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Astron. Astrophys. 354, 573-578 (2000)


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Shaping of elliptical planetary nebulae

The influence of dust-driven winds of AGB stars

Christian Reimers 1, Ernst A. Dorfi 1 and Susanne Höfner 2,1

1 Institute for Astronomy (IfA), University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
2 Uppsala Astronomical Observatory, Box 515, 75120 Uppsala, Sweden

Received 12 November 1999 / Accepted 2 December 1999

Abstract

We calculated a model to investigate the shaping of a PN morphological group, i.e. elliptical PNe, in terms of the so-called Interacting Winds Model. The angle-dependent mass loss generated by a dust driven wind due to a slow rotation of the AGB star is an effective way for the shaping of PNe. The matter which is more concentrated in the equatorial region of the star influences the flow of the fast hot wind originating from the central star, resulting in elliptical or weakly bipolar shapes for the corresponding PNe. A wide range of elliptical shapes can be explained by this model. In contrast to previous studies the angle-dependent mass loss on the AGB is not parameterized by an arbitrary formula but is taken from self-consistent dust-driven wind models. Furthermore we discuss the influence of the different inclination of the PNe in the sky, the interaction with an inhomogenous interstellar medium and the possible effect of a magnetic field in or around the old AGB star. Using detailed morphology studies with the Hubble Space Telescope (HST) we discuss possible scenarios to explain the sometimes very complex structures.

Key words: stars: AGB and post-AGB – ISM: planetary nebulae: general – ISM: planetary nebulae: individual: Abell 75 – ISM: planetary nebulae: individual: Abell 78 – ISM: planetary nebulae: individual: NGC 3132

Send offprint requests to: C. Reimers

Correspondence to: reimers@astro.univie.ac.at

© European Southern Observatory (ESO) 2000

Online publication: February 9, 2000

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