bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study of the Variability and Proper Motions of Quasars based on Tautenburg Schmidt Plates
Authors: Meusinger H. , Klose S. , Ziener R. , Scholz R.-D. 
Published: July 2016

AbstractWe report on the present status of an ongoing study of variability and proper motion of quasars based on Tautenburg Schmidt plates of the field around M3. The main aspects are: (i) a thorough investigation of variability of a sample of known quasars based on a large number of B plates with a long time baseline and the comparison of variability in U, B, and V; (ii) the variability - proper motion diagram for the objects with B ≲ 20.5 mag in this field and the loci of known quasars in this diagram. The primary aim of this work is to check the suitability of Tautenburg Schmidt plates for a combined variability - proper motion quasar survey.
Compact Groups of Galaxies found using the COSMOS Catalogue
Authors: Barnes D. G. , Drinkwater M. J. 
Published: July 2016

AbstractWe have developed an algorithm to search the COSMOS/UKST Southern Sky Object Catalogue for compact groups of galaxies, with the aim of finding regions of high mass-to-light ratio. With this catalogue, and quantitative criteria, we select groups objectively and therefore hope to improve upon earlier visual searches. We use a density enhancement measure to define a compact group.We have made a preliminary search of 15 Schmidt fields (total area ∼ 390 deg2), finding 58 compact groups, ie. a mean density of 0.15 compact groups deg−2. In this paper we present finding charts and images of some of the compact groups found.
Galaxy Clustering in the Southern Hemisphere
Authors: Collins C.A. 
Published: July 2016

AbstractIn this paper some of the major results from the COSMOS and APM digitised galaxy surveys are presented. The main motivation behind these catalogues was to study large-scale structure in the universe. We begin by outlining the importance of such studies to cosmology and discussing the early results from the visually compiled galaxy catalogues. The impact of the digitised catalogues is demonstrated by focussing on three key areas of research; the galaxy-galaxy two-point angular correlation function, the cluster-cluster spatial correlation function, and galaxy number counts.
The Red Bright Quasar Survey (RBQS)
Authors: Sealey Katrina M. , Drinkwater Michael J. , Irwin Mike J. , Webb John K. 
Published: July 2016

AbstractWe are using the UK Schmidt telescope (UKST) to carry out a new objective prism survey, covering 2000-3000 square degrees of high galactic latitude sky in the equatorial region. The survey is targeted at discovering both bright (R < 18) quasars in general and bright high redshift (2 < z < 4) quasars in particular, which will be valuable for high resolution spectroscopic follow-up studies. We are using a mixture of ultra-violet excess (XJVX) and a new template matching technique to identify all the bright quasars. Details of the project are discussed and some preliminary results of the survey are presented.
Possible Collaborative Network with Small Telescopes and a Standard CCD in Japan
Authors: Isobe Syuzo 
Published: July 2016

AbstractThere are two obvious ways to make a quick survey work. A: A telescope with a wide field and a large size detector. B: Many telescopes with a rather narrow field and a small size detector. In Japan, there are now 47 telescopes with diameters of 50-100 cm dedicated to public use. If we develop a simple-to-handle detector system, non-professional observers at each public observatory would have the possibility of joining a collaborative survey network. We started a test observation which is expected to extend to a survey network.
Regional Cooperation: The Case in Astronomy
Authors: Hidayat Bambang 
Published: July 2016

In the Asia Pacific environment some astronomical centres already exist. It must be understood that while quite a few are already deeply involved in frontline astronomical research; others are still struggling to make their existence appreciated in their home countries, or, are trying to be recognized within the astronomical community. Whatever their status now, the basic underlying principle for the establishment of astronomy centres is the same and is motivated by the same ideals. These are to pursue scientific truths about the sun, planets, stars and galaxies.It is often the case that inherent national problems (economic or political) can inadvertently push the astronomy institutions behind. Furthermore, there exists among the political elite in a country different, not to say lack of, visions and perceptions about science in general and astronomy in particular. In such a situation the scientists and astronomers in that country find themselves in a twofront battle-line. Firstly, they must try to overcome the shortages of manpower and funds for hardware, so that their institutions can grow. Secondly, they must elevate their national programmes so that they can be accepted by international research standards.
Cryogenic servo-stabilized Fabry-Perot interferometers for imaging at 3-5 and 8-13 microns
Authors: Reay N. K. , Pietraszewski K.A.R.B. 
Published: July 2016

AbstractThe performance of a new liquid Nitrogen cooled Fabry-Perot etalon for imaging at 3-5µm is described. Capacitance sensors monitor the etalon mirror spacing and parallelism, and error signals produced as a consequence of changes in these parameters are used in a feedback loop with piezoelectric actuators for active cavity control. These new cryogenic etalons are designed to be compatible with the Queensgate Instruments Ltd CS100/ET servo-stabilized Fabry-Perot system.The cryogenic etalon has a clear aperture of 50mm and a nominal mirror spacing of between 5 and 60µm. It is coated for the 3 - 5µm spectral region, although coatings are also available for the 2 - 2.5µm and 8 - 13µm regions. Under servo-control at operating temperature the etalon has a response time of 30 msec and a minimum cavity tuning range of ±3µm about the nominal cavity length, corresponding to approximately 3 orders of interference at the midrange wavelength of 4µm.
Fabry-Perot Spectroscopy of Extremely Faint Astronomical Sources
Authors: Roesler F. L. , Reynolds R. J. , Scherb F. 
Published: July 2016

AbstractOur interests in the general field of astrophysics lie principally in two areas: 1) the study of extremely faint emission lines from the interstellar medium, galactic halo, and intergalactic clouds, and 2) the study of neutral and ionized components of the outer atmospheres of solar system objects, including the earth. These studies require instruments of the highest possible area-solid angle product, but typically do not require extremely high spatial resolution. This paper highlights our past work in these areas, and discusses new instrumental approaches we are developing.
Scanning Fabry-Perot observations of multiple profiles of faint and extended gas in the center of elliptical galaxies
Authors: Plana H. , Boulesteix J. 
Published: July 2016

AbstractSome elliptical galaxies possess an extended gaseous disk which is usually detected from Hα and [Nil] emission. 3-D ”Cigale” observations of two of these objects, NGC 1052 and NGC 404, show the evidence of peculiar dynamics a nd in one case multiple profiles of faint extended gas which are probably from different origins. In NGC 1052, the decoupled kinematics of the gas and the stellar systems favors the hypothesis of an external origin of the interstellar matter, while in NGC 404, coherence of the stars and gas axis, as well as the low gas velocity dispersion favors an inner origin of the gas from the stars themselves.
Field Spectroscopy by Optical Fibres: development of the ”ALBIREO” spectrograph
Authors: Herpe G. , Sanchez J. , Vanderriest Ch. , Moles M. 
Published: July 2016

AbstractA multi-function spectrograph has been built for the new 1.52 m telescope in the Sierra Nevada Observatory near Granada (Spain). It uses optical fibres for both multi-object spectroscopy and integral field spectroscopy, in addition to classical imaging and long-slit modes.
First Observations with Multi-Pupil Integral Field Spectrograph on 4-meter Mayall Telescope
Authors: Afanasiev V. L. , Vlasiouk V. V. , Green R. F. 
Published: July 2016

First attempts to get spectra from extended areas were in the middle of 80-th, using fibers techniques: DensePack (Barden, Scott, 1986), SILFID (Vanderriest and Lemonnier, 1988). Bundle of fibers were put at the focus of the telescope and the other ends of fibers rearranged to produce a long slit of the spectrograph.Another method of bidimensional spectroscopy, not using optical fibers, was proposed by Prof. G. Courtes (Courtes et al, 1988). He recommended to put behind the telescope focal plane a bidimensional array of microlenses and to project on it an enlarged image. The lens array separates continuous input image and forms an array of micro-pupils that are images of the main mirror illuminating each lens. They create an input image for a classical spectrograph instead of a normal slit. Using of square lenses allows to achieve correct data sampling, and such scheme is ideal for spectrophotometry, allowing integration of total energy from the observed sky area.
Mixture Modeling of M51
Authors: Johnson Paul E. , Waddill David M. , Townsley Leisa K. , Titus Timothy N. , Spillar Earl J. 
Published: July 2016

AbstractOne of the major problems with 3D spectroscopy is the adequate and meaningful display and analysis of large image cubes. We use linear mixture modeling to analyze multispectral CCD images of M51 in the visible and near-IR. We find that M51 can be modeled within the noise limits of the data as a linear combination of six components taken three at a time.
The PYTHEAS concept and applications
Authors: Georgelin Y.P. , Comte G. , le Coarer E. 
Published: July 2016

AbstractThe PYTHEAS instrumental concept is an attempt to solve the problem of getting a complete tridimensional coverage of the observed field with a high spectral resolution across a wide spectral range. It is an integral field spectrometer derived from the TIGER spectrograph (field sampling with a microlens array) in which a scanning Fabry-Perot (FP) is introduced. The spectral resolution is given by the F P and the spectral range is that allowed by the grism of TIGER. The information is recorded on the CCD as a set of channeled spectra, for each microlens and each scanning step of the FP. The spectrum of each sampled field element is reconstructed from flux measurement of the Fabry spots defining the channeled spectra.The application ranges of this instrument are reviewed with emphasis on the potential interest in globular cluster studies.
Chemistry of Molecular Clouds
Authors: Dalgarno A. 
Published: July 2016

AbstractA discussion is presented of the chemistry of quiescent molecular clouds, and the effects of the presence of polycyclic aromatic hydrocarbon molecules and of cosmic-ray induced ultraviolet photons are examined. A comparison is made with the chemistry occurring in molecular clouds that are subjected to shocks and the differences between dissociative and non-dissociative shocks are described. The changes in composition caused by intense cosmic ray fluxes or intense ultraviolet radiation fields are explored.
The Dynamical Evolution of A Clumpy Medium
Authors: Yorke H.W. , Kunze R. , Spurzem R. 
Published: July 2016

Abstract:We consider the evolution of a multicomponent medium: stars and gas clouds embedded in an ambient gaseous medium. The stars and gas clouds are treated stellar dynamically, using a velocity moment expansion of the Boltzmann equation. The basic equations and interaction terms are discussed. Examples of 2-D numerical calculations are presented (see also Kunze et al., this meeting).
Disks and Outflows
Authors: Rodríguez Luis F. 
Published: July 2016

AbstractThis paper reviews recent developments in the study of bipolar outflows and their possible collimation by disklike structures. The exciting stars of most bipolar outflows are embedded in dense cores, self-gravitating structures with masses in the range of 1 to 103M⊙. In many cases, these dense cores are flattened, with its major axis aligned perpendicular to the axis of the outflow. These flattened structures, the interstellar toroids, appear to play a role in the large scale (0.1 pc) collimation of the bipolar outflows. However, a considerable number of observations point to the presence of collimation on much smaller scales. In particular, the results of Sargent and collaborators have revealed the existence of circumstellar disks (with radii of ~1000 AU) that are gravitationally bound to their stars. I also review recent models of accretion disks around T Tauri stars have been successful in explaining the general features of the continuum spectra of T Tauri stars from the ultraviolet to the infrared. Some radio results that have not been considered by these models are discussed.
A New High-Resolution Optical Study of Halo Gas
Authors: Albert C. E. , Blades J. C. , Morton D. C. , Proulx M. , Lockman F. J. 
Published: July 2016

Abstract:We present preliminary results from a new high resolution optical study of halo gas at the coudé focus of the Canada - France - Hawaii Telescope. Our work is still in progress so two general results are presented here: significant absorption is produced in interstellar gas beyond 500 pc from the galactic plane, and well-resolved halo clouds are identified.
Gamma rays from violent interstellar events
Authors: Bloemen J.B.G.M. 
Published: July 2016

SummaryAs an illustration of what the next generation of γ-ray telescopes may show us, an up-to-date COS-B ‘finding chart’ of potential γ-ray point sources and unexplained extended γ-ray features is presented. The latter, in particular, may be related to energetic phenomena in the interstellar medium, capable of enhancing the local cosmic-ray density. As an example, a prominent feature, extending over at least 10° — 15° almost perpendicular to the Galactic disk, is discussed in some detail, linking it to the giant HII region S54 and Complex C of high-velocity clouds.
Structure of the Diffuse Interstellar Medium
Authors: Cox Donald P. 
Published: July 2016

ABSTRACTThe interstellar medium has a thick disk structure (|z | ≲ 1500 pc, the ECL or extracloud layer) with a thin zone of cloud contamination at |z | ≲ 100 pc. The properties of all components other than clouds (e.g. cosmic rays, magnetic field, extracloud matter, pressure) drop slowly with |z| across the thick distribution, giving this layer a very important influence in the evolution of superbubbles. It seems likely to quench blowout or breakout and virtually all fountain activity. The weight of this layer stabilizes the clouds at low z; its high pressure and low density provide a cushion for impacts of infailing clouds.
Convection and Irradiance Variations
Authors: Fox Peter A. , Sofia Sabatino 
Published: July 2016

In the outer layers of the Sun (≈ 30% by radius), energy is transported by convection. The nature of the highly stratified and compressible convective flow is determined from the components of the energy flux (internal, kinetic, viscous, magnetic and radiative). Local suppressions or enhancements of any of these components may give rise to measurable changes in the emergent radiation.On the solar surface there is direct evidence for modulation of the emerging heat flux covering a large range in spatial and temporal scales, particularly associated with concentrated magnetic fields (e.g. sunspots, plages). Associated with these surface features is the observation that the characteristics of convective motions are also modified. In the deeper layers, the interaction of convection and magnetic fields will play an important role in readjusting the local emerging heat flux and thus should contribute to the modulation of the total solar irradiance.The task of calculating the response of the convection zone structure to developing active regions, and the solar activity cycle in general is difficult and complex due to the highly non-linear nature of the interaction of convection and magnetic fields. Theoretical work has ranged from empirical and global structure models, all the way to fine scale compressible convection simulations. This paper will highlight some recent theoretical advances that may have a direct bearing on the understanding of solar luminosity and irradiance variations and outline the important problems that must be addressed and what observational constraints may be used.
Radio Measurements of Coronal Magnetic Fields
Authors: Gelfreikh G. B. 
Published: July 2016

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.
On 22-Year Pole To Equator Variation of the Corona Intensity
Authors: Makarov V. I. , Tlatov A. G. 
Published: July 2016

AbstractKislovodsk sets of observations (1957.5-1991.0) of the corona in the line Fe XIV 5303 Å have been processed. Half annual intensities of corona have been approximated with the polynoms of the m-degree in dependence on latitude. The coefficients of these sets have been found using the least square solution method. The zone of zero values of the second derivation of the coronal intensity on latitude has been determined. It is shown that this zone emerges after the magnetic field reversal at the latitudes near 80° then migrates equatorward during 22 years with a velocity of 2 m/s. The obtained data were compared with a pattern of torsional oscillations plotted on the basis of the velocity field. A possible reason for 22 year pole to equator variations in the corona is considered.
Possible Errors in Coronagraphic Observations which Could Introduce Asymmetric Emissions from Antidiammetric Points of the Solar Limb
Authors: Noëns J. C. , Tritakis V. P. , Paliatsos A. G. 
Published: July 2016

AbstractAll the possible systematic and random errors which could introduce differential brightness of the optical emissions between the eastern and the western part of the solar corona, have been discussed. Since the above mentioned inequality has been already detected in all the optical emissions of the corona but no error which could introduce it has been determined, additional studies are necessary in both directions. First, to support that this inequality is consistent to a real physical phenomenon and second, that another error far from the already known is responsible for this particular effect.
Measurements of Electric Fields in Coronal Magnetic Structures
Authors: Foukal P. V. , Behr B. B. 
Published: July 2016

AbstractWe review the use of Stark effect to measure d.c. and wave-related electric fields predicted in models of coronal and flare heating, prominence support, and related phenomena. We describe the Mk II limb electrograph now in routine operation at NSO/Sac Peak, using high Paschen series lines around 8500 Å, and its testing (using the Zeeman effect) as a transverse magnetograph, on penumbral magnetic fields. We summarize our new upper limits on the d.c. fields in quiescent prominences and of the Alfvén wave flux in the corona, and a possible detection of 15 – 20 V cm−1electric fields in a bright surge at the limb. We also outline our ongoing observations at Brackettγ(2.16μ) and our plans to observe in the very sensitive 15-9 transition of H I at 11.539μ.
The Small-Scale Structure of Coronal Loops
Authors: Berger M. A. 
Published: July 2016

AbstractHow do we model coronal loops which contain a rich internal structure? Coronal loops usually lie close to the equilibrium state, but equilibrium fields are generally nonlinear, three-dimensional, and contain intense current layers. Nevertheless, it is important to study highly structured loops. Small reconnection events (microflares and nanoflares) which simplify the structure may be the primary source of heat in the closed corona. The magnetic energy released during a reconnection event can be estimated if one knows the equilibrium energy before and after the event. Furthermore, structured or tangled fields dissipate wave energy more efficiently than smooth fields. Here we present a method for studying tangled fields. Lower bounds can be placed on the energy of the equilibrium field, given a measure of the topological complexity known as the crossing number. These bounds provide an estimate of the energy generated in a coronal loop due to random photospheric motions. This calculation is used to estimate the heating rate in Parker’s topological dissipation model.
Interpretation of Magnetic Field Structures of AR 6659 in June 7-10, 1991
Authors: Wu S. T. , Weng F. S. , Hagyard M. J. , Machado M. , Schmieder B. 
Published: July 2016

AbstractWe examine the magnetic structures in AR 6659 by using the observatibn of vector magnetic fields obtained at Marshall Space Flight Center/National Aeronautics and Space Administration (MSFC/NASA). Using these vector magnetic field data as the input for the non-linear force-free model developed by Wuet al.(1990), the structure of coronal loops is revealed. The results obtained include: (i) loop system configurations and (ii) current distributions for AR 6659 during the period 1991 June 7-11. In addition, we also computed the total magnetic energy vs time of this region. It shows that there is indeed enough energy to propel the numerous, energetic flares that were observed in this region. It also revealed that the flare loop system corresponds to the two-ribbon flare on 1991 June 9.
Impulsive Heating of Coronal Loops
Authors: Reale F. , Peres G. , Serio S. 
Published: July 2016

AbstractWe have made hydrodynamic calculations of steady coronal loops maintained close to steady conditions with a heating entirely made of a sequence (either randomic or periodic) of small events of energy input into the plasma. To study their observability, we synthesize the emission in bands observable by X-ray instruments, such as imaging instruments, like Yohkoh/SXT and the forthcoming SOHO/EIT. We present results for one specific calculation and discuss them in terms of the possible diagnostics of variable heating vs. steady one and of the feasibility of direct detection of loop variability.
Large-Scale Coronal Structures Associated with Solar Activity
Authors: Švestka Z. , Fárník F. 
Published: July 2016

AbstractWe summarize observations of filament eruptions, post-flare loops, giant post-flare arches, flaring arches, surges, coronal responses to chromospheric brightenings, and interconnecting loops, made bySkylabandSMM, and confront some of them with soft X-ray observations recently made byYohkoh. It seems likely that many structures observed by Yohkoh are the same phenomena that were seen before, but it may be sometimes difficult to identify them correctly.