bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward understanding nucleosynthesis patterns in intermediate-mass stars: C, S, and Ar in PNe
Authors: Henry R.B.C. , Kwitter K. B. , Buell J.
Published: July 2016

We report on our project to re-evaluate carbon and other abundances in PNe spanning the expected PN progenitor mass range. The ultimate goal of this work is three-fold: (i) to determine the abundance of carbon in this sample; (ii) to assess the abundances of sulfur and argon as metallicity indicators in intermediate-mass stars; and (iii) to incorporate our metallicity results into stellar evolution models to predict nucleosynthesis yields as a function of mass and metallicity.
Observations of gas and dust in compact Planetary Nebulae by imaging and long slit spectroscopy at λ ≈ 10μm
Authors: Käufl H.U. , Stanghellini L.
Published: July 2016

A variety of compact nebulae was observed to retrieve the morphology in the light of infrared recombination lines ([Siv] at λ = 10.5μm and [Neii] at λ = 12.8μm) using TIMMI, ESO's focal reducer for the thermal infrared at the 3.6m telescope (Käufl et al. 1994). Compared to optical images in some cases striking differences are found. It should be noted that the dust in nearly all PNs is transparent at λ ≈ 10μm even if there is substantial extinction in the optical (λ ≤ 1μm). As compared to space based infrared platforms (IRAS and ISO) our observations have lower sensitivity but sub-arcsec spatial resolution. In some cases the data allow also to assess the relative spatial distribution of dust and gas.
Physical conditions in NGC 6543
Authors: Lame Nancy Jo , Harrington J. Patrick , Borkowski K.
Published: July 2016

We observed NGC 6543 (the Cat's Eye Nebula) with the HST WFPC2 camera in ten narrow-band filters covering a range of emission lines. These images are used to further look at the physical conditions in NGC 6543. We discuss the [O III] electron temperature, ionization state throughout the nebula, and the results of photoionization models of individual structures.
The kinematics of the extensive bipolar lobes and symmetric knots of the Planetary Nebula KjPn 8 (PK 112-001)
Authors: López J. A. , Meaburn J. , Bryce M. , Rodríguez L. F.
Published: July 2016

Spatially resolved profiles of the Hα, and [NII] lines have been obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope over the bipolar lobes, the symmetric low ionization knots and the bright core of the planetary nebula KjPn 8. The lobes of this galactic bipolar nebula have the largest angular extent, 14′ × 4′, yet discovered.
Theoretical abundances in Planetary Nebulae
Authors: Marigo Paola
Published: July 2016

A semi-analytical model has been constructed to calculate the TP-AGB evolution of low-and intermediate-mass stars (Marigo et al. 1996), starting from the first thermal pulse until the complete ejection of the envelope by stellar winds. We estimate the changes in the chemical composition of the envelope due to different processes: (i) the intershell nucleosynthesis and convective dredge-up; (ii) envelope burning in the most massive AGB stars (M ≥ 3–4M⊙); (iii) mass loss by stellar winds.
The identification of the O V forbidden line in the ultraviolet spectrum of gaseous nebulae
Authors: McKenna F.C. , Keenan F. P. , Aller L. H. , Hyung S. , Feibelman W. A. , Berrington K. A. , Fleming J.
Published: July 2016

The 2s21S0–2s2p 3P1 intercombination line at 1218.34 Å of Be-like O V has been observed in IUE spectra of gaseous nebulae such as RR Tel (Doschek & Feibelman 1993). However, the forbidden line at 1213 Å has not been detected to date in any astrophysical object, with the possible exception of the Sun, where Sandlin, Brueckner & Tousey (1977) very tentatively identify the line at 1213.90 Å in an off-limb spectrum.
Temperature variations in PN hydro models
Authors: Mellema Garrelt
Published: July 2016

The are often inconsistencies between the results of different methods for deriving electron temperatures from line strengths in PNe. Temperatures derived from forbidden lines ratios such as [OIII]4363/5007, are on average higher than those calculated from permitted lines. This is normally explained by assuming the existence of areas of higher temperatures which have more weight in a forbidden line analysis, the so-called ‘temperature fluctuations’. The magnitude of these fluctuations is expressed by the t2 parameter. See Peimbert (1967). A typical value is about 0.03, corresponding to fluctuations of ∼ 10%. Photoionization models have difficulty in explaining fluctuations of this magnitude (Kingdon & Ferland 1995).
Rapid evolution and nebula formation
Authors: Mellema Garrelt
Published: July 2016

The formation of a Planetary Nebula is determined by the star which lives and evolves in the middle of it. The star produces both the winds and the photons which determine the shape and appearance of the nebula. Here I study how the shape of the PN depends on the stellar properties.
A possible stellar interaction with NGC 246
Authors: Miller Grant J.
Published: July 2016

The planetary nebula NGC 246 has a high degree of symmetry about its central star, and can be described most graphically as a filled disk. Direct images of NGC 246 reveal a relatively homogeneous distribution of gases, with an unusual morphological feature that appears to contain less of the nebular material. At the center of this roughly circular feature, in the southeast quadrant of the nebula, there is a star (hereafter referred to as “the program star”). The placement of the program star is very suggestive of a wind blown cavity in the PN. The question of whether this star actually is interacting with the nebula, or merely along the line-of-sight, is addressed here for the first time.
The neutral shells of Planetary Nebulae
Authors: Natta Antonella , Hollenbach David
Published: July 2016

Recent observations of a number of molecular lines, among them the H2 2μm vibrational transitions, have clearly shown that in many planetary nebulae (PNe) a significant component of the eject mass is neutral.
Spectrophotometric studies of Planetary Nebulae with [WR] central stars
Authors: Peña M. , Stasińska G. , Esteban C. , Kingsburgh R. , Koesterke L. , Medina S. , González R. , Ruiz M. T.
Published: July 2016

We present the first results of a project on PNe with [WR] nuclei whose aim is twofold. One is to search for possible spatial abundance variations inside the nebula. The other is to check whether, for each object, one can build a self-consistent photoionization model (with the code PHOTO, Stasińska 1990, A&AS, 83, 501) using, as an input, the ionizing radiation field from an expanding model atmosphere reproducing the observed stellar lines of He, C and O (Koesterke et al., these proceedings).
Ionisation Structure of NGC 6543
Authors: Pérez E. , Cuesta L. , Axon D. , Robinson A.
Published: July 2016

We have obtained high spectral resolution, high signal-to-noise ratio longslit spectra of a sample of Planetary Nebulae with the purpose of studying their physical conditions, chemical composition and ionisation structure. In particular, we are interested in disentangling the effects of radiation and shock ionisation.
The strength of the low-ionization emission lines in Type I PNe
Authors: Riera A.
Published: July 2016

I have performed a statistical analysis on a group of emission line ratios of a sample of PNe. The optical data was taken from ELCAT2 Catalogue (http://www.stsci.edu/pub/elcat). Some observations of H–H objects were also included for comparison.
Abundances variations in PNe: Real or Illusory?
Authors: Riera A. , Balick B. , Mellema G. , Xilouris K. , Terzian Y.
Published: July 2016

In order to study the putative enrichment within a PN, we have undertaken deep long-slit spectroscopic observations of selected targets in which we expected to find clear evidence of abundance gradients. The targets include NGC 3242: one of the PNs studied by Balick et al. (1994) in which they report N/H enhancements of ∼ 5 in each FLIER; M1-18, M1-8, M3-3, NGC 6537 and Hubble 5. The observations were obtained at the 5-m Hale Telescope of the Palomar Observatory.
HST FOS spectroscopy of M2-29 and DDDM-1
Authors: Torres-Peimbert S. , Dufour R. J. , Peimbert M. , Peña M.
Published: July 2016

The halo planetary nebulae are of special interest insofar as the sample is very limited and they show a wide range of nebular chemical properties. We are interested in deriving their detailed nebular properties and to try to determine the characteristics of their progenitor stars. We selected M2-29 and DDDM-1 since they are the most deficient in Ar and S of their group. During HST Cycle 3 we obtained WFC1 direct imagery in Hα of them to derive information on their morphology and surface brightness for performing FOS spectroscopy.
Radio continuum and long-slit optical spectroscopy of the Planetary Nebulae Cn 3-1 and M 3-27
Authors: Vázquez R. , Miranda L. F. , Torrelles J. M. , Eiroa C. , López J.A.
Published: July 2016

Long-slit optical spectroscopy and VLA-B radio continuum (λ = 3.6 cm) observations toward the compact planetary nebulae Cn 3-1 and M 3-27 are presented. Optical spectra were taken at different position angles (PAs) with the 2.2 m telescope at Calar Alto (Spain), covering the range from 6549 to 6751 Å. The radio and optical data show that the ionized shell of Cn 3-1 is an ellipsoid (size ≃ 6″ × 5″, PA ≃ 72°) containing a bright ring-like equatorial zone (size ≃ 2″.6, expansion velocity ≃ 14 km s–1) and two bright point-symmetric arcs, extending from the equator towards the polar regions of the ellipsoid (Fig. 1). These arcs seem to be filamentary structures embedded in the ellipsoid. An ionized stellar wind has been detected through faint extended wings in the Hα (≃ 660 km s–1) and [N II] (≃ 460 km s–1) emission lines. M 3-27 is unresolved at 3.6 cm (size ≤ 0″6). The detected [N II] and [S II] emission lines arise in a compact (≤ 1″4) probably non-spherical region which is identified with the ionized shell of M 3-27. The Hα emission from M 3-27 is dominated by strong emission from an ionized stellar wind and exhibits a Type III P Cygni profile with very extended wings (≃ 3000 km s–1). The estimated kinematic age and ionized mass of Cn 3-1 (≃ 1300 yr, 4 × 10–2 M⊙) and M 3-27 (≤ 530 yr, ≃ 3 × 10–4 M⊙) indicate that both objects are young planetary nebulae. Extended halos (size ≃ 36″ in Cn 3-1, ≃ 24″ in M 3-27) have been spectroscopically detected in both objects. An analysis of the kinematic and emission properties shows that both halos are reflection nebulosities and suggests that the distribution of neutral material in them probably is largely isotropic. The results suggest that the halos correspond to isotropic mass ejections occurred in the last ≃ 2 × 104 yr of the AGB phase of the Cn 3-1 and M 3-27 progenitors.
Ca and dust in Planetary Nebulae
Authors: Volk Kevin , Dinerstein Harriet , Sneden Chris
Published: July 2016

Under nebular conditions it is expected that the [CaII] lines at 7291.470 and 7323.880 Å should be among the strongest emission lines in the red part of the optical spectrum unless the nebula is matter bounded. The lines are observed in novae, supernovae and some symbiotic systems but the only observation of these lines in planetary nebulae (PN) is for AFGL 618 where the lines are thought to be shock-excited. While higher ionization states of Ca do produce some lines observed in a few high-excitation PN, from which gas-phase Ca abundances averaging to about 5% of solar are found, the CaII lines are not observed even in PN with massive neutral envelopes such as NGC 7027. If the Ca is depleted onto dust grains it would explain the absence of the CaII lines. However it is thought that the dust is destroyed with time in the ionized region. Any observation of the CaII lines would produce better abundance estimates and would test the extent of dust destruction that is taking place in the outer parts of the PN.
Modelling the expansion of NGC 7027
Authors: Walsh J. R. , Dudziak G. , Walton N. A.
Published: July 2016

The high angular resolution and dynamic range of VLA radio continuum mapping of planetary nebulae has raised expansion parallax measurement to the most sensitive method for determining PN distances (Hajian et al 1995). In order to derive the distance, the proper motion in the plane of the sky must be compared to the expansion velocity measured from emission line profiles. For a spherical PN with a measured line of sight expansion velocity, the comparison is simple. However most PN are not spherical, and their axisymmetric structures may be tilted to the line of sight; the line of sight expansion velocity cannot therefore be used for distance estimation from expansion proper motion. 3-D kinematic modelling is required in order to determine the expansion velocity in the plane of the sky.
An imaging and spectroscopic survey of the Abell Planetary Nebulae
Authors: Walton N. A. , Walsh J. R. , Dudziak G.
Published: July 2016

The Abell catalogue of planetary nebulae (PN) are distinguished by their large size, low surface brightness and generally faint central stars. They are thought to be old PN approaching the White Dwarf cooling track. A number have evidence for late thermal pulses (H-poor ejecta near the central star, e.g. A78) and binary central stars.
High velocity collimated flow in a Halo Planetary Nebula, H 4-1
Authors: Yadoumaru Y. , Tajitsu A. , Tamura S.
Published: July 2016

H 4-1, PNG 049.3+88.1 (α = 12h59m27.6s, δ = +27° 38′14″, 2000), was one of well known halo Planetary Nebulae (PNe). During our program to study the expanding characteristics of PNe, the long-slit spectroscopic observations were made by the cassegrain spectrograph of the 74 inch telescope at the Okayama Astrophysical Observatory in March 1995.
Chemical abundances and metallicity of Planetary Nebulae
Authors: Zhang C. Y. , Kwok S.
Published: July 2016

Confrontations of the dredge-up theory with observed patterns of chemical abundances of planetary nebulae (PNs) have been carried out by many authors (see, e.g., Kaler & Jacoby 1990, 1991; Stasińska & Tylenda 1990). Although these studies suggest that the observational abundance ratios of PNs can qualitatively be explained by the current dredge-up theory, scatters around the theoretical predictions in their diagrams are always large. This has led Ratag (1991) to conclude that there is no correlation at all between the nebular abundances and the core mass of CSPNs (see also Pottasch 1993).
Millimeter-wave interferometry of Proto-Planetary Nebulae
Authors: Dayal A. , Bieging J. H. , Bergman P.
Published: July 2016

We have observed 2 compact PPNe, AFGL 2343 and IRAS 22272+5435, in the CO J=1-0 transition using the Owens Valley interferometer (OVRO), and the NRAO 12-meter telescope. Our observations were made in the low and intermediate resolution configurations of the interferometer and we obtain a synthesized beam (HPBW) of ≃ 4″. We are now modelling both sources using statistical equilibrium/radiative transfer codes. Our objectives are to a) map the distribution and kinematics of the molecular gas at high angular resolution and b) estimate the physical conditions (mass loss rate, temperature, density) in the molecular envelopes, through our models.
IR and masing properties of bright IRAS sources
Authors: Lewis B. M.
Published: July 2016

Comparisons between color-color diagrams of OH/IR stars with/out IR flux and/or galactic position constraints show that little of the color dispersion is innate: the most precise colors come from high flux samples away from the Galactic Center. It is advantageous to delineate the color range of O-rich shells by only color selecting objects in the IRAS Point Source Catalog (PSC) with S(25) > 100 Jy, which yields 333 objects. All but 2 of these have published LRS spectra, which often suffice to determine whether an object is carbon or oxygen rich. About 80% of them have been searched for 1612 MHz masers, and ≈70% for SiO, water and/or mainline OH masers. As bright objects, most “oddballs” have been investigated at other wavelengths too. This data, together with information gleaned from a SIMBAD search, was then used to distinguish emission-line, T Tauri and carbon stars from the predominent residuum of O-rich shells.
Kinematics and dust scattering in IRAS 09371+1212
Authors: Phillips J.R. , Cuesta L.
Published: July 2016

We have observed IRAS 09371+1212 using both narrow and broad band filters. As a result, we note that relative color trends B-V/V-R appear to be inconsistent with both the mean IS reddening law, and the variation deduced for model grains (Robinson et al, 1992). There also appears to be a disparity in the B-V/V-R reddening gradient as between the inner and outer source envelopes—a characteristic which, together with other evidence, may indicate a corresponding evolution in grain properties.
Phase-referenced VLBI observations of the OH masers around U Her
Authors: Van Langevelde Huib Jan , Brauher James , Diamond Philip J. , Schilizzi Richard T.
Published: July 2016

We have started phase referenced monitoring of the 1667 MHz masers in the Mira variable U Her. Ultimately we hope to determine the annual parallax for this star. Three sets of VLB A observations have been performed so far. The first on July 22 1994, the second on March 6 1995 and a third on August 14 1995. Observations included bright extragalactic sources to calibrate instrumental effects and cycles of calibrator–source–calibrator (≈ 2° away) of typically 6 minutes. Without any special astrometric analysis software we detect the proper motion of U Her with an accuracy of several milli–arcseconds.
From Planetary Nebula nuclei to white dwarfs: The impact of evolutionary envelope masses
Authors: Blöcker T. , Herwig F. , Driebe T. , Bramkamp H. , Schönberner D.
Published: July 2016

It is well known that the evolution of white dwarfs (WDs) depends sensitively on the question whether they have “thin” or “thick” envelopes of H and He (see Wood 1995). Standard evolutionary caluclations (e.g. Paczynksi 1971) show that at the tip of the Asymptotic Giant Branch the envelope masses are tightly correlated with the mass of the hydrogen exhausted core (≈ total mass). Accordingly, the masses of hydrogen, MH, and helium, MHe, on top of the degenerate C/O interiors decrease by orders of magnitudes with increasing stellar mass. In contrast, many applications of WD calculations consider only single values of qH,He = log(MH,He/M∗) asuming either “thick” or “thin” envelopes.
Kinematics and dynamics of galactic Planetary Nebulae
Authors: Durand S.
Published: July 2016

Planetary Nebulae (PNe) are transient objects of considerable astrophysical interest: there are thought to descend from low and intermediate initial mass stars and therefore cover a large range of ages. On the other hand there are easily identified thanks to their bright emission-line spectra. In view of this it is perhaps surprising that little use has been made of PNe for kinematical studies of the Milky Way.
Luminosity functions of Planetary Nebulae
Authors: Tremblay Marcelle , Kwok Sun
Published: July 2016

Planetary nebulae have recently been shown to be useful as standard candles (Ciardullo et al. 1989, ApJ, 339, 53; Jacoby 1989, ApJ, 339, 39). Distances to many galaxies have been determined by fitting a planetary nebula luminosity function (PNLF) to observations of the OIII 5007å line of PNe. Here, the effect of the core mass distribution on the determination of the luminosity function is investigated and a technique for interpolating between model evolutionary tracks is discussed.
Spectroscopy of new Planetary Nebulae close to the galactic center
Authors: Van de Steene G.C. , Jacoby G. H.
Published: July 2016

Planetary Nebulae (PN) are bright emission line objects, observable at large distances throughout the Galaxy. They serve as probes of abundance gradients and chemical enrichment history of the ISM.
Properties of LMC Planetary Nebulae and parent populations in the MACHO database
Authors: Alves D.R. , Alcock C. , Allsman R. A. , Axelrod T. S. , Becker A. C. , Bennett D. R. , Cook K. H. , Freeman K. C. , Griest K. , Guern J. , Lehner M. J. , Marshall S. L. , Minniti D. , Peterson B. A. , Quinn P. J. , Pratt M. R. , Rodgers A. W. , Stubbs C. W. , Sutherland W. , Welch D.
Published: July 2016

The MACHO microlensing experiment's time-sampled photometry database contains blue and red lightcurves for nearly 9 million stars in the central bar region of the Large Magellanic Cloud (LMC). We have identified known LMC Planetary Nebulae (PN) in the database and find one, Jacoby 5, to be variable. We additionally present data on the “parent populations” of LMC PN, and discuss the star formation history of the LMC bar.
Imaging and spectroscopy of Magellanic Cloud Planetary Nebulae obtained with the Hubble Space Telescope
Authors: Vassiliadis E. , Dopita M. , Bohlin R. C. , Harrington J. P. , Meatheringham S. J. , Ford H.C. , Wood P. R. , Stecher T.P. , Maran S. P.
Published: July 2016

The majority of planetary nebulae (PNe) at the distance of the Magellanic Clouds typically subtend 1 arcsec or less on the sky. The Planetary Camera onboard the Hubble Space Telescope has a scale of 0.044 arcsec per pixel and is therefore ideal to use to image these objects. At present, 16 LMC and 5 SMC objects have been imaged in the [O III] 5007 angstrom emission line, as part of this program. An additional 10 LMC and 5 SMC objects have been imaged in the same line under the Guaranteed Time Observer program.
The Planetary Nebulae in the Sagittarius Dwarf Galaxy
Authors: Zijlstra A. A. , Dudziak G. , Walsh J. R.
Published: July 2016

There are 9 dwarf spheroidal galaxies in the neighbourhood of the Galaxy. The last to be discovered is in Sagittarius (Ibata et al 1994), situated at a distance of 25 kpc and is interacting with the Galaxy. Its mass is ≥107 M⊙ making it perhaps the largest local dwarf spheroidal. The only other dwarf spheroidal known to contain a planetary nebula was Fornax (Danziger et al 1978).
A dedicated camera for extragalactic Planetary Nebulae: The Planetary Nebula Spectrograph
Authors: Douglas N.G. , Taylor K. , Freeman K. C. , Axelrod T. S.
Published: July 2016

Photometry in [OIII] emission of Planetary Nebulae in external galaxies can be used to determine distances as great as that of the Virgo cluster and beyond, as forcefully argued elsewhere during this conference (G.H. Jacoby, invited talk). In addition, measurement of the radial velocities of the PN allows dynamical behaviour to be probed to much greater distance from the galaxian centre than integrated light techniques (e.g. Arnaboldi 1994).
The Hubble Space Telescope Key Project to Measure the Hubble Constant
Authors: Freedman Wendy L. , Mould Jeremy R. , Kennicutt Robert C. , Madore Barry F.
Published: July 2016

A Joint Discussion on the extragalactic distance scale and the Hubble constant took place fifteen years ago, at the 1982 XVIIIth General Assembly of the IAU, held in Patras, Greece. At that time, the newest applications of infrared photometers to Tully-Fisher measurements (Aaronson 1983) and Cepheid distances (Madore 1983) were reported. CCDs were just coming into use and had not yet been applied to extragalactic distance determinations; all of the extragalactic Cepheid distances were based on photographic Argelander (eye-estimated) photometry (Tammann and Sandage 1983 and references therein). No Cepheid distances to type Ia supernova-host galaxies were available.
The Tip of the Red Giant Branch as a Population II Distance Indicator
Authors: Sakai Shoko
Published: July 2016

The period–luminosity (PL) relation of the Cepheid variable stars is the most reliable primary distance indicator for nearby galaxies, and serves as the foundation of the extragalactic distance scale, providing the firm calibration for various secondary distance indicators. However, a major disadvantage of the Cepheid distance scale is that it can only be applied to late–type systems with recent or current star formation. An alternative distance indicator is a Pop II, tip of the red giant branch (TRGB) method, which is extremely attractive because of its applicability to all morphological types of galaxies. As long as a metal–poor RGB stars are present in abundant numbers, the distance can be estimated with an accuracy that is as good as that of the Cepheid PL relation.
Globular Cluster Ages from Hipparcos Subdwarfs
Authors: Pont F. , Vandenberg D.A. , Mayor M. , Turon C.
Published: July 2016

The new Hipparcos parallax data for local subdwarfs allow a much more reliable determination of the distance to globular clusters (by direct sequence fitting) than was previously possible. Earlier studies (Reid 1997, Gratton et al. 1997) have reported larger distances than expected, especially for the most metal-poor clusters, implying much younger ages. In our study of Hipparcos subdwarfs applied to M92 — representative of the oldest, most metal-poor clusters — we find however a distance only slightly in excess of previous expectations. We show, using Monte Carlo simulations, that most of the difference may be explained by our more detailed treatment of the Lutz-Kelker and selection biases. With up-to-date stellar evolution models, we derive a minimum age of 13 Gyr for the Universe. This value, although lower than previous estimates, still imposes a rather strict upper limit to Ho in the context of standard cosmological models.
CO Tully-Fisher Relation for the Distance Measurement to Redshift cz=20,000 to 50,000 km/s
Authors: Sofue Y. , Tutui Y. , Honma M. , Ichikawa T. , Wakamatsu K. , Kazes I. , Dickey J.
Published: July 2016

The accuracy of measurement of the Hubble constant depends not only on the accuracy of distance measurement but also on how small is the effect of local flows: The larger are redshifts of used galaxies, the higher is the accuracy of H0, if the error in distance measurement is comparable. The HI Tully-Fisher relation has been the standard tool for distance measurement up to cz ∼ 10,000 km s–1 (Tully and Fisher 1977), where, however, the local flow is not negligible.
Luminosity Density Evolution in the Universe and Cosmological Parameters
Authors: Totani Tomonori
Published: July 2016

Star formation history in galaxies is strongly correlated to their present-day colors and the Hubble sequence can be considered as a sequence of different star formation history. Therefore we can model the cosmic star formation history based on the colors of local galaxies, and comparison to direct observations of luminosity density evolution at high redshift gives a new test for the cosmological parameters which is insensitive to merger history of galaxies. The luminosity density evolution in 0 < z < 1 observed by the Canada-France Redshift Survey in three wavebands of 2800Å, 4400Å, and 1μm indicates that the Λ-dominated flat universe with λ0 ∼ 0.8 (> 0.53 at 95%CL) is strongly favored.

The cosmic star formation rate (SFR) at z > 2 is also compared to the latest data of the Hubble Deep Field including new data which were not incorporated in the previous work of Totani, Yoshii, & Sato (1997), and our model of the luminosity density of spiral galaxies taking account of gas infall is consistent with the observations. Starbursts in elliptical galaxies, which are expected from the galactic wind model, however overproduce SFRs and hence they should be formed at z ≳ 5 or their UV emission has to be hidden by dust extinction. The amount of metals in galactic winds and escaping ionizing photons are enough to contaminate the Lyα forests or to reionize the universe.
Do All Spiral Galaxies Have a Massive Dark Halo?
Authors: Honma M. , Sofue Y.
Published: July 2016

We have investigated the masses and extents of dark halos of spiral galaxies by two methods. First, we have reanalyzed HI outer rotation curves so far obtained considering the velocity uncertainties. We confirmed that many HI rotation curves indicate the existence of dark matter to some extent. However, we also found that only few rotation curves provide direct evidences for halos extended beyond 10 disk scale length. On the other hand, recent HI observations revealed that several galaxies have declining rotation curves that are approximated by Keplerian in the outermost regions. Considering the velocity uncertainties in the outer rotation curves, we found that these declining rotation curves are not rare compared to flat rotation curves. If these declining rotation curves indeed trace the mass truncation, these results indicate that some dark halos have moderate masses that are comparable or slightly larger than disk masses.
Evolution of Primordial Protostellar Clouds
Authors: Omukai K. , Nishi R. , Uehara H. , Susa H.
Published: July 2016

The formation of stars in proto-galactic clouds can be viewed as two step processes i.e. the fragmentation of proto-galactic clouds and evolution of these fragments into stars. We consider here the latter process, the contraction of protosteller clouds (∼ 1M⊙) which consist of primordial gas. We investigate cooling processes by calculating the radiative transfer of H2 rotational/vibrational lines. We consider clouds in hydrostatic equilibrium as initial conditions. Comparing two timescales, the freefall time and the timescale of quasi-static contraction (∼ tcool, the cooling time) of these clouds, we find that as the clouds contract, the ratio of two timescales tff/tqsc, i.e. the efficiency of cooling, becomes larger even under the existence of cold and opaque envelope. Especially for the fragments of primordial filamentary clouds (tff ∼ tqsc initially), they collapse dynamically in the freefall timescale. This efficiency of cooling is utterly peculiar to the line cooling.
Limits on the Variation of Physical Constants Derived from Molecular Absorption Lines
Authors: Wiklind T. , Combes F.
Published: July 2016

A potential diagnostic application of molecular rotational absorption lines at high redshift is to test the invariance of physical constants. This can be done by comparing the observed redshifted frequency of a molecular absorption line with redshifted lines from other types of transitions such as the 21cm hyperfine transition or electronic resonance transitions. In order to set stringent limits, it is necessary to achieve the greatest possible frequency resolution. This makes radio lines well suited for this purpose.
Analysis of Large Scale Structure using Percolation, Genus and Shape Statistics
Authors: Sahni Varun
Published: July 2016

We probe gravitational clustering in N-body simulations using geometrical descriptors sensitive to ‘connectedness’: the genus curve, percolation and shape statistics. As gravitational clustering advances, the density field in N-body simulations shows an increasingly pronounced departure from Gaussianity reflected in the changing shape of the percolation curve and the changing amplitude and shape of the genus curve. We feel that both genus and percolation curves provide complementary probes of large scale structure topology and could be used to discriminate between models of structure formation and the analysis of observational data such as galaxy catalogs and MBR maps. The filling factor in clusters & superclusters at percolation is small indicating that matter is more likely to lie in filaments and pancakes. An analysis of ‘shapes’ in N-body simulations has shown that filaments are more pronounced than pancakes. To probe shapes of clusters and superclusters more rigorously we propose a new shape statistic which does not fit isodensity surfaces by ellipsoids (as done earlier). Instead our shape statistic is derived from fundamental properties of a compact body such as its volume V, surface area S, integrated mean curvature C, and connectivity (characterized by the Genus). The new shape statistic gives sensible results for topologically simple surfaces such as the ellipsoid, and for more complicated surfaces such as the torus.
Testing Cosmological Models with Clusters of Galaxies
Authors: Gottlöber S. , Retzlaff J. , Klypin A.
Published: July 2016

Currently little is known about the mass distribution on intermediate scales between those probed by deep redshift surveys of galaxies and those probed by COBE. Catalogs of galaxy clusters reach depths of several hundred megaparsecs, and, thus, are very useful for those scales. Only the Las Campanas Redshift Survey (LCRS) is comparable with that depth. However, the LCRS samples only narrow slices whereas cluster catalogs cover a large fraction of the sky. Clusters seems to be the most suitable objects to fill the gap between scales probed by COBE and the galaxy samples. Moreover, clusters are advantageous over galaxies as probes of the matter distribution in the Universe because our understanding of its formation and evolution is better established than it is for galaxies. Clusters are high peaks (mass scaleM≃ 1015M⊙) in the density field, which have collapsed relatively recently. Because of that, it is easy to identify clusters in numerical simulations. But the number of clusters is much smaller than the number of galaxies, which makes the statistics of clusters noisier. Nevertheless, clusters are exceptionally useful objects for the investigation of the matter distribution on scales well above 100h–1Mpc. Thus, it is worth to apply different statistical tests to these objects.
Weak Galaxy-Galaxy Lensing in HST DATA
Authors: Ebbels Tim , Kneib Jean-Paul , Ellis Richard
Published: July 2016

We expand on the work of Brainerd, Blandford & Smail (1996) (BBS), using a larger archival WFPC-2 dataset including many galaxy redshifts. It is clear from our data that the ellipticity distribution of images changes substantially with observed magnitude (figure 1, left) which is shown by simulations to be mainly the result of detection effects. We have detected a lensing signal, using a similar selection method to BBS and are also implementing a maximum likelihood method to constrain halo parameters. Using simulations, we show in figure 1 (right) that the signal is consistant with typical halo velocity dispersions of σ∗ ∼ 70–100 kms−1 However, the radial extent of the halos is less well constrained.
Cosmological Studies from the MRC/1Jy Radio Galaxy Sample: The Spectral Index – Redshift Correlation
Authors: Athreya R.M. , Kapahi V.K.
Published: July 2016

The MRC/1Jy sample of 559 radio sources with S408 MHz ≥ 0.95 Jy (McCarthy et al. 1996; Kapahi et al. in preparation) is a factor of 5 to 6 times deeper than the 3CRR sample; it is therefore, well suited for disentangling the redshift (z) and luminosity (P) dependence of several properties of extragalaxtic radio sources. Here we present results on the spectral index — redshift correlation for radio galaxies, based on a comparison of the well documented radio spectra (in the rest frame frequency range of about 1 to 16 GHz) of the following two matched-luminosity samples, (a) 14 high redshift radio galaxies (HRRG) from MRC with 2.0 < z < 3.2 and linear size i > 10 kpc, and (b) 21 intermediate z radio galaxies (IRRG) from 3CRR with 0.85 < z < 1.7 and l > 10 kpc. Both samples have P1.4 GHz in the range 1028 and 1028.8 WHz−1.
MACHO Detection from Measurements of Gravitational Deflection
Authors: Ohnishi Kouji , Hosokawa Mizuhiko , Fukushima Toshio
Published: July 2016

The observed positions of quasars are fluctuated due to the gravitational lensing of the matters in our galaxy. The magnitude of fluctuation due to stars and MACHOs is of the order of a few micro-arc second (μas) ∼ 10 μas and its time scale is of the order of a few years ∼ hundreds years (Hosokawa et al. 1997). Such fluctuation will reflects the nature of the constituents, both visible and invisible, of our galaxy.
Non-Gaussian Isocurvature Models
Authors: Stirling A.J. , Peacock J.A.
Published: July 2016

Peebles (1997) has proposed a non-Gaussian χ2isocurvature model which gives rise to early galaxy assembly at redshifts ≥ 3–4. We test whether the higher order moments (skewness and kurtosis) of such a model are compatible with the moments of the observed density field, and find that in the absence of bias these models produce moments that are much higher than those measured for the APM survey (Gaztañaga, 1994). We have applied different biasing schemes to see whether bias can bring the moments down, and find that for power law, Cen-Ostriker, and censor threshold biasing schemes (Mann et al 1997) the moments can be brought into agreement with the APM measurements only for linear bias valuesb> 3. This however, would give a redshift distortion parameter, βopticai= (Ω0.6/b) < 0.16 which is inconsistent with current estimates from redshift surveys of βoptical= 0.40 ± 0.12 (e.g. Peacock 1997). We conclude that for an acceptable level of bias in the schemes we have tested, the χ2isocurvature model moments disagree with current measurements of skewness and kurtosis from the APM survey.
An Alternative Cosmology: The QSSC
Authors: Narlikar Jayant V.
Published: July 2016

This review begins with a brief survey of the observational constraints on the standard big bang cosmology, pointing out that the various limits leave a very narrow window in the parameter space of plausible models. There is thus a strong case for alternative cosmologies. The rest of the review concentrates on one alternative, the quasi steady state cosmology (QSSC) and summarises the recent work on this model. This includes, the theoretical formulation and simple exact solutions of the basic equations, their relationship to observations, the stability of solutions and the toy model for understanding the growth of structures in the universe.
Big Bang Nucleosynthesis and Lepton Number Asymmetry in the Universe
Authors: Kohri K. , Kawasaki M. , Sato Katsuhiko
Published: July 2016

Recently it has been reported that there may be a discrepancy between big bang nucleosynthesis theory and observations (BBN crisis) (Hata et al., 1995). One way to solve the discrepancy might be to adopt some modifications of standard physics used in SBBN (Kawasaki et al, 1997). We show that BBN predictions agree with the primordial abundances of light elements, 4He, D, 3He and 7Li inferred from the observational data if the electron neutrino has a net chemical potential ξve due to lepton asymmetry (Kohri et al., 1997). We study BBN with the effects of the neutrino degeneracy in details using Monte Carlo simulation and make a likelihood analysis using the most recent data. We estimate that (95% C.L.) and (95% C.L.) adopting the presolar Deuterium abundance as the primordial values. If we adopted the low D abundance which is obtained by the observation of the high redshift QSO absorption systems, (95% C.L.) and The estimated chemical potential of ve is about 10−5 eV which is much smaller than experiments can detect (≃ 1 eV). In other words, BBN gives the most stringent constraint on the chemical potential of ve.
Reduction of Sound Speed during Cosmological First Order Phase Transition
Authors: Nagasawa M. , Yokoyama J.
Published: July 2016

The degree of sound speed reduction is estimated during the coexistence epoch of quark-gluon and hadron phases in the first-order QCD phase transition[1]. The sound speed in a mixture is obtained by simply replacing the energy density with the mean value in the usual formula[2]. Since the adiabatic condition is nothing but the second law of thermodynamics which is useless for the purpose of calculating the sound speed qualitatively, we adopt the conservation of the quality which is the energy fraction of the high-energy phase[2]. This is appropriate because the transition of the phases through bubble nucleation is totally suppressed at the coexistence temperature and the expansion speed of bubbles is so small that energy transfer through bubble expansion or contraction is also expected to be negligible during sound-wave propagation. Using the bag model, the numerical value of the minimum sound speed can be calculated as

where the uncertainty comes from the selection of the number of relativistic quark species. Thus we can say that the quark-hadron phase transition has no drastic effect on the development of cosmological density perturbations.
Renormalization Group Approach in Newtonian Cosmology
Authors: Sota Y. , Kobayashi T. , Maeda K. , Kurokawa T. , Morikawa M. , Nakamichi Akika
Published: July 2016

Since the real Universe is clumpy and inhomogeneous even at rather large scale such as 100 Mpc, we may wonder whether the isotropic and homogeneous Friedmann model is valid when we compare some cosmological parameters with the observed values. The observed Hubble parameter H0 or the density parameter Ω0 might be deviated from the theoretically expected ones from the Friedmann model. In fact, the density parameter Ω0 seems to vary depending on the observational methods and the distance scales. Furthermore, our Universe seems to possess a fractal property in the galaxy distributions at least at scale up to 10 Mpc.
Highlights of Stellar Modeling with PHOENIX
Authors: Baron E. , Hauschildt P. H. , Allard F. , Lentz E. J. , Aufdenberg J. , Schweitzer A. , Barman T.
Published: July 2016

We briefly describe the current version of the PHOENIX code. We then present some illustrative results from the modeling of Type Ia and Type II supernovae, hot stars, and irradiated giant planets. Good fits to observations can be obtained, when account is taken for spherically symmetric, line-blanketed, static or expanding atmospheres.
Round Table Summary: Radiative Transfer Problems
Authors: Piskunov Nikolai
Published: July 2016

This Round Table addresses various problems related to the radiative energy transport calculations and the challenges related to the introduction of 3D hydrodynamic models, models with pulsations, connecting stellar atmospheres to the circumstellar medium etc. We have discussed several examples of environment not properly treated by radiative transfer calculations and outlined future development directions in this field.
Astrophysical Spectropolarimetry and Magnetic Field Diagnostics
Authors: Bueno J. Trujillo
Published: July 2016

This paper highlights the increasing interest of astrophysical spectropolarimetry by showing how remote sensing techniques based on the Hanle and Zeeman effects are allowing us to investigate the magnetism of the extended solar atmosphere. Particular emphasis is given to the development of new diagnostic windows on the weakest magnetic fields of the photosphere, chromosphere and corona. Spectropolarimetry in the He i 10830 Å multiplet is allowing us to infer the three-dimensional geometry of the magnetic fields that confine the plasma of solar prominences. Multilevel modelling of the Hanle and Zeeman effects in the Ca II IR triplet and other chromospheric lines is helping us to decipher the strength and topology of chromospheric magnetic fields in regions where photospheric magnetograms show the well-known ‘salt and pepper’ patterns of mixed polarities. The Hanle effect in molecular lines, as well as in atomic lines of rare-earth elements like Ce II, offers a novel diagnostic tool for empirical investigations of ‘turbulent’ magnetic fields in relatively deep regions of the ‘quiet’ solar photosphere.
Stellar Abundance Analyses in the Light of 3D Hydrodynamical Model Atmospheres
Authors: Asplund Martin
Published: July 2016

I describe recent progress in terms of 3D hydrodynamical model atmospheres and 3D line formation and their applications to stellar abundance analyses of late-type stars. Such 3D studies remove the free parameters inherent in classical 1D investigations (mixing length parameters, macro- and microturbulence) yet are highly successful in reproducing a large arsenal of observational constraints such as detailed line shapes and asymmetries. Their potential for abundance analyses is illustrated by discussing the derived oxygen abundances in the Sun and in metal-poor stars, where they seem to resolve long-standing problems as well as significantly alter the inferred conclusions.
Round Table Summary: Comparison of Different NLTE Codes and the Role of Atomic Input Data
Authors: Kamp Inga , Korotin Sergey , Mashonkina Lyudmila , Przybilla Norbert , Shimansky Slava
Published: July 2016

We started a comparison between different NLTE codes that calculate the statistical equilibrium in solar-type and late type stars (G - A type stars). Discrepancies between different authors analyzing the statistical equilibrium of the same element in the same atmosphere are often surprisingly large. Hence, this study was meant to nail down the origin of these differences. The preliminary results indicate that even if the atmosphere and the atomic input data is fixed, discrepancies of up to 40% in the outer atmospheric layers are still present; the main reason is the different treatment of the background opacity. Following up, we shortly discuss the completeness and accuracy of atomic data used in analyses of the kinetic equilibrium of atoms in the atmospheres of middle and late type stars.
Interferometric Observations of Mira Variables
Authors: Van Belle G. , Thompson R. R. , Creech-Eakman M.J.
Published: July 2016

Milliarcsecond resolution observations of cool stars are becoming increasingly common and sophisticated as recent advances in telescope technology mature. To varying degrees, these observations rely up on stellar models for interpretation of their data, while at the same time present particular challenges to those models. Indications of departures from spherical symmetry are beginning to be observed as increasingly rich image information is obtained by a new generation of interferometers. Examination the subtle variations of wavelength-specific sizes exhibits rich structure, connected to the atmospheric chemistry. For the pulsating stars, such as Mira variables, that structure varies with time, with the phase lags between the various sizes being connected to the atmospheric dynamics. Complex morphologies associated with atmospheric winds have been revealed with these high resolution experiments. A review of these recent results will be presented, concentrated on their implications upon stellar modelling, and the prospects for future observational data.
Catalogues of Planetary Nebulae
Authors: Acker Agnès
Published: July 2016

Firstly, the general requirements concerning catalogues are studied for planetary nebulae, in particular concerning the objects to be included in a catalogue of PN, their denominations, followed by reflexions about the afterlife and computerized versions of a catalogue. Then, the basic elements constituting a catalogue of PN are analyzed, and the available data are looked at each time.
Narrow Band Photometry and Mapping of the Planetary Nebulae NGC 6210 and NGC 7009
Authors: Mendoza E.E. , Chavarría-K. C. , Arévalo V.M.
Published: July 2016

This paper is based upon observations carried out at the Observatorio Astronómico Nacional, San Pedro Mártir, B.C.N. México. They are of two types: (1) α(16)Λ(9)-photometry, obtained with the 1.5-m Johnson telescope, and (2) maps at the wavelengths of Hα and λ7751 A [Ar III] emission lines secured with the 2.1-m telescope.
New Observations of Planetary Nebulae S22 and YM29
Authors: Arkhipova V.P. , Lozinskaya T.A. , Moskalenko E.I. , Sitnik T.G.
Published: July 2016

Spectral and monochromatic observations of two thin-filamentary nebulae S22 and YM29 have been carried out in the lines [O III] 5007A, [N II] 6584A and [S II] 6717+6732A. Radial stratification of the emission typical for photoionization excitation has been found: displacement between [O III] - bright regions and [S II] - and [N II] -bright regions is equal ΔR ∼ 0.1R (about 0.01 to 0.2 pc), the first ones being closer to the nuclei. Both nebulae are characterized by more diffuse morphology in the [O III] line and by thin-filamentary one in the [N II] and [S II] lines.
The Near Infrared Spectrum of NGC7027
Authors: Baluteau Jean-Paul , Pequignot Daniel
Published: July 2016

NGC7027 has been observed at the 193cm telescope of OHP in the range 6800 - 10500 Å, using the CARELEC spectrograph equiped with a RCA CCD. The dispersion corresponded to a resolution 1 Å/px.