bluuebunny/crossref_metadata_2025 huggingface dataset:
An Imaging Survey of the Galactic H-Alpha Emission with Arcminute Resolution
Authors: Dennison B. , Simonetti J.H. , Topasna G.A. , Kelleher C.
Published: July 2016

We are presently carrying out a northern hemisphere survey of the Galactic Hα emission. Our instrument, the Virginia Tech Spectral Line Imaging Camera (SLIC) utilizes a fast objective lens (f/1.2) with a cryogenically-cooled TK 512×512 CCD. A filter wheel in front of the lens allows us to select interference filters, including a narrowband Hα filter and a broader bandpass continuum filter in a line free part of the spectrum. The fast optics in combination with the low noise CCD result in sub-Rayleigh sensitivity at confusion limited levels. (1 Rayleigh = 106/4π photons cm–2 s–1 sr–1.) This corresponds to an emission measure sensitivity of ≈ 1 pc cm–6. Parameters of our system are given in Table 1.
Formation and Evolution of the Milky Way
Authors: Majewski S.R.
Published: July 2016

To paint with broad brush strokes, the spectrum of Galactic formation models has as extrema what may be termed the “fast and smooth” and the “slow and lumpy” scenarios. Appropriate or not, to ascribe as champions of these views the works of, respectively, Eggen et al. (1962, ELS hereafter) and Searle & Zinn (1978, SZ hereafter) has become de rigueur—though it is prudent to bear in mind the soft focus of historical perspective, and the maxim that “no one remembers what one has said, only what others say one has said” (on this point, see Sandage 1990 and Majewski 1993, section 1).
Investigation of Galactic Structure with Denis Star Counts
Authors: Ruphy S.
Published: July 2016

Thanks to the DENIS program (Deep Near-Infrared Survey of the Southern Sky), relatively deep near-infrared star counts are now available for the first time on a large scale. The basic method to interpret star counts in terms of galactic structure is to compare them with predictions given by models of the point source sky. Of particular promise are studies with DENIS of the spatial distribution of evolved stars in our Galaxy, thanks to its high sensitivity to red giant and to the much lower interstellar extinction that hampers visual observations of far-away stars in the disc of our Galaxy. In this paper, I present a sample of extensive comparisons between two models of the Galaxy and DENIS star counts (Ruphy 1996). I will focus on the analysis of star counts in the anticenter direction, that leads to new values for the distance of the cutoff and the radial scale length of the stellar disc.
Weak Gravitational Lensing—The Need for Surveys
Authors: Schneider P.
Published: July 2016

Light rays from distant sources are deflected if they pass near an intervening matter inhomogeneity. This gravitational lens effect is responsible for the well-established lens systems like multiple-imaged QSOs, (radio) ‘Einstein’ rings, the giant luminous arcs in clusters of galaxies, and the flux variations of stars in the LMC and the Galactic bulge seen in the searches for compact objects in our Galaxy. These types of lensing events are nowadays called ‘strong lensing,’ to distinguish it from the effects discussed here: light bundles are not only deflected as a whole, but distorted by the tidal gravitational field of the deflector. This image distortion can be quite weak and can then not be detected in individual images. However, since we are lucky to live in a Universe where the sky is full of faint distant galaxies, this distortion effect can be discovered statistically. This immediately implies that weak lensing requires excellent and deep images so that image shapes (and sizes) can be accurately measured and the number density be as high as possible to reduce statistical uncertainties. Weak gravitational lensing can be defined as using the faint galaxy population to measure the mass and/or mass distribution of individual intervening cosmic structures, or the statistical properties of their mass distribution, or to detect them in the first place, independent of the physical state or nature of the matter, or the luminosity of these mass concentrations. In addition, weak lensing can be used to infer the redshift distribution of the faintest galaxies. After introducing the necessary concepts, I will list the main applications of weak lensing and discuss some of them in slightly more detail, stressing the need for very deep and wide-field images of the sky taken with instruments of excellent image quality.
Uncovering Ultra-Luminous Galaxies in the IRAS FSC Through Radio and Optical Cross-Identification
Authors: Aldering G.
Published: July 2016

Ultraluminous infrared galaxies (ULIRGs) have luminosities (1012L⊙) once exclusive to QSOs. This suggests they might be the early, dust-enshrouded stages of QSOs. ULIRGs have ∼ 3.5× the space density of QSOs at the present epoch. Quasars reached their peak space density at z ∼ 2, so if ULIRGs are QSO precursors, there should be a dramatic increase in their space density up to z ∼ 2. The small number of known ULIRGs makes it difficult to explore links between ULIRGs and QSOs, much less measure their evolution. To do so, a large sample of ULIRG candidates must be identified. The IRAS FSC contains ∼ 60,000 probable galaxies, of which 1%–3% should have LFIR > 1012L⊙. We discuss an efficient and reliable method which uses IRAS-VLA-APS cross-identification and flux ratios to mine the FSC for likely ULIRGs.
Early Results from an HST Imaging Survey of the Ultraluminous IR Galaxies
Authors: Borne K.D. , Bushouse H. , Colina L. , Lucas R.A.
Published: July 2016

The intense study of interacting galaxies originated in large part with the discovery by IRAS that the most IR-luminous galaxies are nearly all products of collisions and may be the missing link in the chain of evolution from quasars to normal quiescent galaxies (Sanders et al. 1988a,b). These galaxies (with LIR > 1012L⊙) are considered to be the most strongly starbursting of all galaxies in the local universe, have a higher space density than quasars, emit >90% of their power in the IR, are rich in the raw materials of star formation, and to a large extent owe their peculiar morphologies to encounters with other galaxies. The particular importance of IR-luminous galaxies in the grand scheme of cosmology and galaxy evolution has been underscored by the luminosity function studies of Soifer et al. (1986), which indicated that most galaxies have gone through a high-IR luminosity stage. We are using the Hubble Space Telescope to survey the fine-scale features that are associated with the interaction- and activity-related processes that are at work within the Ultraluminous IR Galaxy Sample. It is widely believed that these galaxies are undergoing star formation at a prodigious rate and are abnormally dust-enshrouded. An alternative to the starburst hypothesis is that these galaxies' IR luminosity is powered by a dust-hidden quasar at its center (Sanders et al. 1988a). It is important for our understanding of the evolution of galaxies and quasars to determine which of these two hypotheses is valid, or in which objects they are separately valid.
Hamburg/SAO Survey of Emission-Line Galaxies
Authors: Lipovetsky V. , Engels D. , Ugryumov A. , Hopp U. , Richter G. , Izotov Y. , Kniazev A. , Popescu C.
Published: July 2016

We present first results of the Hamburg/SAO Survey of emission-line galaxies (hereafter HSS, SAO—Special Astrophysical Observatory, Russia) initiated to search for extremely metal-deficient (Z<Z⊙/10) galaxies and to create a large sample of Blue Compact Galaxies (BCG). This “Northern BCG Sample,” will be assembled by merging the HSS with samples from the Second Byurakan Survey (SBS) (Stepanianet al.1987) and the Case Low-Dispersion Northern Sky Survey (Peschet al.1991).
How to Find BL LAC Objects in the RASS
Authors: Nass P.
Published: July 2016

The correlation of an X-ray survey like the ROSAT All-Sky Survey (RASS) with optical surveys like the Hamburg Quasar Survey (HQS) can significantly increase the number of known BL Lac objects.
Statistical Methodology for Large Astronomical Surveys
Authors: Feigelson E.D. , Babu G.J.
Published: July 2016

Multiwavelength surveys present a variety of challenging statistical problems: raw data processing, source identification, source characterization and classification, and interrelations between multiwavelength properties. For these last two issues, we discuss the applicability of standard and new multivariate statistical techniques. Traditional methods such as ANOVA, principal components analysis, cluster analysis, and tests for multivariate linear hypotheses are underutilized in astronomy and can be very helpful. Newer statistical methods such as projection pursuit, multivariate splines, and visualization tools such as XGobi are briefly introduced. However, multivariate databases from astronomical surveys present significant challenges to the statistical community. These include treatments of heteroscedastic measurement errors, censoring and truncation due to flux limits, and parameter estimation for nonlinear astrophysical models.
Main Properties of the Hipparcos Catalogue
Authors: Mignard F.
Published: July 2016

The Hipparcos mission has come to a close with the end of the data processing on August 1996, only three years after the last observations were performed. About 118,000 stellar objects were observed and subsequently solved for their position, parallax and proper motion together with repeated determinations of their magnitude in the Hipparcos band. This paper outlines the main properties of the solution and explains how and when this information will be made available to the astronomical community.
Salvaging an Astrometric Treasure The European Network for the Use of the Carte DU CIEL
Authors: Hiesgen M. , Brosche P. , Gil A. Ortiz , Colin J. , Fresneau A. , Geffert M. , MacGillivray H. T. , Hecht S. , Kallenbach E. , Odenkirchen M. , Schäffel C. , Tucholke H.-J.
Published: July 2016

“Salvaging an astrometric treasure” is an european effort to retrieve the astrometric and photometric information contained in the early Carte du Ciel plates. Five institutes from three european countries are involved. The project was supported by the European Community.
A New High Density, High Precision Astrometric Catalog
Authors: Zacharias M.I. , Wycoff G.L. , Douglass G.G. , Corbin T.E. , Zacharias N.
Published: July 2016

The Version 1.0 of the U.S. Naval Observatory Twin Astrographic Catalog (TAC) contains positions of 705,679 stars (Zacharias et al. 1996). The TAC 1.0 covers over 90% of the sky from +90° to −18° declination; 260 out of 5180 plates are not yet measured. Plates were taken in both the yellow (508-578 nm) and in the blue (410-486 nm) bandpass between 1978 and 1986 at the U.S. Naval Observatory (USNO) in Washington, DC.
The 488,006,860 Sources in the USNO-A1.0 Catalog
Authors: Canzian B.
Published: July 2016

The USNO-A1.0 catalog was generated from the U. S. Naval Observatory's digitization of the Palomar Observatory Sky Survey IOandEsurvey plates for fields with central declination δ ≥ −30°, and from the European Southern ObservatoryRand Science Research CouncilJsurvey plates for fields with central δ ≤–35° using the Precision Measuring Machine (PMM) located at the Flagstaff Station. It lists positions (α and δ in J2000) and brightnesses (red and blue magnitudes on the parent plate system) for all objects. A flag indicates if the entry also exists in GSC1.1.
The Optid Database: Deep Optical Identifications to the IRAS Faint Source Survey
Authors: Lonsdale C. , Conrow T. , Evans T. , Fullmer L. , Moshir M. , Chester T. , Yentis D. , Wolstencroft R. , MacGillivray H. , Egret D.
Published: July 2016

We use a new, robust, method to estimate the identification probabilities of optical matches from digitized plate catalogs (COSMOS/UKST Catalog of the Southern Sky Version 2, Yentis et al. 1992; The Guide Star Catalog Version 1.1, Lasker et al. 1990; The Tycho Input Catalog, Egret et al. 1992; The APM Northern Sky Catalogue, Irwin, Maddox and McMahon 1994) to sources in the IRAS Faint Source Survey (FSS; Moshir et al. 1992), including both the Catalog (FSC) and the Reject File (FSR), utilizing a new random matching procedure with the advantages that it: (1) eliminates systematic uncertainties due to many problems, such as uncertainty in N(m); variations across the optical plate of magnitudes, plate limits or N(m); misclassification of stars and galaxies; the assumption of Gaussian error ellipses, etc. and (2) properly calibrates the identification probabilities. We find that at high SNRs and high galactic latitudes essentially all IR star-colored sources have an optical identification with Pid > 99%. At high SNRs and high galactic latitudes, ∼ 90% of all IR galaxy-colored sources have an optical identification with Pid > 90%.
A new distance indicator to the Galactic Planetary Nebulae based upon IRAS Fluxes
Authors: Tajitsu A. , Tamura S.
Published: July 2016

The distance to Planetary Nebulae (PNe) is a most important parameter to study their evolution and the distribution among our Galaxy, but it has been very difficult to determine it precisely. On the other hand, it is well-known that the IRAS colors of PNe are very similar to the blackbody colors. Taking into account of this characteristic, we define a new method to get some information about the distance to PNe by the blackbody fitting of IRAS 4-band fluxes, assuming these fluxes are due to the thermal emission from the nebular dust envelope.
Modelling the stellar winds of the [WC10] central stars CPD–56° 8032 and He 2–113
Authors: de Marco Orsola , Crowther P. A. , Barlow M. J. , Storey P. J.
Published: July 2016

[WC] stars are H–deficient central stars of PN which can mimic the spectra of massive (Min∼50M⊙) Wolf-Rayet stars of the carbon sequence and can be modelled using the same techniques. Our model calculations for the [WC10] CPD–56° 8032 and He 2–113 are based on the iterative technique of Hillier (A&A 231 111 1990) which solves the transfer equation in the co-moving frame subject to statistical and radiative equilibrium, assuming an expanding, spherically-symmetric, homogeneous and time-independent atmosphere. In extended atmospheres the stellar radius (R∗) is defined as the inner boundary of the model atmosphere at τRoss=20, with the stellar temperature (T∗) defined by the usual Stefan-Boltzmann (T∗ = (L∗/4 π σ R2∗)1/4) relation. For a given mass loss rate (M), the density and velocity field (v(r) = V∞ (1 - R∗/r)β for the supersonic part) are related via the equation of continuity M = 4 π r2 ρ(r) v(r).
Masses of the central stars of Planetary Nebulae
Authors: Górny S.K. , Stasińska G. , Tylenda R.
Published: July 2016

The aim of this study is to derive the masses of the central stars (CSPN) for a large sample of the planetary nebulae (PN). These masses, M∗, are derived from the observed PN positions in three diagnostic diagrams and their comparison with evolutionary tracks of model PN. Two of the diagrams, namely LZan(H) versus TZan(H) and Mv versus Rneb, have already been used in numerous studies. The third one, SHβ versus SV, has recently been introduced by Górny, Stasińska & Tylenda (1996, hereinafter GST96). Here SHβ is the nebular surface brightness in Hβ and Sv is defined as Fv/(πθ2), where Fv is the stellar flux in the V band and θ is the observed nebular angular radius.
Recombination line abundances in the winds of the [WC] Wolf-Rayet stars
Authors: Kingsburgh R. L. , Dashevsky I. , Barlow M. J.
Published: July 2016

We present a preliminary abundance analysis, utilising recombination theory, for the [WC] Wolf-Rayet central stars of the planetary nebulae NGC 6751 and NGC 6905. This analysis is based on optical spectrophotometry of a sample of [WC] stars which show a strong O vi 3811, 34 å feature in emission. We have performed a recombination line analysis of stellar wind emission lines which are judged to be optically thin, in order to derive relative C, O and He abundances. We also present a comparison of the derived wind abundances with those of Population I WO stars. For the [WC 4] central star of NGC 6751, we have derived C/He = 0.35 and C/O = 4.2, by number. And for the [WC 3] central star of NGC 6905, we have derived C/He = 0.36 and C/O< 12. These surface abundances are comparable to the abundances that have been derived for early type [WC] stars via more complex NLTE modelling (e.g. Koesterke & Hamann 1996).
The central stars of the Planetary Nebulae NGC 7027 and NGC 6543
Authors: Van Hoof P.A.M. , Beintema D. A. , Lahuis F. , Pottasch S. R.
Published: July 2016

Infrared spectra of NGC 7027 and NGC 6543 ranging from 2.4 μm to 45 μm were obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory. A first analysis of these spectra, with the aid of photo-ionization models, is presented in Beintema et al. (1996).
HST Snapshot images of Planetary Nebulae
Authors: Bond Howard E. , Fullton Laura K. , Schaefer Karen G. , Ciardullo Robin , Sipior Michael
Published: July 2016

During Cycle 5 of the HST General Observer program we have been carrying out a “snapshot” survey of central stars of planetary nebulae. The snapshots are short exposures in the V (F555W) and I (F814W) filters, taken with the Wide Field Planetary Camera (WFPC2) during brief scheduling opportunities.
X-ray emission from Planetary Nebulae
Authors: Conway Gail M. , Chu You-Hua
Published: July 2016

X-ray emission from planetary nebulae (PNe) may originate from two sources: central stars which are 100,000–200,000 K will emit soft X-rays, and shocked fast stellar winds reaching 106–107 K will emit harder X-rays. The former are point sources, while the shocked winds are expected to be extended sources emitting continuously out to the inner wall of the visible nebular shell (Weaver et al. 1977; Wrigge & Wendker 1996).
The physical structure of NGC 2440
Authors: Cuesta L. , Phillips J. P.
Published: July 2016

We have acquired monochromatic imaging of the bipolar outflow source NGC 2440 in 12 ionic transitions using the 1.5 m Telescope at the Observatorio de San Pedro Mártir, Ensenada, Baja California, Mexico. As a result, we have been able to undertake detailed analysis of the shell ionisation structure. Then, we found that excitation is high close the center, extending towards the exterior at located radial positions. Edges and ansae are zones of low excitation indicating probably shock regions, in particular the outer shell.
[O II] electron density mapping applied to NGC 6826
Authors: Dudziak G. , Walsh J. R. , Walton N.
Published: July 2016

The [O II]3726,3729Å doublet is sensitive to electron densities in the range 100 to 104 cm–3, typical of planetary nebulae, and thus provides an ideal tool for mapping the projected density structure. The first use of the imaging Fabry-Perot TAURUS-II to observe both the [O II] doublet lines, and hence map the electron density, is reported for NGC 6826. If sufficient spectral resolution is achieved both the [O II] lines can be resolved into separate components, opening the way to full 3-D density mapping of PN. Given the low finesse of the etalon and the low expansion velocity in NGC 6826 (10-15 kms–1), this original hope could not be fulfilled. However, a restricted aim of seeing-limited electron density mapping was accepted.
Chemical abundances variations and kinematical ages of multiple shell Planetary Nebulae and their haloes
Authors: Guerrero M. A. , Manchado A.
Published: July 2016

We have carried out a comparative study of the chemical abundances and physical properties of the haloes and main nebulae on a sample of type I multiple shell PNe: M 1-46, NGC 2438, NGC 5882, NGC 6543, NGC 6720, NGC 6751, and NGC 6826.
Modeling hydrogen-deficient Planetary Nebulae
Authors: Harrington J. P. , Borkowski K. J. , Tsvetanov Z. I.
Published: July 2016

Hydrogen-deficient planetary nebulae have central regions devoid of hydrogen. (See Harrington 1996 for a review of these nebulae.) They are characterized by exceptionally strong collisionally excited lines of [O III] and [Ne III], but relatively weak or undetected recombination lines of He or other elements. Such nebulae cannot be modeled successfully unless we include some source of heating in addition to photoionization by the central star.
A near-infrared spectral survey of Planetary Nebulae
Authors: Hora Joseph L. , Latter William B. , Deutsch Lynne K.
Published: July 2016

We have completed a near-infrared spectral survey of more than 40 planetary nebulae (PN). The data were obtained using the KSPEC spectrometer on the University of Hawaii 2.2m telescope on Mauna Kea. KSPEC is a cross-dispersed spectrograph that provides simultaneous sampling of the 1.1–2.4 μm range at a resolution of approximately 700. We used a 1 × 7 arcsec slit and a slit-viewing camera with a second NICMOS3 detector operating in the K-band for positioning and tracking of the source. The survey sample consists of compact IR-bright PN with a range of ages and morphological classifications. For many PN in the survey, spectra of several positions, such as the central star and one or more positions in the nebula, were obtained. There are many spectral features of interest within this wavelength range, such as HI recombination lines, emission lines of HeI, FeI, OI, and [FeII]; molecules such as H2, CN, C2, and CO; and continuum emission from the central star and hot dust in the nebula. A typical spectrum is shown in Figure 1. Emission from H2 was detected for the first time in several PN, including NGC 40, NGC 7026, M 1-92, and Vy 2-2. The survey data will be used to compare the properties of the sample PN, including H2 excitation mechanisms (shocks versus excitation by UV photons) and temperatures, and to correlate the properties with morphology class and age.
The molecular envelopes of Planetary Nebulae
Authors: Huggins P. J. , Bachiller R. , Cox P. , Forveille T.
Published: July 2016

We report the results of an extensive survey of molecular gas in planetary nebulae (PNe) using the millimeter lines of CO. The observations provide a range of information on the kinematics, the structure, and the mass of PN envelopes, which are important for understanding the formation and evolution of the ionized nebulae from the molecular envelopes ejected during the precursor AGB and proto-PNe phases.
The ground based leg for our ISO PNe: Spectroscopy
Authors: Kerber F. , Köberl T. , Gratl H. , Roth M.
Published: July 2016

The Infrared Space Observatory (ISO) has to be regarded as the most powerful infrared facility that has ever been available to the astronomical community. In order to fully exploit the wealth of information contained in ISO data, one has to supplement the satellite observations with a ground-based campaign. In collaboration with the Kiel group, our group in Innsbruck is carrying out two observing programs with ISO. Our observations aim at the study of hot dust in bipolar PNe seen edge-on and in so-called “born-again” PNe.
Density and temperature inhomogeneities in Planetary Nebulae
Authors: Kholtygin A. F.
Published: July 2016

The carbon, nitrogen and oxygen abundances in the Planetary Nebulae (PN) derived from the optical recombination lines are usually much larger than those determined from collisional excited UV, IR and optical lines. This discordance is the bright evidence for PN to be strongly inhomogeneous. Starting with consideration by Peimbert (1967) we have been working out the code for calculation the nebular line intensities taking into account both temperature and density fluctuations.
S II emission lines in Planetary Nebulae
Authors: McKenna F.C. , Keenan F. P. , Aller L. H. , Hyung S. , Bell K. L. , Ramsbottom C. A.
Published: July 2016

Emission lines arising from transitions in S II have been detected in a wide variety of astronomical sources, including planetary nebulae (Hyung, Keyes & Aller 1995). These transitions are used to derive information on emitting plasmas parameters (Te, Ne) through diagnostic line ratios, although to calculate these quantities reliably, accurate atomic data must be employed, especially for electron impact excitation rates.
Millimetre observations of Planetary Nebulae
Authors: Nyman L.-Å. , Garay G. , Schwarz H. E.
Published: July 2016

We have observed a sample of 16 PNe of different morphological classes (from stellar to bipolar) in the mm-region, using the 15m Swedish-ESO Submillimetre Telescope (SEST). Continuum observations at 230 GHz were made with the SEST bolometer, and recombination line and continuum observations at 99 GHz (H40α) and 147 GHz (H35α) were made with SIS receivers.
A simple model for growth of a planar hydrogenated carbon cluster under interstellar or circumstellar conditions
Authors: Pascoli G.
Published: July 2016

The physico-chemical origin of the hydrogenated carbon clusters (cumulenes, PAHs, graphite or amorphous carbon) in space is still an open question. We have worked out a numerical simulation code in order to build up planar (graphite-like) carbon clusters. We assume that hydrogen atoms can fix on the carbon skeleton following a random process allowing for H2 formation. The structures we have found are very complex. In a given cluster, several molecular entities can simultaneously be present: (sp2) carbon chains, rings or compact formations (aromatic structures or small PAHs). We argue that these very contorted hydrogenated structures could be ubiquitous in the interstellar medium, in carbon-rich circumstellar regions and in PNe.
Comparative intensity and density mapping of NGC 40
Authors: Ray Trina L. , Daub C. T.
Published: July 2016

Two dimensional spectro-imaging of the planetary nebula NGC 40 was done to create spatially resolved intensity and electron density images. The CCD images, taken in Hβ, [S ii] λ6717, and [S ii] λλ6717, 6731, were calibrated, then correlated using previously published spectroscopic and photometric data of NGC 40 as a flux standard.
Narrow-band imaging of NGC 7026
Authors: Robberto M. , Stanghellini M. , Ligori S. , Herbst T. M. , Thompson D.
Published: July 2016

NGC 7026 is one of the most remarkable bipolar planetary nebulae in the northern sky. There is an increasing interest in sources of this kind, as they indicate that anisotropic outflow phenomena play a significant role in the final evolutionary stages of massive stars. To investigate the spatial distribution of the excitation conditions in this nebula, and to get information about the structure of the progenitor's red giant wind, we started a multi-wawelength survey taking high spatial resolution line images in the visible, near and mid-infrared range using the Calar Alto and UKIRT telescopes. The instruments used are the STScI optical coronograph (Paresce & Burrows, ESO Messanger 47, 1987), the MAGIC IR camera (Herbst et al., SPIE Proc. N.1946, p.605, 1993), and the new MPIA thermal IR imager MAX. We present here some preliminary results, which allows us to estimate the main physical parameters of the central star, to find evidence for significant shock emission at the polar regions of the nebula, and to reveal an unexpected deficit of H2 emission.
Some new methods of time series analysis: Applications to the AGB stars
Authors: Andronov I. L.
Published: July 2016

Some supplementary methods of time series analysis are described which are used for study of periodic and aperiodic variability of the AGB stars. These are “multiharmonic fits” used to fit the periodic (asinusoidal) curve; running approximations – “parabolae”, “sines”; “asymptotic parabolae”; “linear fits”.
Masers: Probing the mass loss process in PPN
Authors: Engels Dieter
Published: July 2016

With the advent of the IRAS All-Sky Survey a sizeable number of transition objects between the AGB and the PN-phase were found - the Proto Planetary Nebulae (PPN). Oxygen-rich AGB stars often show prominent masers of SiO, H2O, and OH, which are lost during the transition process. The heavy mass loss on the AGB however does not stop abruptly and a new axisymmetric wind develops during the PPN phase. These winds both may host new masers and they can be used to study the changes of the mass loss process after that the stars have stopped their large-amplitude variations on the AGB. Several PPN are known to have OH masers, and at least in one case, HD 101584, the presence of a bipolar outflow could be proven (te Lintel Hekkert et al. 1992). Lewis (1989) found that main-line OH masers become prominent again. I will discuss here conclusions, which can be drawn from observations of H2O masers in PPN.
Mid-infrared imaging of post-AGB objects
Authors: Kömpe C. , Lehmann T. , Gürtler J. , Stecklum B. , Krügel E.
Published: July 2016

The evolution of low- and intermediate-mass stars (about 1 to 8 M⊙) from the asymptotic giant branch (AGB) to the planetary nebulae stage is characterized by intense stellar wind. AGB stars evolve on a very short time scale (several thousand years) via a phase, where the star is hidden from view by a dense dust shell, towards the post-AGB phase (an optically visible star surrounded by a cold dust/gas shell). The observational investigation of these shells is rather difficult due to their small angular extent. However, the resolution of current infrared telescopes is sufficient to resolve the warm dust of the inner part of the envelope.
Core-halo structures in the 12CO emission of CIT 6, AFGL 618 and IRAS 21282+5050
Authors: Meixner M. , Campbell M.T. , Welch W. J. , Likkel L. , Tafalla M.
Published: July 2016

We present full synthesis 12CO J= 1–0 line emission images of three carbon rich evolved stars: CIT 6, AFGL 618 and IRAS 21282+5050. Each of these objects represents a different stage of evolution: CIT 6 is a carbon star still on the AGB, AFGL 618 is a transition object, and IRAS 21282+5050 is a young planetary nebula. Common to all three sources, we find what appears to be two mass loss components: a bright “core” located at the center of the source and a fainter “halo” surrounding the core (see Table below for observed characteristics). We speculate that the bright core was created by a more recent and higher mass loss rate wind than the fainter surrounding halo. However, concrete support for this idea awaits radiative transfer modelling of the 12CO that we are currently pursuing. Our full synthesis data are combined from millimeter interferometry using the Berkeley–Illinois–Maryland millimeter array (BIMA) and single dish maps using the NRAO 12m. We find that full-synthesis imaging, which combines the sensitivity of single dish and the spatial resolution of interferometry, is the only means to reveal such core-halo structures.
Diffraction-limited speckle-masking observations of the Red Rectangle and IRC +10216 with the 6 m telescope
Authors: Osterbart R. , Balega Y. Y. , Weigelt G. , Langer N.
Published: July 2016

We present the first diffraction-limited speckle-masking observations of the bipolar nebula Red Rectangle and of the carbon star IRC+10216. Both objects were observed with the SAO 6 m telescope in the NIR (resolution 0″.092) and the Red Rectangle with the ESO/MPG 2.2 m telescope in the red (resolution 0″.087).
On the evolutionary status of the WR-type PNN
Authors: Tylenda R. , Górny S.K.
Published: July 2016

Some observed parameters of planetary nebulae with H–deficient (mostly WR–type) nuclei (PNN) are compared to those of H–rich ones and to theoretical predictions from the born again scenario. An example is shown in Fig. 1
Infrared observations of candidate post-AGB transition objects
Authors: Van de Steene G.C. , Van Hoof P.A.M.
Published: July 2016

In our search for new obscured PN, candidates were selected from the IRAS PSC based on their infrared colors that are typical for PN. These PN candidates were observed in the radio. On average 20 % of the objects were detected (Van de Steene & Pottasch: 1993, A&A 274, 895; 1995, A&A 299, 238). Optical spectroscopy showed that the PN candidates detected in the radio have emission line spectra typical of PN (Van de Steene et al. 1996a A&AS 118, 243; 1996b A&AS in press).
A late He-flash just in time for ISO?
Authors: Kerber F. , Gratl H. , Kimeswenger S. , Weinberger R. , Roth M. , Duffee B.
Published: July 2016

The peculiar new object (α2000 = 17h52m32.7s, δ2000 = −17°41′08″) in Sagittarius discovered by Y. Sakurai (IAU Circ. 6322 (1996)) first classified as a slow nova turned out to be a star experiencing a late He-flash. The only other examples in historical times are V605 Aql, the central star of A 58 in 1919 and possibly FG Sge. The extremely H-poor central nebulae in A 30 and A 78 are considered the remainder of late He-flashes that happened thousands of years ago.
Sakurai's object: spectroscopic monitoring and nebula observations
Authors: Pollacco D. L. , Walton N.A. , Schwarz H. G. , Bell S. A.
Published: July 2016

Sakurai's object is thought to be undergoing a final thermal pulse or shell flash. It is the first example of this type of object to be studied using modern instrumentation and will be useful and unique for the time being for placing theoretical models of these transient events on a firm observational footing. The only other definite candidate is V605 Aql – now the WC central star of the planetary nebula Abell 58 – which is thought to have undergone a final thermal pulse around 1918.
Abundance gradients from Planetary Nebulae in the galactic disk
Authors: Maciel W.J.
Published: July 2016

Radial abundance gradients in the disks of spiral galaxies are made evident from observations of ionized nebulae (HII regions, planetary nebulae, and SNRs) and stars. They have been observed for several chemical elements, and their presence is an established fact, despite some inconsistencies in the results. Therefore, these gradients can be considered as an additional constraint to the chemical evolution models, as the age-metallicity relation or the metallicity distribution of the G-dwarfs.
Vertical abundances variation in the galaxy: The case of PN
Authors: Cuisinier F. , Köppen J.
Published: July 2016

The vertical structure of the Galaxy is stratified in different populations. Gas and young stars have a low velocity dispersion (about 10 km/s) and thus are confined in a very thin disk (100 pc of scale height). Old stars have larger velocity dispersions, and are thus encountered up to a few kpc.
Formation rates of AGB stars and Planetary Nebulae
Authors: Ortiz R. , Maciel W. J.
Published: July 2016

We study the local population of AGB stars, and determine their densities and scale heights according to their masses, following the classification scheme proposed by Ortiz and Maciel (1994, A&A 287, 552), which discriminates the precursors of type I, II, and III planetary nebulae. The formation (or death) rates of AGB stars are determined by means of stellar evolution models, and are compared to the formation rates of planetary nebulae from the literature. A good agreement is found between these rates; however, the results are very sensitive to the adopted model, especially regarding the time spent at the thermal-pulse AGB phase.(FAPESP, CNPq)
Kinematics and dynamics of galactic systems as probed by Planetary Nebulae samples
Authors: Dejonghe H. , Vauterin P. , Van Caelenberg K. , Durand S. , Mathieu A.
Published: July 2016

At the current epoch, the dynamics of galactic systems is largely controlled by the behaviour of the stellar component. There is probably also a large amount of non-stellar matter present, which probably dominates the dynamics on large scales. Nevertheless, the (centers of) galaxies are still, for better or worse, defined as those regions were there happens to be a lot of stellar light.
Cosmological Parameters and the Evolution of the Universe: Progress and Prospects
Authors: Longair Malcolm S.
Published: July 2016

I have been invited by the organisers to provide an overall perspective on the subject of this Symposium. Necessarily, this will be a subjective impression of topics in which there has been quite remarkable progress since the last General Assembly of the IAU, and which are of the greatest interest for the whole of science. In preparing a review of such an enormous field, one veers between optimism and pessimism about the successes and problems which have arisen. I hope to steer a realistic course between these extremes. Fortunately, there are many experts participating in this Symposium who will be able to neutralise my personal biases and provide authoritative opinions on all the topics I will cover.
Measuring Cosmological Parameters with Very Long Baseline Interferometry
Authors: Gurvits L.I. , Kellermann K.I. , Frey S.
Published: July 2016

Very Long Baseline Interferometry (VLBI) allows us to study a core of AGN with a sub-parsec resolution. We analyze the dependencies “apparent angular size – redshift” and “apparent motion – redshift” which contain an imprint of the source's properties and cosmology. We present data on the “angular size – redshift” relation obtained with VLBI at 5 GHz on a sample of 300 AGN distributed over the widest available range of redshifts 0.016 ≤ z ≤ 4.5. The sample exceeds those used in similar studies earlier by Kellermann (1993, 79 sources) and Wilkinson et al. (1997, 160 sources). Unlike extended source, the angular size-redshift for compact radio sources appears consistent with the predictions of standard Friedmann world models with qo ≃ 0.5 without taking into account evolutionary effects or selection effects due to a “linear size – luminosity” or “linear size – spectral index” dependences. We discuss different approaches allowing us to disentangle intrinsic evolutionary properties of sources and parameters of the cosmological model. Recent estimates of parameters of the cosmological model are given. We also discuss a perspective of conclusive cosmological tests using the VLBI technique.
Theoretical Light Curves for Type Ia Supernovae and Determination of the Hubble Constant
Authors: Iwamoto Koichi , Nomoto Ken'Ichi
Published: July 2016

The large luminosity (MV ≈ −19 ∼ −20) and the homogeneity in light curves and spectra of Type Ia supernovae(SNe Ia) have led to their use as distance indicators ultimately to determine the Hubble constant (H0). However, an increasing number of the observed samples from intermediate- and high-z (z ∼ 0.1 − 1) SN Ia survey projects(Hamuy et al. 1996, Perlmutter et al. 1997) have shown that there is a significant dispersion in the maximum brightness (∼ 0.4 mag) and the brighter-slower correlation between the brightness and the postmaximum decline rate, which was first pointed out by Phillips(1993). By taking the correlation into account, Hamuy et al.(1996) gave an estimate of H0 within the error bars half as much as previous ones.
The Value of H0 from the TF Diameter Relation
Authors: Theureau G.
Published: July 2016

Our KLUN sample (6600 spirals) is presently the largest homogeneous catalogue for using the Tully-Fisher (TF) relation as distance indicator, to study both the Hubble constant and peculiar velocities at the scale of the local Universe up to z=0.025.
Extended Rees-Sciama Effect and Anisotropy of Cosmic Microwave Background Radiation
Authors: Wu X. , Xu C. , Brüning E.
Published: July 2016

The anisotropy of cosmic microwave background radiation (CMBR) was measured by COBE satellite (Smoot et al. 1992). Their remarkable results show a rms-normalized amplitude of (1.3 ± 0.4) ×10−5 on the scale of 10° with a thermal spectrum for CMBR quadrupole anisotropy. In near future a new generation of COBE, e.g. COBERAS or Planck (Lubin, 1997) would be lunched, the precision of which is 3–4 magnitude higher than nowaday COBE's. But the anisotropy can be explained in a different way, since a 10−5 anisotropy on scale of 10° might be caused by voids and supercluster (Blumenthal et al., 1992). The additional redshift from voids or supercluster is called Rees-Sciama effects.
A Revised Age for the z = 1.55 Galaxy LBDS 53W091
Authors: Bruzual Gustavo A. , Magris Gladis C.
Published: July 2016

Empirical evidence suggests that the stellar population in LBDS 53W091 is significantly younger than the dominant population in M32. We have used evolutionary population synthesis models to estimate the age of the dominant population in these stellar systems. The age of LBDS 53W091 is in the range from 1 to 2 Gyr and depends on the specific model. Older ages require sub-solar metallicity models. The estimates of the age of the dominant population in M32 range from 3 to 5 Gyr and depend not only on the model but also on the SED of this galaxy used in the fits. The same models predict an age of 11 to 13 Gyr for the stars in a typical old E/S0 galaxy. This age is consistent with the age of the metal-rich galactic bulge globular clusters NGC 6553, NGC 6528, and Terzan 5. Passive evolution seems an adequate scenario for the evolution of the stellar population in E galaxies from z = 1.6 to z = 0. The dominant population in M32 is genuinely young (3 to 5 Gyr), independently than an older stellar population may be present in this galaxy. Thus, M32 may not be representative of galaxies that evolve passively. The length of time for which these galaxies have existed as individual dynamical entities is not determined by our models. The age of the Λ = 0, Ω = 1 universe at z = 1.552 is 1.6h–1 Gyr. Hence, a 1 to 2 Gyr old galaxy at z = 1.552 poses no problem for this universe as long as h ≤ 0.8. In this universe, the 13 Gyr limit for the E/S0 galaxy at z = 0 requires h ≤ 0.5. The most likely reason for the difference between our age estimate of 1 to 2 Gyr for LBDS 53W091 and the value of 3.5 Gyr derived by Dunlop et al. (1996) and Spinrad et al. (1997), is the fact that these authors did not require that the population synthesis models that they used fitted simultaneously the UV break amplitudes and the observed R – J, R – H, and R – K colors of this galaxy. This will be discussed in detail elsewhere. We thank H. Spinrad, A. Dey, and D. Stern for kindly sending to us their remarkable spectrum of LBDS 53W091.
Formation and Evolution of Disk Galaxies
Authors: Firmani C. , Avila-Reese V.
Published: July 2016

We have developed a semianalitical approach to study galaxy formation and evolution in the cosmological context. Disk galaxies (dark matter halo+luminous disk) are considered to be formed through an extended process of gravitational collapse, whose character is determined by the statistical properties of the density fluctuation field assumed here to be Gaussian. Gas disks in centrifugal equilibrium within the collapsing dark halos are built up (detailed angular momentum conservation is assumed), and their galactic evolution is calculated with a model which consider all the gravitational interactions, the hydrodynamics of the ISM, and the SF process. A bulge as product of stellar disk gravitational instabilities is constructed. To study general behaviors a Gaussian σ8 = 1 SCDM model is used. For a given mass one obtains a range of dark matter configurations. The average case is in excellent agreement with results of cosmological N-body simulations. The slope of the mass-velocity relation agrees with the slope of the H- and I-band Tully-Fisher relations, but the velocities are too high. This problem dissapears if the power spectrum is renormalized to σ8 = 0.57, suggesting that the TF relation is result of the natural extension to galactic scales of the galaxy distribution power spectrum, and that on the basis of its origin are the cosmological initial conditions. The scatter on the mass-velocity relation is realistic. The models predict disk exponential surface brightness (SB) profiles, nearly flat rotation curves, and negative radial gradients in the B-V color. The obtained, gas fractions, B-V colors, central SBs μB0, bulge-to-disk (b/d) ratios, and rotation velocities (for σ8 = 0.57) are in agreement with observations, and their correlations are similar to those which define the Hubble sequence, including the LSB galaxies. These properties and correlations are the product of the combination of three fundamental physical factors: the mass, the mass aggregation history (MAH), and the initial angular momentum. The intensive properties are almost invariant to the mass, the MAH determines the B-V color, and the spin parameter λ mainly influences on μB0, and b/d ratio.
Fragmentation of the Primordial Gas Clouds
Authors: Uehara H. , Susa H. , Nishi R. , Yamada M. , Nakamura T.
Published: July 2016

We discuss the fragmentation of primordial gas clouds in the universe after decoupling. Comparing the timescale of collapse (tdyn) with that of fragmentation (tfrag), we obtained the minimum mass of a fragment analytically as following way.
The AAO 2DF QSO Redshift Survey
Authors: Boyle B.J. , Smith R.J. , Shanks T. , Croom S.M. , Miller L.
Published: July 2016

The study of large-scale structure through QSO clustering provides a potentially powerful route to determining the fundamental cosmological parameters of the Universe (see Croom & Shanks 1996). Unfortunately, previous QSO clustering studies have been limited by the relatively small sizes of homogeneous QSO catalogues that have been available. Although approximately 10,000 QSOs are now known (Veron-Cetty & Veron 1997), the largest catalogues suitable for clustering studies contain only 500–1000 QSOs (Boyle et al. 1990, Crampton et al. 1990, Hewett et al. 1994). Even combining all such suitable catalogues, the total number of QSOs which can be used for clustering studies is still only about 2000.
Determining Ω0 and λ0 from Cosmological Redshift Distortion of Galaxies and Quasars
Authors: Suto Yasushi
Published: July 2016

The three-dimensional distribution of galaxies in the redshift surveys differ from the true one since the distance to each galaxy cannot be determined by its redshift z only; for z ≪ 1 the peculiar velocity of galaxies, typically ∼ (100–1000)km/sec, contaminates the true recession velocity of the Hubble flow, while the true distance for objects at z ≳ 1 sensitively depends on the (unknown and thus assumed) cosmological parameters. This hampers the effort to understand the true distribution of large-scale structure of the universe. Nevertheless such redshift-space distortion effects are quite useful since through the detailed theoretical modeling, one can derive the peculiar velocity dispersions of galaxies as a function of separation, and also can infer the cosmological density parameter Ω0, the dimensionless cosmological constant λ0, and the spatial biasing factor b of galaxies and/or quasars, for instance. In this talk, I discuss the importance of such redshift distortion induced by the geometry of the universe, which summarizes the recent results of my collaborative work in this topic (Matsubara & Suto 1996; Nakamura, Matsubara, & Suto 1998; Magira, Matsubara, Jing, & Suto 1998).
Pancake Collapse and Structure Formation from CDM Density Fluctuations
Authors: Hosokawa T. , Yokosawa M.
Published: July 2016

Several scales' density fluctuations which exist in the early universe will first gravitationally collapse along one axis and make pancake-like structures. If the collapsed baryonic pancake heats up over 104K by shock formation, radiative cooling begins to work and mass accretion toward the central region will advance. Because of this effect, mass fraction of the high density layer becomes large. Densities and widths of the layers will reflect masses of structures (e.g. galaxy) which will be formed after caustics. In this respect, we assumed an Einstein-de Sitter universe dominated by cold dark matter (ΩDM = 0.9) and investigated the evolutions of fluctuations numerically using one-dimensional hydrodynamic plus N-body codes. We applied a new method for larger fluctuation scales; it is a hybrid method of Eulerian PPM and Zeldovich approximation and it can simulate around the central pancake region with high accuracy.