bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape, structure, and morphology in planetary nebulae
Authors: Shaw Richard A.
Published: August 2012

A revival over the past two decades in planetary nebula (PN) morphological studies springs from a combination of factors, including the advent of wide-area, high dynamic range detectors; the growing archives of high resolution images from the X-ray to the sub-mm; and the advent of sophisticated models of the co-evolution of PNe and their central stars. Yet the story of PN formation from their immediate precursors, the AGB stars, is not yet fully written. PN morphology continues to inspire, provide context for physical interpretation, and serve as an ultimate standard of comparison for many investigations in this area of astrophysics. After a brief review of the remarkable successes of PN morphology, I summarize how this tool has been employed over the last half-decade to advance our understanding of PNe.
Are planetary nebulae derived from multiple evolutionary scenarios?
Authors: Frew David J. , Parker Quentin A.
Published: August 2012

Our understanding of planetary nebulae has been significantly enhanced as a result of several recent large surveys (Parkeret al., these proceedings). These new discoveries suggest that the ‘PN phenomenon’ is in fact more heterogeneous than previously envisaged. Even after the careful elimination of mimics from Galactic PN catalogues, there remains a surprising diversity in the population of PNe and especially their central stars. Indeed, several evolutionary scenarios are implicated in the formation of objects presently catalogued as PNe. We provide a summary of these evolutionary pathways and give examples of each. Eventually, a full census of local PNe can be used to confront both stellar evolution theory and population synthesis models.
X-ray observations of central stars of planetary nebulae and their winds
Authors: Guerrero Martín A.
Published: August 2012

The photospheric emission from the hottest central stars of planetary nebulae (CSPNe) is capable to extend into the X-ray domain, with emission peaking at 0.1-0.2 keV and vanishing above 0.4 keV. Unexpected, intriguing hard X-ray emission with energies greater than 0.5 keV has been reported for several CSPNe and for a number of white dwarfs (WDs). Different mechanisms may be responsible for the hard X-ray emission from CSPNe and WDs: coronal emission from a late-type companion, shocks in fast winds as in OB stars, leakage from underneath the star photosphere, or accretion of material from a disk, a companion star, or the circumstellar medium. Therefore, the hard X-ray emission associated with CSPNe may have significant implications for our understanding of the formation of PNe: binary companions, disks, and magnetic fields are thought to play a major role in the shaping of PNe, whereas clumping in the stellar wind may have notable effects in the PN evolution by modifying the stellar mechanical energy output. Here I present the results of different observational efforts to search for hard X-ray emission from CSPNe and discuss the different mechanisms for the production of hard X-rays.
Post-AGB stars in the LMC and SMC
Authors: Van Winckel Hans , van Aarle Els , Wood Peter R. , Kamath Devika , Evans Tom Lloyd , De Smedt Kenneth , Gorlova Nadya , Gielen Clio
Published: August 2012

Galactic post-AGB stars show a large diversity in chemical compositions as well as in the kinematical and geometrical properties of their circumstellar material. The theoretical interpretation is hampered by the lack of good distances to almost all Galactic objects. We therefore initiated a large project to study systematically post-AGB stars in the Large and Small Magellanic Cloud (LMC, SMC respectively). Here we report on our preliminary results.
M31 Planetary nebulae as seen by the Panchromatic Hubble Andromeda Treasury
Authors: Rosenfield Philip A. , Johnson L. Clifton , Girardi Léo , Dalcanton Julianne J. , Williams Benjamin F. , Bianchi Luciana , Marigo Paola , Caldwell Nelson , Seth Anil C. , Gordon Karl , Lan Dustin
Published: August 2012

We present a preliminary analysis of known planetary nebulae (PNe) in M31 that were observed in the first year of the Panchromatic Hubble Andromeda Treasury HST Multi-cycle program. We use the properties of this sample to discuss PNe from this new multi-band survey.
The central planetary nebulae populations of external galaxies with SAURON
Authors: Sarzi Marc
Published: August 2012

Thanks to SAURON integral-field observations we uncovered the planetary nebulae (PNe) populations inhabiting the central and nuclear regions of our galactic neighbours M32 and M31, respectively, and discuss the significant differences between their corresponding PNe luminosity functions in light of the properties of their parent stellar populations. In particular, we conclude that the lack of bright PNe in the nuclear regions of M31 is likely linked to the nearly Solar value for the stellar metallicity, consistent with previous suggestions that a larger metallicity would bias the horizontal-branch (HB) populations toward bluer colors, leading to fewer red HB stars capable of producing PNe and more blue HB stars that instead could contribute to the far-UV flux observed in metal-rich early-type galaxies and, incidentally, in the nucleus of M31.
Combined modelling of the He2-131 planetary nebula and of its central star
Authors: Arrieta Anabel , Morisset Christophe , Hillier D. John , Stasińska Grażyna , Georgiev Leonid N.
Published: August 2012

We present a unified model of the central star and the ionized gas of the planetary nebula He2-131. Preliminary values of the nebular and stellar parameters are given together with those of the chemical composition.
Spectral analysis of mid-IR excesses of central stars of planetary nebulae
Authors: Bilikova Jana , Chu You-Hua , Su Kate Y.L. , Gruendl Robert
Published: August 2012

In our Spitzer 24 μm survey of hot white dwarfs (WDs) we found 9 WDs with IR excesses, 7 of them are still central stars of planetary nebulae (CSPNs). We have thus carried out a Spitzer archival survey of CSPNs, and found additional objects with IR excesses. To date, a total of 13 CSPNs show IR excesses from Spitzer observations. These mid-IR excesses are indicative of the presence of circumstellar dust, which could be produced by collisions or disruption of sub-planetary objects. To further assess the nature of these IR excesses, we have obtained Spitzer IRS, Gemini NIRI and Michelle, and KPNO 4m echelle spectra of these objects. In this poster, we summarize the spectroscopic observations and discuss the nature of these IR excesses.
VISIR-VLT images of the water maser: Emitting planetary nebula K3-35
Authors: Blanco Mónica W. , Guerrero Martín A. , Miranda Luis F. , Lagadec Eric , Suárez Olga
Published: August 2012

K3-35 is an extremely young bipolar planetary nebula that contains a precessing bipolar jet and a small (radius 80 AU) water maser equatorial ring. We have obtained VISIR-VLT images of K3-35 in the PAH1 (λ=8.6 μm), [S iv] (λ=10.6 μm), and SiC (λ=11.85 μm) filters to analize the mid-IR morphology and the temperature structure of its dust emission. The images show the innermost nebular regions undetected at optical wavelegths and the precessing bipolar jets. The temperature map shows variations in the temperature in the equatorial zone and in regions associated to its jets.
A barium-rich binary central star in Abell 70
Authors: Boffin Henri M. J. , Miszalski Brent , Frew David J. , Acker Agnes , Köppen Joachim , Moffat Anthony F. J. , Parker Quentin A.
Published: August 2012

We have found the central star of Abell 70 (PN G038.1–25.4, hereafter A 70) to be a binary consisting of a G8 IV-V secondary and a hot white dwarf. The secondary shows enhanced Ba II and Sr II features, firmly classifying it as a barium star. The nebula is found to have Type-I chemical abundances with helium and nitrogen enrichment, which combined with future abundance studies of the central star, will establish A 70 as a unique laboratory for studying s-process AGB nucleosynthesis.
Herschel/HIFI observations of molecular lines from young planetary nebulae
Authors: Bujarrabal Valentín , Santander-García Miguel , Alcolea Javier , Soria Rebeca ,   the HIFISTARS team
Published: August 2012

We present results from systematic Herschel/HIFI observations of molecular lines in the FIR/sub-mm from young planetary nebulae. The high spectral resolution provided by the hetorodyne spectrometer HIFI allows properly studying the line profiles, whose structure corresponds to the various kinematics of the most massive nebular components, including fast bipolar outflows and slow shells. In particular, we have studied the excitation properties of the high-velocity (dense) flows. In some cases we find typical temperatures of the fast gas over 100-200 K, though in others it remains cool, ≲30K. We argue that the thermodynamics of the molecule-rich bipolar outflows is driven by fast radiative cooling, after the passage of the shock that accelerated it.
Could some meteoritic stardust have originated from the winds of post-AGB stars and planetary nebula nuclei?
Authors: Buntain Joelene , Lugaro Maria , Karakas Amanda
Published: August 2012

After very dense and slow winds erode the outer layer of an asymptotic giant branch (AGB) star down to a thin H-rich layer (≃10−3 M⊙) the star becomes a post-AGB star and evolves at constant luminosity towards hotter temperatures. It may then becomes a planetary nebula nucleus (PNN) at the centre of a planetary nebula (PN). During these phases, the thin H-rich surface layer of the star is eroded by winds. Stardust oxide and silicate grains are recovered from meteorites. The origin of the “Group II grains” that show enrichments in 17O and depletions in 18O is currently explained by invoking the occurrence of some kind of extra-mixing process in AGB stars. We suggest instead that these grains originated from the winds of post-AGB stars and PNN. These winds show the signature of H-burning. We will do this by comparing our predictions from stellar models to the compositions observed in Group II stardust oxide and silicate grains. We find that the composition of the thin H-rich layer lost in the post-AGB and PNN winds is close to that of Group II grains, however the match with the Al ratios needs to be improved. Considering the uncertainities in the 25Mg and 26Al proton capture rates may be helped in this respect.
Molar extinction coefficient of fullerenes and related hydrogenated derivatives “fulleranes”
Authors: Cataldo Franco , Iglesias-Groth Susana , Manchado Arturo
Published: August 2012

Fullerenes, the carbon molecules with 60 and 70 atoms, were recently detected in a series of planetary nebulae, in protoplanetary nebulae and in other astrophysical objects. The detection and the quantitative determination of these molecules was made possible by the measurement of their reference infrared spectra and the relative molar extinction coefficients and integrated molar absorptivity on laboratory scale. It is expected that also fulleranes the hydrogenated derivatives of C60 and C70 may be present in the same objects where fullerenes were detected. This prompted us to synthesize the hydrogenated fullerenes, to record their infrared spectra and the measure the molar extinction coefficients and integrated molar absorptivity on laboratory scale to have a reference in the search of these fullerene derivatives in space
A detailed spatiokinematic model of the multipolar planetary nebula NGC 7026
Authors: Clark David M. , López Jose Alberto , Steffen Wolfgang , Richer Michael G.
Published: August 2012

We present the most extensive, long-slit, high-resolution coverage of the complex planetary nebula (PN), NGC 7026. Ten spectra were acquired using the Manchester Echelle Spectrometer at San Pedro Martir Observatory in Baja California, Mexico, and each shows exquisite detail, revealing the intricate structure of this object. Incorporating these spectra into the 3-dimensional visualization and kinematic program, Shape, and using HST images of NGC 7026, we have produced a detailed structural and kinematic model of this PN. Knowledge of the 3-D structure of this nebula is relevant to understand the physics behind the extended X-ray emission in this object.
Radio planetary nebulae in the Magellanic Clouds
Authors: Crawford Evan J. , Filipović Miroslav D. , Bojičić Ivan S. , Cohen Martin , Payne Jeff L. , De Horta Ain Y. , Reid Warren
Published: August 2012

We present preliminary results of our deep Australia Telescope Compact Array (ATCA) radio-continuum survey of the Magellanic Clouds Planetary Nebulae.
Physical parameters and chemical abundances in bipolar PNe
Authors: Costa Roberto D. D. , Faes Daniel M. , Morisset Christophe
Published: August 2012

Bipolar nebulae constitute a large subset of the planetary nebulae population. We present the first results of a project aimed to map physical parameters and chemical abundances across extended planetary nebulae with bipolar structure. These results can be used as input and constraints into numerical simulations in order to reproduce their properties in the visual band of the spectrum. This provides a way to examine the non-homogeneity present in this kind of object, as well as a tool to derive their intrinsic properties, like tridimensional geometry and matter distribution, central star properties, distance, and other properties in a self-consistent way. Here we show our results for two of these objects: IC 4406 and NGC 6572.
Estimating the binary fraction of planetary nebulae central stars
Authors: Douchin D. , De Marco O. , Frew D. J. , Jacoby G. H. , Passy J.-C. , Hillwig T. , Howell S. B. , Bond H. , Peyaud A. , Zijlstra A. , Napiwotzki R. , Jasniewicz G. , Parker Q.
Published: August 2012

During the past 20 years, the idea that non-spherical planetary nebulae might need a binary or planetary interaction to be shaped was discussed by various authors. It is now generally agreed that the varied morphologies of planetary nebulae cannot be fully explained solely by single star evolution. Observationally, more binary central stars of planetary nebulae have been discovered, opening new possibilities to understand the connections between binarity and morphology. So far, ≃45 binary central stars of planetary nebulae have been detected, most being close systems detected via flux variability. In order to determine the PN binary fraction, one needs a method that can detect wider binaries. We present here recent results concentrating on binary infrared excess observations aimed at detecting binaries of any separation.
3D ionization structure and kinematics of NGC 2392
Authors: Dufour Reginald J. , Sick Jonathan N. , Hartigan Patrick M. , Henry Richard B. C. , Kwitter Karen B. , Bohigas Joaquin
Published: August 2012

We discuss the 3D morphology, ionization structure, and kinematics of NGC 2392, the “Eskimo,” based on new and archival HST imagery and new long-slit echelle spectroscopy. High spatial resolution ionization maps of the nebula were made from HST WFPC2 imagery and compared with their velocity structure in various emission lines from echelle spectra taken with the 4m telescope at Kitt Peak. The imagery and spectra were then compared to map the kinematics of the nebula in several emission lines and decode the 3-dimensional morphology and ionization structure of the nebula, including that of C+2 from C III] 1909 Å for the first time.
Herschel observations of NGC 7027
Authors: Exter Katrina M. , van Hoof Peter A.M , Van de Steene Griet C. , Ottensamer Roland , Wesson Roger , Barlow Mike J. , Ferland Gary J. , Porter Ryan L. ,   the MESS consortium
Published: August 2012

We present our analysis of the spectra of NGC 7027 taken with the PACS and SPIRE instruments of the Herschel satellite.
Abundances and ADFs in planetary nebulae with [WC] central stars
Authors: García-Rojas Jorge , Peña Miriam , Morisset Cristophe , Ruiz Maria-Teresa
Published: August 2012

We present preliminary results obtained from the analysis of very deep echelle spectra of a dozen planetary nebulae with [WC] or weak emission lines (wels) central stars. The computed abundance discrepancy factors (ADFs) are moderate, with values lower than 4. In principle, no evidence of the H-poor metal enriched inclusions proposed by Liu et al. (2000) have been found. However, a detailed analysis of the data is in progress.
Planetary nebulae as tracers of the kinematic structure of the starburst galaxy IC 10
Authors: Gonçalves Denise R. , Teodorescu Ana M. , Alves-Brito Alan , Méndez Roberto H. , Magrini Laura
Published: August 2012

The Local Group dwarf irregular galaxy IC 10 is the nearest starburst galaxy (at 725 kpc) and presents extended and complex HI kinematics. It is believed that IC 10 is still experiencing an intense and very recent burst of star formation, likely triggered by infalling gas from an extended envelope which is counter-rotating with respect to the galaxy proper rotation. In this contribution we summarize our preliminary results (Gonçalves et al. 2011, in prep.) obtained by performing a kinematic analysis of the PN population of IC 10. Our aim is to explore the kinematic connection of its intermediate to old stellar populations with that obtained from HI observations. Some PNe were found at large galactocentric distances and could therefore represent a trace of past tidal interactions.
Deep spectroscopy of the dwarf spheroidal NGC 185
Authors: Gonçalves Denise R. , Magrini Laura , Martins Lucimara P. , Teodorescu Ana M. , Quireza Cintia , Lanfranchi Gaia
Published: August 2012

Dwarf galaxies are crucial to understand the formation and evolution of galaxies, since they constitute the most abundant galaxy population. Abundance ratios and their variations due to star formation and inflow/outflow of gas are key constraints to chemical evolution models. The determination of these abundances in the dwarf galaxies of the Local Universe is thus of extreme importance. NGC 185 is one of the four brightest dwarf companions of M31, but unlike the other three it has an important content of gas and dust. Interestingly enough, in an optical survey of bright nearby galaxies NGC 185 was classified as a Seyfert galaxy based on its integrated emission-line ratios in the nuclear regions. However, although its emission lines formally place it in the category of Seyfert it is probable that this galaxy does not contain a genuine active nucleus. In this contribution, we resume, firstly, our results of an empirical study of the galaxy, on which we characterise its emission-line population and obtain planetary nebulae abundance ratios (Gonçalves et al. 2012). And, secondly, we discuss our attempt to identify the possible ionization mechanisms for NGC 185 enlighting the controversial classification of this galaxy dwarf spheroidal (dSph) as well as Seyfert, via stellar population synthesis and chemical evolution modelling (Martins et al. 2011).
Spectroscopic observations of southern Galactic planetary nebulae
Authors: Górny Slawomir K.
Published: August 2012

We present preliminary results from low resolution spectroscopic observations of planetary nebulae located in the southern Milky Way disk.
The curious conundrum regarding sulfur and oxygen abundances in planetary nebulae
Authors: Henry Richard B. C. , Speck Angela , Karakas Amanda I. , Ferland Gary J.
Published: August 2012

We carefully consider numerous explanations for the sulfur abundance anomaly in planetary nebulae. No one rationale appears to be satisfactory, and we suggest that the ultimate explanation is likely to be a heretofore unidentified feature of the nebular gas which significantly impacts the sulfur ionization correction factor.
Chemical evolution models for NGC 6822 using planetary nebulae abundances
Authors: Hernández-Martínez Liliana , Carigi Leticia , Peña Miriam , Peimbert Manuel
Published: August 2012

We present chemical evolution models for the dwarf irregular NGC 6822, using chemical abundances of Planetary Nebulae (PNe) and HII regions and also the mass of gas (Mgas) as observational constraints. Chemical evolution models have been calculated to reproduce the abundances as derived from both, collisionally excited lines (CELs) and recombination lines (RLs). In our models, the chemical contribution of low and intermediate mass stars (LIMS) is time delayed, while for the massive stars the chemical contribution is instantaneous, as in Franco & Carigi (2008). The chemical contribution of SNIa is included in our model, thus we are also able to reproduce the observational Fe/H abundance obtained from A stars.
A systematic study of young multipolar planetary nebulae
Authors: Hsia Chih-Hao , Kwok Sun
Published: August 2012

We have analyzed the HST images of ten young planetary nebulae (PNe) and found them to possess multipolar structures. Concentric arcs and 2-D rings are also found in some objects.
On the production of multicharge ions in planetary nebulae
Authors: Ibadov Subhon
Published: August 2012

Production of multicharge ions due to generation of hot expanding plasma blobs, short-living “compound particles”, at high-velocity collisions between dust grains of a planetary nebula and dust particles of the interstellar medium is analytically considered. Dependence of the multiplicity of charge of produced ions on the relative velocity of colliding dust particles is determined.
Trigonometric parallax measurements of post-AGB stars with VERA
Authors: Imai Hiroshi , Tafoya Daniel ,   VERA collaboration
Published: August 2012

A trigonometric parallax distance is measurable for a planetary nebula if it harbors H2O (or OH) maser spots. We have demonstrated it for H2O maser sources, K3-35, IRAS 19312+1950 and IRAS 18286-0959 using the VLBI Exploration of Radio Astrometry (VERA). They are post-AGB stars and exhibit peculiar morpho-kinematical structures like a bipolar planetary nebula or a bipolar molecular jet (water fountain). The luminosities and secular motions of these sources derived from the trigonometric distances and proper motions of the H2O masers suggest that their parental stars may be intermediate-mass (2M⊙ < M* < 8 M⊙) evolved stars.
The nature of the Galactic bulge: A view from bulge planetary nebulae and globular clusters
Authors: Kholtygin Alexander F. , Milanova Yulia V. , Nikiforov Igor' I. , Vasyakina Olga V.
Published: August 2012

Modern data concerning the planetary nebulae (PNe) in the bulge, bar and disk of the Milky Way are used to study the chemical history of bulge. We show that the abundance pattern is similar for PNe in the bulge and Peimbert's type II PNe. We also found that the globular clusters (GCs), especially their metal-rich disk subsystem, form on metallicity maps a bar-like structure which parameters are very close to those for the Galactic bar. These results evidence an old age of the Galactic bulge and bar. We propose a scenario of the successive star formation in the bulge, bar and thin disk.
Morphology of the Red Rectangle proto-planetary nebula
Authors: Koning Nico , Kwok Sun , Steffen Wolfgang
Published: August 2012

Using the 3D morpho-kinematic modeling software SHAPE, we have created a model of the Red Rectangle that naturally reproduces many exotic morphological features including the notorious “ladder rungs”.
Investigation of the recombination of the retarded shell of “born-again” CSPNe by time-dependent radiative transfer models
Authors: Koskela Antti , Dalnodar Silvia , Kissmann Ralf , Reimer Anita , Ostermann Alexander , Kimeswenger Stefan
Published: August 2012

A standard planetary nebula stays more than 10 000 years in the state of a photoionized nebula. As long as the timescales of the most important ionizing processes are much smaller, the ionization state can be characterized by a static photoionization model and simulated with codes like CLOUDY (Ferland et al. 1998). When the star exhibits a late helium flash, however, its ionizing flux stops within a very short period. The star then re-appears from its opaque shell after a few years (or centuries) as a cold giant star without any hard ionizing photons. Describing the physics of such behavior requires a fully time-dependent radiative transfer model. Pollacco (1999), Kerber et al. (1999) and Lechner & Kimeswenger (2004) used data of the old nebulae around V605 Aql and V4334 Sgr to derive a model of the pre-outburst state of the CSPN in a static model. Their argument was the long recombination time scale for such thin media. With regard to these models Schönberner (2008) critically raised the question whether a significant change in the ionization state (and thus the spectrum) has to be expected after a time of up to 80 years, and whether static models are applicable at all.
New faint planetary nebulae from the DSS and SDSS
Authors: Kronberger Matthias , Jacoby George H. , Ciardullo Robin , Crisp Richard D. , De Marco Orsola , Douchin Dimitri , Frew David J. , Harmer Dianne , Howell Mike , Howell Steve B. , Parker Quentin A. , Patchick Dana , Rector Travis , Riddle Dave , Teutsch Philipp
Published: August 2012

Having surveyed ≈ 10% of the sky, we have identified more than 130 PN candidates by surveying multicolour Digitized Sky Survey (DSS), Sloan Digitized Sky Survey (SDSS), and combined [O III], Hα and [S II] images. In a first imaging and spectroscopy campaign, 51 objects were identified as true and probable PNe. This work presents an additional 17 probable or possible PNe identified since that study. The majority of these candidates are situated at Galactic latitudes |b| > 5^, with the exception of seven objects located closer to the Galactic plane. Using the techniques described here that do not require any new survey data, we anticipate that many more PNe are waiting to be found, perhaps as many as 90.
Abundances of Disk PNe in M31 and the radial oxygen gradient
Authors: Kwitter Karen B. , Lehman Emma M. M. , Balick Bruce , Henry Richard B. C.
Published: August 2012

We have obtained spectra of 16 PNe in the disk of M31 and determined the abundances of He, N, O, Ne, S and Ar. Here we present the median abundances and compare them with previous M31 PN disk measurements and with PNe in the Milky Way. We also derive the radial oxygen gradient in M31, which is shallower than that in the Milky Way, even accounting for M31's larger disk scale length.
PyNeb: a new software for the analysis of emission lines
Authors: Luridiana Valentina , Morisset Christophe , Shaw Richard A.
Published: August 2012

We describe an ongoing project to migrate the emission-line analysis package nebular from its current environment, IRAF, to a modern programming environment where it can be used from command line, a local GUI, or the web. We are also updating the supporting atomic data where they have been superseded by superior calculations or measurements.
Plasma diagnostics for planetary nebulae and H ii regions using N ii and O ii optical recombination lines
Authors: McNabb Ian A. , Fang Xuan , Liu Xiao–Wei , Storey Peter J.
Published: August 2012

We carry out plasma diagnostic analysis for a number of planetary nebulae (PNe) and H ii regions. We use N ii and O ii optical recombination lines (ORLs) with new effective recombination coefficients calculated under the intermediate coupling scheme, for a range of electron temperatures (Te) and densities (Ne), and fitted against the most reliable measurements. Comparing Te derived from ORLs, collisionally excited lines (CELs), the hydrogen Balmer Jump, and/or He i if available, we find the relation Te (ORLs) < Te (He i) < Te (H i BJ) < Te (CELs), confirming the physical conditions in the bi-abundance model postulated by Liu et al., i.e. the nebula contains another cold, metal-rich and probably H-deficient component.
Planetary nebula spectra in M 60 and M 82
Authors: Méndez Roberto H. , Teodorescu Ana M. , Hattori Takashi , Magrini Laura , Johnson Lent C.
Published: August 2012

Using the Subaru telescope and its FOCAS spectrograph in multi-object mode, we have obtained spectra of a selection of bright PNs in two galaxies: the Virgo giant elliptical M 60 (NGC 4649), and the starburst spiral M 82. We report on individual extinctions, as determined from the Balmer decrement, and also on the intensities of [O III] 4959 and 5007 relative to Hβ.
A consolidated online database of Galactic planetary nebulae
Authors: Miszalski Brent , Acker A. , Ochsenbein F. , Parker Q. A.
Published: August 2012

Since the issue of the unifying Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SECGPN) a large number of new discoveries have been made thanks to improved surveys and discovery techniques. The increasingly heterogeneous published population of Galactic PNe, that we have determined totals <2850 PNe, is becoming more difficult to study on the whole without a centralised repository. We introduce a consolidated and interactive online database with object classifications that reflect the latest multi-wavelength data and the most recent results. The extensible database, hosted by the Centre de Donnees astronomique de Strasbourg (CDS), will contain a wealth of observed data for large, well-defined samples of PNe including coordinates, multi-wavelength images, spectroscopy, line intensities, radial velocities and central star information. It is anticipated that the database will be publicly released early 2012.
Modeling the dust emission from PN IC418
Authors: Morisset Christophe , Szczerba Ryszard , Anibal García-Hernández D. , García-Lario Pedro
Published: August 2012

We construct a detailed model for the IR dust emission from the PN IC 418. We succeed to reproduce the emission from 2 to 200 μm. We can determine the amount of emitting dust as well as its composition, and compare to the depletion of elements determined for the photoionized region.
Distance determination to PNe using the extinction-distance method
Authors: Navarro Silvana G. , Corradi Romano L. M. , Mampaso Antonio
Published: August 2012

We present individual distances to three PNe: NGC 6537, NGC 6781 and NGC 7027, determined by the extinction-distance method. These objects are part of a larger sample (35) of PNe that we observed at ORM. In order to apply this method, and to obtain accurate distances, we determined the spectral type of 40 to 60 stars in the line of sight of each PNe. This implied the necessity of classifying few thousands of stellar spectra with S/N ratio between 10 and 60. To solve such need we developed an ANN system to perform automatic spectral classification which could classify spectra with S/N ratio as low as 20 with an accuracy better than 2 spectral subtypes. In this poster we compare the accuracy of such distances with previous distance determinations using other methods. We conclude that it is possible to use this method to obtain the distance of a large number of PNe with better precision.
The kinematics of evolved planetary nebulae
Authors: Pereyra E. Margarita , Richer Michael G. , López Jose-Alberto
Published: August 2012

We have selected a group of 85 evolved planetary nebulae to study their kinematic characteristic based on spatially resolved, long-slit echelle spectroscopy. The data have been drawn from the San Pedro Mártir Kinematic Catalogue of PNe. The aim is to characterize in detail the global kinematics of PNe at advanced stages of evolution with the largest sample of homogenous data used to date for this purpose. The results reveal groups that share kinematic and photo-ionization characteristics of the nebular shell at the different late stages under study. The expansion velocities are typically larger than seen in earlier evolutionary stages, with the largest velocities occurring in objects with very weak or absent [N II]λλ6548, 6584 emission line. These results shall serve to be compared to predictions of hydrodynamical models.
The kinematical behavior of Galactic PNe with [WC] central star
Authors: Rechy-García Jackeline S. , Peña Miriam , García-Rojas Jorge
Published: August 2012

High resolution spectroscopic data of a large sample of galactic planetary nebulae with [WC] central stars ([WC]PNe) are analyzed to determine their kinematical behavior. Their heliocentric velocities have been determined with a precision better than a few km/s. Distances obtained from the literature are used to derive the peculiar velocities of the objects. Our preliminary results are: (a) The [WC] PNe are distributed in the galactic disk and they appear more concentrated than the normal PNe. (b) Separating the sample in Peimbert's types, we find that Type I PNe show in general low peculiar velocities (<50 km/s) except for a couple of objects apparently belonging to the galactic bulge. For the other [WC]PNe, most of them belong to the Peimbert's Type II (defined as having Vpec ≤ 60 km/s). However there is an important fraction (28%) showing Vpec larger than 60 km/s therefore they are classified as Peimbert's Type III.
A complete survey of mm line emission from CO and 13CO in water fountain stars
Authors: Rizzo J. Ricardo , Gómez José F. , Miranda Luis F. , Osorio Mayra , Suárez Olga
Published: August 2012

“Water fountains” (WF) are post-AGB stars characterized by very fast and often bipolar jets in the water maser line at 22 GHz. We conducted a survey of the CO and 13CO line emission using the IRAM 30m radio telescope of all the sources visible from the observatory. Over a total of 10 WFs observed, we identified CO and 13CO associated to IRAS 18460-0151 and IRAS 18596+0315. As the CO line emission is ubiquitous in the Galactic plane, the confirmed detections have met strict criteria to consider these cases as confirmed detections. The velocity components associated to the WFs are ~ 40 km s−1 wide, centered at the star velocity, present only at the star position, and detected in the four observed transitions, the CO and 13CO J=1→0 and 2→1 lines. A preliminary study, based on line ratios, indicates that this molecular component has a high opacity, and a very low 12C/13C isotopic ratio.
Kinematic age determinations of planetary nebula central stars
Authors: Rodrigues Thaise S. , Maciel Walter J.
Published: August 2012

Central stars of planetary nebulae (CSPN) have a relatively large mass interval, so that it is expected that these stars also have different ages, typically above 1 Gyr. Apart from the properties of the CSPN themselves, the problem of age determination is also important in the context of the chemical evolution of the Galaxy, for instance in the understanding of the time variation of chemical abundance gradients. In this work, we estimated the ages of a sample of CSPN on the basis of some correlations between their kinematic properties and the expected ages. According to these correlations, the observed dispersions in the U, V, W velocities are uniquely defined by the stellar ages. The adopted correlations were derived from the recent Geneva-Copenhagen survey of galactic stars. Preliminary results suggest the most CSPN in the galactic disk have ages under 3 Gyr. These results are also compared with some recent age distributions based on independent correlations involving the nebular chemical abundances.
A Herschel study of Planetary Nebulae
Authors: Van de Steene Griet C. , Exter Katrina M. , van Hoof Peter A. M. , Lim Tanya L. , Barlow Michael J. , Matsuura Mikako , Ueta Toshiya ,   the MESS consortium
Published: August 2012

We present Herschel PACS and SPIRE images of the dust shells around the planetary nebulae NGC 650, NGC 6853, and NGC 6720, as well as images showing the dust temperature in their shells. The latter show a rich structure, which indicates that internal extinction in the UV is important despite the highly evolved status of the nebulae.
The Σ – D relation for Galactic planetary nebulae: Application of orthogonal fitting procedure
Authors: Vukotić Branislav , Urošević Dejan
Published: August 2012

We estimate the parameters of the radio surface brightness to diameter (Σ – D) relation for the sample of Galactic planetary nebulae (PNe). The bootstrap re-sampling and orthogonal offsets fitting procedure are applied. The orthogonal fitting procedure provides that the parameter values of D – Σ and Σ – D fits are invariant within the estimated uncertainties. We discuss the probability statistics of the fitted (log Σ = log A - β log D) relation and the resulting fit parameters which is indicative for PN distance determination.
A study of the effect of ionization and illumination on morphologies of planetary nebulae
Authors: Zhang Yong , Kwok Sun , Ko Chung-Ming
Published: August 2012

We carry out a modelling study of the effect of ionization and illumination on the morphologies of planetary nebulae (PNs), aiming to investigate the hypothesis of Kwok (2010) that the bipolar and multipolar lobes of PNs can be produced by leakage of UV photons into those directions. Using photoinization code, we construct a series of nebular models consisting of a dense envelope and cones of low density. The results show that the visible morphologies of PNs may be fundamentally different from their intrinsic structures.
[Fe iii] lines in the planetary nebula NGC 2392
Authors: Zhang Yong , Fang Xuan , Chau Wayne , Hsia Chin-Hao , Liu Xiao-Wei , Kwok Sun
Published: August 2012

The Eskimo Nebula (NGC 2392) is a young double-shell planetary nebula (PN). Its intrinsic structure and the responsible shaping mechanism are still not fully understood. We present new optical spectroscopy of NGC 2392 at two different locations to obtain the spectra of the inner and outer shells. Several [Fe iii] lines are clearly detected. We find that these [Fe iii] lines mostly originate from the inner shell. Therefore, we suggest that NGC 2392 might have an intrinsic structure similar to the Ant Nebula Mz 3, which exhibits a number of [Fe iii] lines from the central dense regions. In this scenario, the inner and outer shells correspond to the central emission core and the outer lobes of Mz 3, respectively.
Expression patterns reveal niche diversification in a marine microbial assemblage
Authors: Gifford Scott M , Sharma Shalabh , Booth Melissa , Moran Mary Ann
Published: August 2012

Resolving the ecological niches of coexisting marine microbial taxa is challenging due to the high species richness of microbial communities and the apparent functional redundancy in bacterial genomes and metagenomes. Here, we generated over 11 million Illumina reads of protein-encoding transcripts collected from well-mixed southeastern US coastal waters to characterize gene expression patterns distinguishing the ecological roles of hundreds of microbial taxa sharing the same environment. The taxa with highest in situ growth rates (based on relative abundance of ribosomal protein transcripts) were typically not the greatest contributors to community transcription, suggesting strong top-down ecological control, and their diverse transcriptomes indicated roles as metabolic generalists. The taxa with low in situ growth rates typically had low diversity transcriptomes dominated by specialized metabolisms. By identifying protein-encoding genes with atypically high expression for their level of conservation, unique functional roles of community members emerged related to substrate use (such as complex carbohydrates, fatty acids, methanesulfonate, taurine, tartrate, ectoine), alternative energy-conservation strategies (proteorhodopsin, AAnP, V-type pyrophosphatases, sulfur oxidation, hydrogen oxidation) and mechanisms for negotiating a heterogeneous environment (flagellar motility, gliding motility, adhesion strategies). On average, the heterotrophic bacterioplankton dedicated 7% of their transcriptomes to obtaining energy by non-heterotrophic means. This deep sequencing of a coastal bacterioplankton transcriptome provides the most highly resolved view of bacterioplankton niche dimensions yet available, uncovering a spectrum of unrecognized ecological strategies.
Activation of PLC by an endogenous cytokine (GBP) inDrosophilaS3 cells and its application as a model for studying inositol phosphate signalling through ITPK1
Authors: Zhou Yixing , Wu Shilan , Wang Huanchen , Hayakawa Yoichi , Bird Gary S. , Shears Stephen B.
Published: August 2012

Using immortalized [3H]inositol-labelled S3 cells, we demonstrated in the present study that various elements of the inositol phosphate signalling cascade are recruited by a Drosophila homologue from a cytokine family of so-called GBPs (growth-blocking peptides). HPLC analysis revealed that dGBP (Drosophila GBP) elevated Ins(1,4,5)P3 levels 9-fold. By using fluorescent Ca2+ probes, we determined that dGBP initially mobilized Ca2+ from intracellular pools; the ensuing depletion of intracellular Ca2+ stores by dGBP subsequently activated a Ca2+ entry pathway. The addition of dsRNA (double-stranded RNA) to knock down expression of the Drosophila Ins(1,4,5)P3 receptor almost completely eliminated mobilization of intracellular Ca2+ stores by dGBP. Taken together, the results of the present study describe a classical activation of PLC (phospholipase C) by dGBP. The peptide also promoted increases in the levels of other inositol phosphates with signalling credentials: Ins(1,3,4,5)P4, Ins(1,4,5,6)P4 and Ins(1,3,4,5,6)P5. These results greatly expand the regulatory repertoire of the dGBP family, and also characterize S3 cells as a model for studying the regulation of inositol phosphate metabolism and signalling by endogenous cell-surface receptors. We therefore created a cell-line (S3ITPK1) in which heterologous expression of human ITPK (inositol tetrakisphosphate kinase) was controlled by an inducible metallothionein promoter. We found that dGBP-stimulated S3ITPK1 cells did not synthesize Ins(3,4,5,6)P4, contradicting a hypothesis that the PLC-coupled phosphotransferase activity of ITPK1 [Ins(1,3,4,5,6)P5+Ins(1,3,4)P3→Ins(3,4,5,6)P4+Ins(1,3,4,6)P4] is driven solely by the laws of mass action [Chamberlain, Qian, Stiles, Cho, Jones, Lesley, Grabau, Shears and Spraggon (2007) J. Biol. Chem. 282, 28117–28125]. This conclusion represents a fundamental breach in our understanding of ITPK1 signalling.
A reflective optical transport system for ultraviolet Thomson scattering from electron plasma waves on OMEGA
Authors: Katz J. , Boni R. , Sorce C. , Follett R. , Shoup M. J. , Froula D. H.
Published: August 2012

A reflective optical transport system has been designed for the OMEGA Thomson-scattering diagnostic. A Schwarzschild objective that uses two concentric spherical mirrors coupled to a Pfund objective provides diffraction-limited imaging across all reflected wavelengths. This enables the operator to perform Thomson-scattering measurements of ultraviolet (0.263 μm) light scattered from electron plasma waves.
Compact radio-frequency resonator for cryogenic ion traps
Authors: Gandolfi D. , Niedermayr M. , Kumph M. , Brownnutt M. , Blatt R.
Published: August 2012

We report on the investigation and implementation of a lumped-component, radio-frequency resonator used in a cryogenic vacuum environment to drive an ion trap. The resonator was required to achieve the voltages necessary to trap (∼100 V), while dissipating very little power. Ultimately, for an input voltage of 1.35 V, a voltage gain of 100 was measured at 5.7 K, using a design which dissipated only 18 mW. The resonator operated at a frequency of 7.64 MHz and had a Q of 700. Single 40Ca+ ions were confined in a trap driven by this device, providing proof of successful resonator operation at low temperature.
Liouville theorems in unbounded domains for the time-dependent stokes system
Authors: Jia Hao , Seregin Gregory , Šverák Vladimír
Published: August 2012

In this paper, we characterize bounded ancient solutions to the time-dependent Stokes system with zero boundary value in various domains, including the half-space.
Well-posedness on large time for a modified full dispersion system of surface waves
Authors: Saut Jean-Claude , Xu Li
Published: August 2012

By a nonlinear change of variables from the original one, we derive a “small steepness full dispersion” system for surface water waves which is consistent with the water wave system. This system is symmetrizable and we prove that the Cauchy problem is well-posed on large time of order 1/ε where ε is the steepness coefficient, implying (together with the results of D. Lannes) its full rigorous justification as an asymptotic model to the full Euler equations with free surface.
Three-axis correction of distortion due to positional drift in scanning probe microscopy
Authors: Follin Nathan D. , Taylor Keefer D. , Musalo Christopher J. , Trawick Matthew L.
Published: August 2012

Two common sources of distortion in scanning probe microscopy are piezo creep and thermal drift, the latter caused by slow thermal expansions of materials in the sample and microscope due to small changes in temperature over the course of a scan. We present a technique for correcting distortion due to thermal drift along all three spatial axes, along with simultaneous correction of z-axis piezo creep. Our method works by comparing each scanned topographical image to a second, partial scan, taken immediately afterwards, on which the fast and slow scan axes have been reversed. We model the positional distortion as a low-order polynomial function in three dimensions, searching for the set of correctional coefficients that minimizes the root-mean-square difference between the two scans. We demonstrate in a variety of real-world and simulated tests that this technique can routinely reduce distortion from these effects by over 90%, often to a precision of better than a single pixel.
Continuum representation of a continuous size distribution of particles engaged in rapid granular flow
Authors: Murray J. A. , Benyahia S. , Metzger P. , Hrenya C. M.
Published: August 2012

Natural and industrial granular flows often consist of several particle sizes, approximately forming a continuous particle size distribution (PSD). Continuous PSDs are ubiquitous, though existing kinetic-theory-based, hydrodynamic models for rapid granular flows are limited to a discrete number of species. The objective of this work is twofold: (i) to determine the number of discrete species required to accurately approximate a continuous PSD and (ii) to validate these results via a comparison with molecular dynamics (MD) simulations of continuous PSDs. With regard to the former, several analytic (Gaussian and lognormal) and experimental (coal and lunar soil simulants) distributions are investigated. Transport coefficients (pressure, shear viscosity, etc.) of the granular mixture given by the polydisperse theory of Garzó et al. [“Enskog theory for polydisperse granular mixtures. I. Navier-Stokes order transport,” Phys. Rev. E 76, 031303 (2007)10.1103/PhysRevE.76.031303;Garzó et al. “Enskog theory for polydisperse granular mixtures. I. Navier-Stokes order transport,” Phys. Rev. E 76, 031304 (2007)10.1103/PhysRevE.76.031304] are compared using an increasing number of species s to approximate the given PSD. These discrete approximations are determined by matching the first 2s moments of the approximation and the given continuous distribution. Relatively few species are required to approximate moderately wide distributions (Gaussian, lognormal), whereas even wider distributions (coal and lunar soil simulants) require a larger number of species. Regarding the second objective, a comparison between MD simulations and kinetic-theory predictions for a simple shear flow of both Gaussian and lognormal PSDs reveal essentially no loss of accuracy stemming from the polydisperse theory itself (as compared to theories for monodisperse systems) or from the discrete approximations of continuous PSDs used in the polydisperse theory.
Copper activation deuterium-tritium neutron yield measurements at the National Ignition Facility
Authors: Cooper G. W. , Ruiz C. L. , Leeper R. J. , Chandler G. A. , Hahn K. D. , Nelson A. J. , Torres J. A. , Smelser R. M. , McWatters B. R. , Bleuel D. L. , Yeamans C. B. , Knittel K. M. , Casey D. T. , Frenje J. A. , Gatu Johnson M. , Petrasso R. D. , Styron J. D.
Published: August 2012

A DT neutron yield diagnostic based on the reactions, 63Cu(n,2n)62Cu(β+) and 65Cu(n,2n) 64 Cu(β+), has been fielded at the National Ignition Facility (NIF). The induced copper activity is measured using a NaI γ-γ coincidence system. Uncertainties in the 14-MeV DT yield measurements are on the order of 7% to 8%. In addition to measuring yield, the ratio of activities induced in two, well-separated copper samples are used to measure the relative anisotropy of the fuel ρR to uncertainties as low as 5%.