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Issue A&A Volume 385, Number 1, April I 2002 Page(s) 205 - 215 Section Diffuse matter in space DOI 10.1051/0004-6361:20011800

A&A 385, 205-215 (2002)
DOI: 10.1051/0004-6361:20011800

Morphology of planetary nebulae with binary cores

The effect of gravitational focusing by the companion to the mass-losing star

A. J. Gawryszczak, J. Mikolajewska and M. Rózyczka

Nicolaus Copernicus Astronomical Center, Bartycka 18, Warsaw 00-716, Poland

(Received 30 July 2001 / Accepted 13 December 2001)

Abstract
We present hydrodynamical models of planetary nebulae with detached binary cores. The models are obtained according to the interacting winds scenario. Slow AGB wind models are produced by means of 3-D SPH simulations. The SPH results provide initial conditions for the evolution of a fast and rarefied wind injected into the AGB wind. In close binaries the density distribution of the slow wind is significantly modified by the gravity of the secondary, resulting in an enhanced density region close to the orbital plane of the system, and low density regions elongated perpendicularly to the orbital plane (we refer to those effects as gravitational focusing). The fast wind propagating through such a medium naturally develops a bipolar structure. In wider binaries the effect of gravitational focusing is weaker, and elliptical nebulae are produced instead of bipolar ones. In binaries wider than ~10 AU the effect becomes unimportant, and the resulting nebulae are almost entirely spherical apart from local corrugations caused by hydrodynamical instabilities. Thus, gravitational focusing alone is capable of generating a broad range of morphologies (from nearly spherical to strongly bipolar). The results are discussed in relation to nebulae associated with symbiotic stars.

Key words: planetary nebulae: general -- stars: winds, outflows -- stars: binaries: symbiotic -- hydrodynamics

Offprint request: A. J. Gawryszczak, gawrysz@camk.edu.pl

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