bluuebunny/crossref_metadata_2025_split huggingface dataset:
Galaxy Counts
Authors: Tyson J.A. 
Published: July 2016

AbstractCounts of faint galaxies should reveal any evidence of galaxy luminosity or color evolution, as well as new information on the faint end of the galaxy luminosity function. The FOCAS automated detection and classification software is reviewed, and results of the deep 4m PF photographic survey to 24th magnitude in 23 fields covering 9 sq. degrees are presented. Color-magnitude plots for stars and galaxies are shown, and galaxy color evolution is discussed. Evidence is found for a faint galaxy blue trend at 22-24 J mag. However, the k-correction becomes so severe at redshift ~1 that the intrinsically fainter galaxies are emphasized in any magnitude-limited survey. No unambiguous evidence is found for evolution. New 4m limit CCD multi-color data are shown and discussed. The limiting magnitude for detection is 27th J magnitude in 2 hours integration. The data exclude evolution starting at any one epoch for z<10.
Superclustering and Substructures
Authors: Chincarini Guido 
Published: July 2016

The history of the Universe is infinitely more interesting than the history of the study of the Universe.- Zel'dovich and Novikov (1983) -PROLOGUEThe understanding we have today of the distribution of galaxies resolves some of the debates which were going on in the seventies. Future data and analysis may allow us to discriminate among cosmological models.
Cosmology with the Space Schmidt Telescope - Galaxy Colors and Color Distributions
Authors: Bruzual A. Gustavo 
Published: July 2016

AbstractGalaxy spectral evolutionary models are used to compute the following quantities in optical and UV bandpasses: (a) galaxy color, luminosity, two-color diagrams, and surface brightness profiles as functions of redshifty and (b) galaxy counts, and color and redshift distributions as functions of apparent magnitude. These predictions may be used as a guide to prepare and interpret observing runs with the Space Telescope, the Space Schmidt Telescope, and the Starlab Observatory.
Iron K-Line Emission from X-Ray Binaries
Authors: Masai K. , Hayakawa S. , Nagase F. 
Published: July 2016

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx&gt; 10 keV is likely due to fluorescence outside the He II ionization front.
Laser-Driven Soft X-Ray Lasing in Copper and Germanium Plasmas
Authors: Mclean E.A. , Lee T.N. , Elton R.C. 
Published: July 2016

AbstractSoft x-ray lasing has been achieved for the first time on 3p-3s transitions in neon-like copper (Cu19+) and germanium (Ge22+). The elongated lasant plasma was produced using the NRL Pharos III laser operating atλ= 1.05 μm, 300–480 J with a pulse duration of 2 ns. Lasing was observed in the wavelength interval 196 to 286 Å for J = 2 → 1 and J = 0 → 1 lines, using both thin film and thick slab targets.
The Measurement and Interpretation of NeV 2–2 Line Intensity Ratios
Authors: Lang J. 
Published: July 2016

AbstractA theta-pinch was used to produce NeV 2–2 spectral lines. The intensities of the lines were measured using a grazing incidence spectrometer which had been intensity calibrated by the branching ratios method. The electron temperature and density of the theta-pinch discharge were found by laser scattering. The measured intensity ratios are compared to theoretical predictions based on electron excitation rate coefficients calculated using the R-matrix close coupling method. For two of the measured ratios experiment and theory agree within the experimental uncertainty, For the other two ratios the theoretical prediction is greater than the experimental result.
Spectral Observations of the Extreme Ultraviolet Astronomical Background Radiation
Authors: Labov S. , Bowyer S. 
Published: July 2016

AbstractObservations in the far ultraviolet and soft x-ray bands suggest that the interstellar medium contains several components of high temperature gas (105to 106K). If large volumes of local interstellar space are filled with this hot plasma, emission lines will be produced in the extreme ultraviolet (EUV). Diffuse EUV radiation, however, has only been detected with photometric instruments; no spectral measurements exist below 520Å. We have designed a unique grazing incidence spectrometer to study the diffuse emission between 80 and 650Å with 10 to 30Å resolution. This instrument was successfully flown on a sounding rocket in April of 1986 and a preliminary analysis reveals several features. In addition to the expected interplanetary He I 584Å emission and the geocoronal He II 304Å emission, other features appear which may originate in the hot ionized interstellar gas. These features are discussed along with the possible implications to the hot phase of the interstellar medium.
High Resolution Spectroscopy of Dite Tokamak in the 10Å Region
Authors: Dunn J. , Barnsley R. , Evans K.D. , Peacock N.J. 
Published: July 2016

AbstractAn account is given of the X-Ray emission from the DITE tokamak in the spectral region 4Å–10Å measured by a Johann curved crystal photographic spectrometer. This high resolution instrument has been used for detailed line identifications eg. of L-shell transitions in the Fe spectrum at wavelengths ∼8Å and of the He-like ion spectra of Al, Si and Ar. The fine structure has been resolved for H-like Mg, Al and Si. Departures from the statistical value of 0.5 forβ, the intensity ratio of the Lyman-αdoublet, have been observed. Experimental values for the fine structure separation are presented for these medium Z metals.
Spectroscopy in Ne-Like Plasmas. Z-Dependence of the Atomic Data Used in a Collisional-Radiative Model
Authors: Cornille M. , Dubau J. , Loulergue M. , Jacquemot S. 
Published: July 2016

AbstractThe Livermore X-ray Laser experiments in 1984 have shown the existence of Ne-like 3p-3s population inversions in a collisional Se plasma (Z=34) with significant gains (5 cm-1). We have focused our efforts on the behavior of the gains along the target neon Isoelectronic sequence. This study implies the determination of the Z-dependance of the rate coefficients of all the Involved atomic processes: collisional excitation (C). radiative decay (A) and dielectronic recombination (αd). Thus we use atomic structure and electron-ion collisional codes (SUPERSTRUCTURE. Distorted Waves. AUTOLSJ and JJOM). The different calculations have been done on a large selection of ions, from Ar to Ag. They Include relatlvistic effects in a fine structure scheme. The Z-dependance of the numerical results is expressed as polynomial or rational forms.
Soft X-Ray Images of the Solar Corona Using Normal Incidence Optics
Authors: Bruner M.E. , Haisch B.M. , Brown W.A. , Acton L.W. , Underwood J.H. 
Published: July 2016

AbstractA solar coronal loop system has been photographed in soft X-rays using a normal incidence telescope based on multilayer mirror technology. The telescope consisted of a spherical objective mirror of 4 cm aperture and 1 m focal length, a film cassette, and a focal plane shutter. A metallized thin plastic film filter was used to exclude visible light. The objective mirror was covered with a multilayer coating consisting of alternating layers of tungsten and carbon whose combined thicknesses satisfied the Bragg diffraction condition for 44 Å radiation. The image was recorded during a rocket flight on 1985 October 25, and was dominated by emission lines arising from the Si XII spectrum. The rocket also carried a high resolution soft X-ray spectrograph that confirmed the presence of Si XII line radiation in the source. This image represents the first successful use of multilayer technology for astrophysical observations.
Review of X-ray Spectroscopy from Laser-Produced Plasmas
Authors: Kauffman R.L. 
Published: July 2016

AbstractRecent progress in x-ray spectroscopy from laser plasmas is reviewed. Advances in the use of K-shell spectra as a diagnostic tool is discussed. Much activity in understanding complex spectra especially from Ne I and Ni I isoelectronic series have been made. Much of the progress has been due to observation of amplification from Δn=0 transitions from these configurations. The spectroscopy will be discussed and examples of spectra of the amplified lines will be shown. Finally, recent work on using x-ray spectroscopy to diagnose high density implosions will be discussed.
Continuous Ultraviolet Absorption BY Si+(4Pe): an Exploratory R-Matrix Calculation
Authors: Tully J.A. 
Published: July 2016

AbstractThe R-matrix method is used to calculate photoionisation from the first excited state 3s3p23Pe of Si+. The lowest two triplet terms 3s3p3Poand 3p23Peof the residual ion Si++are included in the calculation. They are approximated by configuration interaction wavefunctions which are constructed from six spectroscopic orbitals: 1s,2s,2p,3s,3p,3d. Partial and total cross-sections are tabulated for photon energies ranging from threshold (705 A) up to 2.5 Ryd (365 A). Some of the 3p2np autoionising resonances are delineated and shown graphically.
The Diagnostics of Astrophysical Plasmas, using the Oxygen VII Soft X-Ray Lines
Authors: Gabriel A.H. , Bely-Dubau F. , Faucher P. , Acton L.W. 
Published: July 2016

AbstractWe present a revised theory and atomic model for the line intensities emitted by O VII, taking into account all of the processes responsible for the emission. This is used to provide a revision of the density measurements made during solar flares, as well as in an attempt to understand the spectrum of the Puppis A supernova remnant. In order to explain the strange intensity ratios observed from Puppis A, previous authors have proposed an interpretation based upon a high temperature thermal plasma (&gt;5 106K), in a non-equilibrium ionisation state. We present here an alternative model, based upon the assumed presence of a proportion of fast non-thermal electrons imbedded in an otherwise thermal plasma at a temperature of below 1 106K. This can adequately explain the observations, without the necessity of invoking departures from ionisation balance.
Quick Interpretation of Unresolved Hyperfine and/or Zeeman Structures in Stellar Spectra
Authors: Bauche J. , Oreg J. 
Published: July 2016

AbstractSome atomic or ionic lines emitted by the stellar atmospheres are very useful clues for estimating the local magnetic fields. However, their use is often complicated by insufficient experimental resolution and by the occurence of hyperfine structure. But the average wavelength and the width of the component set corresponding to each type of polarisation are given by compact formulae, in terms of the magnetic field, and of the Landé factors and hyperfine magnetic and electric constants of both involved levels.
Results of the Leban Diagnostic Procedure Applied to Two SMM - Observed Flares
Authors: Sylwester B. , Sylwester J. , Jakimiec J. 
Published: July 2016

AbstractIn a previous paper (B. Sylwester et al., 1986) we proposed a new procedure called LEBAN (Loop Energy Balance Analysis) for deriving the basic geometrical parameters of flaring loops. In a subsequent paper (B. Sylwester et al., 1987) the Palermo Code resuits of hydrodynamic flare loop modelling have been used to confirm the validity of the LEBAN procedure for this purpose. In the present investigation the LEBAN procedure has been applied to analyse two SMM-observed flares (on 12 Nov. 1980, ∼17:00 UT and on 18 Nov. 1980, ∼15:00 UT). Estimated flare loop lengths and cross-sections have been compared with those derived from deconvolved HXIS images and/or estimated in different way by other authors. If the loop semi-length L is known from other observations, this allows to estimate the portionβof the loop which was heated. Time variations of other important parameters characterizing the flare plasma (the heating rate, the mean density, the total energy content) are also discussed.
Theoretical Spectra of Fe XXIII - Fe XIX Ions in Two Calculation Methods
Authors: Cornille M. , Dubau J. , Loulergue M. , Bely-Dubau F. , Faucher P. , Safronova U.I. , Shlyaptseva A.S. 
Published: July 2016

AbstractTwo different calculation methods are compared for Fe XXIII – Fe XIX spectra in the X-ray range between 1.85–2 Å, for transitions of the type 1s2sk2pn−1s22sk2pn−1. Wavelengths, radiative transition and autoionization probabilities as well as the intensity factors are compared. These parameters are given in order to diagnosis low density plasmas as found in solar flares and Tokamak devices.
Axial Observation of X-Ray Spectra from a Beam-Foil Source
Authors: Laming J.M. , Silver J.D. , Barnsley R. , Dunn J. , Evans K.D. , Peacock N.J. 
Published: July 2016

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.
A Perturbation Theory for the Population of Atomic Energy Levels in Non-Lte Plasmas
Authors: Klapisch M. 
Published: July 2016

AbstractA formal expansion of the CRM in powers of a small parameter is presented. The terms of the expansion are products of matrices. Inverses are interpreted as effects of cascades.It will be shown that this allows for the separation of the different contributions to the populations, thus providing a natural classification scheme for processes involving atoms in plasmas. Sum rules can be formulated, allowing the population of the levels, in some simple cases, to be related in a transparent way to the quantum numbers.
VUV Spectroscopy of Ar9+ and Kr9+ Low Energy Collision with H2
Authors: Druetta M. , Bouchama T. , Martin S. , Désesquelles J. 
Published: July 2016

Photon spectroscopy of low energy collisions between multicharged ions and neutrals has opened new possibilities of wavelength and energy level determination since recent multicharged ion sources like the E.C.R. source, giving μA electric current of highly multicharged ions, are available.The experimental set-up has been already described (1.2) The ion beam is produced by an E.C.R. ion source. Light emitted as a result of the collision is observed at 25* to the beam axis with a 3m grazing incidence (82*) spectrometer equipped with a 300 or 600 lines/mm grating blazed at 55.2 or 27.6 nm respectively. The detection is realised by micro-channel plates (MCP). Typical beam currents are 0.45 and 0.40 μA for Kr9+and Ar9+respectively, through the 8 mm diameter entrance hole of the gas cell. The gas pressure was kept at 5 × 10−5mbar. The emission cross sections of all the new observed lines have been mesured. Taking into account the statistics; the error on the beam intensity due to double collisions; the errors on the pressure, on the relative efficiency curve of the spectrometer and on the absolute calibration; we may estimate the error bar to ± 30%.
Doppler Shift in X-Ray Spectrum for Laser-Imploded Spherical Microshells
Authors: Fiedorowicz H. , Denus S. , Jeziak K. , Kolanowski M. , Parys P. , Pawłowicz W. , Wołowski J. 
Published: July 2016

AbstractDoppler shifts due to plasma motion have been observed in the space-resolved X-ray spectra for the laser-imploded spherical microshells. The analysis of the X-ray spectrum makes it possible to study the ablation process from the microshell surface.
Mirrors: Fabrication, Processing, Testing and Tolerances
Authors: Meinel A.B. , Meinel M.P. , Shannon R.R. , Parks R.E. 
Published: July 2016

The construction of very large telescopes is impeded by very large costs. Much effort is going into finding ways to get below the traditional cost-scaling trend line. We will address several factors that lead to reduction in cost without reduction in performance. Clearly, a very fast primary f-ratio is necessary. The practical lower limit is set by three factors:1) width of the Nasmyth platform2) new optical processing techniquesand 3) maintenance of collimation.
Pointing Errors of Large Telescopes Due to Wind
Authors: Ulich Bobby L. 
Published: July 2016

AbstractScaling laws are presented which show the dependence of the tracking error of large telescopes on structural materials, mechanical properties and dimensions of the mount, and wind speed. Based on direct measurements on the Multiple Mirror Telescope, predictions are made for future very large telescopes. It is shown that good tracking can be achieved most of the time even without a traditional dome to block the wind, and this may result in better images by eliminating “dome seeing”.
Pathlength Stability of Synthetic Aperture Telescopes - the Case of the 25 cm CERGA Interferometer
Authors: Mariotti J.M. , Di Benedetto G.P. 
Published: July 2016

Synthetic aperture telescopes are more and more considered as a promising scheme for the next generation of Very Large Telescopes : the basic idea is to combine the beams of two or more independent telescopes. The question immediately raising when considering such a technique is the pathlength stability and the amount of pathlength difference that can be tolerated, assuming a reasonable bandwidth, to preserve coherent addition of the wavefronts and hence, high spatial frequencies observations.To that respect the I2T (two telescopes interferometer) in operation at CERGA constitutes a remarkable test-bench for studies of mechanical, optical and atmospheric constraints that are to be faced when dealing with amplitude interferometry between several telescopes.
16 m Large Slit Aperture Telescope for Very High Angular Resolution Astronomy
Authors: Petrov R.G. , Aime C. , Borgnino J. , Martin F. , Ricort G. 
Published: July 2016

AbstractThe expected progress of diffraction limited imaging methods and the apparition of new super resolution techniques like differential speckle interferometry would justify the construction of a 15 m class telescope dedicated to diffraction limited observations in order to fulfil the potential of high angular resolution astrophysics of 15 m class instruments, but the construction of such a telescope is conceivable only if its cost is much smaller than the cost of the equivalent all purposes VLT. In this paper we suggest that a telescope with a long and thin rectangular primary ( 16 m X.4m say ) , able to rotate around the optical axis to ensure a full coverage of the frequency plane, would do almost as well than a conventional 16 m aperture telescope for high angular resolution astronomy for a cost substancially reduced. The performances of such a Large Slit Aperture Telescope ( LSAT ) for classical and differential speckle interferometry are examined and the releases on the optical and mechanical constraints allowed by the dedication of the instrument to speckle techniques are discussed.
The Mersenne-Schmidt Telescope
Authors: Willstrop R.V. 
Published: July 2016

SummaryA three-mirror telescope is described which covers a field 4° in diameter at f/1.6 with images smaller than 0.31 arcsec total spread (0.17 arcsec r.m.s.); an alternative version, also f/1.6, covers a field 2° in diameter with images smaller than 0.049 arcsec (0.023 arcsec r.m.s.). Both forms of this telescope are fully baffled against sky fog contamination, the illumination is uniform over the central 2° field and decreases by about 13 per cent at the edge of the 4° field, and the tube length is little more than the focal length.
System Requirements for Polarization Capability
Authors: Tinbergen J. 
Published: July 2016

The purpose of this paper is to point out that1) proper treatment of polarization by a telescope is not only important for polarimetry, but also for other observations requiring high signal-to-noise ratio, and2) this does put a constraint on telescope design, which, however, is not unduly restrictive.Polarimetry is the observational technique which can detect anisotropics in point sources, their environment, or the medium between them and us. Modern optical polarimetry can be linear or circular, and is making progress towards spectropolarimetry and imaging polarimetry using panoramic detectors (e.g. McLean, 1984). Given sufficient photons, the precision obtained is as high as 1 part in 50 000 (see Odell, 1981 for a project requiring this precision), but more often a precision between 1 part in 1 000 to 10 000 is sufficient. (Spectro)polarimetry has been applied to planets, the Sun and other stars, stellar systems and galaxy nuclei; for a few modern investigations, see Baur, 1981; Jones et al, 1981; Schmidt and Miller, 1980. Experience in radio-astronomy has shown that when facilities for polarimetry are offered, many applications emerge from the astronomical community, yielding data that cannot be obtained by other techniques. It is essential that at least some of the large optical telescopes are capable of ob-serving polarization cleanly.
Two-Dimensional Infrared Detector Arrays
Authors: McCreight C.R. 
Published: July 2016

AbstractThe technology and terminology of integrated infrared detector arrays are discussed. Specific infrared array multiplexer designs include the charge-coupled device (CCD) and charge-injection device (CID). Laboratory data and telescope imagery obtained with three arrays (inSb CCD, Si:In CCD, and Si:Bi CID) are used to illustrate the performance and promise of integrated arrays in astronomical applications.
Very Large Telescopes and Stellar Astrophysics
Authors: Castellani Vittorio 
Published: July 2016

Let me start by reminding you in a very general frame what kind of information we expect to be able to derive from the observation of stars.First of all, there are observations - of photometric nature - which allow us to detect the location of stars in the sky. Modern astrophysics enables us, in the general case, to add more or less stringent information on the star distances. On the whole, one reaches in this way a picture of the galactic distribution of stars, i.e. information on the space location.A second kind of information we can derive from photometric measurements is that concerned with the age of stellar objects. As is well known, this is done - mainly - by constructing HR diagrams for stars which are members of stellar clusters.
Uses of Very Large Telescopes for Galaxy Research
Authors: Ulrich M.-H. 
Published: July 2016

SummaryMany areas of extragalactic research will greatly benefit from observations with a very large telescope. We concentrate, here, on four of them as illustrative examples:First we briefly discuss the study of the absorption lines in quasar spectra.In the second section we suggest the possibility of doing serendipity large field imaging during high spectral resolution exposures on point sources.In sections 3 and 4 we discuss two topics which have long been recognized as important drivers for the construction of very large telescopes, the determination of the nature of the missing mass, and the study of elliptical galaxies.