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.
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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.
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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).
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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.
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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.
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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.
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Strasbourg - ESO catalogue of galactic planetary nebulae. Part 1; Part 2
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Statistical properties of winds in central stars of planetary nebulae
Results are presented of an investigation of 834 low-resolutionshort-wavelength primary spectra taken with the IUE satellite of 159planetary nebulae for the presence of stellar winds in the centralstars. It is found that about 60 percent of central stars have a stellarwind. The wind's existence is examined against the optical spectral typeof the star. Previous information is incorporated into an updated listof the edge velocities in the central stars having fast winds. Theyrange from 600 to 3500 km/s. A positive correlation between the edgevelocity of the stellar wind and the expansion velocity of the opticalnebula is found. This correlation is consistent with the multipleinteracting wind theory in the adiabatic case.
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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.
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Winds in Central Stars of Planetary Nebulae
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The IRAS low-resolution spectra of planetary nebulae
This paper presents the low-resolution spectra of 170 planetary nebulaeobserved by IRAS, most of which were not included in the Atlas ofLow-Resolution Spectra. These have been classified into eight groupsbased upon the spectral morphology, with emphasis on the dust continuumrather than the spectral lines. The Low-Resolution Spectrometer (LRS)spectra are nearly evenly divided between spectra which show only a dustcontinuum with no lines, and spectra where there are strong lines with adust continuum appearing longwards of about 15 microns. A study has beenmade of the strength of the 11.3-micron PAH emission feature as afunction of the nebular C/O ratio, combining ground-based and LRS data.The C/O ratio for IC 2621 is derived from IUE spectra and used in thisstudy. The 11.3-micron feature is present with essentially constantstrength in all nebulae with C/O above about 1. Only marginal evidenceexists for its presence below C/O about 1 and then at a level about 5times lower than in carbon-rich nebulae.
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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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Planetary nebulae in the Galaxy
It is shown that the planetary nebulae can be divided into three typesaccording to the values of the mass of shell and a central star. Thecriteria are given using which one can determine the mass type of thenebula. The distance scale of each mass-type planetary nebulae is given.The distribution of planetary nebulae in the Galaxy, their formationrate, scale-height and other physical and kinematic characteristics areinvestigated. A catalogue of planetary nebulae emitting in the ratiorange is given.
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The absolute H-beta fluxes for southern planetary nebulae
The absolute H-beta fluxes of 462 southern PN are measured on 400-740-nmspectra obtained with a conventional spectrograph and theimage-dissector scanner on the 1.52-m telescope at ESO during 1984-1988.The data are presented in extensive tables and graphs and brieflycharacterized. The accuracy of the observations is considered adequatefor statistical analyses but not for detailed investigations ofindividual objects.
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New and misclassified planetary nebulae.
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Spectroscopic observations of faint and misclassified planetary nebulae
Using low resolution IDS spectra, an attempt is made to clarify theclassification of 264 objects which appeared as planetary nebulae invarious listings, and were originally included in two lists of Sanduleak(1976): (1) misclassified or doubtfully classified planetary nebulae;and (2) faint, suspected planetary nebulae. The new data show that 67percent of the objects can be considered as true planetary nebulae, ofwhich 46 percent present low excitation characteristics. The status ofthe other objects remains quite uncertain, some of them being symbioticstars (14 percent), or various emission-line objects. In four cases, nopositive indication of emission-line objects in the observed areas wasfound.
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Near-infrared photometry of IRAS planetary nebulae
JHKL photometric observations of 117 objects from the Perek-KohoutecCatalog of Planetary Nebulae are reported. Data obtained using cooledInSb detectors on the 1-m and 3.6-m telescopes at ESO and on the 1.5-mItalian IR telescope TIRGO are presented in extensive tables andcolor-color diagrams and analyzed. From the positions of the PN on theJ-H/H-K diagram it is inferred that 57 percent have NIR emissiondominated by the stellar continuum, 30 percent have nebula-dominatedemission, and 13 percent have emission attributed to either extremereddening of nebular emission or to a combination of hot dust withnebular or (hot) stellar emission.
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Statistical survey of planetary nebulae - Distances, masses, and distribution in the galaxy
A new empirical scale of distances to planetary nebulae (PNs) ispresented based on the interdependence between the PN diameter and thevalue of the surface brightness in the radio range. The dependence ofthe mean electron density in PNs on the diameter is determined, and themasses of the ionized matter in PNs are estimated. The variation of theproperties of PNs as a function of the type of stellar population towhich they belong is investigated, and the frequency of PN formation inthe Galaxy is evaluated and compared with that of white dwarf formation.Finally, the dependence of the PN expansion velocity on linear size isdefined.
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A catalogue of distances of planetary nebulae
This catalog contains distances of 468 galactic planetary nebulae pluslower limits to 61 objects and upper limits for 134 nebulae. Thedistances were calculated assuming a relationship between the nebularionized mass and radius.
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Index and cross-identification of planetary nebulae
The index of 86 discovery lists of planetary nebulae contains all theknown planetary nebulae in the Galaxy, including the probable, possibleand misclassified objects. A cross-identification gives all the names ofthe 1518 PN ordered by increasing galactic longitude.
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Misclassified and misidentified planetary nebulae and nuclei
Observations are reported for 17 objects that are listed in theCatalogue of Galactic Planetary Nebulae (CGPN). These have either beenmisclassified as planetary nebulae, have been identified incorrectly bytheir observers or in the CGPN, or have had peculiar central starserroneously assigned to them. In about one-half of the cases, we confirmprevious reclassifications. The general characteristics of each objectare described, and we provide relative emission-line fluxes for two thatare already known to be symbiotic stars.
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Radio observations at 14.7 GHz of southern planetary nebulae
Peak and integrated radio flux densities at 14.7 GHz are presented for397 celestial objects located south of declination +27 deg and listed asplanetary nebulae in the Perek and Kohoutek (1967) catalog. The objectsinclude 260 confirmed planetary nebulae (CPN's), 25 suspect faintplanetary nebulae (SFPN's), 21 nebulae of the MV (misclassified, verylow excitation) class, five diffuse nebulae, 20 stars, five peculiarobjects, 21 objects that were not detected optically, and 40unclassified nebulae. The integrated flux densities of 264 of theobjects (including 236 CPN's) are compared with 5-GHz data for the sameobjects, and all 264 objects are shown to be optically thin in theirradio emission between 5 and 14.7 GHz. It is found that the followingpercentages of the 397 objects were detected above the 2-sigma level (10mJy) of the survey: (1) 87% of the 211 CPN's classified on the basis oftheir optical spectra; (2) 84% of the 49 CPN's classified on the basisof their optical appearance; (3) 95% of the nebulae of the MV class; (4)76% of the SFPN's; (5) 100% of the diffuse nebulae; (6) 26% of the 46objects in the remaining classes; and (7) 50% of the unclassifiednebulae.
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Observations of 196 southern planetary nebulae at 408 MHz
The Molonglo Radio Telescope, operating at 408 MHz with half-powerbeamwidth 3 arcmin, has been used to observe 196 planetary nebulae southof declination +18 deg. The observations were limited mainly byconfusion with a typical rms noise plus confusion of 40 mJy. Fluxdensities are presented for the 43 nebulae which were detected, and fluxdensity limits are given for the remainder. There is no evidence ofnonthermal radio emission from any of the planetary nebulae in thissurvey.
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Catalogue of the central stars of true and possible planetary nebulae
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Evolution of planetary nebulae and their nuclei - Temperatures of nebular nuclei
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Radio Observations at 5 GHz of Southern Planetary Nebula II
Abstract image available at:http://adsabs.harvard.edu/abs/1979A&AS...36..227M
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2.7 GHz radio frequency measurements of planetary nebulae
Radio flux densities at 2.7 GHz are presented for 98 planetary nebulaesouth of +27 deg declination. It is shown from a comparison with data at5 GHz that the majority of these objects are optically thin at thesefrequencies.
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The distance scale of planetary nebulae
The paper reviews recent attempts to establish a distance scale for therelation between distance to planetary nebulae and its radius if it isoptically thin to the Lyman continuum. Other possible correlates withdistance are also examined. After a critical study of the variousscales, recommendations are made on how to adjust them.
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The ESO/Uppsala survey of the ESO (B) Atlas of the Southern Sky. IV.
Abstract image available at:http://adsabs.harvard.edu/abs/1977A&AS...27..295H
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Optical positions for planetary nebulae. II.
Abstract image available at:http://adsabs.harvard.edu/abs/1976AJ.....81..753M
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