europe Derived from DMSP Satellite Data
Authors: Cinzano P. , Falchi F. , Elvidge C. D. , Baugh K. E.
Published: July 2016

We present maps of the artificial sky brightness in Europe in V band with a resolution of ~1 km. The aim is to understand the state of night sky pollution in Europe, to quantify the present situation and to allow future monitoring of trends. For each terrestrial site the artificial sky brightness in a given direction on the sky is obtained by integrating the contributions from each surface area in the surroundings, using detailed models of the propagation in the atmosphere of the upward light flux emitted by the area. The top-of-atmosphere light flux is measured by the Operational Linescan System of the Defence Meteorological Satellite Program (DMSP) satellites. The modelling technique, which was introduced and developed by Garstang, takes into account the extinction along light paths, double scattering of light from atmospheric molecules and aerosols, and Earth curvature. Use of this technique allows us to assess the aerosol content of the atmosphere.
Japanese Government Official Guideline for Reduction of Light Pollution
Authors: Isobe Syuzo
Published: July 2016

After 3-year discussions within a working group of the Japanese CIE and then 2-year discussion under a committee of the Environmental Agency in Japan, “Guideline for Light Pollution - Aiming for Good Lighting Environments” was published by the Environmental Agency. This is the first governmental guideline in the world and therefore a good example to be discussed in the other countries.
Chelmos (Aroania): a New European Telescope Site for the 2.3-m Telescope of the National Observatory of Athens
Authors: Sinachopoulos D. , Maragoudaki F. , Hantzios P. , Kontizas E. , Korakitis R.
Published: July 2016

The National Observatory of Athens (N.O.A.) will install a new, advanced technology 2.3-m telescope in Greece. A favoured location for the installation of the new telescope is the top of Mount Chelmos. We present preliminary results concerning the conditions at this site. It is found that the site has a quite dark sky, a good percentage of clear nights (about 60%) and very good seeing conditions.
The Impact of Light Pollution on a Proposed Automatic Telescope Network (ATN) and Vice Versa
Authors: Mattox John R. , Wagner Stefan , Tosti Gino , Honeycutt Kent
Published: July 2016

We are proposing to operate a Network of Automatic Telescopes (ATN) for CCD imaging to conduct diverse astrophysical investigations and as a resource for science education. Coordinated utilization of telescopes at diverse sites provides the possibility of obtaining continuous photometry without diurnal interruption. We describe this project and discuss how it is impacted by light pollution, and conversely, how it might mitigate the growth of light pollution.