bluuebunny/crossref_metadata_2025 huggingface dataset:
Bow Shock Induced Star Formation in the LMC
Authors: de Boer K.S. , Braun J. M. , Vallenari A. , Mebold U.
Published: July 2016

The supergiant shell LMC 4 is known for its ring of HII regions and the deep minimum in HI in the interior (Rohlfs et al. 1984). LMC 4 shows X-ray emission detected by ROSAT and highly ionised gas (C IV) detected with HST (Bomans et al. 1994, 1996). The velocities of its neutral gas indicate it cannot have been formed by the collision with a high velocity cloud (Domgörgen et al. 1995).
Recent Migratory Star Formation in Nearby Magellanic Irregulars
Authors: Ruotsalainen Robert
Published: July 2016

UBV measurements of resolved stars in the associations of two Magellanic irregulars, Leo A and Sextans B, are compared with synthetic color-magnitude diagrams based upon stellar evolutionary models.
Recent Star Formation History of the Magellanic Clouds
Authors: Grebel Eva K. , Brandner Wolfgang
Published: July 2016

A new age calibration of Cepheids and supergiants is used to study the large-scale recent star formation history of the LMC and the SMC. We find evidence for migration of star formation along the LMC bar as well as for the existence of long-lived (≈ 200 Myr) extended star-forming features.
The Magellanic Stream and the History of the Tidal Interaction between the LMC and SMC
Authors: Sawa T. , Fujimoto M. , Kumai Y.
Published: July 2016

Adopting observed proper motions of the MC's and cluster formation histories of the LMC as observational constraints, we found a new binary orbit for the LMC and SMC in which the geometry and kinematics of the Magellanic Stream are well reproduced. In this orbit, the LMC and SMC experienced very close encouters 0.2 and 3 Gyr ago.
Two Hundred Years of Celestial Mechanics under the Auspices of Bureau Des Longitudes
Authors: Morando Bruno
Published: July 2016

Lagrange and Laplace were two of the first members of Bureau des longitudes which, among other tasks, were responsible for the improvement of astronomical tables and the progress of celestial mechanics. Between 1795 and 1850, many improved tables were published under the auspices of Bureau des longitudes: tables of the Sun by Delambre (1806), of the Moon by Burg (1806), Burckhardt (1812) and Damoiseau (1828), of Jupiter, Saturn and Uranus by Bouvard (1808, 1821), of Mercury by Le Verrier (1844), of the satellites of Jupiter by Delambre (1817) and Damoiseau (1836). In his tables, Bouvard showed there was a problem for Uranus. This led to the calculations of the elements of an unknown planet by Le Verrier and Adams and the discovery of Neptune in 1846. Le Verrier's calculations were published in Connaissance des Temps for 1849. In the second half of the XIXth century, two prominent members of Bureau des longitudes, Le Verrier and Delaunay, made major contributions to celestial mechanics by building elaborate theories for the motions of the Sun, the planets and the Moon. Other theories, which improved the above, appeared elsewhere at the end of the century, especially those of Newcomb, Hill and Brown. During the first half of the XXth century, there was a decline of the studies in celestial mechanics which seemed to have reached its limits owing to the difficulties of the computations involved. Yet Sampson's theory of the motion of the satellites of Jupiter and Chazy's first attempts to introduce general relativity into classical celestial mechanics should be quoted. In 1961, thanks to A. Danjon, Bureau des longitudes was reorganized so that its computation service became a research laboratory where, since then, important work in the theories of the planets, the Moon and the satellites has been made.
Using spacecraft range data and radar observations for the improvement of the orbital elements of planets and parameters of Mars rotation
Authors: Pitjeva E.V.
Published: July 2016

The extremely precise Viking (1972–1982) and Mariner data (1971–1972) were processed simultaneously with the radar-ranging observations of Mars made in Goldstone, Haystack and Arecibo in 1971–1973 for the improvement of the orbital elements of Mars and Earth and parameters of Mars rotation. Reduction of measurements included relativistic corrections, effects of propagation of electromagnetic signals in the Earth troposphere and in the solar corona, corrections for topography of the Mars surface. The precision of the least squares estimates is rather high, for example formal standard deviations of semi-major axis of Mars and Earth and the Astronomical Unit were 1–2 m.
New semi-analytic theory of the four outer planets
Authors: Simon J.L.
Published: July 2016

A planetary theory of the planets Jupiter, Saturn, Uranus and Neptune is presented here. It is a classical planetary theory where the perturbations are computed in the form of Poisson series of only one angular variable. It is built with modern values of the planetary masses and fitted to the numerical integration DE245 of the Jet Propulsion Laboratory (Standish, 1994). Its validity time span is of several thousand of years.
The orbital stability of the Sun-Jupiter-Saturn system
Authors: Donnison J. R. , Mikulskis D. F.
Published: July 2016

Kuiper(1973) suggested that the stability of the Solar System may be meaningfully investigated by studying the stability of the Sun-Jupiter-Saturn system. Numerical investigations by Nacozy(1976) showed that mass enhancement of the two planets beyond a factor of 29.25 led to instabilities in the system. In this new investigation similar mass enhancements were studied in detail numerically and compared with the analytical values derived from the c2H method. In addition, the eccentricities of the two planets were varied as well as their masses. It was found that the system soon showed signs of instability for the increased eccentricities when the masses of the planets were enhanced by fairly small factors.
The motion of Hyperion: On the accuracy of the observations
Authors: Kirsanov Nikolai O.
Published: July 2016

93 observations of the seventh satellite of Saturn, Hyperion, with 473 observations of Titan—Saturn's sixth and the most massive satellite and the one nearest to Hyperion—are considered. The observations were made in 1967–1981 at several observatories. The values of (O–C) across and along the orbits are obtained. The normality of the distributions of (O–C) is studied.
The Mimas-Tethys and Enceladus-Dione systems
Authors: Vienne A. , Duriez L. , Champenois S.
Published: July 2016

We have recently built a coherent theory of the motion of the satellites Mimas, Enceladus, Tethys, Dione, Rhea, Titan and Iapetus. The final form of the “Théorie Analytique des Satellites de Saturne” (TASS1.6) is presented in Vienne & Duriez (1995). The internal precision of TASS is a few kilometers over three years and some tens kilometers over one century. The root-mean-square residuals of the adjustment of TASS over one century of Earth based observations reach 0″.12 for the best data sets, until 0″.015 for the few mutual phenomenas of 1981.
Hypothetical evolutions of short-period comets
Authors: Batllo V.
Published: July 2016

The hypothetical model of capture I consider is as follows: a comet with an initial conic orbit, meets close to one of its vertices an outer planet and generates one or several little comets (crossing of the Roche limit) with an elliptic orbit. This initial vertex always remains one of the vertices of the captured orbit by the Solar System. Even if there is a discontinuity of all the orbital elements during a very short time of the capture, I assume that the orbital plane is unchanged during the capture, as indeed was the case for Brooks 2 in 1886 (see Belyaev et al., 1986) or will be for Gehrels 3 in 2300 (see Carusi et al., 1985). After this first decisive step, the “new” comets may be subject to some other captures by jovian planets during their evolution with the same scenario. All these hypotheses allow to find particular numerical results for 142 comets whose current orbital elements were found in the Marsden catalog or given by P. Rocher, but I shall only give several examples in the following section.
Angular velocity of rotation of extended bodies in general relativity
Authors: Klioner S.A.
Published: July 2016

We consider rotational motion of an arbitrarily composed and shaped, deformable weakly self-gravitating body being a member of a system of N arbitrarily composed and shaped, deformable weakly self-gravitating bodies in the post-Newtonian approximation of general relativity. Considering importance of the notion of angular velocity of the body (Earth, pulsar) for adequate modelling of modern astronomical observations, we are aimed at introducing a post-Newtonian-accurate definition of angular velocity. Not attempting to introduce a relativistic notion of rigid body (which is well known to be ill-defined even at the first post-Newtonian approximation) we consider bodies to be deformable and introduce the post-Newtonian generalizations of the Tisserand axes and the principal axes of inertia.
On the orbital motion description with a proper reference frame in a complete Schwarzschild field
Authors: Gambi J.M. , Zamorano P. , Romero P. , Del Pino M.L. Garcia
Published: July 2016

It is a fact that, none of the diverse coordinate systems unified in the Post-Newtonian formalism used to describe the exterior Schwarzschild field can be regarded as being materialized by a reference frame. Only the polar Gaussian coordinates (ρ, ϑ, ϕ, t), or their naturally associated Fermi coordinates, can be shown to have this property (Synge, 1960).
Production d'éléments orbitaux de comètes sur PC
Authors: Rocher P. , Cavelier C.
Published: July 2016

La puissance de calcul des ordinateurs PC actuels permet leur utilisation pour des travaux qui étaient, jusqu'à ces dernières années, effectués exclusivement sur de gros ordinateurs. Le mode interactif utilisé pour la gestion et la saisie des données, facilement mis en œuvre sur les PC, permet un gain de temps important par rapport au travail classique en traitement par lot (batch). Nous présentons ici un logiciel PC, permettant le calcul et l'amélioration des éléments orbitaux des comètes. Une bonne connaissance de ces éléments est indispensable pour le calcul des éphémérides, notamment pour la redécouverte des comètes périodiques.
CCD astrometry oriented analysis of digitized multiple images (planets, satellites, etc.) obtained with the Pulkovo PVC
Authors: Goncharov George A.
Published: July 2016

The Charge Coupled Device (CCD) has become the detector of choice in astrometry. The mechanical or electronic (drift scanning) tracking of objects by the telescope leads among observing strategies developed for CCD observations (Stone and Dahn, 1995).
Solar system objects observed by Hipparcos
Authors: Hestroffer D. , Morando B.
Published: July 2016

The ESA satellite Hipparcos provides valuable photometric and astrometric results on minor planets and natural satellites. Observations of 48 asteroids, JII-Europa, S VI-Titan and S VIII-Iapetus were made from November 1989 to March 1993. A twenty seconds averaged normal place is constructed, providing thus positions accurate to a few hundredths of arcseconds and relative to a very precise and homogeneous reference frame.
Corrected GSC: Reference catalogue for CCD observations. Now
Authors: Garcia A. Lopez , Yagudin L.I.
Published: July 2016

Astrometrical properties of the Hubble Space Telescope Guide Star Catalogue (GSC) were recently investigated by the same authors through its comparison with the PPM catalogue. In this paper, a new systematic plate-based magnitude dependent error produced by telescope optics and by the incompleteness of plate reduction model has been found after applying a simplified block adjustment procedure. New subroutine for correction of all systematic errors is developed and GSC can be used now as a dense reference catalogue on about 0.4″ accuracy level.
Application of GSC catalogue to minor planets plate reduction
Authors: Garcia A. Lopez , Yagudin L.I. , Martinez M.J.
Published: July 2016

An automatic reduction process is applied to observations of minor planets obtained at Valencia Observatory, using PPM and GSC catalogues. Systematic corrections of GSC, obtained by the same authors in a previous study, are also considered. The comparison of results is done by the statistical analysis of several parameters. Preliminary conclusions about the improvement obtained using corrected GSC are included.
Selection Effects and Biases
Authors: Disney M.
Published: July 2016

A respected astronomer recently suggested, because the whole spectrum has been explored, that the heroic days of astronomy are now over. I will try, by referring to the narrow optical and 21-cm windows with which I am familiar, to argue that the he was quite wrong. We still haven't covered the whole spectrum, and in any case prejudices, biases and selection effects could still veil much of the truth from sight.
Electronic Optical Sky Surveys
Authors: McKay T.A.
Published: July 2016

The introduction of of Charge Coupled Devices (CCDs) in the middle 1970s provided astronomy with nearly perfect (linear, high-sensitivity, low-noise, high dynamic-range, digital) optical detectors. Unfortunately, restrictions imposed by CCD production and cost has typically limited their use to observations of relatively small fields. Recently a combination of technical advances have made practical the application of CCDs to survey science. CCD mosaic cameras, which help overcome the size restrictions imposed by CCD manufacture, allow electronic access to a larger fraction of the available focal plane. Multi-fiber spectrographs, which couple the low-noise, high QE performance of CCDs with the ability to observe spectra for many objects at once, have improved the spectroscopic efficiency of telescopes by factors approaching half a million. An improved understanding of image distortion gives us telescopes on which we expect sub-arcsecond images a large fraction of the time. Finally, and perhaps most important, the performance of computer hardware continues to advance, to the point where analysis of multi-terabyte datasets, while still daunting, is at least conceivable.
Wide Field Optical Imaging at CTIO
Authors: Walker A. R.
Published: July 2016

The CTIO 4-m and 0.6/0.9-m Schmidt telescopes provide a wide-field CCD imaging capability unequalled in the southern hemisphere. Characteristics of present and future CCD imaging systems for these telescopes are discussed.
The AAT's 2-Degree Field Project
Authors: Taylor K. , Cannon R.D. , Parker Q.A.
Published: July 2016

The “Two-degree Field” (2dF) project at the Anglo-Australian Observatory (AAO) gives the 3.9m Anglo-Australian Telescope (AAT) a field of view two degrees in diameter at the prime focus, equipped with 400 optical fibres for multi-object spectroscopy. The basic components of 2dF are the corrector lens optics, the robot which positions the fibres and a pair of spectrographs. All these are mounted on a new ‘top end ring’ so that the whole assembly can be easily put on and off the telescope. Here we will give an update on the status of 2dF, highlighting features which have changed or been developed since earlier reports.
The Marseille Observatory Hα Survey: Comparisons by CO, 6 CM and IRAS Data
Authors: Russeil D. , Amram P. , Georgelin Y.P. , Georgelin Y.M. , Marcelin M. , Viale A. , Le Coarer E. , Castets A.
Published: July 2016

The Marseille Observatory Hα survey supplies Hα velocities of the ionized hydrogen over large zones of the sky towards the galactic plane. This survey, led at the ESO La Silla, uses a 36 cm telescope equiped with a scanning Fabry-Perot interferometer and a photon counting camera (Le Coarer et al. 1992). About 250 fields (39′×39′) toward the galactic plane have already been covered (see Figure 1) with a spatial resolution of 9″×9″ and a spectral resolution of 5 km s–1. This allows us to observe the discrete HII regions and the diffuse ionized gas widely distributed between them and to separate the distinct layers found along the line of sight. HII regions are often grouped on the molecular cloud surface, then CO, radio continuum and recombination lines surveys of the galactic plane are also essential to distinguish the HII region-molecular cloud complexes met on the line of sight, and in order to take dynamical effects into account, such as the champagne effect, for the kinematic distance determination. Indeed, the spiral structure pattern determination requires avoiding any artificial spread by clearly identifying the giant complexes composed of molecular clouds, HII regions, diffuse ionized hydrogen widely surrounding them, and exciting stars. On the other hand the ionized gas data (Hα and recombination lines) associated with IRAS data help us to study the nature of the young objects constituent of these complexes and to assess their detectability. We present two fields from the Hα survey and parallel large scale investigations.
Survey of Correlated FIR, HI, CO, and Radio-Continuum Emission Features in the Multi-Phase Milky Way
Authors: Wall W.F. , Waller W.H.
Published: July 2016

The interstellar medium (ISM) is rich with structure on varying size scales, reflecting its diverse energetics and dynamics. A step toward understanding this structure is to enhance the visibility of the structure on finer size scales. We present maps of a section of the Galactic plane filtered with the Median Normalized Spatial Filter (MNSF, a median smoothed map is divided into the original map), which emphasizes higher latitude emission relative to that of the plane itself (see also Waller et al., this volume, p. 194). The maps also illustrate the spatial correlations between the interstellar dust and the various gas phases: ionized, atomic, and molecular. The dust is represented by the IR emission maps of the IRAS survey, the ionized gas by the radio continuum maps at 1.4 GHz (Reich 1978, northern sky) and 2.3 GHz (Jonas & Baart 1995, southern sky), the atomic gas by surveys of the HI 21 cm line emission (Heiles & Habing 1974, Weaver & Williams 1973, Cleary et al. 1979, Kerr et al. 1986), and the molecular gas by surveys of the CO J = 1 → 0 line emission (Dame et al. 1987).
Using Multi-Wavelength All Sky Information to Understand Large Scale Galactic Structure
Authors: Smart R.L. , Drimmel R. , Lattanzi M.G.
Published: July 2016

Our galaxy was first seen to be warped, similarly to other galaxies, in 21cm HI surveys (Kerr 1957). Since then a large database on our and other warps has been built but they remain a puzzle for theorists trying to construct a general warp theory. Warps are observed to be common rather than rare features of spiral galaxies, which implies they are long lived. They are observed in both isolated and multiple galaxy systems in the gas but the stellar warp is often difficult to detect. The galactic warp is always below b=10° making it difficult to observe because of absorption and confusion, to add to this problem the sun appears to lie near to the line of nodes and to view the warp at it's largest extent we must observe through a large part of the disk. A theoretical model must evoke driving forces that explain the longevity, commonality, and independence of environment that we see in warps.
Galactic Structure with GSC-II Material
Authors: Spagna A. , Lattanzi M.G. , Massone G. , McLean B.J. , Lasker B.M.
Published: July 2016

Faint surveys of accurate colors and proper motions are fundamental for studying the physical and kinematical properties of the stellar populations in the Galaxy. A program designed to address such issues has been initiated on selected fields utilizing prototype material from the GSC-II project (see McLean et al. in this volume, p. 431). Photographic photometry V, B–V, V–Rc, is derived down to V = 18.5 with a precision of about 0.1 mag, together with absolute proper motions to σμ ≃ 3 mas/yr.
The Radio Properties of X-Ray Selected Extragalactic Objects
Authors: RamíRez-Castro L. , Pérez-Fournon I. , Cabrera-Guerra F.
Published: July 2016

We have used the 1st revision of the WGACAT catalogue, generated from all ROSAT PSPC pointed observations from February 1991 to March 1994, available at the HEASARC public archive. This catalogue, described by White et al. (1994), contains 68,907 detections, with more than 62,000 individual sources.
QSO Color Selection in the SDSS
Authors: Newberg H. J. , Yanny B.
Published: July 2016

The Sloan Digital Sky Survey (SDSS) will image 10,000 square degrees in the north galactic cap in five filters. We hope to identify and obtain spectra for about 100,000 quasars brighter than 20th magnitude in this area. The selection will be primarily on the basis of point spread function and colors, but we will also identify quasars from a catalog of FIRST radio sources. The selection areas in color space must be determined during the testing period prior to the official start of the survey. This task may determine the length of the test period. In anticipation of this becoming the critical path, we have written a body of software that will allow us to quickly analyze a set of multicolor data and make a first cut at the selection limits.
The Calar Alto Deep Imaging Survey: First Results
Authors: Thommes E. , Meisenheimer K. , Fockenbrock R. , Hippelein H. , Röser H.-J.
Published: July 2016

The Calar Alto Deep Imaging Survey (CADIS) is a very deep emission line survey using a Fabry-Pérot (FP), combined with deep broad- and medium-band photometry (for an overview see Hippelein et al. 1996). This survey is specifically designed to detect primeval galaxies, but it will in addition produce a large data base for investigations of faint galaxies at intermediate redshifts (0.2 < z < 1.2). We present some first results from the initial data recorded with the CADIS strategy.
The Warps Blazar Survey Searching for the Faintest X-Ray Selected Blazars
Authors: Perlman E.S. , Padovani P. , Jones L. , Giommi P. , Tzioumis A. , Reynolds J. , Sambruna R.
Published: July 2016

The WARPS (Wide-Angle ROSAT Pointed Survey) blazar survey is a deep X-ray search for BL Lac objects and flat-radio-spectrum quasars (FRSQs), drawn from a cross-correlation of serendipitous sources in the ROSAT PSPC database WGACAT (White et al. 1994) with the Green Bank 6 cm and 20 cm (Condon et al. 1989, Condon & Broderick 1985), the Parkes radio (Bolton et al. 1979), and the Parkes-MIT-NRAO (Griffith & Wright 1993, Wright et al. 1994, Griffith et al. 1994, 1995) catalogs. Our sample contains 165 new blazar candidates and 95 previously known blazars.
Large Scale Structure of the Universe
Authors: Bahcall N.A.
Published: July 2016

How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions of a rather smooth early universe to the present time? The answers to these questions will shed light on the cosmology we live in, the amount, composition and distribution of matter in the universe, the initial spectrum of density fluctuations that gave rise to this structure, and the formation and evolution of galaxies, lusters of galaxies, and larger scale structures.

To address these fundamental questions, large and accurate sky surveys are needed—in various wavelengths and to various depths. In this presentation I review current observational studies of large scale structure, present the constraints these observations place on cosmological models and on the amount of dark matter in the universe, and highlight some of the main unsolved problems in the field of large-scale structure that could be solved over the next decade with the aid of current and future surveys. I briefly discuss some of these surveys, including the Sloan Digital Sky Survey that will provide a complete imaging and spectroscopic survey of the high-latitude northern sky, with redshifts for the brightest ∼ 106 galaxies, 105 quasars, and 103.5 rich clusters of galaxies. The potentialities of the SDSS survey, as well as of cross-wavelength surveys, for resolving some of the unsolved problems in large-scale structure and cosmology are discussed.
Digital Colour Mapping of the Sky from Supercosmos
Authors: MacGillivray H.T.
Published: July 2016

The major photographic surveys of the sky (undertaken with the ESO, Palomar and UK Schmidt telescopes) still hold enormous potential regarding the information content of the original plate material. The problem to date has been to extract that information in a meaningful and quantitative way, hence giving rise to the large number of digitisation programmes currently underway and which are reported elsewhere in this volume.
Progress in Wide Field CCD Astrometry
Authors: Zacharias N.
Published: July 2016

Instrumental parameters and astrometric results from five telescopes are summarized in Table 1. The KPNO 0.9m has field-corrector optics. The CTIO 0.9m is a classical Cassegrain. The 4-meter telescopes both have doublet field-correctors. The USNO 0.2m (8-inch) astrograph has a 5-element lens which is designed for a 9° flat field of view for photographic plates. A bandpass of 570-650 nm is used at the USNO 0.2m while most frames with the other telescopes have been taken through a Gunn r (600-710 nm) filter. Stellar images on the CCD frames have been fitted with a 2-D circular symmetric Gaussian profile, giving the centroiding error σfit. Plots of σfit vs. instrumental magnitude look similar in shape for all telesopes. The asymptotic fit precision, σafp, is the limit in σfit achieved for bright stars, given in milli pixels (mpx) in Table 1. This centering error is overestimated by an amount depending on the deviation of the real image profile from the model function (Winter 1997).
The Astrographic Catalogue
Authors: Jones D.H.P.
Published: July 2016

The most reliable method of cross-wavelength identification is the coincidence of accurately determined positions, both referred to the same reference frame. But objects move with time and the more accurate their positions, the more important their proper motions are.
Completion of the Sternberg Astronomical Institute Astrographic Catalogue Project
Authors: Nesterov V. , Gulyaev A. , Kuimov K. , Kuzmin A. , Sementsov V. , Bastian U. , Röser S.
Published: July 2016

The first astronomical photographic survey, the Carte du Ciél was initiated in 1887 by a group of French astronomers. The observational campaign was started in 1891, while the last of more than 22,000 total plates were photographed in 1950; most of observations (more than 90%) were performed prior to 1920. Detailed description of the Carte du Ciél development can be found elsewhere (Kolchinsky 1989, Eichhorn 1974, Debarbat et al. 1987).
Identification of a Complete Sample of Northern Rosat All-Sky Survey X-Ray Sources
Authors: Krautter J. , Thiering I. , Zickgraf F.-J , Appenzeller I. , Kneer R. , Voges W. , Serrano A. , Mujica R.
Published: July 2016

We present results of the optical identification of a spatially complete, flux limited sample of about 700 ROSAT All-Sky X-ray sources contained in 6 study areas north of δ = −9° with |bII|> 20° (including one region near the North Galactic pole (NGP), another one near the North Ecliptic pole (NEP)). Countrate limits are 0.01 cts s–1 near the NEP and 0.03 cts s–1 for the other areas. The optical observations were performed at the 2.15-m telescope of the Guillermo Haro Observatory, Mexico, using the Landessterwarte Faint Object Spectrograph Camera which allows to carry out direct CCD imaging and multi-object spectroscopy. The limiting magnitude is about 19m for spectroscopy and about 23m for B and R direct imaging. Our analysis shows a dependency of the ratio of ‘extragalactic’ (e.g., AGN, cluster of galaxies) to ‘stellar’ (e.g., coronal emitters, active binaries) counterparts on NH. In the area near the NGP (low NH) ‘extragalactic’ counterparts dominate, while in the area with the highest NH ‘stellar’ counterparts dominate.
The Wide-Field Plate Database: A New Tool in Observational Astronomy
Authors: Tsvetkov M.K. , Stavrev K.Y. , Tsvetkova K.P. , Semkov E.H. , Mutafov A.S. , Michailov M.-E.
Published: July 2016

Since the first applications of wide-field photography in astronomy nearly 2 million plates and films have been obtained and stored in archives all over the world. The Wide-Field Plate Database (WFPDB) provides astronomers with detailed information about the wide-field photographic observations. Its preparation started in 1991 as one of the main projects initiated by the Working Group on Wide Field Imaging at the IAU Commission 9.
A WWW Database of APS Poss Images
Authors: Cornuelle C.S. , Aldering G. , Sourov A. , Humphreys R.M. , Larsen J.A. , Cabanela J.
Published: July 2016

We have used the Automated Plate Scanner (APS) at the University of Minnesota to digitize glass copies of the blue and red plates of the original Palomar Observatory Sky Survey (POSS I) with |b| > 20°. The APS Image Database is a database of all digitized images larger than the photographic noise threshold. It includes all of the matched images in the object catalog, as well as those unmatched images above the noise threshold. The matched image data of the catalog has the advantage of confirming the reality of the image. This is especially important for small images near the plate limit. But these are not all of the detected real images; very blue or very red faint objects may be excluded by this matching requirement. The image database allows information on them to be retrieved, and is therefore a valuable complement to the object catalog. The operation of the APS and the scanning procedures are described in detail in Pennington et al. (1993). We are now processing plate data into the image database. A set of query forms, a tutorial and documentation can be found at http://isis.spa.umn.edu/IDB/homepage.idb.html.
The GSC-I and GSC-II Databases: An Object-Oriented Approach
Authors: Greene G. , McLean B. , Lasker B. , Wolfe D. , Morbidelli R. , Volpicelli A.
Published: July 2016

The original GSC-I (Jenkner et al. 1990) which contains 25 million entries and requires approximately 1GB of storage was at the edge of technological capability at the time catalogue construction began in 1984. At that time, a custom coded database was built since the relational databases of the era were unsuited to the HST-specific access requirements. A second generation GSC is now being constructed (Lasker et al. 1995), with an estimated 10 billion entries and a size of 2 Terabytes. The current generation of object-oriented database (OODB) systems are more suited to the needs of large astronomical catalogues and are being adopted by many large-scale projects. In a joint effort between the Space Telescope Science Institute and Osservatorio Astronomico di Torino, we are currently designing such an OODB for the Guide Star Catalogues and are implementing a prototype using the GSC-I data.
The Nature and Significance of Surveys
Authors: Trimble V.
Published: July 2016

We present here some of the ideas and questions mentioned by the panelists and other participants during the discussion that immediately preceded Ofer Lahav's concluding remarks. Official panelists were George Djorgovski, Michael Disney, Ofer Lahav, and Virginia Trimble (chair). The topics of the posters are very briefly summarized as well.
Early days of Planetary Nebular theory
Authors: Aller Lawrence H.
Published: July 2016

The spectra of gaseous nebulae differed strikingly from those of stars which were well understood since 1922 thanks to the work of Saha. Gaseous nebulae exhibited exotic bright line spectra characterized by strange emissions of unknown origin as well as familiar lines of hydrogen and helium. The strongest lines in most nebulae fell at 4959A and 5007A. They were originally attributed to an unknown element. First came the interpretation of the lines of H.
Basic data
Authors: Acker A.
Published: July 2016

Basic data on planetary nebulae concern all the fields related to these objects. As an illustration of the increasing importance of planetary nebulae in large fields of contemporary science, let me note that, in a communication for a conference on “bibliometrics, informetrics and scientometrics”, Bassecoulard and Zitt (1994) chose planetary nebulae as the best example of a complicated network allowing and needing interesting cluster analysis.
Quantitative classification of [WC] nuclei of Planetary Nebulae
Authors: Acker A. , Parthasarathy M. , Leindecker W. , Koeppen J. , Stenholm B.
Published: July 2016

We have carried out spectral classification of 65 [WC] stars, using spectra obtained at ESO in 1994-1995 with a spectral resolution of 1500 and high signal to noise ratio. We quantify the visual classification, by using the line ratios of CIII, CIV, OV, OVI in the 530-580 nm range, correlated with the blue CIII - IV lines. We measured the total strength of the above emission lines and derived the ratios of the emission line strengths. Using the stellar emission line ratios we classified about 32 CSPN as [WC] and about 30 as WELS which show only relatively weak CIV 5806 and CIV 4650 and He II 4686 stellar emission lines. The presence of CIV 5806 and the absence of CIII 5696 the WELS appear to belong to the [WC3] type. However the OV lines are very weak or absent. Some stars are reclassified, and 4 stars are found in the [WC5-7] gap. We classified 34 CSPN as [WC]. The [WC2] CSPN NGC 2867 and PB 6 show narrow and weak He II 5412 absorption feature. Based on the relative strengths of the stellar emission features NGC 2867 [WC 2], PB 6 [WC2] and M1-61 [WC4] appear to be related to WELS (Weak Emission Line Central Stars of Planetary Nebulae). The observed spectral characteristics of the central stars of these PN suggest that they are related to [WC] - PG 1159 type of objects.
Winds in the atmospheres of central stars of Planetary Nebulae
Authors: Kudritzki R. P. , Mendez R. H. , Puls J. , McCarthy J. K.
Published: July 2016

For this review we have chosen to concentrate on recent progress concerning the model atmosphere analysis of stellar winds in central stars of planetary nebulae (CSPNs). Since there is another review in these proceedings (by W.R. Hamann) devoted specifically to Wolf-Rayet type CSPNs, we will not consider them here. The reader interested in recent work on windless model atmospheres applied to CSPNs is referred to reviews by Napiwotzki (1995) and Werner et al. (1996). There is also an interesting paper by Werner (1996) on the Balmer line problem.
Spectra of Wolf-Rayet type central stars and their analysis
Authors: Hamann W.-R
Published: July 2016

Wolf-Rayet (short: WR) stars are characterized by the bright and broad emission lines which dominate their spectra. This class was originally established for Pop. I stars, distinguishing a nitrogen (WN) and carbon (WC) sequence according to the dominating lines. Wolf-Rayet (specifically, WC) type spectra are also shown by a considerable fraction of central stars of planetary nebulae.
Analysis of hydrogen rich PG 1159 central stars of Planetary Nebulae
Authors: Dreizler S. , Werner K. , Heber U.
Published: July 2016

The PG 1159 stars represent the hottest stage of post-AGB evolution. Quantitative spectral analyses of most known PG 1159 stars have been carried out by us from optical, UV and EUV observations (see Dreizler et al 1995 for a review). It has been shown that these stars have atmospheres dominated by C and He with a significant admixture of O. These abundances reveal the inter–shell matter of a former AGB star. The four stars, HS 2324+3944, NGC 7094, Abell 43, and Sh 2-68, define a small group of peculiar PG 1159 stars (termed hybrid PG 1159). Unlike all other PG 1159 stars hydrogen is detected in their spectra. Three of them are CSPNe. Our Non-LTE analyses (Dreizler et al 1995; Dreizler et al 1996) show that these stars have typical PG 1159 Teff, log g as well as C and He abundances (Table 1). In contrast, the O abundance is lower than in PG 1159 stars. N is probably present but near the detection limit of the currently available spectra. Hybrid PG 1159 stars tend to have lower masses/luminosities than ordinary PG 1159 stars. A reduced mass-loss in their post-AGB evolution might be responsible for the incomplete removal of the H rich envelope. However, peeling of a post-AGB star alone can not produce the observed abundance pattern. In addition, mixing is required. A first evolution calculation with time dependent mixing of Iben & MacDonald (1995) shows some qualitative agreement in the abundance pattern like the C/He ratio it is, however, not able to explain the overall abundances.
Spectral analyses of late–type [WC] central stars: element abundances of N, Ne and Si
Authors: Leuenhagen U.
Published: July 2016

The optical spectra of [WC] central stars of the latest subtypes ([WC11], [WC12]) exhibit not only stellar emission lines of hydrogen (in some cases), helium, carbon and oxygen, but also features of nitrogen (N ii, N iii), neon (Ne i), magnesium (Mg ii), aluminium (Al iii), silicon (Si iii, Si iv) and iron (Fe iii). Some of these features are also visible in the peculiar [WC9]–type object SwSt 1 which has a lower final wind velocity and a smaller wind density than normal [WC9] stars.
The discovery of heavy elements (Z > 30) in NGC 7027
Authors: Péquignot D. , Baluteau J.-P.
Published: July 2016

An important aim of nebular spectroscopy is the identification of new elements. Since the pioneering work of Bowen (1928), who identified the “nebulium” lines with forbidden lines of abundant elements, most elements in nebulae have been discovered thanks to forbidden lines. The number of elements known in planetary nebulae and H II regions was 2, 5, 15, 17, and 20 in 1896, 1927, 1938, 1960, and 1975 respectively.
The discovery of Raman lines in NGC 7027
Authors: Péquignot D. , Baluteau J.-P. , Boisson C. , Morisset C.
Published: July 2016

Broad emission lines λλ 682.5, 708.2 nm, observed for years in the spectrum of symbiotic stars, have been identified by Schmid (1989) as due to Raman scattering of O VI 103.2, 103.6 nm by H0. In one symbiotic star, van Groningen (1993) detected Raman scattered He II.
ISO results on AGB and post-AGB objects
Authors: Cox P.
Published: July 2016

We present results obtained on well-known AGB and post-AGB sources with the Long Wavelength Spectrometer (LWS) and ISOCAM on board the Infrared Space Observatory (ISO). The main findings of these studies are briefly summarized.
Atomic data for PN analysis
Authors: Storey P.J.
Published: July 2016

This paper will review a selection of the work that has been published on the calculation of atomic parameters, relevant to PN, in the period since the 1992 Symposium. It will also attempt to address the accuracy of theoretical results, where possible. The review will concentrate primarily on results obtained using the powerful electron-scattering codes that describe resonance phenomena with ever increasing precision. Calculations of oscillator strengths and photoionisation cross-sections will not be discussed.
Deep optical spectroscopy and modelling of Planetary Nebulae
Authors: Pequignot D.
Published: July 2016

Shall we leave this millennium with a template spectrum for PNe based on photographic plates taken nearly half a century ago? Is photoionization being demolished by shock waves in PNe? Is icf getting on well with t2?
Global analysis of a southern Planetary Nebulae sample
Authors: Costa R.D.D. , de Freitas Pacheco J.A.
Published: July 2016

In this work we present a summary of the results of a long term observational program aimed to derive physical parameters and chemical abundances of southern PNe developed in the last years at the University of São Paulo, Brazil. Results shown here were derived from 74 nebulae, all of them observed (at least twice) with the 1.60m telescope at the Pico dos Dias Observatory, Brazil, using a Cassegrain spectrograph, a 300 lines/mm (4.4 å/pixel) grating, and UV-coated CCD detectors. Observational runs took place between 1988 and 1995. Data reduction followed the standard procedure of bias and flat-field corrections, extraction of the spectrum, wavelength calibration, and flux calibration through spectrophotometric standard stars observed each night. The table below summarizes our results. Nebulae were classified among the Peimbert types and mean abundances are shown for each type, using the notation ∊(X)=log(X/H)+12.
Stark broadened line profiles of neutral strontium lines in plasma conditions
Authors: Dimitrijević Milan S. , Sahal-Bréchot Sylvie
Published: July 2016

During more than twenty years, we are making a continuous effort to provide Stark-broadening parameters needed for research of astrophysical, laboratory and laser produced plasma. A review of our results is presented in Dimitrijević, 1996). Such data are of interest for the consideration of a number of problems in astrophysics, physics and technology as e.g. for stellar plasma diagnostic, opacity calculations, the investigation/modelling of stellar spectra or a particular line, laboratory plasma diagnostic, laser produced plasmas, thermonuclear research, plasma technology, as well as for different examinations of regularities and systematic trends for e.g. homologous atoms (Dimitrijević and Popović, 1989) or in general (Purić et al. 1991).
A new code for comprehensive self-consistent modelling of Planetary Nebula luminescence
Authors: Golovaty V. V. , Malkov Yu.F. , Rokach O. V.
Published: July 2016

A new code PAN (Photoionized Axially-symmetrical Nebula) for the self-consistent modelling of a cylindrical gaseous nebula photoionized by a central source of ionizing radiation is developed. All of the processes which play an important role in the ionization and thermal equilibrium of the nebular gas are included in the code.
Far-infrared spectroscopy of Planetary Nebulae with the KAO
Authors: Rubin R. H. , Colgan S.W.J. , Haas M.R. , Lord S. D. , Simpson J. P.
Published: July 2016

We present new far-infrared line observations of the planetary nebulae (PNs) NGC 7027, NGC 7009, NGC 6210, NGC 6543, and IC 4997 obtained with the Kuiper Airborne Observatory (KAO). The bulk of our data are for NGC 7027 and NGC 7009, including [Ne V] 24 μm, [O IV] 26 μm, [O III] (52, 88μm), and [Nm] 57 μm. Our data for [O III] (52, 88) and [N III] 57 in NGC 7027 represent the first measurements of these lines in this source. The large [O III] 52/88 flux ratio implies an electron density (cm–3) of log Ne[O III] = 4.19, the largest Ne ever inferred from these lines. We derive N++/O++ = 0.394±0.062 for NGC 7027 and 0.179±0.043 for NGC 6210. We are able to infer the O+3/O++ ionic ratio from our data. As gauged by this ionic ratio, NGC 7027 is substantially higher ionization than is NGC 7009 – consistent with our observation that the former produces copious [Ne V] emission while the latter does not. These data help characterize the stellar ionizing radiation field.
Proto-Planetary Nebulae
Authors: Hrivnak Bruce J.
Published: July 2016

We review the properties of proto-planetary nebulae, highlighting the advances in our quantitative knowledge of these objects. The discussion focuses on the chemistry and morphology of their circumstellar envelopes and the chemistry and variability of their central stars.
Multiple shell Planetary Nebulae: Evolutionary paths and observed configurations
Authors: Stanghellini Letizia
Published: July 2016

Recent observations of multiple shell planetary nebulae confirm the existing subdivision into two morphological types: attached halo and detached halo. The multiple shell phenomenon appears in about twenty-five percent of round and elliptical planetary nebulae of the Instituto de Astrofisica de Canarias morphological survey. The analysis of these nebulae together with that of their central stars lead to the interpretation that detached halo nebulae are formed through discontinuous mass loss at the Asymptotic Giant Branch tip. The attached halo nebulae, instead, are probably produced via dynamical nebular shaping.
The morphology of dust emission in Planetary Nebulae and proto-Planetary Nebulae
Authors: Meixner M.
Published: July 2016

This review covers recent results from ground based mid-infrared (mid–IR; 8–25μm) imaging of thermal dust emission. The mid–IR images of proto–PNe show evidence for axially symmetric superwinds. In young PNe, the dust appears to be well mixed with the gas in the ionized gas regions. In carbon rich PNe and proto–PNe, the 11.3μm feature attributed to PAHs appears more spatially extended than “continuum” dust emission and the near–IR (1-3μm) excess appears spatially coincident with mid–IR dust emission. This review is not meant to cover the broader topic of dust in PNe and proto-PNe and we refer the reader to (Barlow 1993) for the most recent broad review.
Near-IR imaging and optical Spectroscopy of M 2-9
Authors: Arrieta A. , Torres-Peimbert S.
Published: July 2016

IR OBSERVATIONS. We have extended previous infrared imaging studies (cf. Hora & Latter 1994 ApJ 437, 281; Kastner et al. 1996 ApJ 462, 777) through wide and narrow band filters.

In these images: (a) JHK′ morphology is similar to the optical structure. The knots are brighter at the shorter wavelengths, while the core is brighter at K′. (b) [He I] 1.083 μm that traces the highly ionized region, is concentrated along the axial region and extends throughout the lobes (33″ × 9″). It shows the knots very prominently. (c) [Fe II] 1.644 μm, that traces the shock excited regions, extends []throughout the lobes; it is more prominent in the northern knot and it is very strong in the core. (d) The excited molecular H2 lines are concentrated on a wide ‘torus’ in the equatorial plane. This geometry is similar to that exhibited by most bipolar planetary nebulae where H2 has been detected (e.g., Kastner et al. 1996). No H2 emission is seen in the core. (e) Paγ shows emission in only in the core and the northern knot. (f) Brγ shows emission in the core and in knots N2, S2 and S3. (g) No significant emission in CO was obtained.
Mid-infrared imaging of dust shells around young Planetary and Proto-Planetary Nebulae
Authors: Dayal A. , Hoffmann W. F. , Bieging J. H. , Hora J. L. , Deutsch L. K. , Fazio G. G. , Meixner M. , Skinner C. J.
Published: July 2016

The results presented here are from an ongoing mid-infrared imaging study of PPNe and PNe, using MIRAC2 the UA/SAO mid-IR camera. Our 8-21 μm observations have a spatial resolution of about 0.7″ to 1.5″, and a pixel scale of 0.25″/pixel (at UKIRT) or 0.34″/pixel (at IRTF). The high S/N and good spatial sampling in our images of IRAS 22272+5435 and IRAS 07134+1005 allow us to construct temperature and optical depth maps. Using our 11.7μm and 20.6μm images we also construct maps which isolate the 11.3μm (UIR) and 21μm emission features (Justannont et al. 1995). As a second part of this project, we are modelling the dust emission from PPNe and young PNe, using a axisymmetrical radiative transfer code.
Light and velocity variability in Proto-Planetary Nebulae
Authors: Hrivnak Bruce J. , Lu Wenxian
Published: July 2016

We have been carrying out a program of monitoring light and velocity variability in proto-planetary nebulae (PPN). Variability might arise due to binarity or pulsation. Many planetary nebulae display a bipolar shape, and it is suggested that this is caused by binarity. This can be investigated in PPN, particularly by radial velocity studies of those of spectral types F and G. Pulsation is known to exist in other types of post-AGB stars, and can be a means to learn more about the physical properties of the stars. No previous study of a sample of PPN has been published.
Multiharmonic analysis of Mira-type stars
Authors: Kudashkina L. S. , Andronov I. L.
Published: July 2016

The shapes of light curves of Mira-type variable stars are analyzed by using the multi–harmonic fit (Andronov 1994). The light curves of 63 stars best covered by the AAVSO observations and published by Mattei (1978) were used. Some correlations between the characteristics of the mean light curves were found.