J/A+A/373/1032 Radio emission from planetary nebulae (Siodmiak+, 2001)
An analysis of the observed radio emission from planetary nebulae.
Siodmiak N., Tylenda R.
<Astron. Astrophys. 373, 1032 (2001)>
=2001A&A...373.1032S 2001A&A...373.1032S
ADC_Keywords: Planetary nebulae ; Radio lines ; Stars, diameters
Keywords: planetary nebulae: general - radio continuum: ISM -
ISM: dust, extinction
Abstract:
We have analysed the radio fluxes for 264 planetary nebulae for which
reliable measurements of fluxes at 1.4 and 5 GHz, and of nebular
diameters are available. For many of the investigated nebulae, the
optical thickness is important, especially at 1.4 GHz. Simple models
like the one specified only by a single optical thickness or
spherical, constant density shells do not account satisfactorily for
the observations. Also an r-2 density distribution is ruled out. A
reasonable representation of the observations can be obtained by a
two-component model having regions of two different values of optical
thickness. We show that the nebular diameters smaller than 10" are
uncertain, particularly if they come from photographic plates or
Gaussian fitting to the radio profile. While determining the
interstellar extinction from an optical to radio flux ratio, caution
should be paid regarding optical thickness effects in the radio. We
have developed a method for estimating the value of self absorption.
At 1.4 GHz self absorption of the flux is usually important and can
exceed a factor of 10. At 5 GHz self absorption is negligible for most
of the objects, although in some cases it can reach a factor of 2. The
Galactic bulge planetary nebulae when used to calibrate the Shklovsky
method give a mean nebular mass of 0.14M☉. The statistical
uncertainty of the Shklovsky distances is smaller than a factor of
1.5.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 264 Observational data
table1.tex 122 465 LaTeX version of table1
refs.dat 155 36 References
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See also:
V/84 : Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker+, 1992)
VII/34 : ESO/Uppsala Survey of the ESO(B) Atlas (Lauberts 1982)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- PNG PNG designation
12- 21 A10 --- Name Usual name
23- 28 F6.1 mJy F1.4GHz Flux measurement at 1.4GHz from Condon &
Kaplan (1998, Cat. J/ApJS/117/361)
30- 35 F6.1 mJy F5GHz Flux at 5GHz
37- 43 A7 --- r_F5GHz References for F5GHz in refs.dat file
46- 51 F6.2 arcsec DiamRad ? Angular diameter from radio observations
52 A1 --- n_DiamRad [+] +: more reliable measurement
54- 57 A4 --- r_DiamRad References for DiamRad in refs.dat file
58 A1 --- l_DiamOpt Limit flag on DiamOpt
59- 63 F5.1 arcsec DiamOpt ? Nebular diameter from optical observations
65 A1 --- n_DiamOpt [+] +: more reliable measurement
66- 67 A2 --- ST [ST ] ST: stellar
69- 75 A7 --- r_DiamOpt References for diamOpt in refs.dat file
77- 82 F6.2 arcsec Diam Adopted diameter
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Ref Reference code
4- 22 A19 --- BibCode BibCode
24- 42 A19 --- Aut Author's name
44-155 A112 --- Com Comments
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Acknowledgements: Natasza Siodmiak
(End) Patricia Bauer [CDS] 15-Aug-2001