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Astron. Astrophys. 319, 98-108 (1997)

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The variation of abundances in planetary nebulae with height above the Galactic plane *

J. Köppen 1, 2, 4 and F. Cuisinier 1, 3

1 Equipe 'Evolution Galactique', URA 1280, Observatoire de Strasbourg, 11 rue de l'Université, F-67000 Strasbourg, France
2 Institut für Astronomie und Astrophysik der Universität, D-24098 Kiel, Germany
3 Astronomisches Institut der Universität Basel, Venusstr. 7, CH-4102 Binningen, Switzerland
4 International Space University, Parc d'Innovation, F-67400 Illkirch, France

Received 5 March 1996 / Accepted 24 July 1996

Abstract

In a sample of 94 planetary nebulae of the Galactic disk we find a systematic decrease of the abundances of He, N, O, S, and Ar with height above the Galactic plane, and also with radial velocity. Over an interval of 3 kpc the abundance of O, S, and Ar decrease by 0.1 ... 0.2 dex. This value is in good agreement with the predictions of an empirical model for the chemical and kinematical evolution of the disk, based on relations and constraints of the solar neighbourhood. The radial migration of the progenitor stars, caused by the velocity dispersion increasing with age, is found to be quite important for the vertical metallicity profile.

Key words: Galaxy: abundances – Galaxy: structure – Planetary nebulae: general – Galaxy: evolution

* Partially based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: J. Köppen (Kiel)

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998
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