Journal Article

Flows along cometary tails in the Helix planetary nebula NGC 7293

J. Meaburn and P. Boumis

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 402, issue 1, pages 381-385
Published in print February 2010 | ISSN: 0035-8711
Published online February 2010 | e-ISSN: 1365-2966 | DOI:
Flows along cometary tails in the Helix planetary nebula NGC 7293

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Previous velocity images which reveal flows of ionized gas along the most prominent cometary tail (from Knot 38) in the Helix planetary nebula are compared with that taken at optical wavelengths with the Hubble Space Telescope and with an image in the emission from molecular hydrogen. The flows from the second most prominent tail from Knot 14 are also considered. The kinematics of the tail from the more complex Knot 32, shown here for the first time, also reveal an acceleration away from the central star. All of the tails are explained as accelerating ionized flows of ablated material driven by the previous, mildly supersonic, asymptotic giant branch wind from the central star. The longest tail of ionized gas, even though formed by this mechanism in a very clumpy medium, as revealed by the emission from molecular hydrogen, appears to be a coherent outflowing feature.

Keywords: circumstellar matter; planetary nebulae: individual: Helix nebula: NGC 7293

Journal Article.  2430 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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