EDP Sciences
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Volume 369, Number 3, April III 2001
Page(s) 1088 - 1103
Section Diffuse matter in space
DOI http://dx.doi.org/10.1051/0004-6361:20010229

A&A 369, 1088-1103 (2001)
DOI: 10.1051/0004-6361:20010229

3-D ionization structure (in stereoscopic view) of planetary nebulae: the case of NGC 1501

R. Ragazzoni, E. Cappellaro, S. Benetti, M. Turatto and F. Sabbadin

Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy

(Received 9 January 2001 / Accepted 29 January 2001 )

Long-slit echellograms of the high excitation planetary nebula NGC 1501, reduced according to the methodology developed by Sabbadin et al. (2000a,b), allowed us to obtain the "true"distribution of the ionized gas in the eight nebular slices covered by the spectroscopic slit. A 3-D rendering procedure is described and applied, which assembles the tomographic maps and rebuilds the spatial structure. The images of NGC 1501, as seen in 12 directions separated by 15o, form a series of stereoscopic pairs giving surprising 3-D views in as many directions. The main nebula consists of an almost oblate ellipsoid of moderate ellipticity ($a\simeq44$ arcsec, $a/b\simeq1.02$, $a/c\simeq1.11$), brighter in the equatorial belt, deformed by several bumps, and embedded in a quite homogeneous, inwards extended cocoon. Some reliability tests are applied to the rebuilt nebula; the radial matter profile, the small scale density fluctuations and the 2-D (morphology) -3-D (structure) correlation are presented and analysed. The wide applications of the 3-D reconstruction to the morphology, physical conditions, ionization parameters and evolutionary status of expanding nebulae in general (planetary nebulae, nova and supernova remnants, shells around Population I Wolf-Rayet stars, nebulae ejected by symbiotic stars, bubbles surrounding early spectral type main sequence stars etc.) are introduced.

Key words: planetary nebulae: individual: NGC 1501 -- ISM: kinematics and dynamics

Offprint request: F. Sabbadin, sabbadin@pd.astro.it

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