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Bi-abundance Photoionization Models for Planetary Nebulae

Published online by Cambridge University Press:  26 May 2016

D. Péquignot
Affiliation:
1 Observatoire de Paris - Meudon, F-92195 Meudon Cedex, France
X.-W. Liu
Affiliation:
2Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, U.K.
M. J. Barlow
Affiliation:
2Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, U.K.
P. J. Storey
Affiliation:
2Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, U.K.
C. Morisset
Affiliation:
3Institut d'Astrophysique de Marseille, Traverse du Siphon, BP 8, F-13376 Marseille Cedex 12, France

Extract

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A new class of planetary nebulae, in which abundances derived from optical recombination lines (ORL) seem to be much larger than those derived from collisionally excited lines (CEL) by up to one or two orders of magnitude is now well identified (Liu, these proceedings and references therein).

Photoionization models including two components, one highly enriched in C, N, O, Ne and deficient in H and the other one of more usual composition, can account for most of the numerous spectroscopic data available from UV to far-IR in two of the best observed, most extreme examples, namely NGC 6153 and M142 (Péquignot et aI., 2002, and in preparation). The few discrepancies left can generally be understood in terms of inaccuracy of the observations (calibration of infrared line fluxes relative to the optical) and some atomic data, particularly in the unusual conditions prevailing in the H-deficient component.

Type
Part VI: The Ionized Gas in Planetary Nebulae
Copyright
Copyright © Astronomical Society of the Pacific 2003 

References

Garnett, D. R., Dinerstein, H. L., 2001, ApJ, 558, 145 CrossRefGoogle Scholar
Liu, X.-W., Storey, P. J., Barlow, M. J., et al. 2000, MNRAS, 312, 585 Google Scholar
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Quignot, et al., 2002, Rev. Mex. Astron. Astrofis., Ser de Conferencias, 12, 142 Google Scholar