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A reexamination of electron density diagnostics for ionized gaseous nebulae
We present a comparison of electron densities derived from opticalforbidden line diagnostic ratios for a sample of over a hundred nebulae.We consider four density indicators, the [O II]λ3729/λ3726, [S II] λ6716/λ6731, [Cl III]λ5517/λ5537 and [Ar IV] λ4711/λ4740 doubletratios. Except for a few H II regions for which data from the literaturewere used, diagnostic line ratios were derived from our own high qualityspectra. For the [O II] λ3729/λ3726 doublet ratio, we findthat our default atomic data set, consisting of transition probabilitiesfrom Zeippen (\cite{zeippen1982}) and collision strengths from Pradhan(\cite{pradhan}), fit the observations well, although at high electrondensities, the [O II] doublet ratio yields densities systematicallylower than those given by the [S II] λ6716/λ6731 doubletratio, suggesting that the ratio of transition probabilities of the [OII] doublet, A(λ3729)/A(λ3726), given by Zeippen(\cite{zeippen1982}) may need to be revised upwards by approximately 6per cent. Our analysis also shows that the more recent calculations of[O II] transition probabilities by Zeippen (\cite{zeippen1987a}) andcollision strengths by McLaughlin & Bell (\cite{mclaughlin}) areinconsistent with the observations at the high and low density limits,respectively, and can therefore be ruled out. We confirm the earlierresult of Copetti & Writzl (\cite{copetti2002}) that the [O II]transition probabilities calculated by Wiese et al. (\cite{wiese}) yieldelectron densities systematically lower than those deduced from the [SII] λ6716/λ6731 doublet ratio and that the discrepancy ismost likely caused by errors in the transition probabilities calculatedby Wiese et al. (\cite{wiese}). Using our default atomic data set for [OII], we find that Ne([O II]) Ne([S II]) ≈Ne([Cl III])< Ne([Ar IV]).
| Planetary nebula distances re-examined: an improved statistical scale
The distances of planetary nebulae (PNe) are still quite uncertain.Although observational estimates are available for a small proportion ofPNe, based on statistical parallax and the like, such distances are verypoorly determined for the majority of galactic PNe. In particular,estimates of so-called `statistical' distance appear to differ byfactors of ~2.7.We point out that there is a well-defined correlation between the 5-GHzluminosity of the sources, L5, and their brightnesstemperatures, TB. This represents a different trend to thoseinvestigated in previous statistical analyses, and permits us todetermine independent distances to a further 449 outflows. Thesedistances are shown to be closely comparable to those determined using aTB-R correlation, providing that the latter trend is taken tobe non-linear.This non-linearity in the TB-R plane has not been noted inprevious analyses, and is likely responsible for the broad (andconflicting) ranges of distance that have previously been published.Finally, we point out that there is a close accord between observedtrends within the L5-TB and TB-Rplanes, and the variation predicted through nebular evolutionarymodelling. This is used to suggest that observational biases areprobably modest, and that our revised distance scale is reasonablytrustworthy.
| The relation between Zanstra temperature and morphology in planetary nebulae
We have created a master list of Zanstra temperatures for 373 galacticplanetary nebulae based upon a compilation of 1575 values taken from thepublished literature. These are used to evaluate mean trends intemperature for differing nebular morphologies. Among the most prominentresults of this analysis is the tendency forη=TZ(HeII)/TZ(HeI) to increase with nebularradius, a trend which is taken to arise from the evolution of shelloptical depths. We find that as many as 87 per cent of nebulae may beoptically thin to H ionizing radiation where radii exceed ~0.16 pc. Wealso note that the distributions of values η and TZ(HeII)are quite different for circular, elliptical and bipolar nebulae. Acomparison of observed temperatures with theoretical H-burning trackssuggests that elliptical and circular sources arise from progenitorswith mean mass ≅ 1 Msolar(although the elliptical progenitors are probably more massive).Higher-temperature elliptical sources are likely to derive fromprogenitors with mass ≅2 Msolar, however, implying thatthese nebulae (at least) are associated with a broad swathe ofprogenitor masses. Such a conclusion is also supported by trends in meangalactic latitude. It is found that higher-temperature ellipticalsources have much lower mean latitudes than those with smallerTZ(HeII), a trend which is explicable where there is anincrease in with increasing TZ(HeII).This latitude-temperature variation also applies for most other sources.Bipolar nebulae appear to have mean progenitor masses ≅2.5Msolar, whilst jets, Brets and other highly collimatedoutflows are associated with progenitors at the other end of the massrange (~ 1 Msolar). Indeed it ispossible, given their large mean latitudes and low peak temperatures,that the latter nebulae are associated with the lowest-mass progenitorsof all.The present results appear fully consistent with earlier analyses basedupon nebular scale heights, shell abundances and the relativeproportions of differing morphologies, and offer further evidence for alink between progenitor mass and morphology.
| Galactic Planetary Nebulae and their central stars. I. An accurate and homogeneous set of coordinates
We have used the 2nd generation of the Guide Star Catalogue (GSC-II) asa reference astrometric catalogue to compile the positions of 1086Galactic Planetary Nebulae (PNe) listed in the Strasbourg ESO Catalogue(SEC), its supplement and the version 2000 of the Catalogue of PlanetaryNebulae. This constitutes about 75% of all known PNe. For these PNe, theones with a known central star (CS) or with a small diameter, we havederived coordinates with an absolute accuracy of ~0\farcs35 in eachcoordinate, which is the intrinsic astrometric precision of the GSC-II.For another 226, mostly extended, objects without a GSC-II counterpartwe give coordinates based on the second epoch Digital Sky Survey(DSS-II). While these coordinates may have systematic offsets relativeto the GSC-II of up to 5 arcsecs, our new coordinates usually representa significant improvement over the previous catalogue values for theselarge objects. This is the first truly homogeneous compilation of PNepositions over the whole sky and the most accurate one available so far.The complete Table \ref{tab2} is only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/408/1029}
| Angular dimensions of planetary nebulae
We have measured angular dimensions of 312 planetary nebulae from theirimages obtained in Hα (or Hα + [NII]). We have appliedthree methods of measurements: direct measurements at the 10% level ofthe peak surface brightness, Gaussian deconvolution and second-momentdeconvolution. The results from the three methods are compared andanalysed. We propose a simple deconvolution of the 10% levelmeasurements which significantly improves the reliability of thesemeasurements for compact and partially resolved nebulae. Gaussiandeconvolution gives consistent but somewhat underestimated diameterscompared to the 10% measurements. Second-moment deconvolution givesresults in poor agreement with those from the other two methods,especially for poorly resolved nebulae. From the results of measurementsand using the conclusions of our analysis we derive the final nebulardiameters which should be free from systematic differences between small(partially resolved) and extended (well resolved) objects in our sample.Table 1 is only available in electronic form athttp://www.edpsciences.org
| The distances of planetary nebulae: A scaling factor based upon radial velocities
We have used the observed radial velocities of planetary nebulae, andthe galactic rotation curve to define a new distance scale for planetarynebulae. Care has been taken to restrict the analysis to sources inwhich distance non-linearities are minimised, and for which distortionof the distance scale is likely to be small. We conclude, as a result,that the so-called ``long'' distance scales are the most valid, and thatvarious ``shorter'' scales are unlikely to be correct. The primarysystematic errors in this procedure derive from uncertainties in thegalactic rotation profile, and in Θ0 and R0.Such errors are less than those normally associated with PN distancedeterminations.
| Expansion velocities and dynamical ages of planetary nebulae
The [O Iii] expansion velocities are presented for planetary nebulae inthe Galactic Bulge and Halo, and in the Sagittarius Dwarf spheroidalgalaxy. The velocities are shown to increase with the distance from thestar, in agreement with hydrodynamical models. Dynamical ages arederived from these velocities and are corrected for the effects ofpost-AGB acceleration and non-uniform velocities. Masses for the centralstars are obtained from relations between dynamical ages and stellartemperatures. The stellar core mass distribution is narrow, peaking at0.61 M_sun. This is higher than predicted for the Bulge by initial-finalmass relations, but consistent with the local white dwarf massdistribution. Based on observations obtained at ESO
| The dust content of planetary nebulae: a reappraisal
We have performed a statistical analysis using broad band IRAS data onabout 500 planetary nebulae with the aim of characterizing their dustcontent. Our approach is different from previous studies in that it usesan extensive grid of photoionization models to test the methods forderiving the dust temperature, the dust-to-gas mass ratio and theaverage grain size. In addition, we use only distance independentdiagrams. With our models, we show the effect of contamination by atomiclines in the broad band IRAS fluxes during planetary nebula evolution.We find that planetary nebulae with very different dust-to-gas massratios exist, so that the dust content is a primordial parameter for theinterpretation of far infrared data of planetary nebulae. In contrastwith previous studies, we find no evidence for a decrease in thedust-to-gas mass ratio as the planetary nebulae evolve. We also showthat the decrease in grain size advocated by Natta & Panagia(\cite{NattaPanagia}) and Lenzuni et al. (\cite{Lenzuni}) is an artefactof their method of analysis. Our results suggest that the timescale fordestruction of dust grains in planetary nebulae is larger than theirlifetime. Table~1 is only accessible in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| A Survey of Planetary Nebulae in the Southern Galactic Bulge
We present the results of a deep and uniform narrowband Hα imagingsurvey for planetary nebulae (PNs) in the southern Galactic bulge. Inour survey, we have found 56 new PNs and have rediscovered 45 known PNs.We have measured the radial velocities of this uniformly selected sampleand have also remeasured radial velocities for a subset of 317 PNs fromthe Acker catalog. Using the COBE/DIRBE 1.25, 2.2, and 3.5 μm images,we show that there is a similar longitude distribution of the PNs andthe COBE light in the zone of our deep survey. Also, we find that theextinction in our surveyed fields is not severe and that itsdistribution is fairly uniform. Finally, we present Hα fluxes for47 of our 56 newly discovered PNs and estimate the survey detectionlimit.
| The kinematics of 867 galactic planetary nebulae
We present a compilation of radial velocities of 867 galactic planetarynebulae. Almost 900 new measurements are included. Previously publishedkinematical data are compared with the new high-resolution data toassess their accuracies. One of the largest samples in the literatureshows evidence for a systematic velocity offset. We calculate weightedaverages between all available data. Of the final values in thecatalogue, 90% have accuracies better than 20 km s(-1) . We use thiscompilation to derive kinematical parameters of the galacticdifferential rotation obtained from least-square fitting and toestablish the Disk rotation curve; we find no significal trend for thepresence of an increasing external rotation curve. We examine also therotation of the bulge; the derived curve is consistent with a linearlyincreasing rotation velocity with l: we find V_b,r=(9.9+/-1.3)l -(6.7+/-8.5) km s(-1) . A possible steeper gradient in the innermostregion is indicated. Table 2 is available in electronic form only, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Orientation of planetary nebulae within the Galaxy
Narrow-band CCD images of 209 axially symmetrical planetary nebulae(PNe) have been examined in order to determine the orientation of theiraxes within the disc of the Galaxy. The nebulae have been divided intothe bipolar (B) and elliptical (E) PNe morphological types, according tothe scheme of Corradi & Schwarz. In both classes, contrary to theresults of Melnick & Harwit and Phillips we do not find any strongevidence for non-random orientations of the nebulae in the Galaxy.Compared with previous work in this field, the present study takesadvantage of the use of larger and morphologically more homogeneoussamples and offers a more rigorous statistical analysis.
| Properties That Cannot Be Explained by the Progenitors of Planetary Nebulae
I classify a large number of planetary nebulae (458) according to theprocess that caused their progenitors to blow axisymmetrical winds. Theclassification is based primarily on the morphologies of the differentplanetary nebulae, assuming that binary companions, stellar orsubstellar, are necessary in order to have axisymmetrical mass loss onthe asymptotic giant branch. I propose four evolutionary classes,according to the binary-model hypothesis: (1) Progenitors of planetarynebula that did not interact with any companion. These amount to ~10% ofall planetary nebulae. (2) Progenitors that interact with stellarcompanions that avoided a common envelope, 11^{+2}_{-3}% of all nebulae.(3) Progenitors that interact with stellar companions via a commonenvelope phase, 23^{+11}_{-5}% of all nebulae. (4) Progenitors thatinteract with substellar (i.e., planets and brown dwarfs) companions viaa common envelope phase, 56^{+5}_{-8}% of all nebulae. In order todefine and build the different classes, I start with clarifying somerelevant terms and processes related to binary evolution. I then discusskinematical and morphological properties of planetary nebulae thatappear to require the interaction of the planetary nebula progenitorsand/or their winds with companions, stellar or substellar.
| Radial velocities of planetary nebulae towards the Galactic bulge
Accurate radial velocities for a sample of 71 planetary nebulae, mostlylocated in the direction of the Galactic Centre, are presented. Most ofthe nebulae discussed in this paper are likely members of the Galacticbulge, based on their radial velocity, longitude and derived distance.The data give a large improvement over existing catalogues, doubling thesample of bulge planetary nebulae with well-determined velocities andsuggesting that kinematics of the Galactic Bulge can usefully be studiedby planetary nebulae. Based on observations obtained at the EuropeanSouthern Observatory. Table 1 is also available in electronic form atthe CDS vis anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| A statistical distance scale for Galactic planetary nebulae
A statistical distance scale is proposed. It is based on the correlationbetween the ionized mass and the radius and the correlation between theradio continuum surface brightness temperature and the nebular radius.The proposed statistical distance scale is an average of the twodistances obtained while using the correlation. These correlations,calibrated based on the 1`32 planetary nebulae with well-determinedindividual distances by Zhang, can reproduce not only the averagedistance of a sample of Galactic Bulge planetary nebulae exactly at thedistance to the Galactic center, but also the expected Gaussiandistribution of their distances around the Galactic center. This newdistance scale is applied to 647 Galactic planetary nebulae. It isestimated that this distance scale can be accurate on average to35%-50%. Our statistical distance scale is in good agreement with theone recently proposed by Van de Steene and Zijlstra. The correlationsfound in this study can be attributed to the fact that the core mass ofthe central stars has a very sharp distribution, strongly peaked atapprox. 0.6 solar mass. We stress that the scatter seen in thestatistical distance scale is likely to be real. The scatter is causedby the fact that the core mass distribution, although narrow andstrongly peaked, has a finite width.
| On an alternative statistical distance scale for planetary nebulae. Catalog with statistical distances to planetary nebulae.
We have proposed a statistical method to determine distances toplanetary nebulae. The method is based on an empirical correlationbetween the radio-continuum brightness temperature and radius. Here wepresent a catalog of distance determinations calculated using thismethod.
| A catalogue HeII 4686 line intensities in Galactic planetary nebulae.
We have compiled the intensities of the HeII 4686 lines measured inGalactic planetary nebulae. We present a few observational diagramsrelated to this parameter, and discuss them with the help of theoreticaldiagrams obtained from simple model planetary nebulae surroundingevolving central stars of various masses. We determine the hydrogen andhelium Zanstra temperature for all the objects with accurate enoughdata. We argue that, for Galactic planetary nebulae as a whole, the maincause for the Zanstra discrepancy is leakage of stellar ionizing photonsfrom the nebulae.
| The correlations between planetary nebula morphology and central star evolution
The morphology of 111 Galactic planetary nebulae has been studied inrelation to the evolutionary stage of their central stars. In order tolocate these stars on the log Teff - Log L/solar luminosityplane, we have calculated the Zanstra temperatures with the most up todate fluxes and magnitudes available in the literature. Distances to thenebulae were estimated with statistical methods. The different natureand evolutionary stages of central stars have been related to themorphologies of the surrounding nebulae in a statistical sense. We foundthat multiple shell nebulae contain stars that are at a differentevolutionary stage than those of single shell nebulae; we also foundthat bipolar and elliptical planetary nebulae very likely containcentral stars with a different mass distribution; furthermore, we buildan optical thickness sequence of morphological types.
| Trace of planetary nebula evolution by distance-independent parameters
Using existing infrared and radio data on a sample of 432 planetarynebulae, we derived a number of distance-independent parameters forcomparison with evolutionary models of planetary nebulae. We find thatmany of the observed properties of planetary nebulae can be explained bycurrent central star evolutionary models, even if the time scales aresubject to significant change by a factor of up to an order ofmagnitude. Specifically, we find that the evolutionary tracks are wellseparated in the radio surface brightness-central star temperatureplane, therefore allowing us to determine the core mass of individualplanetary nebulae. We also obtain the luminosity and gravity of thecentral stars of individual nebulae, from their temperature and coremass, without relying on the distance assumptions. We find that ourresults of the core mass are in good agreement with those of Mendez etal. (1992) and Tylenda et al. (1991). A systematic, large discrepancy isfound between the luminosity found in this work and that found byGathier and Pottasch (1986).
| The Correlations Between Planetary Nebula Morphology and Central Star Evolution
Abstract image available at:http://adsabs.harvard.edu/abs/1993A&A...276..463S
| On the distance to Galactic planetary nebulae
The distances are determined for 145 Galactic PNe using two methods. Thedistances for a sample of 131 PNe are determined using method A, basedon the stellar mass and surface gravity. Method B, making use of thestellar luminosity, is applied to another sample of 61 PNe, of which 47are in common with those in the sample for method A. The properties ofthe central star, such as the core mass, luminosity, and surfacegravity, are inferred from the modeling of the distance-independentparameters. The results from the two methods used in this paper areconsistent with each other. A distance of 11.3 kpc is found for K648using method A of this work. This is in good agreement with the distanceof 10 kpc of its hosting globular cluster M15.
| Distances for Galactic planetary nebulae. II - A southern hemisphere survey
New integrated forbidden O II 3726, 3729 A doublet ratio observationsare presented of 65 southern Galactic PN, and their distances arederived. Integrated forbidden S II 6716, 6731 A double observations arealso given, and it is concluded that both density diagnostics yield thesame densities for a large homogeneous data set. Regions of extendedemission surrounding 23 of the objects are detected. Upper limits on theelectron densities are derived for these regions, and it is concludedthat the emission originate from regions of diffuse Galactic backgroundemission.
| A catalogue of narrow band images of planetary nebulae
The paper presents a catalog of narrow-band images of 255 planetarynebulae (PNe) taken with the 3.5 m ESO NTT, using EFOSC2, the faintobject camera, and spectrograph. The results include properties ofseveral PNe which were previously listed as unresolved, show extendedstellar objects, list several new bipolar proto-PNe, and describe a fewpreviously unknown faint haloes. A new list is presented of sizes inH-alpha and forbidden OIII images, including information on all peculiarobjects and features which have not been seen previously.
| The extinction constants for galactic planetary nebulae
The extinction constants are determined from Balmer decrementmeasurements for over 900 planetary nebulae. Comparison with publishedextinction constants shows that the results from ESO are fairlyreliable. An analysis of the extinction constants derived from theBalmer decrement and from the radio/Hβ flux ratio indicates thatthe latter tends to be systematically smaller than the former forincreasing extinction. We suggest that the radio measurements ofPottasch's group probably underestimate the radio fluxes, at least forsome (faintest) objects.
| A catalogue of absolute fluxes and distances of planetary nebulae
The paper presents a complete list of averaged recalibrated absoluteH-beta fluxes, global (where possible) relative He II lambda 4686fluxes, 5 GHz radio flux densities, and H-alpha/H-beta interstellarextinction constants for 778 Galactic planetary nebulae. The catalogprovides much of the fundamental data required to generate Zanstratemperatures. When data with the lowest errors are selected, the opticaland radio/optical extinctions show a peculiar correlation, with theradio values slightly high at low extinction and notably low at highextinction. The data are used, along with the best estimates of angulardiameters, to calculate Shklovsky distances according to the Daub schemeon the scale used earlier by Cahn and Kaler (1971). Use of this distancescale shows approximate equality of the death rates of optically thickand optically thin planetary nebulae. The method gives the correctdistances to the Magellanic Clouds.
| Strasbourg - ESO catalogue of galactic planetary nebulae. Part 1; Part 2
Not Available
| The absolute H-beta fluxes for galactic planetary nebulae
The absolute H-beta flux measurements from spectrophotometricobservations of about 880 galactic planetary nebulae are presented. Thegalactic coordinates of PNe and the adopted diameters for the nebulae inarcsec are given. The final values of the H-beta flux, corrected for thenebular extension, are presented and compared to the results of othermeasurements.
| The B and V magnitudes of the central stars of planetary nebulae
The B and V magnitudes are determined for about 350 central stars ofplanetary nebulae, 190 of which are being given for the first time. Thestellar continuum was measured on spectra taken at ESO, Chile, and atOHP, France, in range of 400-740 nm, with a resolution of about 1 nm.
| The energy-balance temperature of central stars of galactic planetary nebulae. II
The color temperature of the central star of planetary nebulae iscalculated using data from the ongoing spectroscopic survey of galacticplanetary nebulae carried out by Acker and Stenholm in conjunction withan energy-balance (EB) method of Preite-Martinez and Pottasch (1983). Inthese calculations it was assumed that thermal equilibrium holds in thephotoionization nebula. The derived EB temperatures are found to beconsistent with the corresponding temperatures derived by the Zanstra(1931) method. The T(EB) values derived for six planetary nebulae alsoagree with those of Preite-Martinez and Pottasch.
| Properties and evolution of dust grains in planetary nebulae
The IRAS data of 233 planetary nebulae (PNs) determining the propertiesof the dust contained in their envelopes have been analyzed. The mainresult is that the dust grains undergo substantial evolution during thelifetime of a PN. In particular, the grain size and the total dust massdecrease systematically with the nebular radius whereas the number ofemitting grains increases. Two scenarios which can explain these resultsare discussed. A first possibility is that grains undergo processeswhich both 'erode' and 'shatter' them. It is argued that sputtering byfast atoms of a stellar wind and grain-grain collisions may plausiblyproduce such effects. Alernatively, the dust present in PNs may have asize distribution since the very beginning and large grains may beselectively destroyed during the PN evolution.
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