Journal Article

‘Distance mapping’ and the 3D structure of BD +30° 3639

S. Akras and W. Steffen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 1, pages 925-933
Published in print June 2012 | ISSN: 0035-8711
Published online May 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20928.x
‘Distance mapping’ and the 3D structure of BD +30° 3639

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BD +30° 3639 is a member of a group of uncommon planetary nebulae with Wolf–Rayet central star and higher expansion velocities in [O iii] than in [N ii] lines. Images and high-resolution spectra from the literature are used in order to construct a 3D model of the nebula using the morpho-kinematic code shape. We find that two homologous expansion laws are needed for the [N ii] and [O iii] shells. We conclude that the internal velocity field of BD +30° 3639 decreases with the distance from the central star at least between the [O iii] and [N ii] shells. A cylindrical velocity component is used to replicate the high-speed bipolar collimated outflows. We also present a new kinematic analysis technique called ‘distance mapping’. It uses the observed proper motion vectors and the 3D velocity field to generate maps that can be used as a constraint to the morpho-kinematic modelling with shape as well as improve the accuracy for distance determination. It is applied to BD +30° 3639 using 178 internal proper motion vectors from Li, Harrington & Borkowski and our 3D velocity field to determine a distance of 1.52 ± 0.21 kpc. Finally, we find evidence for an interaction between the eastern part of the nebula and the ambient H2 molecular gas.

Keywords: methods: data analysis; ISM: jets and outflows; ISM: kinematics and dynamics; planetary nebulae: individual: BD +30° 3639

Journal Article.  6021 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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