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Astron. Astrophys. 334, 670-677 (1998)

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Localised, high-speed flows within the hydrogen-deficient planetary nebula Abell 78

J. Meaburn 1, J.A. López 2, M. Bryce 1 and M.P. Redman 1

1 Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
2 Instituto de Astronomía, UNAM, Apdo. Postal 877, Ensenada, B.C. 22800, México

Received 24 December 1997 / Accepted 24 February 1998


The remarkable velocity structure of the different components of the hydrogen-deficient planetary nebula Abell 78 have been revealed by obtaining spatially resolved profiles of the [O III ] 5007Å line with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope.

The outer, diffuse, hydrogen-rich, [FORMULA] diameter shell is expanding radially at 40  [FORMULA]. The irregular, knotty, hydrogen-deficient [FORMULA]   [FORMULA]   [FORMULA] inner shell has a similar overall expansion velocity but more complex kinematical structure. Similar to A 30, velocity `spikes' are found in the position-velocity arrays of [O III ] 5007Å profiles from the inner shell. These extend to a further [FORMULA] than the radial velocity of the approaching side of this inner shell.

The [O III ] 5007Å bright, hydrogen-deficient core knots are distributed throughout an elongated disk expanding at [FORMULA]. There is kinematical evidence that `polar bullets' are being ejected perpendicularly to this central feature at [FORMULA]. Altogether `velocity spikes' and other high-speed knots in the pv arrays of [O III ] 5007Å profiles are found over a [FORMULA] range of radial velocities.

Many of the kinematical phenomena are considered to be a consequence of the mass-loaded, shocked, wind from the central star.

Key words: planetary nebulae: individual: Abell 78 – ISM: kinematics and dynamics – ISM: jets and outflows

Send offprint requests to: Professor J. Meaburn

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© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998