2007A&A...461.1019G


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.04CET19:48:04

2007A&A...461.1019G - Astronomy and Astrophysics, volume 461, 1019-1025 (2007/1-3)

Radio-continuum spectrum, brightness temperature, and planetary nebulae properties.

GRUENWALD R. and ALEMAN A.

Abstract (from CDS):

Radio-continuum spectra are frequently used to infer the density distribution of ionized gaseous regions, while observed correlations between the brightness temperature and other distance-independent parameters are used to test evolutionary models of planetary nebulae. We check empirical correlations among features derived from the observed radio data and the inferred conclusions available in the literature, using self-consistent photoionization models. Photoionization models are computed for the physical conditions of planetary nebulae in order to derive self-consistent radio-continuum spectra, as well as the brightness temperature. The temperature and ionization distributions throughout the nebulae explain the observed range of spectral indexes in the thick region of the spectrum, even for a uniform density distribution, usually challenged in the literature. The obtained models fit the observed radio spectra for planetary nebulae in a large range of spectral indexes. Our calculations show a correlation between the spectral index obtained in a given frequency range and the nebula size, as well as reproduce the observed relations between the brightness temperature and other distance-independent parameters. Such diagrams are frequently used to check evolutionary models of the central star and/or of the nebula. Since PNe images clearly show that the density is not constant inside the nebulae, and models with uniform and non-uniform density distributions can both reproduce the observed radio spectra, we conclude that it is not possible to favour one of them from the radio data, or to infer a particular density distribution for planetary nebulae.

Abstract Copyright:

Journal keyword(s): ISM: planetary nebulae: general - radio-continuum: ISM

Simbad objects: 9

goto Full paper

goto View the reference in ADS

Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 IC 418 PN 05 27 28.2060343141 -12 41 50.282659007   9.78 13.0     O7fp 1004 2
2 NGC 6369 PN 17 29 20.4566547788 -23 45 34.771598164   16.6 12.00     [WC4] 304 0
3 NGC 6572 PN 18 12 06.3140077888 +06 51 13.030152295   9.3 10.8     [WC] 740 0
4 M 57 PN 18 53 35.0969571234 +33 01 44.883146221   15.405 15.769 15.901 16.062 DA(O?) 796 2
5 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1814 2
6 PN Vy 2-2 PN 19 24 22.2390166933 +09 53 56.259102426   14.02 12.65 13.38   ~ 251 0
7 EM* AS 373 Sy* 19 57 05.0184580246 +39 49 36.085051314     11.50   10.592 M6/8e 571 0
8 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2353 1
9 PN Hb 12 PN 23 26 14.8207203464 +58 10 54.538636094   13.51 11.49 12.44   Oe 316 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2007A&A...461.1019G and select 'bookmark this link' or equivalent in the popup menu


2021.03.04-19:48:04

© Université de Strasbourg/CNRS

    • Contact