bluuebunny/crossref_metadata_2025 huggingface dataset:
Three campaigns of solar observations with an astrolabe at Simeiz
Authors: Kolesnik Yu. B.
Published: July 2016

Positional observations of the Sun have become, in recent years, one of the most important contribution of astrolabes to fundamental astrometry. After pioneer observations at CERGA and Sao Paulo, both in 1974, other astrolabes have been adapted for observations of the Sun in Paris (now at Malatya, Turkey), Santiago de Chile (Chollet & Noël 1993) and San-Fernando (Sánchez et al. 1993, 1995). First experimental campaign of solar observations with an astrolabe installed at Simeiz Observatory (Crimea, Ukraine) has been undertaken in 1986 (Kolesnik 1987). After some instrumental improvements, observations covering about 2.5–3 months were continued in 1987, 1990, 1991. The results are reported here.
Ultraviolet Sky Surveys
Authors: Brosch N.
Published: July 2016

Among all spectral bands, the ultraviolet has long been neglected, despite the advantage of small space experiments: the sky is very dark, thus detection of faint objects does not compete against an enhanced background (O'Connell 1987) and the telescope construction techniques are very similar (at least longward of ∼50 nm) to those of optical astronomy.
Gamma Ray Sky Surveys
Authors: Gehrels N.
Published: July 2016

Prior to the current Compton Gamma Ray Observatory (Compton) mission, no comprehensive all-sky gamma-ray surveys had been performed. There were, however, some surveys performed over limited energy bands and/or over portions of the sky. These include the HEAO-A4 hard X-ray survey and the COS-B and SAS-2 high-energy gamma-ray surveys. The early work forms a basis for understanding and appreciating the Compton results, and so is reviewed in Section 2.
Wide-Field Low-Frequency Imaging with the VLA
Authors: Kassim N.E. , Briggs D.S. , Foster R.S.
Published: July 2016

The 330 MHz observing system at the VLA is a potentially powerful survey system. It can map fields many degrees in size quickly and at high sensitivity. However imaging characteristics unique to this data pose excessive computational burdens on conventional mapping systems. Hence while data acquisition is quick and efficient, data reduction has been difficult and slow. Here we describe how powerful new scalable processing algorithms have been used to generate the first full resolution 330 MHz images, demonstrating also that lower resolution survey work is now a tractable problem.
Kilometer-Square Area Radio Synthesis Telescope Karst Project
Authors: Peng B. , Nan R.
Published: July 2016

One way to realize the Large radio Telescope with a collecting area approaching one square kilometer, continuously covering a frequency range between 200 MHz and 2 GHz, is to construct a passive spherical reflector array of about 30 individual unit telescopes, each ∼ 300 m diameter(Butcher 1995). Valleys amid the hills of southwest China would be ideal for such LT concept. We refer to this effort as the Kilometer-square Area Radio Synthesis Telescope project. Site surveying and Radio Interference monitoring looks promising. Engineering considerations are summarized.
Radio Continuum Surveys above 2 GHz
Authors: Jonas J.L.
Published: July 2016

The Rhodes/HartRAO 2326 MHz radio continuum survey was observed at HartRAO over a 13 year period (Jonas et al. 1985, Mountfort et al. 1987, Jonas & Baart 1995, Jonas et al. 1996). This is the highest frequency and highest angular resolution (HPBW=20′) all-sky radio continuum survey made using a ground-based telescope. The 1σ noise level is better than 30 mK. A high-pass filtered image of the data is shown in Figure 1.
Sirtf Surveys and Legacy Science
Authors: Fazio G.G. , Clemens D.P.
Published: July 2016

The Space Infrared Telescope Facility (SIRTF), a 0.85-meter, cryogenically-cooled telescope, will be launched in 2002. SIRTF will extensively make use of large-format detector arrays. These, combined with the sky visibility of SIRTF's solar orbit will facilitate significant surveys. SIRTF surveys will complement observations by NASA's other Great Observatories and will enable follow-up SIRTF studies. Data from the large, “SIRTF Legacy Science Program” will be made widely available, on a rapid, non-proprietary release, to the general astronomical community.
First Observations with the 1.5 M RC Telescope at Maidanak Observatory
Authors: Artamonov B.P.
Published: July 2016

Since 1975, the Sternberg Astronomical Institute of Moscow University (SAI) has been conducting a search of Middle Asia for good astronomical sites. After investigating the meteorological conditions, temperature fluctuations and seeing quality of different sites, Maidanak Mountain (an isolated summit 150 km south of Samarkand) was chosen. This site has 2000 hours per year of clear observing conditions with a median seeing of about 0.7″ (Artamonov et al. 1987, Bugaenko et al. 1992). The construction of a 1.5m RC telescope for the Maidanak Observatory was mostly completed when it was nationalized by Uzbekistan in 1993. Tashkent Astronomical Institute is now working with SAI to form the International Maidanak Observatory and to continue with joint observations.
EUV Sources and Transients Detected by the Alexis Satellite
Authors: Roussel-Dupré D. , Pfafman T. , Bloch J. , Theiler J.
Published: July 2016

Because ALEXIS is a spinning satellite, it is an ideal platform with which to study the time variability of the EUV cosmos. The main thrusts of this effort are to 1) detect EUV sources at known and unknown locations, 2) provide notification of transients in near real time to enable immediate follow-up from other observatories, and 3) create a time history of observed sources for comparison with previously published catalogs to aid in determining long duration variability from EUV sources.
The UIT Survey of the Ultraviolet Sky Background
Authors: Waller W.H. , Stecher T. P. ,   The Ultraviolet Imaging Telescope Science Team
Published: July 2016

When viewed from above the Earth's atmosphere, the nighttime ultraviolet sky background is profoundly dark. Recent measurements indicate that the diffuse UV sky background is up to 100 times (5 magnitudes) fainter than the equivalent visible background as measured from the ground. Much of this difference can be attributed to the Sun's lower emissivity at UV wavelengths, leading to reduced irradiation of and scattering by the interplanetary dust. Because the resulting Zodiacal light is so much weaker in the UV, a comprehensive characterization of the UV sky can yield important information on the more distant Galactic and extragalactic backgrounds and, ultimately, on their material origins (see Brosch, this volume, p. 57).
Galactic Structure with the APS Catalog of the POSS I
Authors: Larsen J.A.
Published: July 2016

The maturity of all-sky surveys hold great promise for galactic structure studies. Surveys such as the APS Catalog of POSS I allow large scale studies of stellar distributions where the data is very complete to a reasonably faint magnitude, uniformly reduced, and independently calibrated. The APS data covers a large portion of the sky, allowing studies where the primary source of uncertainty is no longer small-number statistics.
Starcounts in the Hubble Deep Field: Fewer Than Expected, More Than Expected The Halo Main-Sequence & Halo White-Dwarf Luminosity Functions
Authors: Méndez R. A. , de Marchi G. , Minniti D. , Baker A. , Couch W. J.
Published: July 2016

The Hubble Deep Field (HDF, Williams et al. 1996), recently acquired with the Hubble Space Telescope, is the deepest, most detailed optical view of the Universe. Even though intended primarily for the study of the high-redshift Universe, the HDF provides a unique opportunity to find faint stellar objects in our Galaxy, set constraints on number of low-mass Halo stars, estimate the contribution of baryonic matter to the dark Halo, investigate the nature of microlensing sources, and to calibrate Galactic Structure models. The HDF has been an STScI initiative to provide the deepest exposures yet acquired with HST on a non-proprietary basis. Observations of an ‘anonymous field’ located at l = 125.9°, b = 54.8° were performed on the continuous viewing zone, for a total of 150 orbits (10 consecutive days) in the four HST passbands F300W, F450W, F606W and F814W. These observations reached 5σ magnitude limits (for Galaxies) of roughly (STMAG) 30th mag in all these passbands (except F300W which reaches 27th mag). We have used a novel software detection & classification algorithm to create a sample of point-like objects in the HDF. We have also compared the observed stellar counts to constrain the faint end of the Halo field luminosity function by using a recent Galactic Structure model. The unexpected appearance of a faint-blue group of very compact objects is discussed as well.
Measures of Galactic and Intergalactic Mass in Clusters
Authors: Windridge D. , Phillipps S. , Birkinshaw M.
Published: July 2016

If a galaxy cluster's X-ray gas distribution follows an isothermal polytropic β model, we may write the electron radial density distribution as; ne = ne0(1 + r2/rc2)–3/2β, rc being the core radius and ne0 the central electron density. This may be related to both an X-ray surface brightness distribution and a Sunyaev-Zel'dovich effect distribution (Sarazin 1986). Fitting to observational data then enables us to constrain the value of β. The normalisation value, ne0, to obtain a total mass estimate is calculated via the relationship between the X-ray and S-Z distribution normalisation constants, and the gas temperature and spectral emissivity parameters from fits to the X-ray spectrum. We are then in a position to evaluate ne(r) and its integral; the total electron gas mass. If we can further assume that there exists a simple ratio between the electron and proton number densities within the gas, we may straightforwardly posit a value for the total gas mass. An additional method of determining the polytropic gas index exists, with optical constraints on the galactic velocity dispersion, through the relation; β = μmHσz2/kBTe. Studies at optical, as well as X-ray and radio wavelengths are thus useful as a corroborative measure in determining the total gas mass.
Multi-Color Surface Photometry of Nearby Galaxies
Authors: Ichikawa T. , Itoh N. , Yanagisawa K.
Published: July 2016

Near-infrared (NIR) emission in galaxies is mainly radiated by old population low temperature stars, which construct the basic stellar structure and keep the trails of past galaxy evolution. On the other hand, optical observations show recent star formation activity, especially in spiral galaxies. Therefore multi-color observations from optical to near-infrared wavelengths are very important to understand the past and recent star-formation history. Nearby large galaxies are well studied not only in optical but also in mid- and far-infrared by IRAS, CO and HI radio observations. However, the study in the near-infrared is still limited because large format arrays are not common. Here we show a wide-field, near-infrared imaging of nearby elliptical and spiral galaxies and discuss their star-formation history.
Clustering Properties of Faint Blue Galaxies
Authors: Kümmel M.W. , Wagner S.J.
Published: July 2016

Log N - log S diagrams are being used as powerful diagnostic tools to probe evolutionary properties of different extragalactic populations. In the optical/near-infrared regime the discrepancy between near-infrared number counts which follow theoretical predictions and counts in the B band which show an excess density revealed a new population of galaxies. The nature of this population of faint blue galaxies is still unknown.
The K-Band Hubble Diagram for X-Ray Selected Brightest Cluster Galaxies
Authors: Mann R.G. , Collins C.A.
Published: July 2016

The Hubble (magnitude-redshift) diagram for brightest cluster galaxies (BCGs) is a classic cosmological tool, widely studied because of the remarkably small dispersion (∼ 0.3 mag) in the absolute optical magnitudes of low redshift BCGs (Postman and Lauer 1995). Extending the BCG Hubble diagram to higher redshifts would greatly enhance its role as a cosmological probe, but this has been frustrated by several technical problems:

– the conventional means of cluster selection in the optical become increasingly compromised by projection effects at z > 0.1

– at higher redshifts the interpretation of optical magnitudes becomes increasingly complicated by the effects of possible star formation.
Colour Equations for Techpan Films
Authors: Morgan D.H. , Parker Q.A.
Published: July 2016

The UK 1.2m Schmidt Telescope (UKST) at Siding Spring Observatory in Australia has been routinely using panchromatic Tech-Pan emulsion on film as a detector since 1992. Details of how the telescope was adapted to take film and how hypersensitization techniques have been modified for film have been described by Parker (1992). The film has a much finer grain than its equivalent spectroscopic emulsion on glass (IIIa-F) and consequently records images typically one magnitude fainter than IIIa-F when properly hypersensitized. The improved depth, resolution and low noise also permit better differentiation between stars and galaxies (see Parker et al. 1994). Consequently Tech-Pan film has become one of the most useful and commonly used emulsions at the UKST for a variety of passbands and may in time be used for a full or partial sky survey.
An Objective Approach to Spectral Classification
Authors: Connolly A.J. , Szalay A.S.
Published: July 2016

The next generation of spectroscopic surveys, both Galactic and extra-galactic (e.g., SDSS, 2dF), present the challenge of classifying spectra in an efficient and objective manner. The standard approach to this problem has been to visually classify spectra based on a number of spectral features (e.g., the equivalent widths of emission lines). The size of new spectral surveys (> 106 galaxies) and the desire to compare the luminosity and environments of galaxies with their spectral properties make these techniques infeasible. We describe here an automated classification scheme that is being developed for the SDSS.
Linking the Radio and Optical Frames with Merlin
Authors: Garrington S.T. , Davis R.J. , Morrison L.V. , Argyle R.W.
Published: July 2016

MERLIN positions of 12 radio stars are used to link the provisional Hipparcos reference frame to the International Celestial Reference Frame. The accuracy of the link using these radio stars is 2.3 milliarcseconds. Further observations are planned to check the accuracy of the link in the future.
Contents, Test Results, and Data Availability for GSC 1.2
Authors: Röser S. , Morrison J. , Bucciarelli B. , Lasker B. , McLean B.
Published: July 2016

A collaboration between STScI and ARI has produced a new astrometric reduction of the Guide Star Catalog (GSC, Lasker et al. 1990). This new version, GSC 1.2, has dramatically reduced the systematic errors present in GSC 1.1. The positions in GSC 1.1 are affected by plate-based systematic distortions which are largest at the plate edges (1.0″, north; 1.2″, south) (Taff et al. 1990a). These positions also suffer from systematic errors which are a function of magnitude and radial distance from the plate center (Morrison et al. 1996). This effect is small for radii under 2.7° from the plate center, then rapidly increases producing an average offset of the faint stars (15m) versus the reference stars (10m) of 0.9″ at the plate edges.
Global Network Access and Publication of Survey Data
Authors: White N.E.
Published: July 2016

The results of astronomical surveys include 1) catalogs containing anywhere from a few to many million objects, 2) data products used to generate the catalogs (e.g., images or spectra), 3) publications and 4) object based compilations of information from many sources. The ubiquitous growth in the Internet and the dramatic reduction in the cost of mass storage systems now allows instant global access to this information. Astrophysics on-line services have grown up with the Internet, and represent an invaluable resource whose access is a routine part of any research project. Unfortunately users are also faced with searching and accessing multiple sites with different content, access and response methods. There can also be inconsistencies amongst the various systems, which can involve extra effort to resolve. A network-integrated astrophysics system has long been sought because it would remove multiple user interfaces and allow much simpler integration of services. In an era of shrinking budgets, the issue is how to achieve this in a cost effective manner. This review gives an overview of the current situation and discusses the likely evolution towards a network-integrated astrophysics system.
Quantitative spectral classification of late WC stars
Authors: de Marco Orsola , Crowther P. A. , Barlow M. J.
Published: July 2016

We present a revised classification scheme for late WC-type stars based on new high quality optical observations of seven stars. For consistency with the usual WC scheme (Smith, ApJ 358 229 1990), our principal diagnostic is Cvi λ5801/Ciii λ5696, while Ciii λ5696/Cii λ4267, and He II λ4686/He I λ5876 serve as secondary criteria. Our quantitative scheme forms an natural extension to the existing WC scheme and provides an unambiguous definition of subtypes, with natural breaks found between subclasses.
A new atomic line catalogue for Planetary Nebulae
Authors: Feklistova T. , Kholtygin A. F.
Published: July 2016

The detailed line catalogue for the PN spectra is very useful for line identification. The first version of such catalogue was issued by Feklistova et al. (1994). Since the first edition the numerous weak lines belonging to the heavy elements (Z>30) have been identified in the spectra of NGC 7027 (Péquignot et al. 1994, Baluteau et al. 1995). Moreover, many newly identified lines were found in the spectra of other PN (e.g., Hyung and Aller 1996 and references given therein). This means that the PN line catalogue is needed to be extended and updated.
Trigonometric parallaxes of Planetary Nebulae
Authors: Harris H.C. , Dahn C.C. , Monet D.G. , Pier J.R.
Published: July 2016

The accuracy of parallaxes obtained with ground-based CCD cameras now often reaches or exceeds 0.5 milliarcseconds. This improved accuracy permits us to measure significant parallaxes and determine distances for the nearest planetary nebulae. At present, the central stars of 11 planetary nebulae have been observed as part of the USNO parallax program. We now have determined distances with accuracies better than 20 percent for four central stars and better than 50 percent for five more. This paper gives the present status of the program, a brief interpretation of the results, and future prospects.
The dynamics of PNe halos and the timescale correlation distance
Authors: Hajian Arsen R. , Frank Adam , Balick Bruce , Terzian Yervant
Published: July 2016

We present deep narrow-band CCD images of four PNe obtained with the Palomar 5-m telescope in the light of [N II]λ6584 + Hα and [O III]λ5007. Several previously undetected structures are found, including faint multiple envelope structures. The inclusion of these sources with data for other multiple envelope PNe published in the literature permit an evaluation of the relationship between PNe ‘shells’ and the thermal pulses of the PN nucleus.
Observations of CSPN
Authors: Heap S. R.
Published: July 2016

It's a good thing that we're starting to meet every four years rather than every five. There has been tremendous progress in understanding the properties and evolution of central stars of planetary nebulae (CSPN) since the last meeting in Innsbruck in 1992. Much of the credit is due to new spectra and images obtained at observatories that weren't even in existence four years ago. Table 1 lists most of the space observatories used by astronomers reporting at this symposium. The ones marked with the asterisk are new to this conference. The double asterisks for the Hubble Space Telescope instruments remind us that the telescope was repaired in December 1993. The reference gives the identification of the poster paper given at this meeting. We can look forward to similar improvements in ground-based observatories to be reported at the next meeting.
Planetary Nebulae with binary nuclei
Authors: Livio Mario
Published: July 2016

High resolution images of planetary nebulae have revealed a variety of non-spherical morphologies. In addition, some planetary nebulae were found to produce highly collimated jets. It is argued that binary central stars may play a crucial role in the production of all of these morphologies. In particular, a specific mechanism is identified for the generation of “point-symmetric” nebulae. It is shown that the study of binary nuclei of planetary nebulae can provide essential information for the understanding of the common envelope phase in the evolution of binary systems.
Asteroseismology of Planetary Nuclei
Authors: Bond Howard E. , Kawaler Steven D. , Ciardullo Robin ,   Worldwide Collaborators
Published: July 2016

The first two pulsating planetary-nebula nuclei (PNNs), those of K 1-16 and Lo 4, were discovered by Grauer & Bond (1984) and Bond & Meakes (1990). They are nonradial multiperiodic g-mode pulsators, with typical periods near 25–31 min and low amplitudes (up to ∼ 0.05–0.1 mag). These PNNs have extremely high temperatures (Teff > 100,000 K), and are hydrogen-deficient with high abundances of C and O. Their spectra and pulsational properties are very similar to those of the pulsating GW Vir (PG 1159–035) white dwarfs.
High resolution observations of BD +30 3639 − A young PN
Authors: Bryce M. , Mellema G.
Published: July 2016

Sub-arcsecond resolution radio and optical images of the young planetary nebula BD +30 3639 look superficially very similar, showing a pronounced box-shaped bright nebular shell. However, a detailed comparison at high spatial resolution reveals several regions where the optical emission is obscured by localised dusty regions. The highest resolution radio image to date of this PN, a 6 cm map obtained by combining MERLIN and VLA observations (Bryce et al, 1996) has been compared to the highest resolution optical Hβ image from the Hubble Space Telescope (obtained by J.P. Harrington and collaborators) to reveal the differences in emission which are probably due in the main to dust obscuration at optical wavelengths (Bryce et al, 1996 & Arnaud, Borkowski & Harrington, 1996). New 6 km s–1 resolution, spatially resolved spectra of optical emission lines, obtained using the Utrecht echelle spectrometer on the 4.2 m William Herschell Telescope, show that this nebula is bright in the low ionisation emission lines of [N II] 6548 + 6584 å and also appears to be more spatially extended than in the fainter, high ionisation [O III] 5007 å emission. The velocity ellipse observed from a long slit oriented north-south was found to be tilted, indicating an inclined, elliptical morphology rather than a simple, radially expanding spherical shell and the gaps in the velocity ellipse observed with an east-west slit suggest that the true shape is probably an open ring-like structure rather than a closed shell. A deep exposure of the [N II] 6584 å emission line appears to show a collimated, accelerating flow in an eastward direction away from the central star and extending well beyond the main bright nebular ring. It was also observed in the Hydrogen and [Nii] 6548 å emission lines. The H2 1–0 S(1) image of BD +30 3639 by Graham et al (1993) also shows a feature to the east of the main nebular ring. This may well be related to faint halo structures detected by Harrington and collaborators from their HST images (private communication).
SNAP: Spreadsheet nebular analysis package
Authors: Krawchuk Curtis A.P. , McCall Marshall L. , Komljenovic Michael , Kingsburgh Robin , Richer Michael , Stevenson Christopher
Published: July 2016

A flexible and extensible software package for analyzing two-dimensional and multi-object spectra of nebulae has been implemented within Microsoft Excel (version 5). From lists of calibrated fluxes (and errors) for lines in a series of spectra, the program first identifies transitions by referring to wavelengths generated from atomic data. Colour excesses can be computed from a reddening law and ratio of total to selective extinction of the user's choice. Line fluxes can be corrected for stellar absorption and reddening and reported in a format suitable for publication. Temperatures, densities, ionic abundances, ionization correction factors, and total abundances can be computed. (The interface for the temperture/density calculation is shown below.) Emission coefficients for forbidden transitions are calculated using an adaptation of the FIVEL five-level atom routine (DeRobertis, 1987). As well, emission coefficients are supplied for an extensive set of recombination lines. The user has complete control over which spectral lines are used in an analysis – there are no pre-ordained methods. Abundance analyses can be performed using the physical conditions either measured or specified for each spectrum. Uncertainties are propagated throughout. The atomic data used in all of the calculations are easily updated or augmented by the user. Since the software is embedded in Microsoft Excel, graphical representations of the data are easily created, and extended analyses using the full functionality of the spreadsheet are easily implemented.
The sphericity effects in model atmospheres of central stars of Planetary Nebulae
Authors: Kubát Jiří
Published: July 2016

The model atmospheres of central stars of planetary nebulae are often calculated under the assumption of the plane-parallel geometry. This assumption seems to be reasonable for stars with relatively thin atmospheres like white dwarfs, where the thickness of the atmosphere is only few kilometers while the corresponding radius is about several thousands of kilometers. Nevertheless, calculations of a grid of pure hydrogen model atmospheres of hot white dwarfs demonstrated that this assumption may fail even for thin atmospheres (Kubát 1995). We found small differences between line profiles (about 1%) calculated under the assumption of plane-parallel and spherically symmetric atmospheres. Such differences are detectable by contemporary observational technique, and, consequently, may not be neglected. In addition, sphericity effects are important also in stars of other types (Kubát 1996). We decided to test the assumption of the plane parallel geometry also for sample model atmospheres of central stars of planetary nebulae. We assumed static atmospheres in radiative, hydrostatic, and statistical equilibrium (NLTE) consisting of hydrogen and helium. We calculated spherically symmetric and plane parallel model atmospheres of two central stars, namely LoTr4 and K1-27. Basic atmospheric parameters of these stars were adopted from Rauch et al. (1996, 1994), respectively. The atmospheric parameters for LoTr4(Teff = 120000K, log g = 5.5, M = 0.65M⊙, n(H)/n(He) = 0.5 yield a model with an extension (r(τR = 10–5)/r(τR = 2/3)) of 1.028. For K1-27, the atmospheric parameters (Teff = 100000K, log g = 6.5, M = 0.52M⊙, n(H)/n(He) = 0.2 produce only a small extension of 1.0035. The differences in temperature structure of our model atmospheres are more pronounced for a star with lower gravity and, consequently, larger extension. Continuum flux is lower for spherical atmospheres. This difference is larger for LoTr4, i.e. a star with more extended atmosphere, and almost negligible for K1-27. Paschen and Pickering He ii lines also show differences. These differences are quite large (several per cent) for α lines, and they decrease towards higher series members. Using plane-parallel model atmospheres instead of spherically symmetric ones introduces a systematic error into results. This error is present also in highly sophisticated NLTE line blanketed models. Due to the above mentioned differences one should avoid using lower series members (e.g. He ii 4686 å) for determination of atmospheric parameters (Teff, log g, abundances,…) from plane-parallel atmospheres. Details of our calculations will be presented in Astronomy and Astrophysics.
Spectral analyses of the [WCL]-type CSPN He 2-459, M 2-43, SwSt 1, PM1-188 and IRAS 21282+5050
Authors: Leuenhagen U.
Published: July 2016

In this work recent results of spectral analyses of five late–type [WC] central stars are presented. We use spherically expanding model atmospheres to simulate non–LTE radiation transfer in mass–loosing envelopes. A detailed description of the model calculations and the stellar parameters of further eight [WCL]–CSPN can be found in Leuenhagen & Hamann 1994, A&A 283, 567, and Leuenhagen et al. 1996, A&A 312, 167.
P Cygni profiles variability in central stars of Planetary Nebulae
Authors: Patriarchi P. , Perinotto M.
Published: July 2016

The variability of P Cygni profiles is important because of its connection with the mechanism of wind production and with the behaviour of the associated mass loss rates.
The influence of new NLTE model atmospheres with wind effects in nebular modeling
Authors: Yamamoto T. M. , Sellmaier F. H. , Pauldrach A. W. A. , Hoffmann T.
Published: July 2016

Emergent fluxes from a non-LTE model atmosphere code designed to calculate realistic O star atmospheres are applied to nebular calculations. The stellar models include wind and blocking effects due to several million doppler-shifted lines in the radiation driven atmosphere in a full NLTE treatment. These lines, which arise from heavy elements, reduce the stellar flux drastically between 228 and 912 å (Pauldrach et al. 1994) — the most important frequency regime for ionization in gaseous nebulae. We have three models with effective temperatures of 50000, 40000 and 35 000 K and log g values of 3.9, 3.8 and 3.5 respectively. They have been used to model Hii regions and their use has led to significant differences in the ionization structure of the nebular models.
ISO-SWS observations of Planetary Nebulae
Authors: Beintema D.A.
Published: July 2016

First results of the ISO1 Short-Wavelength Spectrometer on three bright planetary nebulae NGC 6543, NGC 7027 and NGC 6302 provide a wealth of information on solid-state features and spectral lines. Spectra from 2.4 to 45 μm are presented, at a reduced resolution of about 600.
Planetary Nebulae of type I revisited
Authors: Torres-Peimbert S. , Peimbert M.
Published: July 2016

Type I PNe were defined in 1977; during the last 19 years evidence has accumulated indicating that indeed these objects form a distinct physical group, corresponding to the high mass end of the stellar progenitors of PNe. In this review the definition of PNe of Type I is reanalyzed. Their properties in our Galaxy and other galaxies are discussed.
Jets and Brets in Planetary Nebulae
Authors: López J.A.
Published: July 2016

The presence of high-velocity, collimated outflows in planetary nebulae (PNe) has been observationaly established in recent years. Furthermore, these collimated outflows, or jets, are usually found to be symmetric with respect to the nucleus. In some cases, their morphology and spatial distribution indicates episodic outbursts and rotation of the symmetry axis. In these cases, the bipolar, rotating, episodic jets are identified as BRETs. The existence of bipolar jets in PNe has been considered perplexing since the mechanisms for their formation are unclear. However, substantial progress in their study has been made in the last few years, from both theoretical and observational grounds. Consequently, new results in the field are rapidly coming out, as it can be noticed from the number of related works in this symposium. We still need to reach solid answers in many aspects of this field, but its influence in the study of PNe has already modified the traditional views of PNe shaping and evolution. The main characteristics of some of these phenomena are discussed here, together with prototypical cases, including a compilation of PNe with BRETs charateristics.
Narrow band CCD imaging of four PNe
Authors: Ali A. , Pfleiderer J. , Saurer W.
Published: July 2016

We present first results of a project to construct and study spatio-kinematical models of selected Planetary Nebulae (PNe). Deep monochromatic CCD images of A8, A4, M2-55, and J-320 were made with the Calar Alto 2.2m telescope and the two interference filters 5005/90 and 6574/104 for the [O III] and Hα+[N II] emission lines. The images were corrected for bias and dark, and flatfielded using MIDAS software, and also corrected for atmospheric extinction to derive the total flux in each emission line. The observed parameters are summarized in Table 1. – A8 (PNG167.0–00.9) has a very symmetric, round appearance with large diameter. The Hα+[N II] image clearly shows a round, limb-brightened ring which is less apparent in the [O III] image. Due to its appearance we can classify it as a late round type according to Balick (1987). −M2-55 (PN G116.2+08.5) has a box-like, quadratic and highly structured inner part (slightly more roundish in [O III]), with four maxima at the corners. The faint outer parts seem to consist of two ovals that are perpendicular to each other. Together, they again resemble a square tilted 45° against the inner one. The Hα+[N II] image is larger than [O III]: The square (distance of maxima) by some 20 percent, the faint ovals by about 10 percent. We can classify this PN as a middle elliptical type. – A4 (PNG144.3–15.5) is a spherical shell, with some definite structure in the brightest parts. This structure forms roughly a ring halfway between the center and the rim. A4 can be classified as an early round type. Both images are quite similar, the Hα+ [N II] maximum lying slightly, about 20 percent, farther from the center. In the very faint outer regions, the [O III]/(Hα+[N II]) ratio seems to increase by a factor of about 5 above the average which is otherwise constant within 10 percent over the whole image. -J-320 (PNG190.3–17.7) is elongated, with one maximum on the main axis, slightly off-center. The Hα+[N II] image has an interesting structure which is not present in [O III]: Two stripes of decreased intensity that are roughly parallel to and on both sides of the main axis. At present, we have no explanation for this feature. J-320 has ansae (small knots found in pairs on opposite sides and at equal distance from the nucleus) usually seen best in the light of low-ionization emission lines. Balick (1987) classified this PN as early type butterfly.
Infrared emission from Planetary Nebulae with H-rich and H-poor central stars
Authors: Górny S.K. , Szczerba R. , Zalfresso-Jundziłło M.
Published: July 2016

We report on an investigation of the infrared properties of planetary nebulae (PNe) with H-rich central stars and with [WR]-type central stars ([WR] PNe) which certainly are H-poor. The infrared radiation comes mainly from the layers expelled at the AGB and can reveal the evolutionary history of the two groups.
The database of Galactic PNe in Innsbruck
Authors: Kimeswenger S. , Kienel C. , Wildauer H.
Published: July 2016

Information in Astronomy is available in multiple form. There are the periodicals as well as printed catalogues. Electronic abstract and paper services as well as general data centers as provided by NED, CDS, NASA/ADC, STScI, … and give access via modern communication media. The Deep Near Infrared Southern Sky Survey consortium (DeNIS, Epchtein et al. Astrophys. and Space Sci., 217, 3) itself provides all the survey data at two dedicated centers. Regarding all these services we have to ask:
Sub-arcsecond near-IR imaging and long-slit spectroscopy of NGC 7027
Authors: Manchado A. , Prada F. , Stanghellini L. , Panagia N.
Published: July 2016

We report sub-arcsecond narrow band imaging in the lines of H2 2.1218 μm, Brγ 2.16 μm, [Fe II] 1.664 μm of the Planetary Nebulae NGC 7027. Data were obtained at the 3.5 m telescope at Calar Alto Observatory (Spain), using MAGIC. A false color image was produced by combining these three narrow band images. Thus, and due to extraordinary seeing (0″.6 arcsecond) conditions, allow us to reveal the morphology of the excited molecular and ionized gas. The Brγ and the [Fe II] images allowed us to study the structure of the ionized gas at slightly different excitation levels, according to the ionization potentials of the ions involved in the corresponding transitions (13.6 eV to ionize hydrogen, versus 17.4 eV for iron ionizaton). Since NGC 7027 is a high excitation nebula, the iron is readily double– ionized in the hotter regions, thus what we really see in the [Fe II] image is the low–intermediate excitation zones. By studying the [Fe II] and Brγ images together we infer that: the (non–reddened) low–ionization gas morphology consists of a regular, smooth ring reminder of a projected cylindrical structure. In addition to a brightness level that is at least thirty times the brightness of the maximum [Fe II] emission, the ionized hydrogen image exhibit a strong brightness gradient between the mentioned ring and the outer regions, and the emission is comparatively negligible outside the ring–like feature of about 12 × 10 arcsec (the measures refer to the major and minor axes of the ellipse–like shape). The [Fe II] morphology is less so ring–like and regular, and it seems to indicate smaller scale structure, such as clumps and filaments, at the resolution scale–level. The dishomogeneity in the [Fe II] emission could be ascribed to gradients in the elemental distribution, as well (and more probably so) as to the plasma temperature and density inhomogeneities. The H2 molecular image completely embeds the ionized gas zones, up to a size of about 16 × 11 arcsec. The smaller size refers here to the waist of the markedly bipolar shape, similar to a projected peanut; the larger size is the dimension of the two main lobes. The highest brightness through the molecular filters corresponds to the inner ring, slightly less extended than the ionized one, and to an outer envelope that is not seen in the ionized gas, and has a maximum diagonal extension of about 24 arcsec. Spatially resolved low resolution spectra (R 200) were obtained in the H and K band.
The dramatic kinematics of the hydrogen deficient Planetary Nebula Abell 30
Authors: Meaburn J. , López J. A.
Published: July 2016

The remarkable velocity structure of the different components of the hydrogen deficient planetary nebula Abell 30 have been revealed for the first time by obtaining spatially resolved profiles of the [O III] 5007 å lines with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope.
Imaging and spectroscopy of ejected common envelopes
Authors: Pollacco D. L. , Bell S. A.
Published: July 2016

Imaging and spectroscopy are presented for four planetary nebulae known to contain close binary central stars resulting from a recent phase of common envelope evolution. These objects are Abell 41, Abell 46, Abell 63 and Abell 65. Determinations of the nebula abundances show that He is significantly enhanced in all of the objects. These results are in agreement with theoretical expectations. Uncertainties in the nebular electron temperature constrain other abundances less well. The line fluxes indicate that N is unexpectedly under-abundant. This effect is probably not real and may be an artifact of electron temperature fluctuations within the nebulae.
CCD spectrophotometry of extended PN: Observations at Wendelstein Observatory
Authors: Roth Martin M.
Published: July 2016

Most of the existing flux data on galactic PN is based on measurements with scanners or photoelectric aperture photometers. Also, true global fluxes are not even available for many PNe in lines other than Hβ, and one has to rely on line intensities which have been derived from slit spectrometers. For extended, low surface brightness objects all of these instruments are not appropriate to derive reliable fluxes (see e.g. remark on NGC 7293 by O'Dell, this conference). As part of a PhD thesis a dedicated CCD camera for the Wendelstein Observatory 0.8m telescope has been developed (Roth 1990, 1993), optimized for flux-calibrated imaging through narrow-band interference filters with bandpasses down to 8å FWHM and a thermal control unit for central wavelength tuning. As a test, nebular and central star fluxes have been measured for NGC 2392, NGC 3242, NGC4361, and NGC 6210 in Hβ, HeII 4686, [OIII] 5007, and a continuum passband. The results for these bright objects are in agreement with the best references as compiled from the literature. A detailed comparison shows that the spatial extent of the nebula is now always considered correctly, based on the CCD image information and the curve-of-growth convergence of the surface photometry. The central star photometry is largely improved, in particular for high surface brightness PNe. Another advantage (which however was not important for the test objects here) is the technically easy removal of disturbing field stars within the radius of a faint, extended nebula. The use of very narrow bandwidth, thermally controlled filters proved to be beneficial in substantially reducing the sky and nebular continuum background contribution. From the nebular and central star fluxes, Zanstra temperatures have been derived. The cause of the observed Zanstra discrepancy (which is in accordance with several other determinations for the investigated objects) cannot be attributed to observational uncertainties. From the discussion of Unified NLTE model atmospheres (Gabler et al. 1991) and model fits to the central stars of NGC2392, NGC3242, NGC4361 (Méndez et al. 1988), and NGC6210 (McCarthy et al. 1990) the most likely explanation is a combination of two effects: EUV excess over currently predicted central star flux distributions, and leakage of UV photons from the nebula (see also Méndez et al. 1992).
On the variations of [OIII] lines intensities in the spectrum of PN IC 4997
Authors: Yeghikyan A. G.
Published: July 2016

The causes of asynchronous variations of the intensities of OIII ions forbidden lines in the spectrum of compact planetary nebula IC 4997 are considered on the basis of the observational data of. It is shown that the rise of the intensity of line 4363 å and decrease of the intensities of N1 and N2 lines may be best explained by increase of mass-loss-rate from nucleous from 5 × 10–8 up to 2 × 10–7 M/yr within a few years (at constant nucleous effective temperature), with appropriate change of ionization structure of nebula. The arguments of existence of variable hot stellar wind are discussed. The theoretical intensities of lines are calculated by the ionization model of planetary nebulae [4], gyven the radiation fields of the nucleous and hot stellar wind with electron temperature Te= 500000 K.
Spectroscopy of the Proto-Planetary Nebula CRL 618
Authors: Baessgen M. , Hopfensitz W. , Zweigle J.
Published: July 2016

We present spectroscopic observations of the protoplanetary nebula CRL 618. The spectra in the range from 370 to 800 nm were taken at the 3.5m telescope on Calar Alto (Spain). The slit of the spectrograph covered both the brighter E-lobe and the fainter W-lobe. Using the balmer line we found an extinction of about c= 1.6 for both lobes. The emission lines show a velocity difference between the two blobs. The difference of the forbidden lines is found to be bigger than the v-difference of the permitted recombination lines in agreement with Carsenty and Solf (1982). Exceptions are the OII 732.0nm and 733.0nm and the NII 575.5nm lines. It also seems that the spatial separations of the peak emis-sivities of the forbidden lines are bigger than the separation of the recombination lines. This might be a result of the geometry and structure of the object. The permitted lines are emitted from the central source and reflected towards the observer at the inner edges of the blobs while the forbidden lines are emitted from the lobes themselves. Kelly et al. (1992) found a different I(NII 658.4nm + NII 654.8nm)/I(NII 575.5nm) ratio for the bright E-lobe than the older observations from Schmidt and Cohen (1981). This indicates an increased temperature of the bright lobe. We found now a similar temperature enhancement for the faint W-lobe. This may be caused by a shock reaching the inner edges of the blobs. This may also be the reason that the N II 575.5 nm line seems to originate at the inner blob edges, showing a smaller spatial separation. There is another indication for an increased temperature, we found some evidence for the S III 631.2nm, the He II 468.6nm and the O III 500.7 nm lines. The protoplanetary nebula CRL 618 is one of the few objects in this transition stage where dynamical processes can directly be observed.
Sub-arcsecond optical imaging of Proto-Planetary Nebulae
Authors: Hrivnak Bruce J. , Langill Philip P. , Kwok Sun
Published: July 2016

Sub-arcsecond (0.7″) V and I images have been obtained of 13 new proto-planetary nebulae (PPN). The observations were made with the image-stabilization camera (HRCam) on the 3.6 m Canada-France-Hawaii Telescope. The goal of the program is to study the mass-loss history of the stars and to determine when in the evolution the shaping seen in PN occurs.
An infrared study of Roberts 22
Authors: Molster F.J. , Waters L.B.F.M. , de Jong T. , Prusti T. , Zijlstra A. , Meixner M.
Published: July 2016

Roberts 22 (= AFGL 4104) is a peculiar proto-planetary nebula. Its central star has spectral type A2Ie. An OH maser was detected by Manchester et al. (1969), indicating that the shell is oxygen-rich. However Polycyclic Aromatic Hydrocarbons (PAH) features were observed as well (Allen et al., 1982; Cohen et al., 1993), indicating that carbon rich material is also present. In this poster we present new IR data (images and spectra) of this peculiar star and propose an explanation for this curious behaviour.
Through the AGB towards a Planetary: A hydrodynamical simulation
Authors: Steffen M. , Schönberner D. , Kifonidis K. , Stahlberg J.
Published: July 2016

Based on the mass-loss description developed by Blöcker (1995, A&A, 297, 727), we present first exploratory computations of the dynamical evolution of a dusty stellar wind envelope around an intermediate mass star during the last 300 000 years on the AGB and its transformation into a planetary nebula during the following 5 000 years of post-AGB evolution. To model the dynamics of the cool dusty envelope, we used a two-component (gas/dust) 1D radiation hydrodynamics code which computes the radiation pressure on dust grains and the structure of the envelope in a self-consistent way, including the variable frictional coupling between dust and gas. The grains are either carbon or oxygen based and of single size and spherical shape.
The link between barium stars and optically bright post-AGB binaries
Authors: Van Winckel Hans , Waelkens Christoffel , Jorissen Alain , Van Eck Sophie , North Pierre , Waters Rens
Published: July 2016

Systematic radial velocity monitoring programs revealed that all optically bright, high-latitude post-AGB stars that show a near-IR excess in their energy distribution are binaries (see the contribution of R. Waters et al. in these proceedings). A standard AGB evolution for the shorter period objects seems, however, impossible since the orbits are too small to accommodate an AGB star! Non-standard phenomena connected to the specific binary nature have to be invoked in order to understand these systems.
Structure and evolution of central stars of Planetary Nebulae
Authors: Schönberner D.
Published: July 2016

In this review a critical examination of our present knowledge about the structure and evolution of central stars of planetary nebulae is presented. In particular, the still enigmatic origin of the Wolf-Rayet central stars is addressed, too. Some directions for future work are given at the end.