bluuebunny/crossref_metadata_2025 huggingface dataset:
ORFEUS observation of the central star of NGC 6543
Authors: Zweigle J. , Grewing M. , Barnstedt J. , Gölz M. , Gringel W. , Haas C. , Hopfensitz W. , Kappelmann N. , Krämer G. , Appenzeller I. , Krautter J. , Mandel H.
Published: July 2016

During the ORFEUS-SPAS (Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer on the Shuttle Pallet Satellite) mission STS-51, flown in September 1993, we observed the central star of the planetary nebula NGC 6543 in the far ultraviolet (90 nm to 115 nm) wavelength region using the University of California, Berkeley spectrometer with a spectral resolution of 0.03 nm.
The dynamics of Planetary Nebulae
Authors: Balick Bruce , Frank Adam
Published: July 2016

In this review we focus on new observations and theory that directly pertain to understanding the hydrodynamic evolution of planetary nebulae (PNe). The recent history of the field lead us to break the review into two parts, macroscopic and microscopic structures, since both the size scales and the dominant physics appear to cleave nicely into more-or-less distinct groups.
Multiple collimated outflows in the planetary nebula IC 4593?
Authors: Corradi Romano L.M. , Guerrero Martin , Manchado Arturo , Mampaso Antonio
Published: July 2016

Superb–seeing (0″ .40 FWHM) narrowband images and high resolution (R=60000) spectra of the asymmetrical planetary nebula IC 4593 have been used in order to study its detailed morphology and kinematics.
Airborne observations of far-infrared emission lines from the photodissociation regions in Planetary Nebulae: Properties and masses of the neutral components
Authors: Dinerstein Harriet L. , Haas Michael R. , Erickson Edwin F. , Werner Michael W.
Published: July 2016

Measurements of the main far-infrared cooling lines from photodissociation regions in planetary nebulae were obtained with NASA's Kuiper Airborne Observatory, using a moderate-resolution far-infrared cooled grating spectrometer (Erickson et al. 1985). We surveyed about 20 nebulae in the [O I] 63 μm line, and detected it in most of the observed objects. We found that its strength correlates well with the total far-infrared power, with an average ratio of about 0.2%, as predicted by models of photodissociation regions (e.g. Tielens & Hollenbach 1985; Wolfire et al. 1990). Strong 63 μm emission is absent only for objects in which the ionization of the gas is just beginning and for a few evolved objects where the ionized nebula is probably matter-bounded.
Observations of near-infrared H2 emission in Planetary Nebulae
Authors: Dinerstein Harriet L. , Crawford James
Published: July 2016

We report the results of a near-infrared (mostly K-band) spectroscopic survey of planetary nebulae at McDonald Observatory during the period 1986-1993. These observations were made with a grating spectrometer based on a 1 × 32-element InSb array. Most of the K-band observations were taken with spectral resolving power R = λ/Δλ = 600 in order to resolve the v=1-0 S(1) 2.121 μm H2 line from the adjacent recombination line of He I at 2.113 μm. We also simultaneously measured the strengths of H I Br γ and He II 2.189 μm. The typical limiting line flux detected in our 3.8″ beam was 1-3 × 10–14 erg cm–2 s–1, corresponding to a surface brightness of 3 × 10–5 to 1 × 10–4 erg cm–2 s–1 ster–1. An early result of this study was the first conclusive proof that the UV-pumping or “fluorescence” mechanism, rather than thermal (shock) excitation, is responsible for the H2 emission in a planetary nebula, Hubble 12 (Dinerstein et al. 1988, ApJ, 327, L27). This was also one of the first demonstrated cases of UV-pumped H2 emission in any astronomical source, and Hubble 12 has become a template for the study of this emission mechanism.
A rotating jet in the quadrupolar Planetary Nebula NGC 6881
Authors: Guerrero M. A. , Manchado A.
Published: July 2016

There is a renewed interest in the study of the possible precession of the central sources of planetary nebulae. Three different morphological features are considered the effect of precession:

1.

Point-symmetric PNe: Objects whose morphological components are symmetrical with respect to reflection through the center.

2.

Quadrupolar PNe: Characterized by two well-defined pairs of lobes which are symmetric, in pairs, with respect to two different axes. These PNe are very likely the result of two episodic nebular ejection processes, produced at different positions of the symmetry axis.

3.

Bipolar, rotating episodic jets (or BRET's): Spectacular structures (Lopez, Meaburn, & Palmer 1994) due to the precession of a symmetrical, collimated episodic outflow.
Near-IR emission line imaging of PN
Authors: Hodge T.M. , Woodward C.E. , Kelly D.M. , Fischer J. , Greenhouse M. A. , Satyapal S. , Smith H. A. , Pipher J. L. , Forrest W. J.
Published: July 2016

Spatial studies of the emission line regions in planetary nebulae (PN) can provide insight into the physical and chemical environments across the nebulae. In a collaborative effort by the coauthors, a K-band Fabry-Perot etalon has been coupled with an advanced 256 × 256 InSb focal plane array at the Wyoming Infrared Observatory 2.3m telescope. This system permits us to obtain spatially resolved, 0.24″/pixel, moderate spectral resolution (R ≈ 800), flux-density IR emission line images of astronomical sources. We obtained continuum-subtracted images of Br γ, HeI 2.06 μm, the 2-μm UIR features, and the 3.3 μm PAH dust feature in the PN NGC 6572, NGC 7027, and NGC 7662. One objective was to determine the spatial morphology of two unidentified emission lines, UIR1−2.199 μm, and UIR2−2.287 μm (Geballe et al. 1991). These UIR lines appear in the spectra of many PN (Hora et al. 1997) and in the Orion Nebula (Luhman & Rieke 1996). Geballe et al. suggested that the UIR lines are most likely forbidden transitions and showed that the parent ion ionization potential is ≈ 30–40 eV, while the ionization potential for the ions themselves is 40–60 eV. Here we directly compare the distribution of the UIR emitters to that of the gas (H+,He+) and dust (PAHs).
The ground-based leg for our ISO PNe: NIR-imaging
Authors: Kimeswenger S. , Kerber F. , Kienel C. , Roth M.
Published: July 2016

Two ISO projects of scientists in Innsbruck deal with spatially resolved investigations of planetary nebulae in the infrared. Imaging in the NIR (1.0–2.4μm) is not possible with ISO and the spatial resolution and the limiting flux of the new surveys (DeNIS and 2MASS) will be insufficient for most of our objects.
X-ray, EUV and infrared coronal-line radiation from Planetary Nebulae
Authors: Zhekov S. A. , Perinotto M.
Published: July 2016

The interacting stellar winds (ISW) theory (Kwok, S., Purton, C. R., Fitzgerald, P. M., 1978, ApJL, 219, L125) is nowadays widely accepted in the physics of Planetary Nebulae (PNe). It received much support from the observed fast winds in the central stars of PNe (CSPN), recognized to be a quite common phenomenon (e.g., Perinotto, M., 1993, in IAU Symp. No. 155, Planetary Nebulae, eds. R. Weinberger and A. Acker, Kluwer, Dordrecht, 57). Thus, the existance of a hot bubble in the PNe structure is a cornerstone of the ISW model. The high velocities (600–3500 km s–1) of the CSPN winds, are, according to the ISW model, directly responsible for an high gas temperature in the hot bubble, which is then expected to be the source of an extended X-ray and extreme ultraviolet (EUV) radiation. The PNe should also emit infrared coronal lines (IRCL) of highly ionized species since the high temperature plasma of the hot bubble is in contact with the much colder outer shell (optical PN) and the thermal conduction will produce a region of intermediate temperatures (5 × 105–106 K). A model considering the structure of the hot bubble in PNe with taking into account the thermal conductivity effects was present by Zhekov and Perinotto (1996, A&A, 309, 648).
Late stages of stellar evolution: Numerical tests on AGB models
Authors: Luridiana Valentina
Published: July 2016

We have calculated numerical models for intermediate mass stars, following the evolution from the MS to the AGB phase. The sequences have been obtained with the Göttingen hydrodynamical code. The Schwarzschild criterion for convection is used. Mass loss is modeled using the formula proposed by Blöcker:
The spectral evolution of post-AGB stars
Authors: Oudmaijer R. D. , van Hoof P.A.M. , Waters L.B.F.M.
Published: July 2016

We have performed a parameter study of the spectral evolution of a typical post-AGB star with particular emphasis on the evolution of the IRAS colours. The models are based on the latest evolutionary tracks by Blöcker (1995, A&A 297, 727 and A&A 299, 755), which are used to define the evolutionary rate and the mass loss history of the central star. The resulting model for the post-AGB star is then used to calculate the spectral evolution with the photo-ionization code CLOUDY (Ferland 1993, Univ. of Kentucky, Int. Report), which includes dust in the radiative transfer.
CCD photometry and spectroscopy of 14 IRAS sources having far-IR colours similar to Planetary Nebulae
Authors: Reddy B. E. , Parthasarathy M.
Published: July 2016

CCD imaging and BVRI photometry of 14 IRAS sources with far-IR colours similar to planetary nebulae and post-AGB stars are presented. Also results of optical and near-IR spectroscopy of 10 of these candidates are given. Based on the spectral energy distribution from 0.4 μm to 100 μm, the sample of program stars are put into two groups. The sources IRAS 08187-1905, IRAS 05238-0626 and IRAS 17086-2403 present similar flux distributions. These three sources have detached cold dust components with dust radii Rd ≈ 1000 R∗. The low infrared variability of theses sources suggests that the intense mass loss has been ceased. All three sources are at high galactic latitude (1>9°) suggesting that these are old low-mass evolved stars. In the IRAS colour-colour diagram of Likkel et al (1991) these sources fall in the region where most of the stars are evolved stars and PNe but without CO detection. This is consistent with at least one source IRAS 17086-2403, in which OH and CO molecular features are not detected. The far-IR excess, non-variability and high latitude of these objects suggest that these are post-AGB supergiants, slowly evolving towards planetary nebula phase.
A search for Planetary Nebulae around hot white dwarfs
Authors: Werner K. , Bagschik K. , Rauch T. , Napiwotzki R.
Published: July 2016

Time scales for post-AGB stellar evolution are still unclear. In order to study them it is useful to look for old PNe and compare nebula expansion and stellar evolutionary ages. We have selected very hot members from different white dwarf sub-classes. Many of them are objects recently discovered in the Hamburg-Schmidt Survey (Hagen et al. 1995). The sample includes three peculiar objects whose spectra show signatures of an extremely hot wind (≈ 106 K), namely absorption lines of ultra-high ionized metals, e.g. O VIII (Werner et al. 1995). A complete list is given in the table below. The search was performed by direct Hα narrow band imaging using a wide angle (20′ × 20′) CCD camera (WWFPP) attached to the Calar Alto 1.23m telescope (28.9.-3.10.1995).
The population of galactic Planetary Nebulae
Authors: Köppen J.
Published: July 2016

We report first results from a study comparing directly observable properties of Galactic planetary nebulae with synthetic models for the PN population. In this way we avoid problems such as deriving distances for individual PN.
Hubble Space Telescope observations of Planetary Nebulae in the Magellanic Clouds
Authors: Dopita M. A. , Wood P. R. , Meatheringham S. J. , Vassiliadis E. , Bohlin R. C. , Ford H. C. , Harrington J. P. , Stecher T. P. , Maran S. P.
Published: July 2016

We present the results of our major HST study of the evolution of PN in the Magellanic Clouds. This consists of imaging studies in [O III] and FOS UV spectroscopy. These data are then used in theoretical photoionisation models in conjuction with ground-based spectrophotometry, absolute flux and expansion velocity and density to derive self consistent diameters, ages, masses, and nebular abundances and to accurately place the central stars on the H-R Diagram. We find that observed sizes and ages can be reconciled with evolutionary theory provided that the He-burners outnumber the H-burners in the approximate ratio 2:1. For the LMC observed abundance patterns are qualitatively consistent with the (mass-dependent) operation of the various chemical dredge-up processes as predicted by theory. However, the observed dredge-up efficiencies do not agree with current theory. Finally, since core masses are determined with adequate precision, we are able to derive, for the first time, the metallicity age relation for of the LMC. We find that the base metallicity of the LMC rapidly increased ∼ 2 Gyr ago, consistent with the age of the burst of star formation inferred from field stars and clusters.
Physical parameters and chemical abundances of Planetary Nebulae in the large Magellanic Cloud
Authors: Reyes R. E. Carlos , Steiner J. E. , Elizalde F.
Published: July 2016

In the present work we have computed the physical parameters and chemical abundances for 45 planetary nebulae (PN) in the Large Magellanic Cloud (LMC) using the photoionization code CLOUDY, developed by Ferland (1993). CLOUDY is used as a subroutine in the code DIANA, developed by Elizalde & Steiner (1996), which minimises indices that measures the difference between the calculated and real nebula.
Formation of the SN1987A Ring due to magnetic pressure
Authors: Mori M. , Washimi H. , Shibata S.
Published: July 2016

Several weeks after the explosion of supernova (SN) SN1987A, the UV flash of the SN illuminated a ring-like structure in the circumstellar material at about 0.65 ly from the SN. The interaction between the stellar winds from the SN progenitor is considered to be the candidate for the formation of the circumstellar structure. In the case that the stellar winds are spherically symmetric, the interaction should result in a shell-like structure. However, Washimi, Shibata & Mori (1996) show that the magnetic field in the winds causes an anisotropy which leads to the formation of a ring-like structure. When the fast wind of the blue supergiant phase of the progenitor sweeps up the surrounding slow wind of the red-supergiant phase, the magnetic field as well as the wind material are piled up in the interaction region. Since the magnetic energy increases in proportion to the square of the amplitude, the magnetic field exhibits its effect prominently at the interaction region; due to the magnetic pressure force the material at lower latitudes is compressed into a ring-like structure. It is suggested that this magnetic process can also explain the newly observed pair of rings of the SN1987A nebula. We note that the idea of a magnetic field effect is consistent with the radio observation of a supernova remnant, detected by Staveley-Smith et al. (1992) at about 1200 days after the explosion. This radio emission is explained by the collision of the supernova blast wave with the shocked blue wind. This position corresponds to the averaged expansion speed of the supernova ejecta ∼ 0.08 ly which is consistent with the estimation by Shigeyama and Nomoto (1990). The estimated magnetic-energy density by the minimum-energy argument is ∼ 4 × 10–8f–4/7N m–2, where f is the fractional volume of the radiating acceleration region, suggesting a magnetic field of a few milli-Gauss or more (Chevalier 1992). This field intensity is consistent with an intensity of ≈ 2 · 10–4 Gauss obtained between the reverse shock and the contact surface shown, if one takes into account a further enhancement of the field due to the sweeping-up process by the supernova blast wave. When the SN ejector collides with the ring at the end of this century or at the beginning of the next one, we can also expect more intense radio emission at rather middle and high latitudes where the magnetic intensity is greater, rather than at the equator where the ring-like structure is located.
Theoretical models of the Planetary Nebula populations in galaxies
Authors: Richer M. G. , McCall M. L. , Arimoto N.
Published: July 2016

We consider the possibility of using bright planetary nebulae to study the chemical evolution of their parent galaxies. In particular, we would like to use planetary nebulae as abundance probes in galaxies where star formation ended long ago, such as ellipticals or the bulges of spirals, and in which no other direct probes exist. However, if we are to use planetary nebulae to study the chemical evolution of their parent galaxies, we must relate the oxygen abundance in bright planetary nebulae to the oxygen abundance in the interstellar medium when star formation stopped. Obviously, only theoretical modelling can provide this information once star formation has stopped.
The Linearity of the Cosmic Expansion Field and the Value of the Hubble Constant
Authors: Tammann G. A.
Published: July 2016

A linearity test shows H0 to decrease by 7% out to 18 000 km s–1. The value at 10 000 km s–1 is a good approximation to the mean value of H0 over very large scales. The construction of the extragalactic distance scale is discussed. Field galaxies, cluster distances relative to Virgo, and blue supernovae of type Ia yield H0 (cosmic) with increasing weight; they give consistently H0 = 57 ± 7 (external error). This value is supported by purely physical distance determinations (SZ effect, gravitational lenses, MWB fluctuations). Arguments for H0 > 70 are discussed and shown to be flawed.
Estimation of the Internal Extinction of Spiral Galaxies for Multi-color Tully-Fisher Relations
Authors: Watanabe Masaru , Yasuda Naoki
Published: July 2016

We calculate B-, R- and I-band internal extinction A(λ)i (absorption + scattering) for spirals consisting of an exponential dust layer, a stellar disk and a bulge. The result is applied to local calibrators and cluster spirals (Virgo and Ursa Major) to examine whether or not the wavelength dependence of the relative zero point difference of Tully-Fisher (TF) relations between for local calibrators and for cluster spirals (Pierce & Tully, 1992) could be accounted for by a variation of A(λ)i on the optical depth of galaxies. The extinction is calculated using Monte-Carlo simulations prescribed by Bianchi et al. (1996). For the extinction curve we adopted the one of Cardelli et al. (1989). It is found that a differential extinction A(R or I)i – A(B)i as a function of the optical depth σ(B) has finite upper limits of ∼ 0.3–0.5 mag, depending on an inclination of the spiral. These limits are generally smaller than the offset of the TF relative zero point difference. This indicates that the offset may be fully due to an intrinsic color difference between local calibrators and cluster galaxies, or else that the current extinction model is yet to realize a practical extinction process or geometrical configuration of spirals.
Current Status of the Cosmic Microwave Background Radiation
Authors: Partridge R. B.
Published: July 2016

My goal is to summarize our understanding of the cosmic microwave background radiation (CMBR) at this interesting moment after the detection of fluctuations in the background and before the next generation of satellite experiments. I begin by listing recent reviews and papers on the spectrum of the CMBR. I then sketch the current theoretical description of the power spectrum of fluctuations in the CMBR. Astronomical foregrounds and the nature of secondary fluctuations are treated next. Then I turn to observations, with special emphasis on the final results of the COBE–DMR experiment, on the growing evidence for ΔT/T = 2–3 × 10−5 fluctuations at degree scales, and on what they tell us about cosmological parameters.
The H–ΩO Diagram from Recent CMB Observations
Authors: Lineweaver C.H.
Published: July 2016

The CMB is already one of the pillars of the Big Bang model. However it may also become our most powerful tool to distinguish contending models and to determine their cosmological parameters. To realize this goal, more than 20 observational groups and two new satellites are gearing up to make precise measurements of the CMB at small angular scales. In such a situation it is important to keep track of what the CMB data can already say about cosmological parameters.

Current CMB data can already be used to constrain cosmological parameters. The results are model dependent. We have obtained contraints on Hubble's constant h and the density of the Universe Ωo in the context of open and critical density CDM models with Λ = 0. In critical density models we obtain h = 0.30+0.18−0.07. This low value is inconsistent with direct measurements of h but fully consistent with four other cosmological measurements: Big Bang nucleosynthesis, cluster baryonic fraction, age constraints from globular clusters and limits on the shape parameter Γ of matter power spectra (in Ωo = 1 models). If Ωo is left as a free parameter the constraints on h are less restrictive: h = 0.40+0.57−0.14. This is fully consistent with local h measurements and the four other cosmological measurements mentioned above. The best-fit density is Ωo = 0.85 and we set an upper limit of Ωo > 0.4 at ∼ 95% CL.

At this conference Ostriker has claimed that open-CDM models with Ωo ≈ 0.3 and h ≈ 0.70 are compatible with all current data. However our new CMB data analysis rules this model out at more than ∼ 4σ.
Ages of Giant Elliptical Galaxies as Evidence for the Cosmological Constant
Authors: Lee Young-Wook
Published: July 2016

There is a compelling evidence for old ages of giant elliptical galaxies, about 3 Gyrs older than our Galaxy, from space ultraviolet observations and new population synthesis models. Alternative interpretation requires ad-hoc assumptions yet it produces poor fitting to observational data. If confirmed by future space UV mission, this would provide evidence for non-zero cosmological constant from time scale test.
An ANN Approach to Classification of Galaxy Spectra for the 2DF Galaxy Redshift Survey
Authors: Folkes S.R. , Lahav O. , Maddox S.J.
Published: July 2016

We present a method for automated classification of galaxies with low signal-to-noise (S/N) spectra typical of redshift surveys. We develop spectral simulations based on the parameters for the 2dF Galaxy Redshift Survey and investigate the technique of Principal Component Analysis when applied to spectra of low S/N. It is found that the projection onto the first 8 Principal Components hold most of the real spectral information, with later projections only adding noise. Using these components as input, we train an Artificial Neural Network (ANN) to classify the noisy simulated spectra into morphological classes. We find that more than 90% of our sample of normal galaxies are correctly classified into one of five morphological classes for simulations at bJ=19.7.
CO Observations of High-z Objects
Authors: Ohta K. , Nakanishi K. , Akiyama M. , Takeuchi T.T. , Yamada T. , Shioya Y. , Kohno K. , Kawabe R. , Kuno N. , Nakai N.
Published: July 2016

We have made a CO (J=2−1) observation using the Nobeyama 45m telescope aimed at examining physical properties of the molecular gas in the object. Upper limit obtained is 1.8 mK (3σ) at a velocity resolution of 100 km s−1, which leads to an upper limit on the molecular gas mass of 5.3 × 1011M⊙, if we assume a line width of 250 km s−1 obtained in J = 5–4 line and the Galactic CO-to-H2 conversion factor of 4.5 M⊙ K km s−1 pc2. The line ratio between 2–1 line and 5–4 line as well as those from 7–6 and 4–3 lines (Omont et al. 1996) imply that the mean gas density is as high as 103–5 cm−3, which is comparable to that in nearby star burst galaxies (e.g., Solomon et al. 1992).
Color of Dwarf Galaxies in the Coma Cluster
Authors: Okamura S. , Komiyama Y. , Sekiguchi M. , Kashikawa N. , Shimasaku K. , Yagi M. , Doi M. , Yasuda N. , Kawasaki W. , Iye M. , Carter D. , Mobasher B.
Published: July 2016

We observed three 0.44 square degree fields centered on the Coma cluster center (Coma-1), about 1 degree SW of the Coma center (Coma-3), and on a control field in SA57 with the mosaic CCD camera at the prime focus of the 4.2-m William Herschel Telescope. We detected 5628, 5020, and 4323 galaxies down to R = 22 mag in Coma-1, Coma-3, and SA57 fields, respectively. We measure the magnitude and color within the variable aperture r90 in which about 90% of the total flux is included. The histograms of (B–R) colors of galaxies are made for four magnitude bins of width ΔR = 2 mag covering 13 < R < 21 mag for each of the three fields. The mean colors and the 1σ scatters of the Coma galaxies are obtained by a histogram subtraction technique (Coma-1/3 minus SA57). We find a very shallow slope of the color-magnitude relation (CMR), Δ(B–R)/ΔR=−0.0037, which indicates nearly a constant (B–R) color over 6 magnitude in 15 < R < 21 mag (−19.5 < MR < −13.5 at Coma cluster). Dwarf galaxies are dominant in this magnitude range, and we conclude that the mean color of dwarf galaxies in the Coma clusters is nearly constant at (B–R) ∼ 1.6–1.7, which is similar to the color of the faint end of giant elliptical galaxies.
Post-Newtonian Expansion of Gravitational Waves from a Particle in Circular Orbits around a Rotating Black Hole: Effects of Black Hole Absorption
Authors: Tagoshi Hideyuki , Mano Shuhei , Takasugi Eiichi
Published: July 2016

Coalescing compact binaries are the most promising candidates for detection by near-future, ground based laser interferometric detectors. It is very important to investigate detailed wave forms from coalescing compact binaries. When one (or two) of the stars is a black hole, some of those waves are absorbed by the black hole. Here, we consider a case when a test particle moves circular orbit on the equatorial plane around a Kerr black hole, and calculate the the energy absorption rate by the black hole. We adopt an analytic techniques for the Teukolsky equation which was found by Mano, Suzuki, and Takasugi (1996). We calculated the energy absorption rate to O((v/c)13) beyond the Newtonian-quadrupole formula of gravitational waves radiated to infinity, assuming v/c ≪ 1. Here v is the velocity of the particle. We find that, when a black hole is rotating, the black hole absorption appear at O((v/c)5) beyond the Newtonian-quadrapole formula. These effects become more important as the mass of the black hole becomes larger. We also found that the black hole absorption is more important when a particle moves to the same direction of the black hole rotation. All the details of this paper is presented in Tagoshi et al. (1997).
The Tully-Fisher Relation Using the CO-Line for Interacting Galaxies
Authors: Tutui Y. , Sofue Y.
Published: July 2016

The CO Tully-Fisher (TF) relation is able to measure the distances to farther galaxies than the HI TF relation reaches (Sofue et al. 1997). The galaxies observed for the CO TF relation at the high redshift are often infrared luminous galaxies. The fraction of interacting galaxies is large in the infrared luminous galaxies. Therefore, first we have analyzed the CO and HI linewidths for nearby interacting galaxies in order to examine the influence of the interaction on the linewidths. We found that HI linewidths for the interacting galaxies are significantly larger than CO (Tutui and Sofue 1997a). It suggests that the influence of the interaction is smaller at the inner region of galaxies where the CO gas exists, and that the CO TF relation is more reliable tool for the galaxies which have the evidence of the galaxy interaction as well as galaxies in rich clusters.
Regularity of the Large-Scale Structure of the Universe
Authors: Einasto J.
Published: July 2016

The observed structure of the Universe is hierarchical. Galaxies and clusters of galaxies are concentrated within elongated filamentary chains of various richness. High-density regions of the Universe form superclusters consisting of one or several clusters of galaxies and chains of galaxies surrounding and joining clusters. The space between filaments is void of galaxies. Superclusters and voids form a continuous network of alternating high- and low-density regions in the Universe.
X-Ray Study of Clusters of Galaxies with ASCA
Authors: Ohashi T.
Published: July 2016

X-ray emission from clusters of galaxies is the most useful tool in studying mass distribution and chemical compositions in these enormously large systems. The hot intracluster medium (ICM) has been heated up to kT = 3–10 keV during the gravitational collapse, and X-ray luminosities indicate that the gas is more massive than the total galaxy mass contained in clusters by factors of 3–5. This makes ICM the dominant form of baryons in the universe. In many clusters observations indicate that ICM is in a hydrostatic equilibrium within a potential governed by the dark matter, and the cooling time is longer than the Hubble time except for the bright centers. The ICM, therefore, enables us a close look at the structure of gravitational potential. At the same time, heavy-element abundances in the ICM and their distribution are used to estimate past supernova activities and metal injection mechanism in cluster space.
Tidal Torques Dynamical Friction and the Structure of Clusters of Galaxies
Authors: Del Popolo A. , Gambera M.
Published: July 2016

We study the joint effect of tidal torques and dynamical friction on the collapse of density peaks solving numerically the equations of motion of a shell of barionic matter falling into the central regions of a cluster of galaxies. We calculate the evolution of the expansion parameter, a(t), of the perturbation using a coefficient of dynamical friction ηcl obtained from a clustered system and taking into account the gravitational interaction of the quadrupole moment of the system with the tidal field of the matter of the neighboring proto-galaxies. We find that the tidal torques and the dynamical friction slow down the collapse of low-v (v < 3) peaks producing an observable variation of a(t) (Del Popolo & Gambera 1996,1997). As consequence we have a reduction of the mass bound to collapsed perturbations and a raising of the critical threshold, δc. Besides, we have a bias of dynamical nature arises because high-density peaks preferentially collapse to form halos within which visible objects. We calculate the selection function and using it and the prescriptions given by Bardeen et al. 1986 we find a value of the coefficient of bias, b = 2.25 on clusters scales for Rf = 4h–1Mpc comparable both with that obtained from the mean mass-to-light ratio of clusters, APM survey, or from N-body simulations combined with hydrodynamical models and with the values of b given by Kauffmann et al. 1996. This means that non-radial motions and dynamical friction play a significant role in determining the bias level.
Faint Structures in Low Density Regions of the Nearby Universe
Authors: Lindner U. , Fricke K.J. , Einasto J. , Einasto M.
Published: July 2016

We present an investigation of the galaxy distribution in the huge underdense region between the Hercules, Coma and Local Superclusters, the so-called Northern Local Void (NLV), using void statistics (for details refer to Lindner et al. this Volume). Reshift data for galaxies and poor clusters of galaxies are available in low and high density regions as well. Samples of galaxies with different morphological type and various luminosity limits have been studied separately and void catalogues have been compiled from three different luminosity limited galaxy samples for the first time. Voids have been found using the empty sphere method which has the potential to detect and describe subtle structures in the galaxy distribution. Our approach is complementary to most other methods usually used in Large–Scale Structure studies.
Kinematical Evolution of the Pairwise Velocity Field of Galaxies
Authors: Seto Naoki , Yokoyama Jun'ichi
Published: July 2016

It has been a long-standing cosmological issue to explain why the statistical distribution of the radial pairwise peculiar velocity of galaxies has an exponential shape rather than the Gaussian, as suggested by observations and explicitly shown by results of N-body simulations. Previous explanations on the exponential distribution are based on highly nonlinear dynamics of galactic systems (R < 1h–1 Mpc). That is, the exponential feature appears as a result of superposition of Gaussian velocity distributions in clumps with various velocity dispersions. Hence although this model is suitable to account for a symmetric exponential distribution with vanishing mean net relative velocity, a more elaborate treatment is necessary in order to reproduce an asymmetric exponential distribution with its peak at a negative relative velocity as observed in numerical simulations.
Anisotropies in Luminosity Distance
Authors: Sugiura Norimasa , Sugiyama Naoshi , Sasaki Misao
Published: July 2016

Anisotropies in luminosity distance-redshift relation (dL − z relation) caused by the large-scale structure (LSS) of the universe are studied. We solve the Raychaudhuri equation on FRW models taking account of LSS by the linear perturbation method. Numerical calculations to evaluate the amplitude of the anisotropies are done on flat models with cosmological constant and open models, employing Cold Dark Matter models and COBE-normalization for the power spectrum of the density perturbations.
Scale-Dependence of Bias from APM-BGC Sample
Authors: Fang L. Z. , Deng Z. G. , Xia X. Y.
Published: July 2016

Applying a discrete wavelet transformation (DWT)1 to the spiral (SP) and elliptical+lenticular (EL) galaxies in A PM bright galaxy catalog (APMBGC)2, we investigated the scale-dependence of bias parameter b in the linear bias model
Linear Evolution of Small Scale Cosmological Density Perturbations
Authors: Yamamoto K. , Sugiyama N. , Sato H.
Published: July 2016

We carefully re-examine the evolution of small scale cosmological perturbations, motivated from the studies of cosmic structure formation in the high-z universe. Under the assumption of the hierarchical clustering scenario, the evolution of density fluctuations on very small scales is especially important for the early formation of the bound objects such as population III stars or primordial sub-galaxies.
A Probe of Planck Energy Physics
Authors: Occhionero F. , Monastra S. , Baccigalupi C. , Amendo L.
Published: July 2016

Large scale voids are a very prominent feature in recent redshift surveys: here we attempt an explanation in terms of a first order phase transition occurring during the slow roll epoch of a two field inflation, a process where one field drives the slow roll while the other undergoes quantum tunneling through a potential barrier. The ensuing bubble like perturbations – nucleated at a number of e-folds N ≈ 55 before reheating – are thought to be the precursors of the voids we observe today, while the zero-point fluctuations of the inflaton are the small, Gaussian perturbations seen by COBE on the large angular scales.

If this is so, primordial bubbles must have left a trace on the CMB, unless Silk damping and/or early reionization have erased it. We predict this imprint to have power on small angular scales, ≈ 10 arcmin or ≈ ≈ 1000. Therefore the physics at the Planck energy may be tested astronomically both indirectly through the large scale structure and directly through the forthcoming high resolution MAP and Planck satellites.
One Bubble Inflation
Authors: Tanaka Takahiro
Published: July 2016

Evaluating the temperature fluctuation in the cosmic microwave background radiation, the viability of the one bubble inflation scenario is studied. It is shown that it is possible to construct a model which explains the creation of an open universe.
3D NLTE Radiative Transfer - Current Status and Future Prospects
Authors: Carlsson Mats
Published: July 2016

The current status and future prospects for methods of 3D NLTE radiative transfer are reviewed. Scaling properties and parallelization issues are discussed. Codes of today are capable of solving the diagnostic problem (given model atmosphere) with atomic models of 20-100 levels making possible detailed 3D NLTE determinations of abundances employing 3D LTE model atmospheres. Calculating consistent 3D NLTE radiation hydrodynamic models is orders of magnitude more demanding computationally but methods exist that give a reasonably correct description of the radiation interactions in a statistical sense.
NLTE Radiative Transfer and Model Atmospheres of Hot Stars
Authors: Werner Klaus
Published: July 2016

We describe our method to construct line blanketed NLTE model atmospheres for hot stars. We employ the Accelerated Lambda Iteration and use statistical methods to deal with metal line blanketing.
Energy Transport, Overshoot, and Mixing in the Atmospheres of Very Cool Stars
Authors: Ludwig Hans-Günter
Published: July 2016

We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows to study processes usually not accessible within the framework of conventional model atmospheres. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency expressed in terms of an equivalent mixing-length parameter amounts to values around ≈ 2 in the optically thick, and ≈ 2.8 in the optically thin regime. The thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e. stays close to radiative equilibrium. Mixing by convective overshoot shows an exponential decline with geometrical distance from the Schwarzschild stability boundary. The scale height of the decline varies with gravitational acceleration roughly as g–1/2, with 0.5 pressure scale heights at log g=5.0.
Modelling Stellar Magnetoconvection
Authors: Weiss N. O.
Published: July 2016

This review focuses on different patterns of magnetoconvection and on aspects of flux expulsion, flux separation and flux pumping. The transition between magnetoconvection and small-scale dynamo action will be described and the rôle of rotation in leading to large-scale dynamo action will be emphasized. An attempt will be made to relate the results of numerical experiments to magnetic features that can be observed on the Sun, and must also be present in other late-type stars.
Simulation of Solar Magnetoconvection
Authors: Vögler A. , Shelyag S. , Schüssler M. , Cattaneo F. , Emonet T. , Linde T.
Published: July 2016

We present a new 3D MHD code for the simulation of solar magnetoconvection. The code is designed for use on parallel computers and in the choice of methods emphasis has been laid on efficient parallelization. We give a description of the numerical methods and discuss the non-local and non-grey treatment of the radiative transfer. Test calculations underlining the importance of non-grey effects and first results of the simulation of a solar plage region are shown.
Helical Surface Structures
Authors: Brandenburg Axel , Blackman Eric G.
Published: July 2016

Over the past few years there has been growing interest in helical magnetic field structures seen at the solar surface, in coronal mass ejections, as well as in the solar wind. Although there is a great deal of randomness in the data, on average the extended structures are mostly left-handed on the northern hemisphere and right-handed on the southern. Surface field structures are also classified as dextral (= right bearing) and sinistral (= left bearing) occurring preferentially in the northern and southern hemispheres respectively. Of particular interest here is a quantitative measurement of the associated emergence rates of helical structures, which translate to magnetic helicity fluxes. In this review, we give a brief survey of what has been found so far and what is expected based on models. Particular emphasis is put on the scale dependence of the associated fields and an attempt is made to estimate the helicity flux of the mean field vs. fluctuating field.
Round Table Summary: Stellar Interferometry as a Tool to Investigate Atmospheres and to Compare Observations with Models
Authors: Wittkowski Markus
Published: July 2016

Long-baseline interferometry at optical and near-infrared wavelengths is an emerging technology which is quickly becoming a useful tool to investigate stellar atmospheres and to compare observations with models. Stellar atmosphere models have so far mainly been constrained by comparisons with stellar spectra which are integrated over the stellar disks. Interferometric observations provide spatially and spectrally resolved information and can thus provide important complementary observational information which can be compared to model predictions. Here, I summarize the different aspects on this topic which were discussed at a round table on Thursday, June 20, 2002, during IAU Symposium 210. This summary gives an overview on discussed interferometric facilities and techniques, concepts to study atmospheres by optical interferometry, and particular classes of objects. We conclude that more frequent interactions between the efforts of atmosphere modelling and interferometric observations promise to lead to increased confidence in stellar model atmospheres and to further advancement of the field in the next years.
The Photometric and Spectral Variability of the Planetary Nebula IC 4997
Authors: Kostyakova E.B.
Published: July 2016

Among the planetary nebulae showing noticeable long-time variations of brightness (see our foregoing contributed paper; Astron. Circ. USSR, No. 1430, 3, 1986, and earlier publications) the young stellar planetary IC 4997 is the most prominent. Our photoelectric observations revealed its rather surprising behaviour. During 1968–85 its total UBV-brightness was monotonously decreasing, especially in filter V: the reduction of the value Δv amounted ∼ 0m.5–0m.6. The colour indices of the planetary showed that during the observation period the object as a whole, became definitely bluer. In 1985–86 our observations revealed an unexpected stop of mentioned brightness decrease, but in 1987 the object appeared to start brightening.
The Shapes and Shaping of Planetary Nebulae
Authors: Balick Bruce
Published: July 2016

One of the most striking attributes of planetary nebulae are their complex, yet highly symmetric shapes. The process(es) which shape planetaries are only beginning to be understood. It is proposed that the morphologies of most PNs can be understood within the context of the “interacting winds” wherein a fast but light wind driven by the nucleus rams into an older, slower, and more massive wind, or red giant envelope (“RGE”) ejected earlier.

In order to explain the shapes of noncircular PNs, it seems necessary to hypothesize that the slow wind was originally ejected with an enhanced density along an equatorial plane. The morphologies of nearly all PNs can be understood through two basic parameters: the equatorial density contrast in their RGEs, and the degree of interaction between the fast and slow winds.
Abundances in Planetary Nebulae
Authors: Clegg R.E.S.
Published: July 2016

Good progress has been made since the last Symposium on the determination of planetary nebulae (PN) abundances. Notable features for modern abundance determinations include the availability of good collision strengths and transition probabilities (reviewed by C. Mendoza (1983) at the last meeting - IAU Symp.103), the use of the IUE & IRAS satellites to obtain UV & IR line fluxes, and the availability of modern sensitive detectors enabling measurements both of faint extra galactic nebulae and of very weak abundance-indicator lines in nearby bright nebulae. The impact of IUE on PN studies was described by Köppen & Aller (1987).
CCD Images of Selected Planetary Nebulae
Authors: Turatto M. , Cappellaro E. , Sabbadin F.
Published: July 2016

Direct interference filter CCD frames of a number of northern planetary nebulae were obtained at the Cassegrain focus of the 182-cm telescope of Asiago Astrophysical Observatory (Italy).
Collimated Outflows in Planetary Nebulae
Authors: Balick Bruce , Preston Heather L. , Icke Vincent
Published: July 2016

The kinematics of the gas motions in several e-m E planetary nebulae (PNs) have been mapped with ∼ 1 - 2″ resolution. All of the eE PNs (e.g., NGC 2392, 3242, 6543, 6826, 7009, and 7662) show evidence of highly focused linear flows at projected velocities of 20 - 170 km s−1. The flows generally appear as linear, almost jet-like features in emission lines of low ionization. mE PNs show expanding protuberances along their polar axes.
The Structure and Velocity Field of A78
Authors: Pismis P. , Moreno M. A.
Published: July 2016

We present a velocity field of the planetary nebula A78 based on three Fabry Pérot Hα (10A) interferograms taken with a focal reducer attached to the 2.1 m reflector of the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico. We have used a single-stage Varo image intensifier and two different étalons with interorder separations of 283 km s−1 (2 interf.) and 100 km s−1 (1 interf.). The scale of the original photographs is 49 arcsec mm−1. Our data have yielded radial velocities in the Hα line at 110 points on the face of A78; the velocity field is far from being smooth. The rings are wide around the central hole, and a few show definite splittings; from these splittings we have estimated an overall expansion velocity of 27 km s−1. The average systemic velocity is found to be around −3 km s−1.
High Velocity Outflows in Post-Main Sequence Nebulae
Authors: Phillips J. P. , Mampaso A.
Published: July 2016

We have observed a broad range of post-main-sequence, type I and irregular nebulae using the intermediate dispersion spectrograph of the Isaac Newton Telescope (La Palma, Spain). Many of these show evidence for high velocity mass outflow, and in particular we find: (i) High velocity (∼ 500 km s−1), and appreciable mass loss outflows within ≅ 10 arcsecs of M2-9 and SH 2-71; (ii) Substantial shell expansion velocities in NGC 7026 (∼ 102 km s−1) with evidence for an appreciable driving wind at the central star, velocity ≅ 103 km s−1; (iii) Jet outflows extending over a range 260 km s−1 in Hb 5, with a distinctly tilted line structure suggestive of shock compression at the edges of an outflow cavity; and finally (iv) similarly strong winds (2 × 10 km s−1) from each member of a WC binary in the nucleus of NGC 6905. The binary separation is approximately 3.6 arcseconds, and the core is further enveloped by two, apparently co-spatial shells, expansion velocity 90 km s−1, and separation ΔV ≅ 130 km s−1. The [N II] emission for the shells is extraordinarily weak, although ansae located outside of the shells, and perpendicular to the binary major axis, possess I([N II]λ6584) > I(HIλ6563). We propose that the two shells were ejected at differing phases of binary evolution.
The Dust Content of Planetary Nebulae with Neutral Halos
Authors: Hoare M. G.
Published: July 2016

Young planetary nebulae (PN) which are still optically thick in the Lyman continuum can have a large fraction of material in neutral halos surrounding the ionized zone. The cool dust in the neutral region can make a significant contribution to the far infrared flux, reducing the derived dust-to-gas ratio. This is important when attempting to understand the apparent decrease in dust-to-gas ratio with nebular radius (age) suggested by Pottasch et al. (1984).
Spatially Resolved Observations of the Unidentified Dust Features in BD +30°3639
Authors: Smith C. H. , Aitken D. K. , Roche P. F.
Published: July 2016

High resolution spatial scans through the planetary nebula BD +30°3639 have been made with the UCL cooled grating spectrometer at the IRTF. A spectral resolution of λ/Δλ = 50 was sufficient to resolve the unidentified dust features at 8.6 and 11.3 μm and separate them from the continuum emission. The scans were made in .7 arcsec steps across the nebula with a 1.8 arcsec diameter beam.