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.
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Far-infrared loops in the 2nd Galactic Quadrant
We present the results of an investigation of the large-scale structureof the diffuse interstellar medium in the 2nd Galactic Quadrant(90°≤l≤180°). 145 loops were identified on IRAS-basedfar-infrared maps. Our catalogue lists their basic physical properties.The distribution clearly suggests that there is an efficient processthat can generate loop-like features at high Galactic latitudes.Distances are provided for 30 loops. We also give an observationalestimate of the volume filling factor of the hot gas in the Local Arm,4.6%≤f2nd<6.4%.Appendices A-C are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/131
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New infrared star clusters in the Northern and Equatorial Milky Way with 2MASS
We carried out a survey of infrared star clusters and stellar groups onthe 2MASS J, H and Ks all-sky release Atlas in the Northernand Equatorial Milky Way (350deg < l < 360deg, 0deg < l < 230 deg). Thesearch in this zone complements that in the Southern Milky Way (Dutra etal. \cite{Dutra03}a). The method concentrates efforts on the directionsof known optical and radio nebulae. The present study provides 167 newinfrared clusters, stellar groups and candidates. Combining the twostudies for the whole Milky Way, 346 infrared clusters, stellar groupsand candidates were discovered, whereas 315 objects were previouslyknown. They constitute an important new sample for future detailedstudies.
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HST Observations of Sakurai's Object (V4334 Sgr) and Related Stars
We describe our ongoing program of HST observations of Sakurai's Object(V4334 Sgr). Direct WFPC2 imaging from August 1996 through August 2000reveals no transient features (such as light echoes), and documents thedecline of the star to below 24th visual magnitude in 2000. Thesurrounding planetary nebula has shown no changes from 1996 through2000. There are no obvious peculiar features (such as blobs or knots) inthe immediate vicinity of the star. We also have in place atarget-of-opportunity program to obtain UV spectra with HST in the eventthat the star begins to retrace its evolution back to high surfacetemperature. We also present older HST FOC imaging of V605 Aql. Thecentral object is a resolved nebula that emits in [O III] (but not inhydrogen), whose 0''.6 diameter is consistent with a dust cloud ejectedduring the 1919 outburst. The central star itself is not seen due to itsbeing embedded in the nebula. Several other central stars (including H3-75, IC 2120, and Abell 14) have late-type nuclei and no evidence forhot companions. They may be further candidates for `born-again'red-giant nuclei.
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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
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A Near-Infrared Imaging Search for Invisible Galaxies behind the Milky Way
We carried out a near-infrared imaging search for optically obscuredgalaxies behind the Milky Way. The imagings were made for a 4' times 4'field on each of 58 IRAS point sources, located within a region of90(deg) < l < 240(deg) , |b| < 10(deg) and having reliable fluxdensities at 25, 60, and 100 mu m, but no Galactic CO emission. Theresults revealed that 16 of these IRAS point sources can be associatedwith galaxies or possible galaxies, and another 16 can be associatedwith stars or HII regions; however, the remaining 26 are `empty' objectswithout any optical and near-infrared counterpart. The empty objects arecolder than galaxies and seem to be Galactic objects.
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H2 Emission from Planetary Nebulae: Signpost of Bipolar Structure
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...462..777K&db_key=AST
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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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A near infrared survey of northern planetary nebulae
We have observed 77 evolved planetary nebulae in the J, H, K, L', and Mphotometric bands. As a consequence, we note that most PN fall into arange -0.6 < (J-H)_0_ < 0.2 mag , and 0.0 < (H-K)_0_ <1.2mag , whilst a few sources have also been detected in the range 1.0< (K-L)_0_ < 5.3 mag . Most indices (J-H)_0_ are almost certainlydepressed through the influence of HeI 2^3^ S 2^3^ P emission, whilststellar continua appear to dominate ~ 6 sources, and components of hightemperature dust enhance (J-H)_0_ in several others. Fully 60% ofsources having (J-H)_0_ >=0.0 appear to be type I nebulae. Finally,we note that H_2_S(1) and Q band quadrupole emission may be important inenhancing K band fluxes for several of the nebulae, and the mean value(H-K)_0_ =~ 0.88 mag for H_2_S(1) emission sources is significantly inexcess of the mean. As a consequence, the parameter (H-K)_0_ may prove auseful tool in the prior selection of nebulae having shocked, neutralgas. By contrast, the various L' band detections are likely to derivefrom a mix of mechanisms, including emission from grains having a broadrange of temperatures.
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IRAS sources beyond the solar circle. III - Observations of H2O, OH, CH3OH and CO
We have used the 100-m Effelsberg and 32-m Medicina radiotelescopes tosearch for H2O maser emission (22.235 GHz) towards 1143 IRAS sources,for OH (1665/67 MHz) towards 303 IRAS sources, and for CH3OH (12.179GHz) towards 19 IRAS sources. The IRAS sources have been selected tohave colors of premain sequence objects. To obtain an estimate of thekinematic distance, we observed (C-12)O (J = 2 to 1) and (C-12)O (J = 3to 2) with the KOSMA 3-m telescope towards 25 sources showing H2Oemission and not yet observed in CO. This paper presents theobservational results in form of tables with line parameters or upperlimits and spectra of detected sources.
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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
Not Available
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Mis-classified planetary nebulae
VLA Radio observations of a number of suspected planetary nebulae arepresented. Based on the morphology of the source, and on the IRAS farinfrared colors, some of these are shown to be compact HII regions. Mostof the other sources show no radio emission down to a level of 1 mJy andare either emission line stars, reflection nebulae, or galaxies. Theradio images of the resolved sources are presented, along with adiscussion of the detected sources. Also a brief description of some ofthe sources is given.
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IRAS sources beyond the solar circle. I - CO observations
C-12O (J = 1-0) has been observed with the 15-m SEST and the 30-m IRAMtelescope in the direction of 1302 IRAS sources with colors of starforming regions located within 10 deg of the galactic plane in theinterval between 85 and 280 deg. Emission components with line profilesthat are non-Gaussian (showing, e.g., possible self-absorption or wings)are identified; this information may serve as a basis for selectingsources for future research. For all components, kinematic heliocentricand galactocentric distances, and distances from the galactic plane arederived. For those components which may be associated with the IRASsources, bolometric luminosities are derived. These data will beanalyzed and compared with HI data in subsequent papers.
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A catalogue of expansion velocities of Galactic planetary nebulae
Published observational data on 288 Galactic PN are compiled in tables,graphs, and sketches based on spatiokinematical models and brieflycharacterized. The criteria used in selecting the data are discussed,and particular attention is given to the accuracies of the distanceestimates and their implications for theoretical models of PN or stellarevolution.
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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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Summarizing remarks on the structure and evolution of planetary nebulae and properties of their central stars.
Not Available
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A VLA radio continuum survey of planetary nebulae.
Not Available
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Catalogues of planetary nebulae.
Not Available
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Misclassified planetary nebulae
In this paper 266 objects taken from catalogs and lists of planetarynebulas are discussed. Opinions are based on observations given in theliterature, on the vast photometric information collected by the IRASsatellite, plus on the observations from the ongoing project of aspectroscopic survey of all planetary nebulas. Of the objects, 199 aredefinitely rejected as planetary nebulas, 63 others are possibly notplanetary nebulas.
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Radio patrol of the northern Milky Way - A catalog of sources. II
The paper presents a catalog of 1274 discrete sources detected during a5 yr, 6 cm, radio-patrol survey of the Galactic plane for variablesources. Approximately 20 percent of the volume of the Galactic disk wasrepeatedly observed on 16 occasions. The survey is capable of detectingboth short-term (few days) and long-term variability. Seventy-fivepercent of the sources are weaker than 75 mJy, and as a consequence,reliable detection of variability generally required luminosityvariations greater than or equal to 50 percent. Thirty-two variablesources and 27 possible variables were detected, of which 64 percentexhibited short-term variability. Two new identifications are proposedfor the short-term variables GT 0116 + 622 and GT 2318 + 620, with thetransient gamma-ray source Cas gamma-1 and the X-ray source 4U 2316 +61, respectively. The absence of giant outbursts leads to an upper limitof three on the number of objects in the survey area with radioproperties like Cyg X-3. A comparison with previous centimetervariability studies suggest the possible existence of two distinctvariability components.
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Internal motions in thirty-two genuine planetary nebulae and in a misclassified object
The forbidden O III, H-alpha, and forbidden N II expansion velocitiesfor thirty-three planetary nebulae are derived from high-dispersionspectroscopy. The expansion-velocity/nebular-radius correlations foundby Sabbadin (1984) for planetary nebulae of the subclasses B and C ofGreig (1971 and 1972) are confirmed. Observational evidence is presentedindicating that A 77 (97 + 3 deg 1) is not a planetary nebula but aquite compact (nebular radius = about 1.1 pc) H II region located atabout 7 kpc from the sun and excited by a late-O/early-B main-sequencestar.
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Dust-distances to planetary nebulae
Accurate new extinction constants have been measured for the planetarynebulae considered by Lutz in her earlier studies of distances. Insteadof fitting a curve to all the stellar data as in the past, the nebularextinction was bracketed with a range in color excess, and the distancesof the stars falling within the band were averaged. This procedure isless distorted by patchiness along the line of sight, and readily allowscomputation of an error. The derived distances marginally support thedistance scale used by Cahn and Kaler as well as the distance methodemployed by Daub.
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The parameters of planetary nebulae and their central stars derived from observations
The empirical calibration dependence between the number of Lyman photonsemitted by a central star, and a planetary nebula (PN) of a givendiameter, is constructed on the basis of UV measurements of PN centralstar temperatures for the cases of 118 PN central stars. Central starmasses are noted to be distributed over the 0.5-1.2 solar mass range.The averaged empirical evolutionary tracks of central stars less andmore massive than 0.6 solar masses are found to differ considerably, andit is shown that the majority of central stars may possess hotchromospheres that spread over several tens of radii from the centralstar. The PN originates in the ionization of matter ejected by a redgiant at the superwind stage; the ionization is in turn due to the UVradiation of the central star.
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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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Explanatory Note - Photoelectric Absolute H-Beta Fluxes for 55 Planetary Nebulae
Abstract image available at:http://adsabs.harvard.edu/abs/1984RMxAA...9..111C
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Arecibo interferometer observations of compact planetary nebulae
New radio observations of compact planetary nebulae made with theArecibo 305-m antenna and with the Arecibo two-element interferometer atthe frequency of 2380 MHz are presented. Peak and mean emission measuresare derived for the detected nebulae which include the very compactobjects CRL 618, HM Sge, and He2-459. The physical parameters of thenebulae are briefly discussed, including the planetary nebula K648 inthe globular cluster M15.
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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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Photoelectric Absolute H-Beta Fluxes for 55 Planetary Nebulae
Abstract image available at:http://adsabs.harvard.edu/abs/1983RMxAA...8..187C
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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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