bluuebunny/crossref_metadata_2025 huggingface dataset:
EUV Observations of Pulsars
Authors: Edelstein Jerry , Bowyer Stuart
Published: July 2016

Three pulsars have been detected with the Lexan (100 Å )filter of the EUVE Deep Survey telescope: the middle-aged isolated pulsars, PSR B0656+14 and Geminga, plus the aged millisecond pulsar PSR J0437–4715. The EUV detections have been used both alone and in combination with observations in other bandpasses to limit the physical state of the objects and to test theories regarding neutron star cooling and re-heating mechanisms. For Geminga, the EUVE data suggests the presence of an optical cyclotron spectral feature superimposed on the Rayleigh-Jeans continuum tail from a hot pulsar surface. We summarize EUV pulsar observations and results.
The X-ray synchrotron nebula around PSR 1509-58
Authors: Brazier K.T.S.
Published: July 2016

PSR 1509-58 is one of the youngest and most powerful pulsars known and is visible not only in soft X-rays, but in gamma-rays. Observations of its supernova remnant (MSH 15-52) offer a rare chance to study such a young pulsar and to explore its surroundings, which in X-rays include the pulsar’s 10×6 arcmin X-ray synchrotron nebula and the peculiar, filamentary optical nebula, RCW 89, that sits on the limb of MSH 15-52 (Seward & Harnden 1982, Seward et al. 1983). This paper will concentrate on the morphology of the synchrotron nebula.
General Relativistic Electrodynamics and Pulsar Theory
Authors: Mestel L.
Published: July 2016

Muslimov & Tsygan (1986, 1990, 1991, 1992) have shown how the dragging of inertial frames modifies the Goldreich-Julian charge density. The consequences are noted for different models of the electron outflow near the neutron star’s surface.
High Energy Continuum Spectra from X-Ray Binaries
Authors: Zhang S.N.
Published: July 2016

A variety of high energy (>1 keV) spectra have been observed in recent years from Black Hole (BH) and Neutron Star (NS) X-ray Binaries (XB). Some common physical components exist between BHXBs and NSXBs, resulting in some high energy spectral features. A common component between a BHXB and a weakly magnetized NSXB is the inner accretion disk region extending very close to the surface (for a NS) or the horizon (for a BH). The inner disk radiation can be described by a multi-color blackbody (MCB) spectral model. The surface radiation of the NS can be approximated by a Single Color Blackbody (SCB) spectrum. For a strongly magnetized NSXB, the high energy emission is from its magnetosphere, characterised by a thermal bremsstrahlung (TB) spectrum. In both BHXBs and weakly magnetized NSXBs, a hot electron cloud may exist, producing the hard X-ray power law (photon index −1.5 to −2.0) with thermal cutoff (50–200 keV). It has been recently proposed that a converging flow may be formed near the horizon of a BH, producing a softer power law (photon index about −2.5) without cutoff up to several hundred keV. Based on these concepts we also discuss possible ways to distinguish between BH and NS XBs. Finally we discuss briefly spectral state transitions in both BH and NS XBs.
Viscosity and Large-Scale Magnetic Fields from Accretion Disc Dynamos
Authors: Tout Christopher A.
Published: July 2016

We review those processes associated with accretion discs that are probably influenced by magnetic fields, specifically, accretiondisc viscosity, energy dissipation and jet formation. We consider how magnetic instabilities in the disc can lead to a self-sustaining dynamical dynamo and how this is manifested as magnetohydrodynamic turbulence in numerical simulations. We show that currently these models do not fit with observational constraints imposed by dwarf-nova outbursts. We also show that the drop in ionisation fraction does not lead to the apparently necessary drop in viscosity in quiescent cataclysmic variable discs. Large-scale magnetic fields are required to launch and collimate jets form discs. We describe an inverse cascade process that can construct sufficient large-scale field from small-scale field generated by a dynamo.
Time-Dependent MHD Simulations of Jets from Accretion Discs: Stationary Solutions
Authors: Romanova M.M. , Lovelace R.V.E. , Ustyugova G.V. , Koldoba A.V. , Chechetkin V.M.
Published: July 2016

A family of stationary solutions for magnetically driven outflows has been discovered by time-dependent, axisymmetric magnetohydrodynamic simulations of outflows from an accretion disk threaded by an inclined magnetic field. At the disk surface matter was given a small initial push with a speed less than the slow magnetosonic speed. In the simulations, the outflowing matter is observed to be accelerated by magnetic force and by centrifugal force up to velocities in excess of the fast magnetosonic speed and in excess of the escape speed from the central object.
Gaseous Disks in the Nuclei of Elliptical Galaxies
Authors: Ford H. , Tsvetanov Z. , Ferrarese L. , Kriss G. , Jaffe W. , Harms R. , Dressel L.
Published: July 2016

HST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.
m = 1 Oscillations of Accretion Disks in Close Binary Systems
Authors: Okazaki Atsuo T.
Published: July 2016

We examine the two-dimensional structure of m = 1 modes in disks around white dwarfs in close binary systems. We find that the odd modes (warping modes) as well as even modes (eccentric modes) are confined to the outermost part of the disk. The period of the fundamental mode is of a few percent of the binary period, and is insensitive to the parity of the mode. These modes naturally explain the superhump periods of SU UMa stars.
ROSAT Observations of 4 Draconis: AM Her or Symbiotic?
Authors: Wheatley Peter J.
Published: July 2016

I present the first X-ray observations of the red giant, 4 Draconis—thought to have an AM Her companion. I find evidence for absorption by the ionised wind of the red giant, but no sign of the soft X-ray emission typical of (high-state) AM Hers.
Beaming in Radio-Quiet AGN
Authors: Young S. , Hough J. H. , Axon D. J. , Bailey J. A.
Published: July 2016

We have obtained new optical spectropolarimetric data for the radio-quiet Seyfert NGC 1068, taken through apertures on the nucleus and at two positions within the ionization/scattering cone. The equivalent width of scattered broad-Hβ at these positions, is consistent with the presence of intrinsically beamed continuum radiation.
Structural Variations in the Quasar 3C 454.3
Authors: Pauliny-Toth I.I.K.
Published: July 2016

Imaging of the OVV quasar 3C 454.3 (z=0.859) shows that a new component was ejected from the core at epoch 1981 ± 1, close to the time of a major radio outburst. The component moved along a curved path with a mean apparent velocity of ~ 17c (Ho = 100 · h km s−1 Mpc−1). The motion, however, showed variations: from ~ 11c (1984–1985), to ~ 22c (1985–1988.5), then to ~ 14c (1988.5–1991.9).
VLBA Observations of 3C 120
Authors: Gómez J.L. , Marscher A.P. , Alberdi A. , Martí J.Mª. , Ibáñez J.Mª.
Published: July 2016

We present 1.3 cm and 7 mm VLBA observations of the radio galaxy 3C 120 at epochs November 11 and December 22, 1996. The 7 mm maps, with linear resolution of ~0.1 pc, show a very rich structure consisting of up to eight superluminal (~ 7 c) components.
CME and Ejection of Large Scale Magnetic Fields, Helical Magnetic Fields, and Intrinsically Asymmetric Jets - New Findings in AGN
Authors: Chu H. S. , Zhang F. J. , Spencer R. E.
Published: July 2016

The orthodox model of active galactic nuclei (AGN), as is generally accepted, is that of Rees. We have found an AGN (3C 147) which has a counter-jet much longer than the main jet. It also has an unusual sideways ejection from the nuclear region. Both of these and the 3-jet structure per se do not seem to conform with the general accepted model, and are also not explained by relativistic beaming effects. We speculate that this is due to coronal mass ejection (CME) in the accretion disk corona. Recently, we have found convincing new evidence that this is true. We have also found direct evidence of helical magnetic fields in the core region of 3C 147. These results may be of importance to the understanding of AGN.
EVN Observations of BL Lac Objects with Distorted Structures
Authors: Chariot P. , Sol H. , Vicente L.
Published: July 2016

We present results of observations of two BL Lac objects, 0735+178 and 0723–008, with the European VLBI Network (EVN) at 1.7 GHz. These objects have a distorted morphology, characterized by a large misalignment between their inner and outer radio structures. Our EVN observations at intermediate resolution reveal the presence of a highly curved jet in 0735+178, providing evidence for continuity of the radio emission from milliarcsecond to arcsecond scales. No indication of connecting radio structure is found in the case of 0723–008.
Compact Radio Emission in 60 µm Peaker Galaxies
Authors: Heisler C. A. , Norris R. P. , Jauncey D. L. , Reynolds J. E. , King E. A.
Published: July 2016

We present radio interferometric observations of a well defined sample of IRAS galaxies with warm far-infrared colors — 60 µm Peakers (60PKs). The core radio power of 60PKs is intermediate to that of “normal” Seyfert 2 galaxies and radio ellipticals, and follows the same relationship with respect to total radio emission as low and high power radio galaxies. This is consistent with the suggestion that 60PKs represent nascent radio elliptical galaxies.
VLA Imaging of Class I Methanol Masers at 7 mm with Angular Resolution
Authors: Slysh V. I. , Kogan L.
Published: July 2016

Eight Class I methanol masers were imaged at 44 GHz with A–configuration of the VLA providing angular resolution 0″.2. The images show a distribution of unresolved maser spots forming pairs in simple structure sources, and a distribution of pair clusters in complex sources. We found that the maser pairs are associated with hot, dense gas cores of sub–stellar masses. In complex sources the cores were found over the whole extent of the host molecular clouds.
PKS 0405–385 as Seen by the ISM Telescope
Authors: Kedziora-Chudczer L. L. , Walker M. A. , Jauncey D. L. , Wieringa M. H. , Reynolds J. E. , Tzioumis A. K. , Nicolson G. D.
Published: July 2016

We have found large amplitude intraday variability in the radio quasar PKS 0405–385 on timescales less than an hour. If intrinsic to the source, the inferred brightness temperature is TB ~ 1021 K, far exceeding the inverse Compton limit for a static synchrotron source. We argue that our data are in agreement with interstellar scintillations of a source component which is < 5μarcsec in size.
The Nature of a Homogeneous Sample of Compact Radio Sources Variable at 151 MHz
Authors: Minns A. R. , Riley J. M. , Warner P. J. , Rioja M. J. , Röttgering H. J. A.
Published: July 2016

Global VLBI snapshot observations at 1.6 GHz (5 EVN + 4 VLBA) of a sample of low-frequency variable (LFV) radio sources found using the Cambridge Low Frequency Synthesis Telescope (CLFST) are presented. Variability at 151 MHz is almost certainly due to propagation effects in our Galaxy (e.g., refractive interstellar scintillation). Theory indicates that only sources with a significant fraction of their low-frequency flux coming from components with angular sizes ≲ 30 mas will show such effects. This is confirmed by the VLBI images.
CSS Radio Sources and their Optical Characteristics
Authors: Morganti R. , Tadhunter C. N. , Tadhunter C. N. , Tzioumis A. , King E.
Published: July 2016

An optical study of CSS radio sources is presented.
Measuring the Hubble Constant with the Gravitational Lens System CLASS 1608+656
Authors: Fassnacht C. D. , Pearson T. J. , Blandford R. D. , Readhead A. C. S.
Published: July 2016

We present results on the promising new gravitational lens system 1608+656.
Disk Structure of the H2O Maser IC 1396N
Authors: Val’tts I. E. , Slysh V. I. , Migenes V. , Umemoto T. , Furuya R. , Kawabe R. , Fomalont E. B. , Hirabayashi H. , Inoue M.
Published: July 2016

The VLBA map of the H2O maser IC 1396N, which was obtained during the VSOP pre-launch survey, shows an ordered position of maser spots. The maser spots are located along an almost straight line with the separation between extreme maser spots of 20 mas. The radial velocity varies along the line from by 3 km s−1. In total 9 maser features have been located on the line, all of them unresolved by the VLBA beam. This geometry is consistent with the disk model of masers. The mass of the disk is estimated between 10−7 and 10−4 M⊙, depending on the thickness and density. The disk must be supported by a central star with the mass of about 0.07 M⊙. The H2O maser in IC 1396N may be a proto-planetary disk around a low mass protostar in the process of accretion.
OH and H2O Maser Distribution in Orion KL
Authors: Horiuchi S. , Migenes V.
Published: July 2016

In order to study the powering source behind KL nebula, we made a map of OH and H2O masers from VLA observations of this region, and compared their spatial distribution and velocity structure with that of the SiO masers. The distribution of the OH masers consists of a multi-stream structure and seems to be related to the Hot Core molecular emission. The low velocity H2O masers may be classified as two groups: i) an inner clump of maser spots surrounding the SiO maser disc and continuum source “I”, and ii) component associated with the Hot Core represented by HDO emission peaks.
The Astronomical Low-Frequency Array (ALFA)
Authors: Jones D. L. , Weiler K. W. , Allen R. J. , Desch M. M. , Erickson W. C. , Kaiser M. L. , Kassim N. E. , Kuiper T. B. H. , Mahoney M. J. , Marsh K. A. , Perley R. A. , Preston R. A. , Stone R. G.
Published: July 2016

The ALFA mission is designed to map the entire sky at frequencies between approximately 0.3 and 30 MHz with angular resolution limited by interstellar and interplanetary scattering. Most of this region of the spectrum is inaccessible from the ground because of absorption and refraction by the Earth’s ionosphere. A wide range of astrophysical questions concerning solar system, galactic, and extragalactic objects could be answered with high resolution images at low frequencies, where absorption effects and coherent emission processes become important and the synchrotron lifetimes of electrons are comparable to the age of the universe.
Position Angle of the HALCA Antenna Feed
Authors: Kogan L. R.
Published: July 2016

Knowledge of the position angle of an antenna feed is very important for polarization observations. The issue had been developed for ground based antennas but has not been considered for a orbiting antennas. We provide a calculation of the position angle of the Japanese satellite VSOP/HALCA which was successfully launched in a space VLBI mission.
On Hamiltonian Averaging Theories and Resonance
Authors: Ferraz-Mello S.
Published: July 2016

In this article, we review the construction of Hamiltonian perturbation theories with emphasis on Hori’s theory and its extension to the case of dynamical systems with several degrees of freedom and one resonant critical angle. The essential modification is the comparison of the series terms according to the degree of homogeneity in both and a parameter which measures the distance from the exact resonance, instead of just .
Applications of Parallel Processing to Astrodynamics
Authors: Coffey S. , Healy L. , Neal H.
Published: July 2016

Parallel processing is being used to improve the catalog of earth orbiting satellites and for problems associated with the catalog. Initial efforts centered around using SIMD parallel processors to perform debris conjunction analysis and satellite dynamics studies. More recently, the availability of cheap supercomputing processors and parallel processing software such as PVM have enabled the reutilization of existing astrodynamics software in distributed parallel processing environments. Computations once taking many days with traditional mainframes are now being performed in only a few hours. Efforts underway for the US Naval Space Command include conjunction prediction, uncorrelated target processing and a new space object catalog based on orbit determination and prediction with special perturbations methods.
Astrometry in the Future
Authors: Seidelmann P. K.
Published: July 2016

The introduction of the extragalactic reference frame and the availability of the Hipparcos and Tycho catalogs will have major impacts on changing the accuracy levels of astrometry in the future.

There is a need for accurate densification of the reference frames down to at least 20thmagnitude. Also accurate space motions and distances will be required. The ground based observations must be supplemented by space missions. In addition to traditional positional astrometry, the scientific applications of planetary detection, distance scales, multiple star systems, mass detections, solar system motions and geodesy will be advanced by the new accuracies.
Earth Rotation in the Hipparcos Reference Frame
Authors: Vondrák J. , Ron C. , Pešek I.
Published: July 2016

New determination of the Earth orientation parameters (EOP), based on optical astrometry observations since the beginning of the century, is now under preparation by the Working group established by Commission 19 of the IAU. The Hipparcos catalog is to define the celestial reference frame in which the new series of EOP are to be described. The novelties of the prepared solution are the higher resolution (5 days) and more parameters estimated from the solution (celestial pole offsets, rheological parameters of the Earth, certain instrumental constants). The mathematical model of the solution is described, and the results based on the observations made with 46 instruments at 29 observatories and a preliminary Hipparcos catalog are presented.
Determination of Some Physical Parameters of the Moon with Lunar Laser Ranging Data
Authors: Wenjing Jin , Jinling Li
Published: July 2016

Information about the structure of lunar interior and evolution could be obtained from measurements of lunar free librations, gravitational field, dissipation etc. In this paper the precision of determining free librations from Lunar Laser Ranging (LLR) data are estimated. Using the observing data from four telescopes for eighteen years, the amplitudes and phases of free librations, and ratios of the moments of inertia of the Moon were determined.
The Ephemerides of the Inner Planets from Spacecraft Range Data and Radar Observations 1961–1995
Authors: Pitjeva E. V.
Published: July 2016

A numerical theory of motion of the inner planets and Jupiter is presented. The numerical ephemerides were compared with the set of American and Russian radar observations of planets, obtained during 1961–1995 (nearly 60000 observations), together with range measurements of Martian landers Viking-1,-2 and Mariner-9 tracking data.

The main fitted parameters were the elements of Mercury, Venus, Earth, Mars, the Astronomical Unit, the scale corrections to the reference surface of planets and variability of the gravitational constant. The parameters of Mars rotation, coordinates of Viking landers, elements and the mass of Jupiter, the masses of the three asteroids were evaluated from Viking landers observations.
Asteroid Spins: From the Very Fast to the Very Slow
Authors: Harris A. W. , Wisniewski W.Z.
Published: July 2016

The application of CCD photometry to monitoring the light variations of very small asteroids has led to an explosion of data available, and perhaps as importantly, has made it possible to probe fainter, and hence smaller asteroids. In this paper, we review several new results from the analysis of such lightcurve data, much of it taken by the late W. Z. Wisniewski, a native of Poland who studied at Poznan University (Wisniewski et al., 1997).

At the time of the last close pass of the asteroid 4179 Toutatis by the Earth in 1992, it became apparent from radar observations that the asteroid was in a bizarre rotation state, and that the rotation rate was extremely slow. Harris (1994), re-evaluating the work by Burns and Safronov (1973) found that very small and slowly rotating asteroids can have a time scale of damping into a principal-axis rotation state which is long compared to their expected collisional lifetime, or for that matter, the age of the solar system:
Long term Evolution of Earth Orbiting Debris
Authors: Rossi A.
Published: July 2016

The space environment is presently dominated by man-made debris, for particles larger than 1 mg. A comprehensive survey of the debris population from 1 mg to the larger sizes in view of the recent data from radar and optical observations, and from the analysis of materials retrived from space is given.

A brief description of the major source and sink mechanisms acting on the debris population is given, along with a very short introduction to the two models for the long term evolution developed by the group in Pisa in the last years.

The results of the long term evolution analysis are presented in some detail. A likely scenario of the future space activities leads to a large growth of mmsize particles due to several catastrophic collisions. The simulation highlights the necessity of more realistic explosion models, since the current ones overestimate the 10 cm-sized fragments.

An enlarged version of this paper can be found at the CNUCE Spaceflight Dynamics Group Web site: http://apollo.cnuce.cnr.it/~rossi/homerossi.html.
Contributions of the USNO to the Optical Reference Frame
Authors: Corbin Thomas
Published: July 2016

A good, working definition of what is required in a celestial reference frame is that it must provide observable fiducial points on the Celestial Sphere with internally consistent positions that are referred to coordinate axes of known direction. In reality, this statement gives the goals in the reverse order from that in which each must be achieved, the definition of the axes, or zero points of the system give orientation to the observationally defined set of primary objects whose coordinate relation to each other must give the frame rigidity. Finally, the primary objects are generally too sparse to define the frame within areas of less than tens of square degrees, and so additional objects must be related to the frame to increase the density. This last step is required to make the frame useful for most observational applications.
Ita-Crao Minor Planet Survey: Results and Prospects
Authors: Chernykh N. S. , Sokolsky A.G.
Published: July 2016

Results of minor planet observation programme that is made jointly by the Institute of Theoretical Astronomy and the Crimean Astrophysical Observatory during three decades with the Zeiss 40-cm double astrograph at Crimea are presented. Almost all permanently numbered minor planets were observed. A catalogue of astrometrical results obtained in the course of this survey contains more than 60 thousand minor planet positions. Many thousand unnumbered asteroids were discovered, 875 of which had received permanent numbers by June of 1996.

In the development of this survey programme we plan to use another Crimean telescope – the fast 64-cm telescope of Richter and Slevogt system. We intend to equip it with a CCD camera and use it for searching and observation of the Near Earth Asteroids. In the future this CCD-telescope must be a part of the national Russian network for Near Earth Asteroid (NEA) observations.
Yohkoh Observations of Coronal Structures Surrounding Dark Filaments
Authors: Uchida Yutaka
Published: July 2016

We describe in this paper some of the findings of the Yohkoh satellite about the coronal structure surrounding dark filaments in the pre-event and initial phases of high latitude arcade formation events. The knowledge of pre-event structure and its change is essential for the proper understanding of the arcade flaring process from the causality point of view. The wide dynamic range and high sensitivity obervations by Yohkoh allow us to look into the faint structures and their changes with the use of a faint-feature-enhancing technique in the image analysis.
Magnetic Flux Transport and Formation of Filament Channels
Authors: van Ballegooijen A.A. , Cartledge N.P. , Priest E.R.
Published: July 2016

We present a model of the transport of photospheric and coronal magnetic fields with the aim of explaining the observed global pattern of dextral and sinistral filaments on the quiet sun. The model is based on the assumption that the axial field in a filament channel originates in the surrounding coronal arcade. The model predicts that switchbacks in the polarity inversion line have opposite chirality on the two arms of the switchback: the higher latitude “lead” arm has sinistral (dextral) orientation in the North (South), while the lower latitude “return” arm has dextral (sinistral) orientation. This is in conflict with prominence observations which show that the chirality is the same on the two arms of a switchback. The model predicts the wrong sign of the axial field in polar crown filaments. This suggests that axial field in quiescent filaments are not produced by differential rotation acting on the surrounding coronal arcades.
Simulation Studies of Solar Prominence Formation
Authors: Choe G.S. , Cheng C.Z.
Published: July 2016

A series of numerical simulations are presented for formation of solar prominences. We have investigated the dynamic and thermodynamic evolution of coronal plasma in response to photospheric horizontal motions. In three different setups of field configurations and footpoint motions, different types of prominences are found to be formed by thermal instability.
Ultraviolet Spectroscopy of a Coronal Mass Ejection
Authors: Ciaravella A. , Raymond J.C. , Fineschi S. , Gardner L. , Michels J. , O’Neal R. , Kohl J. , Romoli M. , Noci G. , Benna C. , Giordano S. , Antonucci E.
Published: July 2016

A coronal mass ejection (CME) event was observed on December 23, 1996 with the Ultraviolet Coronagraph Spectrometer in both ultraviolet and visible light channels at 0.5 R⊙ over the solar limb. The CME was followed during its evolution in the bright lines of Lyα (1216Å), Lyβ (1026Å), Lyγ (972Å), C III (977Å) and the OVI doublet (1032, 1037Å) and in several weaker lines. The Lyα peak intensity shows an excursion of two orders of magnitude during the CME evolution, and blue shifts up to 0.8Å (~200 km/sec). The data provide the emission measure in the Log T range 4.0–5.5 with a 0.3 sampling. Line intensities and profiles have been measured, providing important diagnostics for a detailed study of the CME’s physical and dynamical parameters.
Filament Activity Associated With an Umbral Flare
Authors: Li Wei , Wang Jingxiu
Published: July 2016

An umbral flare in NOAA 6223 was observed at Huairou Solar Observing Station of Beijing Astronomical Observatory. Vigorous filament activity took place in association with this umbral flare. Several filaments formed and/or disappeared, leaving the magnetic neutral lines pointing to or rooted in the P spot in which the umbral flare occurred. We describe the observed configuration and evolution of the vector magnetic fields in the photosphere, and Doppler velocity patterns in the chromosphere during the course of the umbral flare and related filament activity.
Some comments on the design of échelle spectrographs using R2 or R4 gratings for precise radial-velocity measurements
Authors: Hearnshaw John , Rumsey Norman , Nankivell Garry
Published: July 2016

A new fiber-fed échelle spectrograph (Hercules) is being designed for the 1-m telescope at Mt John University Observatory. The goals are to have a wavelength capability of 380 to 880 nm, covered in a single exposure on a 50-mm square CCD, to have a choice of resolving powers of 35000 or 70000 and to have no moving parts. High precision radialvelocity observations are a major but not the only goal. Designs with both R2 (blaze angle 63.4 deg) and R4 (blaze angle 76 deg) échelle gratings are being considered, in either case with a dimension of 408 mm perpendicular to the grooves.
Doppler Imaging of Stars with Surface Inhomogeneities
Authors: Cameron Andrew Collier
Published: July 2016

I review recent progress in the field of stellar surface imaging, with particular reference to advanced methods for mapping surface-brightness distributions on magnetically active late-type stars. New signal enhancement techniques, utilising profile information from hundreds or thousands of photospheric lines simultaneously, allow images to be derived for stars several magnitudes fainter than was previously possible. For brighter stars, the same techniques make it possible to map features as small as two or three degrees in extent on the stellar surface. While this opens up whole new areas of research, such as the ability to use starspot tracking to study surface differential rotation patterns on single and binary stars, caution must be exercised in the treatment of “nuisance” parameters such as the stellar rotation rate, surface abundances and radial velocity. At the very high S:N levels we now use, the effects of systematic errors in these parameters are easier to identify, isolate and eliminate. This leads to the possibility of making precise radial velocity variations (at the few hundred m s−2 level or better) in late-type stars even with equatorial rotation speeds as high as 100 km s−1. This is particularly topical given the recent discovery that one of our prime imaging targets, the young southern K0 dwarf AB Doradus, has an astrometric companion in a highly eccentric orbit with an inferred mass close to the H-burning limit.
The Problem of Uniqueness in Doppler Imaging
Authors: Al-Malki M. , Eker Z.
Published: July 2016

The uniqueness problem in Doppler imaging is discussed. Most of the problem appears to be confusion between different meanings of the word “uniqueness”. According to specific definitions presented in this study, there should not be any uniqueness problem.
Discovering new spectroscopic components in visual multiple stars
Authors: Tokovinin A.A.
Published: July 2016

A radial velocity survey of the components of visual multiple stars has been done since 1994 with the correlation radial velocity spectrometer. About 50 spectroscopic sub-systems have been discovered, and a summary of the 30 published orbits is given. Difficulties of measuring the radial velocities of multiple stars are discussed and illustrated by 2 examples. New discoveries will lead to a better understanding of the formation of multiple stellar systems. Close and wide sub-systems can not be considered as a result of independent random combination, but are related by common origin. Almost all close binaries with periods less than 6 days possibly have more distant components which assisted in the formation of close pairs by taking away their angular momentum. On the other hand, among the distant visual tertiary companions the frequency of sub-systems with periods under 100 days is about 3 times higher than for field G dwarfs.
Global Photometric Properties of Barred Galaxies
Authors: Ohta Kouji
Published: July 2016

Global photometric properties of barred galaxies are reviewed based on the surface photometry of barred galaxies.
HII Regions in Resonance-Ring Spiral Galaxies
Authors: Crocker Deborah A. , Baugus Pamela D. , Buta R.
Published: July 2016

Resonance ring galaxies are barred (and sometimes nonbarred) spiral galaxies which display an inner, outer, or nuclear ring in the light distribution. This study is of the HII region properties in 32 probable resonance ring galaxies selected mainly from the Catalog of Southern Ringed Galaxies (CSRG; Buta 1995). The objective of the study is to illustrate the distributions of HII regions in classic examples of ringed galaxies, and to relate the observed properties to resonance theory. Here we present a brief summary of a more extensive paper on the results of this study (Crocker, Baugus, & Buta 1996).
Inner Spiral Arms of the Barred Galaxy NGC 4314
Authors: Ann H. B. , Kwon K. H.
Published: July 2016

The nuclear region of the barred galaxy NGC 4314 was observed and modeled by VIJHK photometry, long-slit spectroscopy, and SPH simulations. Young stellar populations is supposed to be made from the gas which are accumulated in the nuclear ring and/or inner spiral arms by the strong bar potential.
Global Rotational Properties of Barred Galaxies
Authors: Bosma A.
Published: July 2016

A general overview is presented of the global gas kinematics of barred spirals, using HI and Hαdata. The question of dark matter in barred spirals is also discussed.
Neutral Gas in Resonance-Ring Galaxies
Authors: Ryder Stuart , Buta Ronald , Toledo Hector
Published: July 2016

We have mapped the distribution and kinematics of H ɪ in NGC 1433 and NGC 6300 with the Australia Telescope Compact Array, in order to test the association between resonances and ring phenomena. We find a bar pattern speed in NGC 1433 of Ωp = 26 ± 5 km s kpc−1, and postulate that NGC 6300 is still evolving to a mature resonance-ring galaxy.
Buckling Bars and Boxy Bulges
Authors: Merrifield M. R.
Published: July 2016

It has been suggested that the peanut-shaped bulges seen in some edge-on disk galaxies are produced when bars in these galaxies buckle. This paper reviews the modelling which seeks to show how bars buckle, and I present a very simple new model which captures the essential physics of this process. I then discuss the problems in establishing observationally the connection between peanut-shaped bulges and bars. Confirmation of the link has proved difficult because boxy bulges are only apparent in edge-on galaxies whereas bars are only easily detectable in more face-on systems. Finally, I present a new technique which avoids this difficulty by searching for the distinctive kinematic signature of an edgeon bar; application of this method to spectra of peanut-shaped bulges reveals that they are, indeed, associated with hidden bars.
Gas and Stellar Kinematics in the Disk and Bar of Mrk 573
Authors: Afanasiev V. L. , Burenkov A. N. , Shapovalova A. I. , Vlasyuk V. V.
Published: July 2016

Results of 3D-spectroscopy for the nearby Seyfert galaxy Mrk 573 obtained at the 6-m telescope with the scanning Fabry-Perot interferometer and the Multi-Pupil Field Spectrograph (MPFS) are presented. Emission lines images of the galaxy center demonstrate a complex structure of ENLR, coinciding with the radio data. An analysis of the velocity field shows that some gas structures do not lie in the plane of the galaxy. An explanation of the observed velocity field and gas distribution by radiation of a helical structure located inside an ionization cone is proposed.
Radio Continuum Emission in the Resonance-Ring Galaxies NGC 1433 and NGC 6300
Authors: Shukla Hemant , Ryder Stuart D.
Published: July 2016

NGC 1433 is a nearly face-on prototypical ringed, barred galaxy. It has a nuclear ring, an inner ring and an outer pseudoring. Also present are symmetrical spiral arcs, also called “plumes”, leading the central bar. Based on a study using multicolor surface photometry and Hα Fabry-Perot interferometry, Buta (1986) was able to associate each of the ring features with a specific orbital resonance. NGC 6300, having almost an identical Hubble type and distance to that of NGC 1433, provides for an ideal comparison. It has no nuclear or outer rings. However, the inner ring is quite broad and dusty (Buta 1987). Radio continuum data were obtained with the Australia Telescope Compact Array (ATCA) at 1.38 GHz (bandwidth = 128.0 MHz) with maximum baselines of 1.5 km, yielding a resolution of ∼ 30″ and r.m.s. noise per map of 0.2 mJy Beam−1 for both of the galaxies. The Hα + N[II] images for both of the galaxies were obtained with the CTIO 1.5 m telescope.
Barred Extreme IRAS Galaxies
Authors: van Driel Wim , van den Broek Bert
Published: July 2016

We studied a statistically complete sample of 57 southern socalled extreme IRAS galaxies, i.e., objects with a high far-infrared/blue luminosity ratio, LFIR/LB>3, using optical (imaging and spectra), radio continuum, and CO(1–0) line observations. The sample can be divided into three distinct categories: dwarfs (20%), barred spirals (35%), and interacting systems (35%). The barred galaxies are generally morphologically undisturbed, isolated systems, with average star formation rates (4 M⊙ yr–1) and efficiencies (LFIR/MH2 = 16 L⊙/M⊙) for galaxies in our sample. An enhanced massive star formation rate is the cause of the infrared brightness in 93% of all galaxies in the sample. The nuclear region is the most important star formation locus, generally unresolved at 1" resolution, i.e., less than 0.2-0.6 kpc size (H0=75 km s–1 Mpc–1), though 2 kpc size in three cases. In about two-thirds of the extreme IRAS SB’s, fainter, diffuse (2.5-10 kpc size) massive star formation is seen in the bar as well.
Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1365
Authors: Lindblad P. A. B. , Lindblad P. O. , Athanassoula E.
Published: July 2016

Several authors have explored the field of gas dynamics in barred systems. One of the aims of these investigations was to compare the model gaseous response, due to some assumed underlying stellar gravitational field, with observed gas density distribution and kinematics of barred galaxies. The gas is known to respond in a highly non-linear way, and therefore should give clues to dynamical parameters like the mass distribution, positions and existence of principal resonances and thereby the pattern speed.

High resolution HI data now exist for NGC 1365 (Jörsäter & van Moorsel 1995), and the kinematical HI data have been combined with optical long slit measurements to obtain the velocity field (Lindblad et al. 1995) used for extracting the rotation curve, representing the axisymmetric forces in NGC 1365, and for comparisons with models. A mosaic image of NGC 1365 in the J-band was used to compute the perturbing potential used in the models.
A New Fueling Process in a Weak Bar
Authors: Wada Keiichi , Habe Asao
Published: July 2016

A massive gaseous disk in the central region of a galaxy sensitively responds to a weakly distorted potential, and a large amount of gas can be fed into within 1/20 of the core radius of the potential in several 107 yr. The ILRs, the dissipative nature of the gas, and the self-gravity of the gas are essential for triggering this effective fueling. We also found that a counterrotating gaseous core can be formed as a result of the fueling. Our result suggests that the merger of galaxies is not the only way to form the observed counterrotating core in galaxies.
NGC 3227 - An Interacting Barred Spiral with an Active Nucleus
Authors: Mundell C. G. , Pedlar A. , Shone D. L. , Axon D. J. , Meaburn J. , Unger S. W.
Published: July 2016

Recently, bars have become a favored mechanism for transporting material at larger radii towards the nuclei of active galaxies, with the possibility of inflowing gas (on kiloparsec scales) accumulating in circumnuclear rings, bar-like features or structures reminiscent of spiral arms. In addition, it seems clear that interactions play some role in the triggering and fuelling of nuclear activity, as well as in the formation and evolution of galactic bars. NGC 3227 is a barred Seyfert galaxy which appears to be interacting with the nearby elliptical galaxy NGC 3226. The NGC 3227 system thus appears to be an excellent ”laboratory case“ in which to study the relationship between the bar phenomenon, and an active nucleus in an interacting system.
Galactic Slow Bar as an Unstable Mode of a Stellar Disk
Authors: Polyachenko Evgenij V. , Polyachenko Valerij L.
Published: July 2016

An estimate for the slow bar instability boundary for a generalized disk polytropic model is derived. The effects of a spherical halo are studied: it turns out that a halo can be favorable to this instability (at the same time suppressing the bending instability).
The Dynamics of the Galactic Bar
Authors: Weinberg Martin D.
Published: July 2016

The dynamics of formation and evolution of structure in barred galaxies is subtle and will require many and detailed observations to discriminate between the alternative hypotheses. Why should someone interested in such problems consider the Milky Way? In terms of data volume, our knowledge of the Milky Way is vast and the availability of detail is its major advantage. In principle, one can study morphological details such as orientations, strengths of asymmetries and kinematics details such as velocity field/pattern speeds using a wide variety of tracers. To illustrate, theorists have not converged on a single mechanism to explain bars (witness the instability vs. secular formation debate). It is possible that both operate in different regimes depending on internal or external influences: internally, triaxialities and misalignments in the bulge, spheroid or halo can apply torques and drive angular momentum waves which saturate to form a bar; and externally, satellite galaxies can exchange orbital angular momentum with its disturbance which has the similar effect. In short, if the Galaxy is indeed barred, it may hold clues to some of the detailed problems posed at this meeting.
Some Problems Related to Geodetic Datum Definitions for Terrestrial Measurements
Authors: Groten E.
Published: July 2016

Problems related to the precj se definition of reference systems for measurements of crustal motion are discussed. Difficulties in defining vertical positions are emphasized. Using the Goddard Earth Model 6 and surface gravity data, a new absolute orientation vector for the European Datum is evaluated and corresponding deficiencies are discussed.
On the Interrelation of Classical and Space Geodetic Systems of Position Reference
Authors: Aardoom L.
Published: July 2016

Attemps to relate classical geodetic datums to global satellite geodetic systems of position reference are reviewed. Implications of such investigations for geodynamics are considered.
1.1.4 Pioneer 10 Observations of Zodiacal Light Brightness near the Ecliptic: Changes with Heliocentric Distance
Authors: Hanner M. S. , Sparrow J. G. , Weinberg J. L. , Beeson D. E.
Published: July 2016

Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.
1.1.6 The S10 (V) Unit of Surface Brightness
Authors: Sparrow J. G. , Weinberg J. L.
Published: July 2016

A source for some of the discrepancies among reported zodiacal light measurements is suggested, and a plea is made for more uniformity in the choice of units used to report zodiacal light results.
1.1.12 Summary of Observations of the Solar Corona/Inner Zodiacal Light from Apollo 15, 16, and 17
Authors: Ross C.L.
Published: July 2016

The orbital track of the Apollo Command Service Module (CSM) around the moon during the flights of Apollo 15, 16, and 17 provided unique opportunities to observe the solar corona and zodiacal light. Photographs of the lunar sunrise and sunset were made with a 70 mm electric Hasselblad camera, 80 mm lens at f/2.8, using Eastman Kodak 2485 High Speed Recording film.
1.2.2 Polarimetry of the Zodiacal Light and Milky Way from Hawaii
Authors: Wolstencroft R. D. , Bandermann L. W.
Published: July 2016

This paper describes the results of a program of observations of the polarized intensity vector of the night sky in the anti-solar hemisphere obtained on 72 nights between May 1973 and November 1974. The observations were made with the night sky polarimeter at Mt. Haleakala, Maui, Hawaii, using a 5300A interference filter, 62A wide, to define the passband. They were made at fixed altitudes from 35° to 90° along the north-south meridian and repeated in sequence throughout the night. The diameter of the field of view was 6.0° and the integration time per point was either 30 or 120 seconds. Polarization was detected using a rotating polaroid (11 1/4 revs sec−1); the signal from the polaroid drive generator provided a phase trigger allowing the photo-multiplier signal to accumulate and be digitized for each of the four 90° phase intervals of the polarization modulation cycle. This process continued for the entire integration period. The digitization and data handling and recording (paper tape and teletype) was carried out by a PDP-81 computer, and calibrated Stokes parameters (I, Q, U) and the polarized intensity pI were calculated later. Intensity calibration in S10 (V, G2V) units was obtained using a C14 low brightness source, and the amplitude and phase of the polarization modulation were checked each night.
1.3.1. Some Formulae to Interpret Zodiacal Light Photopolarimetric Data in the Ecliptic from Ground or Space
Authors: Dumont René
Published: July 2016

A fundamental step towards the knowledge of interplanetary matter from zodiacal light photometry is to eliminate the integral along the line of sight – an intrinsic, cumbersome feature of all z.l. observations – so as to reach, by inversion, the local optioal properties of elementary volumes of space.
2.1.7 Dust in the Outer Solar System – Review of Early Results from Pioneers 10 and 11
Authors: Soberman R. K. , Alvarez J. M. , Weinberg J. L.
Published: July 2016

The Pioneer 10/11 spacecraft, launched in 1972 and 1973, carried three experiments to measure cosmic dust. A comparison of these first direct measurements of dust in the outer solar system indicates that the sizes, optical properties, and spatial distribution are more complex than previously supposed.
3.5 The Dust Coma of Comets
Authors: Michel K.W. , Nishimura T.
Published: July 2016

Analytical expressions for the dust entrainment in the limits of low and high gas production from cometary nuclei are derived. The resulting volume density is used to evaluate the dust production of Comets Encke and Kohoutek from IR-measurements. It is predicted, that the dust in solar direction was diffuse for Comet Kohoutek during approach to the Sun, but sharp for Comet Encke and nearly independent of heliocentric distance. The dust production rate of Encke ist not sufficient to sustain the Zodiacal cloud of micron sized particles. Particle impact probabilities and hazards are estimated for a space probe in a fly-by mission to Encke.
The Discovery and Observation of Multiple Stellar Systems
Authors: Batten A. H. , Scarfe C. D.
Published: July 2016

The difficulties of discovering and observing multiple stellar systems are reviewed and discussed with especial reference to those systems which are best observed by a combination of visual and spectroscopic or visual and photometric means. Attention is drawn to the difficulties that often exist in reconciling the results of two different methods of observation. A brief discussion of the possibility of detecting spectroscopically invisible companions of low mass is included in the paper.
A New Michelson Stellar Interferometer
Authors: Twiss R. Q. , Tango W. J.
Published: July 2016

A new 1.87 m fixed-baseline interferometer designed for binary star observation is now in operation at the Italian outstation of the Royal Observatory Edinburgh. It has a theoretical resolving power of 0.015 arcsee and a limiting B magnitude of 6.5. Atmospheric seeing is dynamically corrected, allowing a quantitative measurement of fringe visibility.