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J/ApJ/459/606       Distances of planetary nebulae    (Schneider+ 1996)

The distances of planetary nebulae and the galactic bulge Schneider S.E., Buckley D. <Astrophys. J. 459, 606 (1996)> =1996ApJ...459..606S (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Morphology ; Radio lines Keywords: circumstellar matter - Galaxy: center - planetary nebulae: general - radio continuum: ISM Abstract: We describe an improved method for determining the distances of planetary nebulae (PNe) based on a theoretical/empirical relationship between their radii and radio surface brightness. Like the Shklovsky (constant mass) distance method, our relationship requires only radio flux density and angular size measurements, which are widely available in the literature. Based on models matching the overall Galactic distribution of PNe, we determine how PNe observed in the direction of the Galactic center are actually distributed relative to the bulge in order to establish the usefulness of these PNe for distance studies. We then use the bulge PNe along with PNe with independent distances to establish, calibrate, and test the accuracy of the method. When compared to the best available data our distance method appears to yield distance errors consistent with a scatter of <25% (1σ). And, based on our models scaled to local PNe, we find a mean Galactic center distance of 8.3±2.6kpc for the bulge PNe. The relationship that PNe exhibit between radius and surface brightness is in excellent agreement with our simulated nebulae from Paper I (Buckley & Schneider, 1995ApJ...446..279B). We find that no simple power law can describe the changing mass and radius of a PN as it ages; however, our empirical relationship has a limiting behavior that is almost indistinguishable from the assumption made in Shklovsky's distance method that PNe have a constant ionized mass. We reexamine the dispute about the validity of the Shklovsky's distance method as applied to Galactic center PNe in light of these results, and we argue that the Shklovsky method does predict the distances of large, low surface brightness PNe well, but it increasingly overestimates the distance of smaller PNe. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1 42 189 Radio flux densities and sizes of Galactic Center PNe
See also: V/84 : Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker+, 1992) Byte-by-byte Description of file: table1
Bytes Format Units Label Explanations
1- 10 A10 --- PN PN designation 12- 17 F6.1 mJy S6cm ? Flux density at 6cm (5GHz) 19 A1 --- l_Diamph Limit flag on Diamph 20- 23 F4.1 arcsec Diamph ? Photographic diameter from the Strasbourg-ESO catalogue (Cat. V/84) 24 A1 --- u_Diamph Uncertainty flag on Diamph 25 A1 --- n_Diamph [s)] Note on Diamph (1) 27 A1 --- l_Diam Limit flag on Diam 28- 32 F5.2 arcsec Diam ? Adopted "metric" diameter 33 A1 --- n_Diam [)] Note on Diam (1)
Note (1): s: stellar ): indicates that the source shows significant discrepancies between radio and photographic measurements
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 10-Apr-1997
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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