bluuebunny/crossref_metadata_2025 huggingface dataset:
Results from Three Dimensional Spectral Classification of Population II Stars Using the DDO Photometric System
Authors: Osborn W.
Published: July 2016

The David Dunlap Observatory (DDO) intermediate-band photometric system described in the previous paper has been used to observe a number of red giant branch, horizontal branch, and asymptotic branch members in each of the five globular clusters M3, M5, M10, M13, and M92. A calibration of the DDO system is described by which it was possible to determine the effective temperatures, surface gravities, [Fe/H] values, and masses of the observed stars. The mean [Fe/H] values for the clusters were found to be −1.01 for M3, −0.68 for M5, −1.44 for M10, −1.69 for M13, and −1.96 for M92. Evidence was found that the masses of the horizontal branch and asymptotic branch stars are systematically smaller than those of red giant branch members. Two stars were discovered to have CN bands that are anomalously strong for Population II objects. The observational results have been compared with the theoretical predictions of two detailed Population II evolutionary tracks and in general the agreement is good.
Neutron Star Structure from Pulsar Observations
Authors: Pines David , Shaham Jacob , Ruderman Malvin A.
Published: July 2016

We examine what inferences can be made regarding neutron star structure from observations of micro- and macroglitch behavior. After considering various theories it seems plausible that crustquakes offer an explanation for the Crab microglitches, while corequakes can explain the Vela macroglitches. It is concluded that the Crab pulsar has a mass of less than 0.5 M⊙ and is ∼ 90% superfluid neutrons while the Vela pulsar may possess a solid neutron core and have a mass of ∼ 0.7 M⊙ with a superfluid neutron abundance of ∼ 15%.
The temperature of galactic neutral hydrogen
Authors: Shuter W. L. H.
Published: July 2016

There appears to be no correlation of the velocity dispersion of Gaussian components observed in 21-cm absorption profiles with the angular diameter of the radio source. Consequently, the difference of typical dispersions observed in absorption and in emission must be due to excitation temperature fluctuations. A hot medium of 600 °K is postulated.
Remarks on the diffuse interstellar lines
Authors: Herzberg G.
Published: July 2016

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.
The run of terminal velocities for the western part of the Galaxy
Authors: Bajaja E. , Garzoli S. L. , Strauss F. , Varsavsky C. M.
Published: July 2016

The rotation curve observed with the Argentine radio telescope is systematically higher than that found at Parkes. The discrepancy appears to be caused by the difference in frequency resolution of the two receivers.
Density waves in disk galaxies
Authors: Lin C. C. , Shu F. H.
Published: July 2016

Density waves in the nature of those proposed by B. Lindblad are described by detailed mathematical analysis of collective modes in a disk-like stellar system. The treatment is centered around a hypothesis of quasi-stationary spiral structure. We examine (a) the mechanism for the maintenance of this spiral pattern, and (b) its consequences on the observable features of the galaxy.
Recent absolute calibration work at Palomar Mountain
Authors: Oke J. B. , Schild R.
Published: July 2016

A four inch hermetically sealed reflecting telescope has been attached to the prime-focus scanner to provide an observing system for absolute calibration work. Light sources, including a platinum and a copper furnace, are observed at a distance of approximately 1200 feet. Since the telescope focal length is only 13 inches these sources look like stars. Thus bright stars such as α Lyr are compared directly with the light sources under identical instrumental conditions.

It has been found that horizontal extinction can be abnormally large; therefore it is measured several times each night. The absolute calibration is being derived at present from 3500 Å to 11000 Å and will be extended to 3200 Å as soon as possible. The calibration lies approximately midway between that measured recently by Hayes and that adopted some years ago by Oke. A very preliminary value for the absolute flux from α Lyr at 5556 Å is 3.5 × 10−20 ergs sec−1 cm−2 Hz−1 or 3.4 × 10−9 ergs sec−1 cm−2 Å−1.
Mariner 5 measurements of ultraviolet emission from the Galaxy
Authors: Barth Charles A.
Published: July 2016

The Mariner 5 ultraviolet measurements obtained while the spacecraft was in interplanetary flight are interpreted as Lyman-α radiation. This radiation may arise from (1) the scattering of solar Lyman-α radiation by interplanetary atomic hydrogen, (2) the scattering of solar Lyman-α by atomic hydrogen that is present at the edge of the solar system, or (3) diffusely scattered Lyman-α radiation from the Galaxy. The Mariner 5 measurements show a symmetry with respect to the galactic equator which suggests that the major source of the observed emission is the diffuse galactic radiation. In the Münch model for the diffuse Lyman-α radiation from an HI region, the sources of the Lyman-α photons are stellar chromospheres, the photons are scattered a large number of times by interstellar atomic hydrogen, and are absorbed by interstellar dust. Some of the Mariner 5 measurements may be attributed to Lyman-α emission from an HII region since the field of observation scanned the edge of the Gum nebula.
Venus: Determination of atmospheric parameters from the microwave spectrum
Authors: Pollack James B. , Morrison David
Published: July 2016

The microwave spectrum of Venus is compared with the structure and composition of the Venus atmosphere as determined by Veneras 4, 5, and 6 and Mariner V. The results are consistent with a radar radius of 6049.5 ± 3 km, surface pressures of 95 ± 20 atm, and a surface temperature of 770 ± 25 K, as well as a water vapor volume mixing ratio of 0.65 ± 0.35%.
Calculations of CO2 Energy Levels: The Ã1B2 State
Authors: Benedict W. S.
Published: July 2016

The Ã1B2 state of CO2, identified by Dixon (1963) as the upper level of the ‘carbon monoxide flame bands’, must be of importance in the upper atmospheres of Venus and Mars. New calculations of the high vibrational levels of the ground state, which lead to improved fits of the observed vibration-rotation bands, confirm Dixon's analysis, except that the numbering must be lowered by two, and fix the energy of the v = 0, K = 0 level of 1B2 at 45210 ± 10 cm−1 = 5.605 eV.
Variations of the martian CO2 abundance with Martian season
Authors: Barker Edwin S.
Published: July 2016

All previous published equivalent widths of the Martian CO2 bands including the 1967 apparition coverage at McDonald Observatory are reduced to CO2 abundances using the same curve of growth parameters. The corresponding CO2 partial pressures (assuming a pure CO2 atmosphere), along with the regression curves of the north polar cap, are presented as functions of Martian heliocentric longitudes, Ls. A correlation is noted between the maximum CO2 abundance and minimum north cap diameter and the decrease in CO2 abundance when the northern polar haze begins to reform. Preliminary results of the 1969 apparition coverage at McDonald Observatory are also presented.
Upper limit of hydrogen and helium concentrations on Titan
Authors: McGovern Wayne E.
Published: July 2016

The satellite Titan is commonly quoted as possessing an atmosphere consisting of at least 2 × 104 cm atm of methane. Plausible additional atmospheric constituents like hydrogen and helium are assumed to have completely escaped from the satellite. However, the employment of recent techniques to the upper atmosphere of Titan permits an improved estimate of the upper limits of the hydrogen to methane and helium to methane mixing ratios existing in the lower atmosphere of Titan, namely 10−6±1 and 10−3.5±0.5.
A review of geodetic parameters
Authors: Kaula William M.
Published: July 2016

It is recommended that the parametric values which are currently most used in orbital computation be adopted as provisional standards rather than those which may be the best available and from which they differ only slightly. It is remarked that the most serious geodetic errors affecting astronomy are tracking station positions. Standard methods of describing positions are suggested.
Collapse of stellar systems
Authors: Ulam S. M.
Published: July 2016

This paper concerns the problem of a possible acceleration of collapse of stars in a very dense configuration—such as one might find in a center of some galaxies. The calculations mentioned in an article inNature(1) were continued by Myron Stein from the Los Alamos Laboratory and by the author.
CLEAN/MEM Deconvolution Errors: Semicompact Sources
Authors: Briggs D. S. , Cornwell T. J.
Published: July 2016

We have run a number of simulations investigating the limitations of noiseless point spread deconvolution with the VLA. On-source errors of more than .01 and off-source dynamic ranges of less than 15,000 were found for some parameters typical of high precision observations. Deconvolution errors were not confined to the support of the source, and limit the dynamic range in at least one VLA observation.
Aspects of the Theoretical Performance of Modal Adaptive Optics
Authors: Wilson R.W. , Jenkins C.R.
Published: July 2016

This paper describes early results of a theoretical investigation of the performance of an adaptive optics system in which a limited number of Karhunen-Loeve modes of the wavefront distortion are corrected. We have determined the on-axis point spread function for an idealised adaptive optics system in Kolmogorov seeing, whose performance is defined in terms of radii of included energy and Strehl ratios for a range of examples. We discuss extensions of the analysis for the off-axis point spread function, and for non-Kolmogorov seeing.
High Resolution Image Reconstruction at Yunnan Observatory
Authors: Qiu P. , Qiu Y. , Qian P. , Liu Z.
Published: July 2016

The research on the high resolution image reconstruction has been carried out at the Yunnan Observatory, the Chinese Academy of Sciences, since 1983. At the early stage in 1983–1987, our research was concentrated on the Speckle Interferometry[1]. The first developed speckle camera for using the film as the recording medium was made up of an intensifier with a gain of 57,000 and an SB-408-B oscilloscope camera. In May, 1985, 144 speckle interferograms of the binary ζBoo and the unresolved single star 32 Boo apiece were obtained with the speckle camera attached to the 1-M Rcc telescope, and the average power spectrum of ζBoo was then acquired by means of the Optical Fourier Transformation[2]. Soon afterwords, the optical couple of the intensifier to a RCA CCD(320×512 pixels) through a lens was used to replace the film and the oscilloscope camera, thereby making an improvement on the detectability up to 7m from 4m. In December, 1986 the improved camera attached to 1-M telescope was used to observe three binary stars, i.e. Kui23, Σ73 and Σ346AB. The speckle interferograms were processed with a computer and angular seperations of these binaries were obtained approximate to the diffraction-limited resolution of the telescope[3].
Comparison of HST and VLA Images at 0.1″ of the Orion Nebula
Authors: O'Dell C. R. , Hu Xihai
Published: July 2016

We have compared the images of two compact sources near the center of the Orion Nebula obtained with the VLA and HST. When the Hα image is scaled to the radio continuum we see similar objects. The VLA shows higher concentration of flux, reflecting the better resolution (FWHM=0.13″ versus 0.18″); but, does not show the extended cometary form of the sources due to the greater sensitivity of the HST.
Trends in Galaxy Formation and Evolution in the Context of the Virial and Fundamental Planes
Authors: Chatterjee Tapan K. , Magalinsky V.B.
Published: July 2016

The kinetic description of gravitating systems has acquired vital importance in the context of trends in galaxy formation and evolution as evidenced by the existence of the virial and fundamental planes. The fundamental plane deviates for brighter and fainter ellipticals; until the brightest cluster members (BCMs), whose structures have been most modified by interactions, seem to occupy a fundamental plane with a different slope as compared to normal ellipticals. Extending the work of Magalinsky (1972, AZh, 49, 1017; Sov. Astron.-AJ, 16, 830), the Vlasov equation is applied to study small perturbations (considered as protogalaxies) of the exact solution corresponding to a spatially homogeneous medium in expansion. It is found that a perturbation attains a saturated size whose scale length, as a function of a reduced parameter of evolution (in terms of the characteristic frequency of dispersion of momenta, τ), R(τ) ∝ K.E./P.E. ∝ (K.E.)2/σ ∝ (δV)2/Proj.density ∝ σ2/I, which has the parametric form of the virial plane. The subsequent evolution is characterized principally by the variation of the energy due to the gravitational interactions between stars (considered as mass points), given by the potential energy such that the harmonic mean separation scale (between stars) characterizes this evolution. In this stage of the evolution the harmonic scale separation has the parametric form, 〈r−1〉 ∝ (K.E.)1/2, and 〈r−1〉 ∝ (P-E.) such that 〈r−1〉 ∝ (K.E.)1/2/(P.E.) ∝ σ/I. Notice that this is the parametric form of the fundamental plane of evolved ellipticals since the harmonic scale separation determines a physically significant scale.
Multimodal Color Distributions in the Globular Cluster Systems of Giant Elliptical Galaxies
Authors: Geisler D. , Lee M.G.
Published: July 2016

We report on new observations of the globular cluster systems (GCSs) of two galaxies: M86 (NGC 4406) in Virgo and NGC 4696, the central giant elliptical (gE) in the Centaurus cluster. Previous observations in M86 showed no evidence for bimodality, but using only (V - I) for small cluster samples. The NGC 4696 GCS is unstudied. We used the integrated Washington (C - T1) color. This metallicity index is more than twice as sensitive to [Fe/H] as (V - I). In M86 we have about 1100 good GC candidates, and about 650 in NGC 4696, with mean internal metallicity errors ~ 0.15 dex. Both of these GCSs are found to have bimodal metallicity distributions (MDs). Our data strengthen previous results that MDs for the GCSs of gEs are widespread. The evidence for 2 separate populations in these galaxies is corroborated by examining the surface density distributions: the metal-rich clusters are more centrally concentrated than their metal-poor counterparts. The overall radial metallicity gradient present in the M86 GCS is due to the varying radial mix of the 2 populations. The existence of 2 GC populations signifies that there were 2 distinct epochs or events of cluster formation in a gE. The simple collapse model of gE formation is ruled out.
Evolution of Subsystems During Collapse of a Cluster
Authors: Tsuchiya Toshio
Published: July 2016

Motivation: In the hierarchical clustering scenario, objects with smaller masses collapse and virialize earlier. I am interested in the effects of the existence of virialized subsystems on the structures of a collapsing larger mass object, and the fate of subsystems.
A Search for Extended Objects with Variable Nuclei
Authors: Trèvese D. , Bershady M.A. , Kron R.G.
Published: July 2016

A large sample of QSOs/AGNs with detectable host galaxies is important to study the relations between the properties of the host and nucleus. Relatively faint active nuclei are of particular interest since they represent the low luminosity part of the QSO luminosity function, whose cosmological evolution is still poorly known. The non-stellar colors criterion cannot be applied to extended objects since most galaxies appear as non-stellar in color space. We have selected a sample of candidate AGNs with extended image structure on the basis of their variability, extending a previous survey for variability in objects with stellar structure (Trèvese et al. 1989, A J, 98, 108; 1994, ApJ, 433, 494). The new sample allows a comparison with different selection techniques and increases the completeness of our previous survey. We add to the previously published spectroscopic observations new data providing the confirmation of some additional candidates. Presently we have 5 confirmed candidates from our primary sample of 16 objects brighter than BJ = 22 (Bershady, Trèvese, & Kron 1997, ApJ, in press). Since it is likely that our sample contains some additional bona fide AGNs, further spectroscopic work is desirable. We can put a lower limit of 106±20 deg−2 on the surface density of AGNs brighter than BJ=22.0 mag. The newly detected extended AGNs are at least ten times fainter than MB=-23 mag and represent 13 % of the total number of AGNs.
Nucleosynthesis in Red Giant Stars
Authors: Mowlavi Nami
Published: July 2016

The production of elements from helium-3 to fluorine in low- and intermediate-mass stars is reviewed and compared to chemical abundances observed at the surface of both red giant branch and asymptotic giant branch stars. It is highlighted that, while the trends predicted by standard models are generally well confirmed, many chemical abundances observed at the surface of red giants require the operation of non-standard mixing in the stellar interior. In addition, chemical abundance predictions from presently available asymptotic giant branch models further suffer from the uncertainties affecting the third dredge-up phenomenon, the source of neutrons and the hot bottom burning process.
Compton Reflection in the Vicinity of a Rotating Black Hole
Authors: Maciołek-Niedźwiecki A. , Magdziarz P.
Published: July 2016

We study the spectra arising from Compton reflection in the innermost parts of the accretion disk. We emphasize that the so far neglected relativistic distortion of the Compton reflection continuum may strongly affect the derived Fe Kα line shapes.
The X-Ray Spectrum and Variability of NGC 4151
Authors: Leighly K. M. , Matsuoka M. , Cappi M. , Mihara T.
Published: July 2016

We report investigation of the iron Kα line in a long (100 ks) ASCA observation of NGC 4151. This observation offers unprecedented good statistics; however, the situation is complicated by the fact that the absorption in NGC 4151 is complex and therefore it is difficult to deconvolve a broad iron line from the power law strongly curved by the absorption. Preliminary spectral fitting with a dual absorber model, using updated abundances and response matrices, and also allowing for iron overabundance, revealed significant spectral residuals around 5 keV which could be modeled with a broad Gaussian. This profile resembles the line characteristic of emission from a relativistic accretion disk; however, that model fit the spectra poorly. Since the energy of the narrow core is nearly 6.4 keV, the orientation of the accretion disk should be nearly face-on, because if the inclination were higher, the blue horn should be shifted to higher energies. If the orientation is face-on, there should be no emission blueward of 6.4 keV; however, a small blue wing as well as a long red wing are present in the residuals.
Search for 10 TeV Gamma-Rays from the Nearby AGNs with the Tibet Air Shower Array
Authors: Ding L.K. , Kobayashi T. , Mizutani K. , Shiomi A. , Tan Y.H. , Yuda T. ,   the other members of the Tibet ASγ Collaboration
Published: July 2016

The detection by EGRET of gamma-rays from more than 50 active galactic nuclei (AGNs) allowed us to expect these objects to be the sources of extragalactic cosmic rays at very high energy. The TeV gamma-rays from nearby BL Lac objects of the AGNs examined were detected by the Whipple Observatory collaboration. In this paper, we present the results given by the Tibet air shower array on the search for 10 TeV gamma-ray emission from 18 relatively nearby AGNs with redshifts of z < 0.07.
Microvariability of S5 0716+714, a γ-Ray Blazar
Authors: Nesci R. , Massaro E. , Maesano M. , Montagni F. , D'Alessio F. , Tosti G. , Luciani M.
Published: July 2016

Like many radio-selected blazars, 0716+714 shows a high level of variability on different time scales, as short as a few days (e.g. Wagner et al 1996, Ghisellini et al. 1997). The mechanism of the emission in the optical band, in the general scheme of a relativistic plasma jet highy collimated toward the observer, is generally believed to be synchrotron radiation from electrons in a strong magnetic field. Our monitoring of S5 0716+714 is aimed to clarify whether the flux variations are chromatic or achromatic. In the first case, one could guess that variations in the spectrum of the injected electrons are responsible for the flux variations; in the second case, geometrical effects like small changes in the angle between the jet and the line of sight could be more likely (Wagner et al. 1993).
ASCA Deep Sky Survey
Authors: Ogasaka Y. , Kii T. , Ueda Y. , Takahashi T. , Inoue H. , Ishisaki Y. , Ohta K. , Yamada T. , Makishima K. , Miyaji T. , Hasinger G.
Published: July 2016

ASCA DSS was intended to carry out unbiased surveys in wide energy range of 0.5-10 keV. The strategy of this project is to survey small sky region with extremely high sensitivity reaching to the source confusion limit of ASCA XRT, in contrast to the Large Sky Survey project (Ueda 1996) which covers much larger sky area with relatively shallow exposure.
The importance of helium and metals diffusion in stars
Authors: Proffitt Charles R.
Published: July 2016

Comparisons between models of the solar interior and sound speed profiles derived from inversions of helioseismic data have demonstrated that it is essential to include the effects of gravitational settling when calculating the structure and evolution of the Sun. Including settling should also be necessary for models of metal poor main-sequence stars and results in a substantial reduction in the ages derived for globular clusters.

In many cases it is clear that competing hydrodynamic processes, such as mass loss or rotationally driven mixing, will limit the effectiveness of gravitational separation of chemical elements. However, the quantitative details and even the relative importance of the different processes in various types of stars remains poorly understood.
Molecular Clouds in the LMC Observed with NANTEN: IV. Comparison with SNRs
Authors: Saito H. , Abe R. , Hara A. , Hayakawa T. , Kato S. , Kawamura A. , Mizuno A. , Mizuno N. , Ogawa H. , Onishi T. , Tachihara K. , Xiao K. C. , Yamaguchi N. , Yamaguchi R. , Fukui Y. , Yonekura Y.
Published: July 2016

We have made 12CO(J=1−0) observations of the LMC with NANTEN. We report the results of a comparison between CO clouds and SNRs in the LMC. Among the 35 known SNRs, only 10 are possibly associated with CO clouds. These 10 CO clouds and SNRs deserve follow-up studies for possible interactions. We present overlays of CO clouds on the optical images of some of these SNRs.
Intermediate-age and Old Populations in the Small Magellanic Cloud
Authors: Hatzidimitriou D.
Published: July 2016

The star formation history and kinematics of intermediate-age and old populations in the Small Magellanic Cloud are the subject of this brief review. New results confirm the occurrence of a period of enhanced SF about 8–10 Gyr ago in the SMC. Younger populations are confirmed to be more centrally concentrated than older ones. The SMC, at least in the areas studied (which do not include the Bar) seems to have had a different history of star formation from the LMC. Although the kinematics of the SMC have been extensively studied, it is still unclear if there are distinct Bar, disk and halo components, or if all populations share the same kinematics.
Star Clusters in the Magellanic Type Irr Galaxy NGC 4449
Authors: Seitzer Patrick , Grebel Eva
Published: July 2016

We compare the luminosity function of star clusters in the LMC and NGC 4449: a IBm/Sm type galaxy very similar in appearance and luminosity (MB = −18.5) to the LMC (MB = −18.4). The brightest of several hundred clusters in NGC 4449 have MV = −10 (assuming a distance of 3.9 Mpc), comparable to the brightest clusters in the LMC.
The MACHO Project LMC Variable Star Inventory: Classical Cepheids, AGB Variables, and the Nine Million Star Color-Magnitude Diagram
Authors: Alves D. R. , Basu A. , Cook K. H. , Welch D. L. ,   The MACHO Collaboration
Published: July 2016

We measure the ratio of ~ 5M⊙ blue and red LMC supergiants (representative of classical Cepheids) using the MACHO Project's 9 million star color-magnitude diagram (9M CMD) of the LMC bar. We find b/r = 0.39, which favors the Z=0.008, 5M⊙ theoretical model of Schaerer et al. (1993) over that of Fagatto et al. (1994). Next, we examine the low mass (old) and low metallicity LMC field population (Pop. II). Features in the 9M CMD and properties of LMC field RRab variables are consistent with a mean iron abundance of [Fe/H] ≈ −1.5 dex for this population. Newly discovered post-HB/early-AGB Pop. II variables are identified in order to delineate the instability strip (IS). Good agreement with the theoretical IS of Bono et al. (1997) is found. We then compare the field RRab with newly identified RRab variables in the LMC clusters NGC 1898 and NGC 1835. We find the mean colors of these cluster RRab lie near the red and blue edges of the IS, respectively, which is similar to their respective (overall) red and blue HB morphologies. Since the field RRab lie on the red side of the IS, we infer the LMC field Pop. II is likely to have a red HB morphology.
Bruno Morando (1931–1995)
Authors: Arlot J.-E. , Ferraz-Mello S.
Published: July 2016

Bruno Morando est né en 1931 à Courbevoie, près de Paris. Après des études à la Faculté des Sciences de Paris, il est nommé assistant à la Faculté en 1960 et, en 1963, il entre au Bureau des longitudes, oò il effectuera sa carrière d'astronome. Il soutient sa thèse en 1966 sur le thème: “Théorie planétaire semi-numérique sans introduction de termes séculaires; application à Vesta”. Grâce à André Danjon, Jean Kovalevsky et Bruno Morando vont transformer le Service des calculs du Bureau des longitudes en un laboratoire de recherche en mécanique céleste mondialement réputé. Il en sera le directeur de 1971 à 1984.
Aspa—Sky Patrol for the Future
Authors: Dous C. La , Kroll P.
Published: July 2016

Ever since the turn of the century sky patrol observations—i.e., the routine surveillance of the visible night sky—has been one of the main foundations of variable star research, and thus of astronomy in general. Historically several of the major Observatories all around the world were contributing. Up to this day all these observations are in the form of large-field photographic plates, constituting a total of some 2 million plates which, collectively, contain the history of the light changes of celestial objects (mostly in the northern hemisphere and down to some 13 magnitudes apparent brightness or fainter) during the past 100 years. In modern times the last place left in the world where sky patrols are still being carried out routinely is Sonneberg Observatory.
Results from ASCA Sky Surveys
Authors: Ogasaka Y. , Ueda Y. , Ishisaki Y. , Kii T. , Takahashi T. , Makishima K. , Inoue H. , Ohta K. , Yamada T. , Miyaji T. , Hasinger G.
Published: July 2016

The origin of the Cosmic X-ray Background (CXB) radiation has been investigated extensively by soft X-ray deep survey imaging observations with Einstein and ROSAT. In contrast, the lack of telescopes capable of detecting hard X-rays has prevented us from extensive study of the nature of the CXB in the energy range above 2 keV before ASCA.
New and misclassified Planetary Nebulae
Authors: Kohoutek L.
Published: July 2016

This fifth supplement to the ‘Catalogue of Galactic Planetary Nebulae’ (CGPN - Perek, Kohoutek, 1967) covers the period 1991-1994 and contains four lists. In Table 1 we present 86 new PN, their PK designations, names and equatorial coordinates together with the references of their discovery as PN (!). The summary of the main properties of a PN and of a central star (Paper III) was used. We believe that the mean values given there are still valid, although some ‘limits’ (in parentheses) of the data have to be changed. It concerns mainly PN with very young central stars (stellar temperature down to ≈ 20000 K, gravity down to log g ≈ 3-4, variable spectrum) as well as old PN (diameter of the main nebular body up to ≈ 2.5 pc). Besides, large exp. velocity up to ≈ 300 km/s was measured for the nebular outer structure.
The Planetary Nebulae in NGC 6441 and Pal 6
Authors: Jacoby G. H. , Morse J. , Fullton L.
Published: July 2016

Jacoby & Fullton (1994, BAAS, 26, 1384) searched 133 of the ∼ 150 Galactic globular clusters for Planetary Nebulae (PNe) using the on-band/off-band imaging technique at [O III] λ5007Å. We present preliminary abundances and central star properties for the 2 new PN identified in that survey (labeled JaFu 1 and JaFu 2 by Acker, Marcout, & Ochsenbein 1996).
Study of photometric and spectral variability of Planetary Nebulae during 1968–1996
Authors: Kostyakova E. B.
Published: July 2016

The photometric and spectral study of 7 selected planetary nebulae has been carried out since 1968. (See: Mem. Soc. Roy. Sci. Liege, 6e ser., 1973, 5, 473). During nearly 30 years of photoelectric observations, 5 planetaries (NGC 6572, IC 4997, Hu2-1, NGC 6891 and NGC 6543) have undergone noticeable variations of integral UVB-brightness in the range 0.1÷0.6 mag. The nebulae NGC 6720 and IC 3568 showed no changes of integral brightness exceeding 0.1 mag. The most remarkable behaviour was found for the nebula IC 4997: a steady decrease of the integral brightness in 1968–85, amounted on the whole to 0.4 ÷ 0.6 mag., an unexpected stop of this decrease in 1985–86, and almost monotonous brightening in 1987–96.
Dynamical simulations of the shaping of PNe including radiation effects
Authors: Zweigle J.
Published: July 2016

In order to investigate the shaping of aspherical planetary nebulae the gasdynamical conservation laws of mass, momentum and energy including radiation effects are solved numerically in twodimensional, spherical coordinates. The simulations describe the dynamical interaction of a fast, tenuous, spherically symmetric wind from the central star with the slow, dense, axisymmetric AGB-wind remnant and include photoionization, collisional ionization, collisional excitation, radiative recombination and forbidden line emission as radiation effects.
Final stages of AGB evolution
Authors: Wood P.R.
Published: July 2016

The final stages of AGB evolution still remain difficult to study theoretically. From the stellar point of view, the main theoretical problems are the evolution of the stars (involving shell flashes and dredge-up of carbon and s-process elements), pulsation, and the production of mass loss by pulsation and radiation pressure on grains. In this paper I will discuss these topics. A recent review concentrating more on the circumstellar aspects of AGB evolution is given by Habing (1996).
Red Galaxies around a Quasar at z=1.1 and their Ages
Authors: Tanaka I. , Yamada T. , Aragón-Salamanca A. , Kodama T. , Ohta K. , Arimoto N.
Published: July 2016

We obtained near-infrared and new deep optical images of the field near the radio-loud quasar 1335.8+2834 at z=1.086 where excess of galaxy surface number density was reported by Huthings et al. [AJ, 106, 1324]. We found a clustering of objects with very red optical-NIR color, 4 < R–K < 6 and 3 < I–K < 5 near the quasar. The colors and magnitude of the reddest objects are consistent with those predicted for luminous (> 0.5L∗) and old (2-4 Gyr old) passively evolving elliptical galaxies at z=1.1.
Scale-Invariant Correlation Functions of Cosmological Density Fluctuations in the Strong Clustering Regime and the Stability
Authors: Yano Taihei , Gouda Naoteru
Published: July 2016

We have investigated the scale-invariant solutions of the BBGKY equations for spatial correlation functions of cosmological density fluctuations and the mean relative peculiar velocity in the strongly nonlinear regime. It is found that the solutions for the mean relative physical velocity depend on the three-point spatial correlation function and the skewness of the velocity fields. We find that the stable condition in which the mean relative physical velocity vanishes on the virialized regions is satisfied only under the assumptions which Davis & Peebles took in there paper. It is found, however, that their assumptions may not be general in real. The power index of the two-point correlation function in the strongly nonlinear regime depends on the mean relative peculiar velocity, the three-point correlation function and the skewness. If self-similar solutions exist, then the power index in the strongly nonlinear regime is related to the power index of the initial power spectrum and its relation depends on the three-point correlation function and the skewness through the mean relative peculiar velocity. We also investigate stability of the solutions of the BBGKY equations for two-point spatial correlation functions. In the case that the background skewness is equal to 0, we found that there is no local instability in the strongly non-linear regime.
Does Inflationary Particle Production Suggest a Low-Density Flat Universe?
Authors: Sahni Varun , Habib Salman
Published: July 2016

In a FRW Universe a massless nonminimally coupled scalar field satisfies the Klein-Gordon equation.
Round Table Summary: Problems in Modelling Stellar Atmospheres
Authors: Castelli Fiorella
Published: July 2016

The aim of the Round Table (RT) ”Problems in modelling stellar atmospheres“ was that of giving a panoramic view of the state of art on the atmospheric models used to predict observations of stars from T to A spectral type, the Sun included.
Non-Local Convection Models for Stellar Atmospheres and Envelopes
Authors: Kupka F.
Published: July 2016

We present an overview of the concepts underlying advanced non-local Reynolds stress models of turbulent convection and review a comparison of this approach with a series of numerical simulations of fully compressible convection. We then discuss results from applications of the model to complete envelopes of A-type main sequence stars. The non-local model reproduces surface velocities in agreement with the lower limit of observed macro- and microturbulence velocities of A-star photospheres, the asymmetry of the surface velocity field as inferred from spectral line profiles, and the overall structure of the photospheric and subphotospheric convection zones, as predicted by the most recent numerical simulations available for these stars. Traditionally, local models of convection are unable to do so. We conclude with a brief survey of extensions of the model which are interesting for other applications such as atmospheres of solar type stars and overshooting below deep convective envelopes or above the core in massive stars.
Atomic Physics Data for Stellar Atmospheres Research
Authors: Cowley Charles R. , Adelman Saul J. , Bord Donald J.
Published: July 2016

The review will cover the following topics: (1) Ionization energies; (2) Partition functions; (3) Sources of data for atomic and ionic wavelengths, transition probabilities, and broadening parameters, including nuclear effects (hfs and isotope shifts); (4) Opacities from photoionization of abundant elements (atoms and atomic ions) with emphasis on integration of TOPBASE material; and (5) Data bases for diatomic molecules. We emphasize topics of direct relevance to the synthesis of stellar spectra, primarily within the domain where LTE is useful. Additional parameters, such as line-broadening parameters, or excitation cross sections are not reviewed.
Recent UV and Optical Observations of Planetary Nebulae
Authors: Torres-Peimbert Silvia
Published: July 2016

This review contains a brief survey of the issues that have been the concern of optical and ultraviolet studies of planetary nebulae since the last IAU Symposium on this subject in 1982.

The nature of this review is such that it is not possible to do justice to the wealth of work that has taken place in this period, I will just point out some characteristic examples of the different aspects of the work done.
Internal Motions of Faint PN Halos
Authors: Chu You-Hua , Jacoby George H.
Published: July 2016

We have obtained long-slit echelle observations of faint halos for 10 PNe - NGC 2022, 2438, 6210, 6309, 6543, 6720, 6751, 6826, 6891, and 7662. Only NGC 2022 and 6720 have linesplits indicative of a hollow expanding-shell structure. The others have observed FWHM ranging from 13 to 47 km/s in the [O III]λ5007 line, with an instrumental FWHM of 9–10 km/s. We have subtracted the instrumental and thermal widths and made geometric corrections to derive the expansion velocities.
Observations and Models of the ‘Helix’ Nebula NGC 7293
Authors: Clegg R. E. S. , Walsh J. R.
Published: July 2016

Long-slit IPCS 2-dimensional spectra in radial directions across the inner and outer shells and across some of the brightest cometary globules are presented. The spectra show the ionization structure of the nebula quantitatively, with He II λ4686 A strong in the inner regions and [N II] λ6584 A prominent in the outer shell, almost due east of the central star. The “[Ne III] anomaly”, previously reported for NGC 6720 and 7293 by Hawley and Miller, is clearly seen. It, together with the [O I] λ6300 A flux, provide constraints on our photo-ionization models, as both depend on the concentration of neutral H in the background gas.
The Metal-Line Spectra of Central Stars of Planetary Nebulae
Authors: Roth M. , Herrero A. , Mendez R. H. , Kudritzki R. P. , Butler K. , Groth H. G.
Published: July 2016

We present spectral descriptions based on high-resolution spectrograms of central stars of planetary nebulae, obtained with the ESO 3,6-m telescope + CASPEC (Cassegrain Echelle Spectrograph). We make preliminary determinations of stellar photospheric metal abundances, using non-LTE model atmospheres and non-LTE line formation calculations.
Revisited Mass-Loss Rates of Planetary Nebula Nuclei Observed with IUE
Authors: Hutsemékers D. , Surdej J.
Published: July 2016

The first order moment of P Cygni line profiles has been computed for the case of resonance doublet and subordinate line transitions, using realistic velocity and opacity distributions. This improved method has allowed us to rederive mass-loss rates for a sample of 17 PNN observed in the low resolution mode with IUE. The average value of our mass-loss rates amounts to 10−7 M⊙/yr.
Morphologies of Planetary Nebulae with Close-Binary Nuclei
Authors: Bond Howard E. , Livio Mario , Meakes Michael
Published: July 2016

We will present photographic and CCD images of planetary nebulae that are known, on the basis of photometric observations of the central stars, to possess close-binary nuclei. All of the orbital periods range from 2.7 to 16 hours, except for the 16-day binary nucleus of NGC 2346.
Hot Gas in the Galaxy: How Extensive is it?
Authors: Shu Frank H.
Published: July 2016

Recent satellite detections of 0 VI absorption and soft X-ray emission leave little doubt that, locally, a substantial fraction of the volume of space between interstellar clouds must be filled with rarified and highly ionized gas at temperatures ranging from 2 × 105 to > 106 K. (See the reviews of Spitzer and Jenkins 1975, and Kraushaar 1977.) The physical state of this gas contrasts sharply with the theoretical picture of a largely neutral, warm, intercloud medium at ∼ 104 K developed by Pikel'ner (1967), Field, Goldsmith, and Habing (1969), and Spitzer and Scott (1969). My purpose here is to review the evidence, observational and theoretical, concerning how extensive hot gas at ∼ 106 K might be.
Morphological investigation of pairs containing Markarian galaxies
Authors: Casini C. , Heidmann J.
Published: July 2016

We have obtained large scale photographs or electronographs for 40 pairs containing Markarian galaxies: 6 Markarian-Markarian pairs and 34 Markarian-normal pairs, most of which are physical close pairs with two similar components (here “normal” means with no UV excess).
Interacting Systems
Authors: Toomre Alar
Published: July 2016

I will confine this brief review to just two examples of galaxies that seem to have interacted recently with impressive consequences: (1) the well-known Messier 51 system NGC 5194/5 = deservedly VV 1, and (2) the so-called Cartwheel, a ring within a ring, separated by vaguely spokelike features and accompanied by two smaller galaxies.
The Absolute Calibration of the HR Diagram: Fundamental Effective Temperatures and Bolometric Corrections
Authors: Hayes D. S.
Published: July 2016

Scales of fundamental bolometric connections (B.C.) and effective temperatures (Teff) as a function of spectral type or color are necessary for the comparison of observations and theory in the HR diagram.
Two-Dimensional Spectral Classification of M Stars by Narrow-Band Photometry
Authors: Wing Robert F. , White Nathaniel M.
Published: July 2016

To place a star on the HR diagram by means of spectroscopic data alone-i.e., without knowledge of the parallax-one must separate the spectroscopic effects of temperature and luminosity as cleanly as possible. Here we discuss the use of the red and near-infrared bands of TiO, VO, CN, and CaH as classification criteria for M stars. Our eight-color system of filter photometry (Wing 1971; White 1971a) has provided data on the first three molecules.
Continuum monitoring of bright quasars
Authors: Valtaoja Esko
Published: July 2016

Beginning in 1980, the fluxes of over 40 bright quasars, BL Lacs and Seyferts have been monitored at radio and optical wavelengths in a Finnish-Soviet collaboration. The chief aims of the program are to provide information about the variability characteristics of active nuclei over a wide range of timescales and to fill a gap in monitoring programs at millimeter wavelengths. The results are also used as a basis for various other investigations.
0.3 to 100 μm continua of Seyfert 1 galaxies
Authors: Fabbiano G. , Elvis M. , Carleton N. , Willner S.P. , Lawrence A. , Ward M.J.
Published: July 2016

The questions we wish to address with this work are: What is the shape of the continuum spectrum of an active nucleus? Can we identify thermal and non-thermal components? Previous work on this subject studied different non-overlapping samples in narrow frequency bands. A significant step forward was taken by Malkan and Sargent (1982) who studied the IR (10μm) through UV continuum of a small sample of objects. We report here results for the first part of the study of the complete continuum for a hard X-ray selected sample of 37 Seyfert 1 galaxies. This selection criterion ensures a sample unbiased for optical-IR studies, as the hard X-rays are not affected by reddening (Lawrence and Elvis 1982). The data consist of our own 1–20 μm ground-based IR observations, 100 and 60 μm IRAS fluxes and optical UBVR photometry.
Radio Induced X-Ray Emission in Radio Quasars
Authors: Kembhavi Ajit
Published: July 2016

The relationship between low energy X-ray emission and radio emission in radio quasars is considered. A survey of early results is presented and the current status summarized. Some remarks are made on the simultaneous correlation of X-ray emission with optical and radio emission.
High densities in QSO and seyfert broad-line clouds
Authors: Puetter R. C.
Published: July 2016

While it is widely held that the densities of QSO and Seyfert broad-line regions lie below 1011 cm−3, there is a growing body of evidence, indicating that at least some of the broad-line gas has densities equal to or exceeding 1011 cm−3. Such evidence includes (1) the presence of a 3μm “bump” in roughly half of all QSOs, (2) the depression of Brγ in several Seyfert galaxies, (3) the broad-line variablity in some objects, and (4) the ability to produce the hydrogen spectrum theoretically.
Gravitationally lensed quasars as cosmological probes: the uniqueness problem
Authors: Birkinshaw M.
Published: July 2016

The generalisation from circular to elliptical mass distributions acting as gravitational lenses produces a number of interesting effects. These effects include an extra indeterminacy in predictions of the time delay between the two brightest images, if only the relative brightness and separation of these images is known. This indeterminacy is removed if further information about the system (such as a measurement of the astigmatism of the lens) is available.
The Sunyaev-Zel'Dovich Effect and H0
Authors: Birkinshaw M.
Published: July 2016

Observational data on the Sunyaev-Zel'dovich effect for three clusters are used to obtain limits to the value of the Hubble constant. Only a wide bound on the value of H0, 10 km s−1 Mpc−1 < H0 < 160 km s−1 Mpc−1, can be derived, mostly because of the large uncertainty in the measured temperature of the intracluster medium in each cluster. Better information on this temperature and on the distribution of the intracluster medium are needed for this method to yield a good measurement of H0.
The Status of the Hubble Diagram In 1986
Authors: Spinrad Hyron , Djorgovski S.
Published: July 2016

We present visual and near-infrared Hubble diagrams for first-ranked cluster galaxies, and moderate-flux and high-flux radio galaxies. The photometric improvements and the extension of the diagrams to large redshifts (up to z ≃ 1.8) for both 3CR and “1 Jy” class radio galaxies are highlighted. The absolute luminosities of these three types of “standard candles”, where their redshifts overlap, agree adequately. The near-IR (2μm) Hubble diagrams may be used to determine the global deceleration parameter, q0, and the current data favor q0 ∼ +0.2 to +0.3. The sensitivity to evolutionary changes in the giant galaxies is quite modest at these long wavelengths. On the other hand, the visual regime (BV R) shows a dramatic dependence on differential evolution effects, which dominate over the cosmological model differences. Most radio galaxies apparently have had active star formation, with a continually declining rate, but a few are quite faint and red; they may have had a relatively passive evolution.
An Interesting Pair of Active Galaxies
Authors: He X.-T. , Xiao X.H. , Okamura S. , Noguchi T. , Maehara H. , Cannon R.D.
Published: July 2016

A pair of emission-line galaxies with separation 7.1 arcseconds was found from the survey of the UK Schmidt objective-prizm plates. The spectroscopic observations by the 1.88m reflector of the Okayama Observatory show the same emission-line features with Z=0.0441.
The Cosmic X-Ray Background
Authors: Boldt Elihu
Published: July 2016

As the sky in the microwave band is dominated by a cosmic background, so too is the X-ray sky. In this presentation the observational situation regarding the extragalactic X-ray background is reviewed, emphasizing data obtained from HEAO-1 and the Einstein Observatory (HEAO-2). Spectral characteristics and spatial variations are described and discussed within the context of what is currently known about individual extragalactic sources. It is concluded that the bulk of the cosmic X-ray background is yet to be understood. Possibilities range from genuinely diffuse emission to an “as yet” unknown large population of unresolved discrete sources. The role of cosmological effects is examined and could be important.