bluuebunny/crossref_metadata_2025 huggingface dataset:
Submillimetre Spectral Indices of Radio-Quiet Quasars
Authors: Hughes D. H. , Dunlop J. S. , Robson E. I. , Gear W. K.
Published: July 2016

Hughes etal. (1993) have made submillimetre continuum observations of 10 IRAS selected radio-quiet quasars (RQQs). Three RQQs, I Zw 1, Mrk1014 and Mrk376, have been detected at 800 and 450μm using the 3He bolometer UKT14 on t he 15-m James Clerk Maxwell telescope. These submillimetre data, together with existing 1.3 mm observations (Chini etal. 1989) demonstrate that the measured submillimetre spectral indices, 〈αsm〉 = 3.8 ± 0.5, significantly exceed the critical theoretical limit of αsm = 2.5 predicted for the self-absorption of synchrotron emission. This result is independent of any contributions to the 100μm IRAS fluxes from cirrus emission in the host galaxies, extended circumnucl ear starformation and FIR emission from companion or confusing sources. All current non-thermal models (de Kool & Begelman 1989, Schlickeiser etal. 1991) are rejected in favour of the alternative explanation that the FIR luminosity is dominated by thermal emission from warm (45–60 K) dust grains. The submillimetre optical depth and source-size for the thermal emission cannot yet be constrained by these data and, as a result, no discrimination can be made between dust heated by an extended (> 1 kpc) starburst region or a central compact luminosity source. However ground-based imaging observations at mid-IR wavelengths and FIR photometry (60–200μm) with the KAO are currently in progress specifically to address this problem. The high gas masses (> 1010M⊙) in RQQs inferred from the submillimetre continuum observations are in agreement with the H2 masses determined from CO measurements. Alternatively the results show that the MH2/Mdust ratio measured in RQQs (∼ 370 ± 150) is consistent with that measured in spiral galaxies and ultra-luminous IRAS galaxies.
Multiwavelength Energy Distributions of Ultraluminous IRAS Galaxies
Authors: Rigopoulou D. , Lawrence A.
Published: July 2016

Ultraluminous IRAS Galaxies (ULG's) have luminosities comparable to quasars while their space density is much higher than that of active galaxies. Much debate has centered around the origin of the energy source for these objects, whether this is a burst of star formation or a hidden quasar. The sample studied here is the Sanders et al. (1988) sample, 10 objects with LFIR ≥ 1012L⊙. We discuss our new observations at X-ray and submm wavelengths together with other published data for some of the objects. Some useful ideas can be gained from comparisons of the shape of the spectral energy distributions (SED's) of the ultraluminous objects with other “archetype” objects such as typical starbursts i.e. M82 or type 2 AGN i.e. NGC1068.
Interaction of Jets with Clouds in Extragalactic Radio Sources
Authors: Fedorenko V. , Zentsova A. , Courvoisier T. J.-L. , Paltani S.
Published: July 2016

Several points indicate that extragalactic jets can interact with dense gaseous obstacles which occur on their ways. Examples of these interactions are the knotty structure of the radio and optical jet in M 87 and in other objects. These observations have been interpreted by Blandford & Königl in terms of collision of a jet with supernova remnants. We have reanalysed this idea taking into account new observations and improvements in the theory of diffusive shock acceleration. We find that the model requires a very high supernova birthrate (∼ 1 SN/year), which is not observed. It is more probable that the “obstacles” are formed by the stellar winds from the red giants. We estimate that the value of the magnetic field is ∼ 10−5 G in the interaction region (r=1kpc) (paper in preparation).
The Hard X-ray Reflection on Cold Matter
Authors: Jourdain E. , Roques J.P.
Published: July 2016

We have simulated the reflection on cold matter in a variety of situations to determine which informations can actually be inferred from observations. We modelled a semi-infinite plane parallel medium of solar abundance matter, semi-isotropically illuminated by a X/γ ray source. The spectra are calculated from a Monte-Carlo method without any approximation in the cross-sections. Θ is the angle over which the reflecting matter is seen (90°=face-on), Θ=all means a spatially integrated spectrum. Fref is the ratio of the reflected over direct component.
Quasi-Spherical Accretion onto the Black Hole: The Virial Regime
Authors: Berezinsky V S , Lapidus I
Published: July 2016

We are studying the slow (ṁ < 1) spherical accretion of a gas onto a supermassive (M ≈ 108M⊙) black hole in the presence of a strong tangled magnetic field. In the core with radius 2.5 rg < r < 10 rg protons are isotropized due to scattering in magnetic field, but are not thermalized since the characteristic time of pp — Coulomb scattering is less than the infall time. A proton moves in the electron gas with a friction due to pe — scattering, gradually transferring energy to electrons. The standard equations for the proton gas allow the virial regime of accretion when the kinetic energy of the proton is a function of a distance only Ek(r) = (2/5) mpc2 (rg/r). The model is relevant to the slow subsonic settling of matter onto the black hole, as, for example, in the upstream region after the shock standing at a distance r ∼ 20 rg (Mészàros and Ostriker 1983). Electrons are thermalized and are cooling predominantly by bremsstrahlung radiation. For ṁ ≲ 0.1 the core is transparent for bremsstrahlung photons. In agreement with Park (1990) the e+e− - pair production is found to be insignificant. The equilibrium between the energy release in pe — scattering and the bremsstrahlung radiation results in the almost isothermal core with the temperature Te ≈ 4 me, which slightly increases towards the inner edge of the core. The only role of magnetic field is the isotropization of the proton gas, as the synchrotron radiation is strongly self-absorbed. Therefore the model is insensitive to the precise value of H.
ROSAT Observations of an Optical Quasar Survey Field
Authors: Brunner H. , Dörrer T. , Friedrich P. , Lamer G. , Staubert R.
Published: July 2016

Deep (T∼35 ksec) pointed ROSAT observations of a 2.2° × 2.2° optical quasar survey field (149 quasars; mlim = 20.5; Crampton et al., 1989) have yielded a detection rate (3 σ) of ∼ 60 % (86 quasars; limiting sensitivity ∼ 5 · 10−15 erg cm−2 s−1 keV−1 at 1 keV). See Fig. 1 for the distribution of the ROSAT PSPC source count rates and Fig. 2a, b for the fraction of quasars detected in X-rays as a function of redshift and optical magnitude. 46 quasars were bright enough to perform spectral power law fits. The mean energy power law index drops from ∼ 1.4 at z = 0 to ∼ 0.9 at z > 2 (Fig. 4; only the 20 brightest sources are plotted). This is interpreted as being due to a break in the spectrum between a soft, thermal accretion disk and a hard power law component, occuring at a source frame energy around 1 keV (Fig. 5). Mean accretion disk model parameters are derived (M = 5.108 M⊙, Ṁ = 0.65 MEdd., αvisc. = 0.5) using an optically thin α-accretion disk model (Dörrer et al., 1992 and references therein). Model predictions for the decline of the X-ray spectral index with redshift are plotted in Fig. 4. The αox distribution (Fig. 3; dotted line: X-ray upper limits) and the optical number-redshift relation (Fig. 6; dotted line: X-ray number-redshift relation) is modeled using the accretion disk parameters as determined from the X-ray spectral data and assuming a constant comoving volume density (H0 = 100 km/s Mpc, q0 = 0.5) and statistical orientation of the inclination angles of the model source population.
ROSAT Observations of Einstein EMSS AGNs
Authors: Cappi M. , Palumbo G.G.C. , Della Ceca R. , Maccacaro T.
Published: July 2016

Active Galactic Nuclei (AGN) can be studied in the ROSAT energy band also when serendipitously observed during long pointed observation of unrelated targets. From the available ROSAT database three Extended Medium Sensitivity Survey (EMSS) AGNs, detected with more than 500 counts, have been studied. One AGN (MS 1803.6+6738 = Kaz 102) was observed twice and in one field the target is the BL Lac 0716+714.

– Spectral studies reveal that all three AGNs are well described by a single power law. Values of relevance are summarized in the table where they are compared to previous values from Einstein and the ROSAT survey (Walter R. & Fink H.H., 1993, A&A, 274, 105). All four sources have a NH value well below the estimated value given by Stark et al. (1992, ApJS, 79, 77) and Elvis et al. (1989, ApJ, 97, 777). This probably is an indication that a soft excess is present.

– Variability studies show flux variations for the BL Lac on time scales of days, while the photon index appears rather constant. The high count rate for this object allows to attribute a probability of variability greater than 99% (running a K-S test against constancy). In the case of Kaz 102, the comparison of previous measurements with the present one does not show evidence of long term (years) variability.
ROSAT All Sky Survey AGN Spectra: Constraints on accretion disks
Authors: Friedrich P. , Dörrer T. , Brunner H. , Staubert R.
Published: July 2016

We found that ROSAT spectra of a sample of 89 AGN are generally steeper than 0.7. The excess above a hard X-ray power law spectrum in this energy range which has been found already with Einstein and EXOSAT for some AGN is now seen very clearly in most sources. Our α-disk models (Dörrer et al., 1992 and references therein) which include Comptonization and relativistic corrections are in agreement with the measured soft excesses when the (ṀEdd., α) parameter space is restricted to α > 0.4 and ṀEdd. ε [0.4, 0.8] (ṀEdd.: Eddington accretion rate).
Long-Term Optical Behavior of BL Lac Objects
Authors: Kikuchi S.
Published: July 2016

On the basis of results of optical photometry and polarimetry of OJ287 and Mrk421 since 1981, we find two states of activities for both objects. In OJ287, a color-magnitude relation which is consistent with the standard jet-shock model is seen after the outburst in 1983, while before 1982 the optical colors were almost constant. In Mrk421, the colors became redder in 1985–87, and the change of the preferred direction of polarization was associated on smaller time scale in 1987.
A Jet Model Interpretation of Multi Frequency Flux Observations of Radio Outbursts in the AGN 0235+16
Authors: Kovalev Y.Y. , Larionov G.M.
Published: July 2016

There are analyzed 1.5 - years observations of a series of bursts in the quasar 0235+16 at 8 frequencies between 0.3 GHz and 15 GHz from July 1981 to December 1982, obtained by Altschuler et al. (1984) and Aller et al. (1985). These observations are compared with a Hedgehog model (see Kovalev and Mikhailutsa, 1980, with full references).
Spectral Variability of Six Bright Bl Lac Objects in the Near IR
Authors: Massaro E. , Nesci R. , Perola G.C. , Lorenzetti D. , Spinoglio L.
Published: July 2016

The results of several photometric campaigns (1986–1993) in the near IR of the six bright BL Lac objects 3C 66A, PKS 0422+004, PKS 0735+178, PKS 0754+100, PKS 0829+046 and OQ 530 are presented. The observations were carried out at the 1.5 m Italian IR Telescope at Gornergrat (TIRGO − 3150 m a.s.l.) equipped with a IR photometer using a InSb detector cooled at the solid nitrogen temperature and the standard J, H, K filters. The principal aims of our program are the search of rapid variability (typical time scales of 1 day or less) and of correlations between the flux level (typically in the J band, where the largest variation amplitude is found) and the spectral slope. In the following we summarize some relevant results.
Spectral Variability of NGC 4151 in 1972–1991
Authors: Oknyanskij V.L. , Lyutyi V.M. , Chuvaev K.K.
Published: July 2016

After a minimum in the spring of 1984, when the broad permitted lines were found to become much weaker, the spectrum of NGC 4151 became much more like a Sy 2 (Lyutyi et al., 1984; Chuvaev and Oknyanskij, 1989; Penston and Perez, 1984). Recently, this object returned to the high state after about 8 yr in the semiquiescent phase (Oknyanskij et al., 1991).
Two Year UV-Optical Monitoring of the Seyfert 1 Galaxy Markarian 335
Authors: Sun Wei-Hsin , Shrader Chris R. , Turner Tracey J. , Malkan Matthew A. , Peterson Bradley M. , Hintzen Paul M.N. , Kondo Yoji , Lin Sung-Nan , Lin Ting-Chang , Stone Remington P.S.
Published: July 2016

We report on the results of a UV-Optical spectral monitoring of the bright Seyfert 1 galactic nuclei Mkn 335. This campaign began in June, 1989, and ended in June, 1991. Ultraviolet spectra of fourteen epochs at nearly uniform sampling of 30-day intervals, except when the object was inaccessible from the IUE satellite, have been obtained, of which twelve were coordinated with quasi-simultaneous ground-based optical observations made at Lick Observatory.
Optical Variability of Faint QSOs and AGNs
Authors: Trèvese D. , Kron R. G.
Published: July 2016

We report some results of a new analysis (Trèvese et al. 1993, ApJ (submitted) (T93)) of the variability of the faint QSO sample of SA57 (Koo, Kron and Cudworth, 1986, PASP, 98, 285), concerning the intrinsic time scales of variability and the dependence of the amplitude of variability on absolute magnitude and redshift. Prime focus plates of SA57 have been obtained with the Mayall 4-m telescope at the Kitt Peak National Observatory since 1974. The present analysis is based on 14 BJ plates spanning 15 years at 11 independent epochs. The digitization, object selection, image classification and photometry are described in Koo (1986, ApJ, 311, 651) and Trèvese et al. (1989, AJ, 98, 108 (T89)). The magnitude limit of the sample is BJ = 22.5 and stellar objects are selected with a threshold in image size. This criteria give a sample of 694 objects in the field, 34 of which are QSOs whose spectra have been measured with the Mayall 4-m telescope. The r.m.s. error in the BJ band is 0.05 mag at BJ Ã 22 mag. All but one of these QSOs appear to be variable according to T93.
Multifrequency Variability of Blazars 3C 279 and 3C 345
Authors: Webb James R.
Published: July 2016

The multifrequency spectra of Blazars 3C 279 and 3C 345 are presented and their implications for theoretical models are discussed. The spectra resulted from two separate but complimentary observational programs; one a serendipitous discovery by CGRO that extended the spectrum up to GEV energies, while the other a program designed to investigate the spectral variability of a Blazar during an outburst.
The Milliarcsecond Structure of Four Seyfert Galaxies at λ 18 cm
Authors: Ghosh T. , Schilizzi R.T. , Miley G.K. , Debruyn A.G. , Kukula M.J. , Pedlar A. , Graham D. , Saikia D.J.
Published: July 2016

The major contending scenarios capable of explaining various aspects of the Seyfert phenomenon in AGNs are (i) the Super-massive Black-Hole model and (ii) the Starburst model. Detailed optical emission-line and radio images of Seyfert nuclei, and their mutual correlations, provide important clues in evaluating the claims of each. Using the EVN at λ 18 cm, we have mapped four Seyfert galaxies, Mkn 1, 3, 231 and 463 at a resolution of ∼ 25 mas. The maps, and comparisons with images at other wavelengths, will be presented elsewhere (Ghosh et al. 1993, in preparation). Here, we present parameters derived from elliptical-Gaussian fits to all discernible components (Table 1).
Neutral Hydrogen in the Seyfert Galaxy NGC 3227
Authors: Mundell Carole G. , Pedlar Alan , Axon Dave J.
Published: July 2016

We present VLA C and D array neutral hydrogen observations of the Seyfert galaxy NCG 3227. The neutral gas is highly disturbed due to the interaction with the nearby elliptical, NGC 3226 and D array observations (with resolution of 40″ and velocity resolution of 40 kms−1) revealed 2 extensive plumes stretching 88 kpc south and 44kpc north of NGC3227. Complex dynamics were observed in the disk, which subsequent C array observations (resolution of 19″ and 20 kms−1) resolved into two components: the galactic disk, which is not significantly disrupted by the interaction and is undergoing predominantly solid body rotation out to a radius of 7 kpc, and an anomalous velocity cloud (with a velocity of 170 kms−1 above systemic) which appears to be associated with the northern plume.
Helical Motion and Non-Adiabatic Expansion in the Jet of 3C345
Authors: Steffen W. , Krichbaum T.P. , Witzel A. , Zensus J.A. , Qian S.J.
Published: July 2016

We developed a kinematic jet model for the motion and flux density evolution of the high frequency VLBI jet components C4 and C5 in the quasar 3C345 (Zensus et al. 1994) assuming the conservation of three basic quantities: the Lorentz factor, the angular momentum, and the opening angle of the jet. This model is a simplified description of the helical motion in a conical jet expected from the magnetodynamical model of Camenzind (1986) which is based on a black hole surrounded by a magnetized accretion disc. Our best fit yields Lorentz factors of 5.7 and 5.0 for components C4 and C5, respectively, and an angle between the jet axis and the observer's line of sight of 7.5°. These values are very close to those obtained by Unwin & Wehrle (1992) from component motion further out. An intrinsic bending of the jet axis is necessary to account for the common bent path of all jet components at core separations larger than about 4 mas. We found that differential Doppler boosting alone is not able to explain the flux density variations of component C4. A non-adiabatic expansion model of an inhomogeneous plasma cloud combined with differential Doppler boosting on a helical path fits the flux density evolution (Steffen et al. 1994). We find that the expansion in the decreasing part of the lightcurve is slower than expected from adiabatic expansion.
HST Images of the Seyfert Galaxy NGC 5929 and its Companion NGC 5930
Authors: Bower G. A. , Wilson A. S. , Mulchaey J. S. , Miley G. K. , Heckman T. M. , Krolik J. H.
Published: July 2016

Images of the Seyfert 2 galaxy NGC 5929 and its interacting companion NGC 5930 have been obtained with HST's Planetary Camera. This interacting pair is also known as Arp 90. Each galaxy was imaged in the wavelength regions of [O III] λλ 4959, 5007, Hα+[N II] λλ 6548, 6583, and the green and red continua. The nuclei of both galaxies contain emission line gas, enhanced in the images by using the appropriate continuum image to remove the contribution of the continuum light in the on-band images.
Implications of Nonlinear Line Response in Variable Seyfert Nuclei
Authors: Shields Joseph C. , Ferland Gary J. , Peterson Bradley M.
Published: July 2016

Variable Seyfert nuclei exhibit correlations between emission-line and continuum luminosity consistent with photoionization, although the emission lines (including recombination features such as Lyα) tend to respond nonlinearly to changes in the continuum. A nonlinear response will result if some of the broad-line region (BLR) clouds become fully ionized in hydrogen, such that their emission measure does not then vary in proportion to the incident continuum flux. For thin clouds, emission in transitions from heavy elements may grow or decline with increasing incident flux, reflecting changes in the ionization structure of the cloud. Direct evidence for a fully ionized component within the BLR is provided by correlation analysis of ultraviolet line response in NGC 5548 (Sparke, 1993).
High Resolution NIR Imaging of the Starburst Galaxy NGC 1808
Authors: Tacconi-Garman L.E. , Krabbe A. , Sternberg A. , Genzel R.
Published: July 2016

We report 0.6″ res. J, H, and K and 1.5″ res. imaging of 2.17 μm HI Brγ and 2.12 μm H2 1-0 S(1) line emission towards the nucleus of the starburst galaxy NGC 1808. In the K-band data we (partially) resolve the nucleus and see several small knots in the circumnuclear region. Further, our JHK continuum images show that a large fraction of the near infrared light in NGC 1808 is produced in young star forming clusters. The Brγ emission originates from a compact nuclear source and from several distinct emission knots in the circumnuclear region. These knots are spatially well correlated with a family of compact radio sources, but uncorrelated with the optical “hot spots”. We propose that the Brγ knots trace the actual sites of starburst activity, while the optical hot spots are just directions of low foreground extinction.

We use our data together with radio and far-infrared continuum emission measurements to constrain the parameters of the individual starburst sites in NGC 1808. The data suggest that the starbursts are unsynchronized and prolonged (5 × 106–5 × 107 yrs). The star formation rates in the active sites range from ∼0.1 to ∼0.6 M⊙ yr−1, and the present rapid rate of star-formation in NGC 1808 can be maintained for at most another ∼7 × 107 yrs.

Portions of this work are presently in press (Krabbe, Sternberg, and Genzel 1993), and a second paper is in preparation (Tacconi-Garman et al. 1993).
FeII, FeI Emission Lines from Accretion Disks: An Explanation for “FeII Problem” in AGNs?
Authors: Wei Chunyan , Cheng Fuzhen , You Junhan
Published: July 2016

For the solution of the puzzling “FeII problem” in active galactic nuclei(AGNs) (Netzer et al. 1983; Wills et al. 1985), we pay our attention to optical band and suggest: (1)the observed so-called “FeII emission lines” features may be blending of FeII multiples and FeI multiples. Our previous work(Wei et al. 1993) has showed that there are many FeI emission lines whose wavelength lie around the observed “FeII emission lines” features. In fact, FeI emission lines have been observed in the spectrum of PHL 1092(Bergeron et al. 1980; Cheng et al. 1993). (2)the emission lines from accretion disk must be considered besides the emission from broad line region.
Scattered Light in a Distant Radio Galaxy
Authors: Cimatti Andrea , Di Serego Alighieri Sperello
Published: July 2016

We present optical polarimetric observations of a radio galaxy at z=2.63 and the results of its spectral modelling made by using stellar and scattered anisotropic nuclear radiation.
Polarized Optical and Infrared Emission from High Redshift Radio Galaxies
Authors: Jannuzi Buell T.
Published: July 2016

We have detected highly polarized (> 5%) optical and/or infrared emission (rest frame UV to near infrared) from 5 of the 8 high redshift radio galaxies (HZRG; z > 0.7) we have observed. There are now a total of 9 (out of 12 observed) HZRG known to be polarized in spatially integrated measurements (cf.). We have made images of the extended polarized emission from two radio galaxies (3C 265 and 3C 256). Detection of extended polarized emission from a HZRG has previously been reported for 3C 368. All of the existing polarization observations support the hypothesis that the “alignment effect” (the tendency of the extended UV light to be aligned with the extended radio emission, e.g.) is not solely produced by a burst of star formation, but contains a very significant component produced by the scattering of the light from a hidden active galactic nucleus (AGN). Our modeling of the frequency dependence of the polarized flux from 3C 265 suggests that the most probable scatterer is dust.
A Tentative Sketch for BL Lacertae Objects
Authors: Sol Hélène , Vicente Lourdes
Published: July 2016

VLBI polarization data show magnetic field configuration parallel to the nuclear jet in quasars and perpendicular to it in BL Lac objects. It appears difficult to account for this contrast within the unified scheme for AGN. To investigate a direct explanation of this peculiarity of BL Lac objects, we study the possibilities of propagation and radiation of beams of particles in transverse ambient magnetic field. High energy streams with kinetic energy density larger than the ambient magnetic one, Ekin > Emag, can easily propagate with enhancement of the transverse magnetic field at the leading edge of the stream and reconnection of magnetic lines in its wake. Synchrotron radiation in front shocks naturally leads to the observed polarization. Moreover self-polarization, with formation of charge layers and E × B drift velocity, allows substantial propagation for even lower energy streams with Ekin < Emag, as long as their density no is large enough, typically κ = 4πnomic2/B2 > 1. Such low energy streams are non diamagnetic and do not modify the ambient field. Any high energy tail of the total particle distribution in the jet therefore radiates in the transverse field pattern. This concerns for instance the BL Lac object W Comae if we assume a proton-electron jet with bulk velocity vo = 0.1c (as the source does not require relativistic beaming so far), an equipartition magnetic field B = 0.02 G and a density of radiating particles nr = 0.05cm−3 at about 7 pc from the nucleus (knot K3). For nr/no = 10−3, one gets the stream density no = 50cm−3 which allows good propagation as κ reaches 2 × 103, and still corresponds to a moderate mass outflow of 0.06 M⊙ /year for a VLBI jet cross-sectional area of 2pc2.
Structure of Outer Regions of Accretion Disks in AGN: Non Irradiated, Vertically Averaged Accretion Disks
Authors: Huré Jean Marc , Collin Suzy , Pineau Des Forêts Guillaume
Published: July 2016

Radial structure of outer regions of α-disks (Shakura & Sunyaev 1973) is investigated in a more sophisticated way than in Collin-Souffrin & Dumont (1990). The vertically averaged equations for the disk structure hold but some of them are reconsidered : the equation of state (atoms, ions and molecules) with a the rigourous treatment of opacities is introduced. The radiative flux is treated as in Hubeny (1990), and finally a rigourous treatment of the self-gravitaty is included.
Hot Accretion Disks with Magnetic Field and Thermal Cyclo-Synchrotron Radiation
Authors: Kusunose Masaaki , Zdziarski Andrzej A.
Published: July 2016

We study the structure of hot, two-temperature accretion disks around black holes, including the effects of thermal cyclo-synchrotron radiation and magnetic viscosity. This work is an extension of previous work by Björnsson & Svensson (1991a, b, 1992) and Kusunose & Mineshige (1992), which did not include those effects. Magnetic field, B, is assumed to be randomly oriented and determined by prescribing the ratio α = Pmag/Pgas or α = Pmag/(Pgas + Prad), where Pmag, Pgas, and Prad are the pressures of magnetic field, gas, and radiation, respectively. We find those effects do not change the qualitative properties of the disks, i.e., there are two critical accretion rates related to production of e± pairs, ṀcrU and ṀcrL that affect the number of local and global disk solutions, as recently found for the case with B = 0 (Björnsson & Svensson 1991a, b, 1992). However, a critical value of the α-viscosity parameter above which those critical accretion rates disappear becomes smaller than αcr = 1 found in the case of B = 0, for Pmag = α(Pgas + Prad). If Pmag = αPgas, on the other hand, αcr is still about unity. Moreover, when Comptonized cyclo-synchrotron radiation dominates Comptonized bremsstrahlung, radiation from the disk obeys a power law with the energy spectral index of ∼ 0.5, in a qualitative agreement with X-ray observations of AGNs and Galactic black hole candidates. The spectral index is weakly dependent on the mass accretion rate.
Galactic Dynamo Models
Authors: Moore N.P. , Panesar J.S. , Nelson A.H.
Published: July 2016

We present the results of 3-d numerical simulations of galactic dynamos. Using reasonably justifiable parameters, kinematic dynamo models are shown to reproduce the gross features of galaxy magnetic fields. The central field morphology is suggestive of an embryonic jet generator.
Variability of Black Hole Accretion Disks
Authors: Nowak Michael A. , Wagoner Robert V.
Published: July 2016

We consider two forms of variability in black hole accretion disks: harmonically oscillating modes trapped near the disk inner edge, and noisy fluctuations throughout the entire disk. We apply the former to AGN disks, and the latter to the X-ray power spectra of GX339-4.
Nuclear Activity in Interacting Galaxies
Authors: Chatterjee Tapan K.
Published: July 2016

Dynamical studies of galactic collisions, conducted previously (Chatterjee, 1992, 1993a, b), indicated that most of the mergers take place in two to three shrinking orbital periods. We extend this line of research work to study induced nuclear activity. We study the binary evolution of a spiral galaxy perturbed by a compact elliptical galaxy of comparable mass and find that each time the perturber penetrates the disk of the spiral, the disk is subjected to an appropriate perturbation, causing inflow of gas towards its nucleus due to loss of angular momentum; there it could activate an inert black hole (consistent with previous studies; e.g. Naguchi, 1988). However a new feature that we find is that repeated episodes of disk penetration by the perturber occur in gradually shorter timescales, causing an overlap of the activity timescale and the dynamical timescale. In fact if the elliptical is very compact and the spiral has a massive bulge, subsequent dynamical timescales reduce by more than an order of magnitude. This periodic increase in the activity of the nucleus is of a secular nature (in contrast to a reactivation process), and could lead to the evolution of the spiral along the following lines, Starburst → Seyfert 2 → Seyfert 1, as interpenetrations follow.
A Possibility of Reveal of Parent Populations for the Objects by Active Nuclei on the Basis of Comparing their Spatial Correlation Functions
Authors: Romberg B.V. , Kravtsov A.V.
Published: July 2016

For a model of the World with q0 = 0.5 and H0 = 100h−1 there was received a 2-point spatial correlation function (CF) (The sample of 300 objects with z < 0.045 and δ > 0 was used) for Seyfert Galaxies with the following parameters: r0 = (9 ± 2)h−1Mpc, γ = –(1.7 ± 0.2).
The QED (Quasar Energy Distributions) Atlas
Authors: Mcdowell J.
Published: July 2016

While the energy distributions of optically and radio selected quasars have the same, reproducible, mean shape in the infrared to ultraviolet region, the strength of the infrared and ultraviolet components can vary by over a decade from object to object.
Are Redshifts of Seyfert Galaxies Cosmological?
Authors: Sapre A.K. , Parihar P.S.
Published: July 2016

We have studied the Hubble diagram for an almost complete sample of 48 Seyfert galaxies. We find that if Malmquist bias is taken into account, the correlation of [log(cz), V] pairs for Seyfert galaxies is statistically significant and that the slopes of the two regression lines are consistent with those expected if the redshifts of Seyfert galaxies are cosmological.
II. The Galaxy
Authors: Weaver H. F.
Published: July 2016

Investigations of the structural form of the Galaxy are being actively carried on at a number of observatories. The portion of the Galaxy surveyed has been markedly increased since the time of the first Symposium for Coordination of Galactic Research. Many new results have been obtained, particularly in the southern hemisphere; additional observing programs are in the planning stage. New observational techniques for some problems have been found and are under investigation.
Symposium Sur l'Avenir du Service International des Latitudes — Compte rendu des séances
Authors: Guinot B. , Murray C.A.
Published: July 2016

Ce symposium a été organisé à la suite de la recommandation de la 10èmeassemblée générale de l'U. A.I. Nous avons essayé d'utiliser le mieux possible le temps écoulé depuis cette assemblée pour effectuer les travaux préparatoires. Je dois exprimer mes remerciements cordiaux à mes collègues, membres du comité d'organisation :

Pr. CECCHINI, Dr. MARKOWITZ, Dr. MELCHIOR, Pr. TARDI, pour leur aide efficace dans ce travail. Mr. Sadler, Secrétaire Général de l'U. A.I. a aussi porté son attention sur toutes les étapes de ce travail et son action diligente a contribué à en assurer le succès.
Comparaison de la lunette zenithale photographique et de l'Astrolabe Danjon dans le cadre de la réorganisation du Service International des Latitudes - Commentaires présentés au Congrès de l'U. G. G. I. à Helsinki pour l'Observatoire de Neuchâtel (Suisse)
Authors: Blaser J. P.
Published: July 2016

Nous désirons présenter ici les expériences faites au cours des observations régulières (heure et latitude) effeetuées par l'Observatoire de Neuchâtel avec une lunette zénithale photographique (PZT, Grubb, Parsons, dès 1956) et avec un astrolabe Danjon (OPL, dès 1957). Les résultats détaillés de ces observations sont publiés régulièrement dans le “Bulletin de l'Observatoire de Neuchâtel”, Série B. L'interprétation des résultats et la discussion des erreurs est donnée dans plusieurs fascicules des “Publications de l'Observatoire de Neuchâtel”.
Sur l'Avenir du Service des Latitudes - Note II - Résumé
Authors: Melchior P.
Published: July 2016

Dans la communication deN. Stoyko, on est frappé par la moindre précision de la coordonnée Y. Celà montre qu'on ne peut trop insister sur la question d'une bonne distribution en longitude. Cette moindre précision a d'ailleurs toujours été notoire mais nous avions trouvé (1954) pour Y (S. I. L.) un écart moyen maximum de 0″019. Il nous semble que la valeur de 0″024 donnée ici est un peu trop forte.
A Study of the Figure of the Moon from Photographs of the Full Moon
Authors: Potter H. I.
Published: July 2016

A study of the general figure of the Moon is of great importance for the solution of many problems. First of all, in astrometric observations of the Moon the position of its centre is determined by reference to its limb; and thus in order to compare the observed coordinates of the Moon with ephemerides it is necessary to adopt a definite hypothesis about the form of the limb. On the other hand, when compiling maps of the marginal zone of the Moon it is necessary to refer the heights of individual points to the barycentric sphere, common for all sections of the limb and all phases of libration. And, thirdly, studies of the rotation of the Moon and of its physical librations are also connected with the measurement of points on the limb and require the knowledge of its general form. Finally, a knowledge of the exact figure of the Moon is highly important for the theory of the origin and evolution of our satellite.
Dispositifs Destinés à Remplacer L'Héliometre
Authors: Rösch Jean , Hugon Marcel
Published: July 2016

Les appareils utilisant, pour la mesure d'un petit angle, un dédoublement du faisceau qui produit deux images séparées par une quantité connue se sont imposés par leur propriété de permettre une mesure indépendante des mouvements de rinstrument. Parmi ces appareils, l'héliomètre est utilisable pour la mesure d'écarts angulaires atteignant quelques dizaines de minutes (et notamment pour la détermination de la forme et du mouvement du globe lunaire), mais il est grévé de défauts importants dans sa conception d'origine–qui n'a d'ailleurs jammais varié. Les micromètres donnant une double image par birefringence, par contre, dont la technique est bien au point, ne sont utilisables que jusqu'à des séparations angulaires de une ou quelques minutes, sous peine de rencontrer des difficultés pour obtenir des matieres biréfringentes du volume voulu. Le présent travail se propose de rechercher un type d'appareil dérivé de l'héliomètre qui conserve son domaine d'applicabilité et soit affranchi de ses défauts.
Lunar Charting on the Scale 1: 1000000
Authors: Carder Robert W.
Published: July 2016

The Aeronautical Chart and Information Center (ACIC), St. Louis, Missouri, U.S.A., with assistance from the scientific community, has embarked on a program to produce 1 : 1 000000 scale charts of the Moon. This work is an Air Force cartographic contribution to the United States Space Program.
Stratigraphic Basis for a Lunar Time Scale
Authors: Shoemaker Eugene M. , Hackman Robert J.
Published: July 2016

The impending exploration of the Moon and geologic mapping of its surface raise the need for an objective lunar time scale. Photogeologic mapping already in progress has made this need immediate, and at the same time furnishes the stratigraphic foundation on which the broad framework of a lunar time scale may be based. This paper is a report of progress in meeting this need. Five major stratigraphic subdivisions will be described which have been adopted for use in detailed photogeologic mapping at a scale of 1 : 1 000 000.
Photogeologic Study of the Moon
Authors: Mason Arnold C. , Hackman Robert J.
Published: July 2016

A generalized photogeologic study of the surface of the Moon was prepared for the Office of the Chief of Engineers by the United States Geological Survey, as a part of a joint program with Army Map Service, which meanwhile was making a lunar topographic map. A “Generalized Photogeologic Map of the Moon” and “Physical Divisions of the Moon” were compiled using a photomosaic in orthographic projection at an approximate scale of 1: 3800000 as a base, prior to the completion of the lunar topographic map. Modified forms of these two maps are presented here, in which details have been simplified appropriate to the smaller scale.
Microrelief of the Lunar Surface and the Probable Ways of its Formation
Authors: Sharonov V. V.
Published: July 2016

Already in the Seventeenth century Galileo Galilei [1] had turned his attention to the peculiarity of the reflection of light from the lunar surface, which consisted of the fact that the disk of the full Moon exhibits no darkening towards the limb. Galilei explained this by assuming that, besides the mountainous macrorelief on the Moon, which could be observed in the telescope, there existed an ubiquitous microrelief pointing to a very rough structure of the lunar surface. Modern photometric observations have fully confirmed this conclusion and have enabled us to unravel many peculiarities of this microrelief—in particular, the rather unique law of reflection from the lunar surface, expressed by a reflection diagram very elongated in the direction of the Sun. The comparison with the laboratory measurements carried out by Orlova [2] showed that the elements of this relief should possess vertical, or very steep, walls and sharp broken-off edges reminding one by their structure of laced volcanic slags and lapilli. At the same time the dimensions of these irregularities are found to be small—of the order of limilmetres or centimetres [3].
On the Photometric Homogeneity of the Lunar Surface
Authors: Barabashev N. P. , Ezersky V. I.
Published: July 2016

The first photometric investigations of the lunar surface [1, 2] revealed the basic peculiarities of the reflecting properties, which proved to be characteristic of formations, with different morphological pecularities and location position. These pecularities were interpreted by Barabashev as being due to the very porous, rough relief of the lunar surface.
The Colour of the Bright Rays on the Moon
Authors: Radlova L. N.
Published: July 2016

The systems of rays on the surface of the Moon are of great importance for selenology because, on any hypothesis concerning the origin of the lunar craters, the formation of bright rays and aureolae should be the results of some kind of explosive phenomena. At the present time two views regarding the nature of bright rays are most widely held. According to one of these, the rays are cracks in the crust of the Moon, filled with lava; while according to the other, the rays are formed by matter ejected from the zone of a crater and spread over a previously existing relief. Photometric and colorimetric data allow the reliability of these two hypotheses to be evaluated.
The Phase Dependence of Radio Emission of the Moon on 3·2 cm
Authors: Strezhneva K. M. , Troitsky V. S.
Published: July 2016

The absolute measurements of the intensity of radio emission of the Moon, carried out with the aid of more advanced equipment and method of calibration, made it possible to reveal its variation with the phase, and yielded the value of the effective temperature for the centre of the disk practically equal toT1= 245° + 15·5° cos(Ωt−50°), the ratio of penetration depth of the electric wave to the thermal wave equal to 6·0, and δ/λ = 2·0.
Measurement of solar X-Ray spectrum between 13 and 26 Å
Authors: Blake R. L. , Chubb T. A. , Friedman H. , Unzicker A. E.
Published: July 2016

In July 1963, the U. S. Naval Research Laboratory flew an Aerobee rocket equipped with a Bragg Crystal Spectrometer in an attempt to record an x-ray spectrum of solar emission. A pointing control was used to keep the device accurately pointed at the Sun. A spectrum of about 12 lines between 12 and 25 Å was recorded, made up mainly of lines from O VII, O VIII, N VII and Fe X VII. The O VII and N VII lines appeared to come from the entire solar disk. The Fe XVII lines originated almost entirely in a single plage region.
Recent solar X-ray studies in the United Kingdom
Authors: Pounds K. A.
Published: July 2016

Solar X-ray data obtained over the past year by scientists in the United Kingdom are reviewed. These include several new X-ray events reduced from the Ariel satellite results, soft X-ray flux measurements from NRL satellite 1963–21 C and notes on recent rocket studies in this field. A brief discussion is added on the nature of solar flare X-rays and their measurement.
Collisional excitation of autoionizing levels
Authors: Goldberg Leo , Dupree Andrea K. , Allen John W.
Published: July 2016

Collisional excitation of autoionizing levels is found to contribute significantly to the ionization rate for certain ions at temperatures characteristic of the solar corona. Preliminary calculations have been carried out for O IV, O V, O VI, Fe XV and Fe XVI. Autoionization may be of importance for O IV and increases by approximately a factor of two the ionization rate of Fe XV and XVI.
1115 Å far ultraviolet stellar photometry
Authors: Byram E. T. , Chubb T. A. , Werner M. W.
Published: July 2016

Stellar brightness measurements in the far ultraviolet at wavelengths above Lyman α have been obtained from several experiments beginning in 1960. The 1960 data were obtained using mirror telescopes and gas gain ion chambers. They indicated far ultraviolet stellar brightness about 1 magnitude lower than predicted by theory. Subsequent Geiger counter data appear to support this conclusion. The reliability of rocket far ultraviolet stellar photometry, however, is still insufficient, to place great confidence in the above conclusions.

Stellar brightness measurements in the band 1150–1180 Å indicate that there may be a considerably greater deficiency in far ultraviolet stellar emission at wavelengths below Lyman α than above.
High energy cosmic photons and neutrinos
Authors: Gould R. J. , Burbidge G. R.
Published: July 2016

This review concentrates primarily on the problem of interpreting the recent X-ray and γ-ray observations of celestial sources. The expected fluxes of hard radiation from various processes are estimated (when possible) and are compared with the observations. We compute the synchrotron, bremsstrahlung, and (inverse) Compton spectra originating from relativistic electrons produced (via meson production) in the galaxy and intergalactic medium by cosmic ray nuclear collisions; the spectra from π°-decay are also computed. Neutron stars, stellar coronae, and supernova remnants are reviewed as possible X-ray sources. Special consideration is given to the processes in the Crab Nebula. Extragalactic objects as discrete sources of energetic photons are considered on the basis of energy requirements; special emphasis is given to the strong radio sources and the possibility of the emission of hard radiation during their formation. The problem of the detection of cosmic neutrinos is reviewed.

As yet, no definite process can be identified with any of the observed fluxes of hard radiation, although a number of relevant conclusions can be drawn on the basis of the available preliminary observational results. In particular, some cosmogonical theories can be tested.
Observational result on X-rays
Authors: Fisher Philip C. , Clark Dwight B. , Meyerott Arthur J. , Smith Kermit L.
Published: July 2016

Final results are presented for a March 20, 1963 search for night sky sources of soft X-rays. Although one sky region was found to be associated with an X-ray flux 2,5 to 3 standard deviations above background, the probability of observing one random fluctuation of this importance in the data for the night sky is estimated to be as high as 20%. The region is located at α= 23 h 40 m, δ = + 78°. Apparently negative results from a search of the data for variations of X-ray background with galactic latitude are presented and discussed.
The X-ray emission of neutron stars
Authors: Morton Donald C.
Published: July 2016

A simple gray atmosphere has been fitted to a sequence of neutron star models with central temperatures ranging from 2 × 109 to 2 × 107 °K in order to estimate the X-ray emission and cooling times. A neutron star with a central temperature hotter than 5 × 107 °K would emit sufficient X-radiation to account for that observed in Scorpius. More detailed atmospheric models including the K absorption edges of carbon, nitrogen, oxygen, and neon were constructed for effective temperatures of 107 and 5 × 106 °K.
Remarks on the Mariner 2 limb-darkening measurements
Authors: Kaplan L. D.
Published: July 2016

It is shown that the limb-darkening observed in the radiometric measurements of Venus cannot be interpreted unambiguously in terms of cloud structure or vertical temperature distribution. In order to understand the nature of the Venus atmosphere in the vicinity of the clouds, these data have to be supplemented with accurate measurements in the absorption spectrum.
Observations of the white-light corona by rocket
Authors: Tousey R.
Published: July 2016

A Lyot coronagraph with a saw-toothed external occulter was flown in an Aerobee rocket on June 28, 1963. Twenty-three white-light photographs, with exposure times from 1 to 56. seconds were secured at altitudes from 131 km to 204 km. The corona was recorded from 3.5 to 10 solar radii from the Sun's center. The coronal brightness function followed distributions determined during total solar eclipses; however, the brightness level was two to three times greater, suggesting that a significant quantity of light originates from small-angle forward-scattering by material between the earth and the sun, which is not illuminated during a total eclipse. One coronal streamer was recorded to about ten radii, before disappearing into the corona. Trails of slow-moving particles in space are conspicuous in most of the photographs.
Results from the UK-2 Satellite
Authors: Harvey C. C.
Published: July 2016

The receiver in the satellite UK-2 is briefly described. Interference-free data received where the satellite is near the apogee of its orbit is of interest for astronomical and ionospheric work, and typical samples of such data are shown, the salient features being pointed out. Among the tatter are the ionospheric noise bands, and the propagation of waves in the i-mode. The method of determination of the orientation of the satellite at any given time is described, and the consequent conclusions about the polarisation of the signals are stated.
Telescope Design
Authors: Baustian W. W.
Published: July 2016

BAUSTIAN : In opening the section which is the beginning of the engineering phase of the symposium, I would like to make a few short remarks. Essentially, as we all know, telescope design is merely a method of combining a number of optical components and maintaining their optical alignment during the operation of the telescope. The engineering problem is not only one of shop fabrication and field erection but also of providing for an unknown host of future improvements, modifications, and additions that will be made to the basic telescopes. Essentially, the engineers should design a mounting that leaves as many doors as possible open to these future modifications and additions. It is one of the few large fabrications that envision a useful life of at least 50 years. Therefore, it might be appropriate to caution engineers, since the expected lifetime of these instruments is 50 years or more, that ease of fabrication, which involves a relatively short period of the total life of telescope, should not be made the basic design consideration.
Part 7 MISCELLANEOUS PROBLEMS
Authors: Heckmann Dr O.
Published: July 2016

HECKMANN: I'll call on Bruce Rule to begin this session.