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Astron. Astrophys. 329, 265-275 (1998)

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Velocity fields of planetary nebulae *

Krzysztof Gesicki 1, Albert A. , Zijlstra 2, Agnes Acker 3 and Ryszard Szczerba 4

1 Torun Center for Astronomy, UMK, ul. Gagarina 11, PL-87100 Torun, Poland (gesicki@astri.uni.torun.pl)
2 European Southern Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching b. München, Germany (azijlstr@eso.org)
3 Observatoire de Strasbourg, 11, rue de l'université, F-67000 Strasbourg, France (acker@astro.u-strasbg.fr)
4 Nicolaus Copernicus Astronomical Center ul. Rabianska 8, PL-87100 Torun, Poland (szczerba@ncac.torun.pl)

Received 28 February 1997 / Accepted 8 August 1997

Abstract

Density distributions and velocity fields are derived for four spatially resolved planetary nebulae, based on high-resolution long-slit emission line spectra. We use a photo-ionization code to fit the spectra and to derive the nebular structure, assuming spherical symmetry. We present the results for individual nebulae and compare with three objects analyzed earlier. The expansion velocities are found to increase outward: this is shown to be likely related to the presence of an ionization front. Six PN in the sample are found to be ionization bounded. For one object, which has a WR-type central star, a large amount of turbulence or irregular structure in the velocity field is found. The results are in agreement with hydrodynamical calculations, in which the velocities also tend to increase with distance from the star. However, the common presence of an ionization front was not predicted.

Key words: planetary nebulae: general – planetary nebulae: individual: M 3-12, NGC 6620, M 3-15, M 1-40

* Based on observations taken at ESO

Send offprint requests to: K. Gesicki

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© European Southern Observatory (ESO) 1998

Online publication: November 24, 1997
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