bluuebunny/crossref_metadata_2025_split huggingface dataset:
Planets, evolved stars, and how they might influence each other.
Authors: Villaver Eva 
Published: August 2012

AbstractOver the last 20 years planetary searches have revealed a wealth of systems orbiting stars on the main sequence. Most of these low-mass stars eventually will evolve into the Giant phases before entering the planetary nebulae (PNe) stage. In the last years, the presence of planets has also been discovered around more massive evolved stars, mostly, along the Red Giant but also along the Horizontal Branch. Moreover, disks have been found around White Dwarfs presumably formed by tidally disrupted asteroids. In all, there is evidence that an evolved (ing) star might influence the survival of planets. In this review I will try to summarize such evidence but furthermore I will present the other side of the story, that is, how the presence of a planet might alter the evolution of stars and with that the PN formation.
The ionization of galaxies by their planetary nebulae
Authors: Stasińska Grażyna 
Published: August 2012

AbstractRecent studies have shown that nuclei of planetary nebulae and their remnants (dubbed HOLMES for “hot low-mass evolved stars”) can easily explain two long-standing problems of extragalactic astronomy: the observed emission-line spectra of ellipticals and LINER-like galaxies and the ionization and heating of the diffuse interstellar medium in spirals. They are summarized in this contribution. It is emphasized that the computation of grids of stellar evolution models until the white dwarf stage is essential not only for the study of planetary nebulae but also for the study of the ionization of galaxies.
PNe in NGC 300: Their abundances and chemical gradients
Authors: Peña Miiriam , Stasinska Grazyna , Bresolin Fabio , Tsamis Yiannis 
Published: August 2012

AbstractSpectrophotometric data of a number of planetary nebulae and compact HII regions of NGC 300 have been obtained with the FORS 2 spectrograph of the VLT. We present a preliminary analysis of such data.
Planetary nebulae populations in external galaxies
Authors: Arnaboldi Magda 
Published: August 2012

AbstractThis review highlights the properties of the planetary nebulae in external galaxies as tracers of light, of the stellar population properties, and of the distances and kinematics of the parent galaxies. Recent results on the kinematics of the outer regions in giant elliptical galaxies and on the luminosity specific PN numbers (the α parameter) in these systems are presented, based on current surveys of planetary nebulae with the Planetary Nebulae Spectrograph (PN.S) and other instruments. Finally a brief discussion is given of planetary nebulae as tracers of the diffuse light in the nearby clusters, such as Virgo and Hydra I.
The frontier of ground-based observations
Authors: Käufl Hans U. 
Published: August 2012

AbstractThe ESO VLT on Paranal is in transition from first generation instrumentation to second generation, or at least to substantially upgraded instrumentation. The new instrumentation shall establish multipicity gain, high image definition or integral field imaging spectroscopy. Starting from observational highlights, status and trends for groundbased instrumentation will be revisited with emphasis on the field of PNe in all evolutionary phases. This review will concentrate on spectroscopy and scientific cases where groundbased observations offer a particular advantage. To the extent possible, a projection will be given as to the potential of the extremely large telescopes on the horizon, which will work best in the (near-)infrared.
Distance mapping technique and the 3-D structure of BD +30°3639
Authors: Akras Stavros , Steffen Wolfgang 
Published: August 2012

AbstractWe present a new kinematic analysis technique called distance mapping. It uses the observed proper motion vectors and the 3-D velocity field to determine the distance for each vector. From this information we generate maps that can be use as a constraint to morpho-kinematic modeling with SHAPE. It is applied to BD +30°3639, using the internal proper motion measurements by Li et al. (2002). We determine its distance at 1.40 kpc ± 0.15 kpc.
Planetary nebulae and their mimics: The MASH-MEN Project
Authors: Boissay Rozenn , Parker Quentin A. , Frew David J. , Bojicic Ivan 
Published: August 2012

AbstractThe total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is about 3000, approximately twice the number known a decade ago. The new discoveries are a legacy of the recent availability of wide-field, narrowband imaging surveys, primarily in the light of Hα. The two most important are the AAO/UKST SuperCOSMOS Hα survey SHS and the Isaac Newton photometric Hα survey IPHAS, which are responsible for most of the new discoveries. A serious problem with previous PN catalogs is that several different kinds of astrophysical objects are able to mimic PN in some of their observed properties leading to significant contamination. These objects include H~II regions and Strömgren zones around young O/B stars, reflection nebulae, Wolf-Rayet ejecta, supernova remnants, Herbig-Haro objects, young stellar objects, B[e] stars, symbiotic stars and outflows, late-type stars, cataclysmic variables, low redshift emission-line galaxies, and even image/detector flaws. PN catalogs such as the Macquarie/AAO/Strasbourg Hα Planetary Nebula catalog (MASH) have been carefully vetted to remove these mimics using the wealth of new wide-field multi-wavelength data and our 100% follow-up spectroscopy to produce a compilation of new PN discoveries of high purity. During this process significant numbers of PN mimics have been identified. The aim of this project is to compile these MASH rejects into a catalog of Miscellaneous Emission Nebulae (MEN) and to highlight the most unusual and interesting examples. A new global analysis of these MEN objects is underway before publishing the MEN catalog online categorizing objects by type together with their spectra and multi-wavelength images.
Identification of three new protoplanetary nebulae exhibiting the unidentified feature at 21 μm
Authors: Cerrigone Luciano , Hora Joseph L. , Umana Grazia , Trigilio Corrado , Hart Alexa , Fazio Giovanni 
Published: August 2012

AbstractSince its discovery, the feature at 21 μm has been detected in all C-rich proto-PNe of intermediate spectral type (A–G) and – weakly – in a few PNe and AGB stars, but the nature of its carriers remains unknown. In this paper, we show the detection of this feature in the spectra of three new stars obtained with the Spitzer Space Telescope. In the attempt to relate the unidentified feature to other dust features, we retrieved mid-IR spectra of all the 21 μm sources currently known from ISO and Spitzer archives and noticed a correlation between the flux emitted in the 21 μm feature and that emitted at 7 and 11 μm (PAH bands and HAC broad emission). Such a correlation may point to a common nature of the carriers.
Searching for binary central stars of planetary nebulae with Kepler
Authors: Douchin Dimitri , Jacoby George H. , De Marco Orsola , Howell Steve B. , Kronberger Mattias 
Published: August 2012

AbstractThe Kepler Observatory offers unprecedented photometric precision (<1 mmag) and cadence for monitoring the central stars of planetary nebulae, allowing the detection of tiny periodic light curve variations, a possible signature of binarity. With this precision free from the observational gaps dictated by weather and lunar cycles, we are able to detect companions at much larger separations and with much smaller radii than ever before. We have been awarded observing time to obtain light-curves of the central stars of the six confirmed and possible planetary nebulae in the Kepler field, including the newly discovered object Kn 61, at cadences of both 30 min and 1 min. Of these six objects, we could confirm for three a periodic variability consistent with binarity. Two others are variables, but the initial data set presents only weak periodicities. For the central star of Kn 61, Kepler data will be available in the near future.
Excitation of emission lines by fluorescence and recombination in IC 418
Authors: Escalante Vladimir , Morisset Cristophe , Georgiev Leonid 
Published: August 2012

AbstractWe predict intensities of lines of CII, NI, NII, OI and OII and compare them with a deep spectroscopic survey of IC 418 to test the effect of excitation of nebular emission lines by continuum fluorescence of starlight. Our calculations use a nebular model and a synthetic spectrum of its central star to take into account excitation of the lines by continuum fluorescence and recombination. The NII spectrum is mostly produced by fluorescence due to the low excitation conditions of the nebula, but many CII and OII lines have more excitation by fluorescence than recombination. In the neutral envelope, the NI permitted lines are excited by fluorescence, and almost all the OI lines are excited by recombination. Electron excitation produces the forbidden optical lines of OI, but continuum fluorescence excites most of the NI forbidden line intensities. Lines excited by fluorescence of light below the Lyman limit thus suggest a new diagnostic to explore the photodissociation region of a nebula.
Integral stellar-nebular model of NGC 7009
Authors: Fierro Celia R. , Peimbert Antonio , Georgiev Leonid , Morisset Christophe , Arrieta Anabel 
Published: August 2012

AbstractWe developed a self-consistent stellar-nebular model for NGC 7009. This model reproduces the available observations ranging from optical to UV. The combined approach to the modeling process produces more constraints and thus more trustworty results. After obtaining the model, we perform a comparative study of the chemical composition of He, N, O, Ne, Cl, and S in the nebula and its central star. Concluding that the stellar composition agrees with the nebular composition with t2 ≠ 0.00.
Green's functions for polarized radiative transfer equation in different geometries
Authors: Freimanis Juris 
Published: August 2012

AbstractA review of some earlier exact analytic solutions of monochromatic stationary vector radiative transfer equation in homogeneous infinite medium is given. It is stressed that Green's functions for plane-parallel, spherical and cylindrical symmetry are expressed through derivatives and integrals from basically one and the same set of functions.
On relation between nebular morphology and infrared photometric properties
Authors: Górny Slawomir K. , Siódmiak Natasza 
Published: August 2012

AbstractWe report on the ongoing study of the infrared properties of different types of planetary nebulae based on the data from recent photometric and spectroscopic infrared surveys. We present our first results concerning the relation between nebular morphology and infrared properties using the observations from the AKARI mission.
Ablation and Wind Mass-Loading in the Born-Again Planetary Nebula A 30
Authors: Guerrero Martín A. , Chu You-Hua , Hamann Wolf-Rainer , Oskinova Lidia , Schönberner Detlef , Todt Helge , Steffen Matthias , Ruiz Nieves , Gruendl Robert A. , Blair William P. 
Published: August 2012

AbstractWe present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.
X-ray spectra of wind-driven bubbles with chemical gradients
Authors: Jacob Ralf , Sandin Christer , Schönberner Detlef , Steffen Matthias 
Published: August 2012

AbstractAs a tool helping to interpret diffuse X-ray emission of PNe, and as a supplement to our RHD simulations, we have started to construct a grid of theoretical X-ray spectra of wind-blown bubbles with temperature and density profiles according to thermal conduction theory. We investigate how the X-ray spectra depend on chemical composition (e.g. H-rich vs. H-deficient) and how temperature and abundance determinations reflect gradients of temperature and chemical composition within the bubbles. These synthetic models shall allow to quickly perform detailed parameter studies without the need for dedicated hydrodynamical simulations. We report on ideas and goals.
The influence of binarity on the morpho-kinematics of planetary nebulae
Authors: Jones David , Tyndall Amy A. , Lloyd Myfanwy , Santander-García Miguel 
Published: August 2012

AbstractThe role of central star binarity in the shaping of planetary nebulae (PNe) has been the subject of much debate, with single stars believed to be incapable of producing the most highly collimated morphologies. However, observational support for binary-induced shaping has been sadly lacking. Here, we highlight the results of a continuing programme to spatio-kinematically model the morphologies of all PNe known to contain a close binary central star. Spatio-kinematical modelling is imperative for these objects, as it circumvents the degeneracy between morphology and orientation which can adversely affect determinations of morphology based on imaging alone. Furthermore, spatio-kinematical modelling accurately determines the orientation of the nebular shell, allowing the theoretically predicted perpendicular alignment, between nebular symmetry axis and binary orbital plane, to be tested. To date, every PN subjected to this investigation has displayed the predicted alignment, indicating that binarity has played an important role in the formation and evolution of these nebulae. The further results from this programme will be key, not only in determining whether binary interaction is responsible for shaping the studied PNe, but also in assessing the importance of binarity in the formation and evolution of all PNe in general.
Grids of synthetic spectra for H-poor central stars of planetary nebulae (CSPNe)
Authors: Keller Graziela R. , Bianchi Luciana , Herald James E. , Maciel Walter J. 
Published: August 2012

AbstractWe present comprehensive grids of model spectra from far-UV to IR, covering the parameter space of [WC] (Keller et al. 2011) and PG1159 stars. Models are calculated with the CMFGEN code, accounting for non-LTE, line blanketing, wind, clumping, and including ions previously neglected. The grids are available at http://dolomiti.pha.jhu.edu/planetarynebulae.html. We used them to analyse UV and far-UV spectra of NGC6905's and NGC5189's central stars.
The growth of the outflows from evolved stars: A live poster
Authors: Liimets Tiina , Corradi Romano L. M. , Balick Bruce , Santander-García Miguel 
Published: August 2012

AbstractWe present our long-term monitoring, using both ground-based telescopes and the HST, of the expansion in the plane of the sky of the outflows from evolved stars. They include the PN M2–9 (suspected of hosting a symbiotic nucleus), the classical nova remnant GK Per, the symbiotic Miras R Aqr, Hen 2–147 and Hen 2–104, and the proto-PNe CRL 618, CRL 2688, and Hen 3–1475.
Radial abundance gradients from planetary nebulae and young objects: Age effects
Authors: Maciel Walter J. , Rodrigues Thaise , Costa Roberto 
Published: August 2012

AbstractWe discuss the effects on the time variation of the gradients resulting from our determinations of the age distributions of CSPN. The main conclusions are: (i) for most CSPN with accurate radial velocities the kinematic ages are usually under 3 Gyr, so that the differences between the gradients of these objects and of younger objects are expected to be small; (ii) results based on age-metallicity relations suggest that there is an older PN population for which the gradients are steeper, in agreement with open cluster data.
Spectral analysis of PG 1034+001, the exciting star of Hewett 1
Authors: Mahsereci Marin , Ringat Ellen , Rauch Thomas , Werner Klaus , Kruk Jeffrey W. 
Published: August 2012

AbstractPG 1034+001 is an extremely hot, helium-rich DO-type star that excites the planetary nebula Hewett 1 and large parts of the surrounding interstellar medium. We present preliminary results of an ongoing spectral analysis by means of non-LTE model atmospheres that consider most elements from hydrogen to nickel. This analysis is based on high-resolution ultraviolet (FUSE, IUE) and optical (VLT/UVES, Keck) data. The results are compared with those of PG 1034+001's spectroscopic twin, the DO star PG 0038+199.
Gaia future contribution to the study of PNe
Authors: Manteiga Minia , Arcay Bernardino , Ulla Ana , Aller Alba , Miranda Luis. F. , Isasi Yago ,   Gaia DPAC
Published: August 2012

AbstractGaia, the forthcoming astrometric ESA survey, is expected to substantially improve our knowledge about the distances to galactic planetary nebulae (PNe). We present an overview of Gaia mission and focus in some aspects which are relevant for the study of PNe. In particular, we present our simulations on Gaia spectrophotometric observations obtained by means of GOG (Gaia Object Generator) for a catalogue of proto-PNe and PNe (Suárez et al. 2006) which can be used as templates to classify and study the suitability of Gaia spectrophotometry to infer physical properties of the sources.
Luminosity and abundance correlations in a carefully-studied sample of PNe
Authors: McKeever Jean , Balick Bruce , Lutz Julie , Braxton Kelsey , Gomez Thomas , Kwitter Karen , Henry Richard C.B. 
Published: August 2012

AbstractWe have searched for correlated trends in He/H, N/H, O/H, Ne/H, Ar/H, Cl/H, and S/H abundances with their luminosities, Peimbert types, galactocentric radius, emission-line luminosities, diameters, morphologies, surface brightnesses among Galactic planetary nebulae (PNe) using a database of 119 PNe with well measured properties. We report selected highlights.
Peculiar CNO photospheric abundances in the central star of NGC 2392
Authors: Méndez Roberto H. , Urbaneja Miguel A. , Kudritzki Rolf-Peter , Prinja Raman K. 
Published: August 2012

AbstractUsing new, high signal-to-noise CFHT ESPaDOnS visual spectrograms, and archive IUE and FUSE UV spectrograms, together with state-of-the-art non-LTE hydrodynamical model atmospheres, we have obtained accurate He, C, N, O photospheric abundance determinations in the central stars of NGC 2392, IC 4593, and NGC 6826. We compare with the corresponding nebular abundances, taken from the literature. The central star of NGC 2392 shows high He, N, and very low C, O abundances. We propose that these peculiar abundances must have originated in a common-envelope phase of interaction with a close binary companion. If we assume that the companion is more evolved than the visible central star, this offers a way of solving the old mystery of the discrepant He II Zanstra temperature of NGC 2392.
Planetary nebulae in the VISTA Magellanic Cloud (VMC) Survey
Authors: Miszalski Brent , Napiwotzki Ralph , Cioni Maria-Rosa L. , Groenewegen Martin A. T. , Oliveira Jose M. , Udalski Andrzej , Nie Jia-Cai 
Published: August 2012

AbstractThe multi-epoch YJKs sub-arcsecond photometry of the VMC survey provides a long anticipated deep near-infrared (NIR) window into further understanding the stellar populations of the Magellanic Clouds. The first year of observations consisted of six tiles covering ~9% of the Large Magellanic Cloud (LMC) survey region and contains 102 objects previously classified as planetary nebulae (PNe). A large proportion of the sample were found to be contaminated by non-PNe. These initial results underline the importance of establishing a clean catalogue of LMC PNe before they are applied in areas such as the planetary nebula luminosity function (PNLF) and searches for binary central stars. As the VMC survey progresses it will play a fundamental role in cleaning extant PN catalogues and a complementary role in the discovery of new PNe.
Early results from ChanPLaNS: Mystery of hard X-ray emitting CSPNe
Authors: Montez Rodolfo , Kastner J. H. , Balick B. , Behar E. , Blackman E. , Bujarrabal V. , Chu Y.-H. , Corradi R. , De Marco O. , Frank A. , Frew D. , Guerrero M. , Kwok S. , Lopez J. A. , Miszalski B. , Nordhaus J. , Parker Q. , Sahai R. , Sandin C. , Schoenberner D. , Soker N. , Sokoloski J. , Steffen W. , Ueta T. , Villaver E. , Zijlstra A. 
Published: August 2012

AbstractWe are presently using the Chandra X-ray Observatory to conduct the first systematic X-ray survey of planetary nebulae (PNe) in the solar neighborhood. The Chandra Planetary Nebula Survey (ChanPlaNS) is a 570 ks Chandra Cycle 12 Large Program targeting 21 high-excitation PNe within ~1.5 kpc of Earth. When complete, this survey will provide a suite of new X-ray diagnostics that will inform the study of late stellar evolution, binary star astrophysics, and wind interactions. Among the early results of ChanPlaNS (when combined with archival Chandra data) is a surprisingly high detection rate of relatively hard X-ray emission from CSPNe. Specifically, X-ray point sources are clearly detected in roughly half of the ~30 high-excitation PNe observed thus far by Chandra, and all but one of these X-ray-emitting CSPNe display evidence for a hard (few MK) component in their Chandra spectra. Only the central star of the Dumbbell appears to display “pure” hot blackbody emission from a ~200 kK hot white dwarf photosphere in the X-ray band. Potential explanations for the“excess” hard X-ray emission detected from the other CSPNe include late-type companions (heretofore undetected, in most cases) whose coronae have been rejuvenated by recent interactions with the mass-losing WD progenitor, non-LTE effects in hot white dwarf photospheres, self-shocking variable winds from the central star, and slow (re-)accretion of previously ejected red giant envelope mass.
∊ Aur in eclipse: Post-AGB primary and disk-shaped secondary
Authors: Muthumariappan Chinnathambi , Parthasarathy Mudumba , Jayakumar Kanniah , Appakutty Manickam 
Published: August 2012

AbstractWe present physical and chemcal properties of the disk in the eclipsing binary system ∊ Aur by solving 2D radiative transfer problem. We also present preliminary results of our high resolution spectroscopic monitoring of K I, Na, and Hα line profiles variation during the totality phase of the recent eclipse of ∊ Aur.
Processing of polycyclic aromatic hydrocarbons in evolved planetary nebulae
Authors: Ohsawa Ryou , Onaka Takashi , Sakon Itsuki , Yamamura Issei , Matsuura Mikako , Kaneda Hidehiro 
Published: August 2012

AbstractWe investigate the infrared emission bands from Polycyclic Aromatic Hydrocarbons (PAHs) in Galactic planetary nebulae (PNe). PAHs in PNe are assumed to be in transition from circumstellar to interstellar PAHs. We select 15 evolved PNe taking account of effective stellar temperatures and obtain infrared spectra of PNe from AKARI (2.5–5 μm) and Spitzer (5–14 μm) observations. Their evolutionary phase is estimated using [SIV]10.51/[NeII]12.81. We find that the near-infrared PAH bands are significantly enhanced along with stellar evolution sequence. We also find that the ratio of 3.4 to 3.3 μm bands is enhanced. The enhancement might indicate some chemical processing, such as hydrogenation, on small PAHs.