Bibcode
Corradi, Romano L. M.; Guerrero, Martín; Manchado, A.; Mampaso, Antonio
Bibliographical reference
New Astronomy, Volume 2, Issue 5, p. 461-470.
Advertised on:
11
1997
Journal
Citations
37
Refereed citations
30
Description
We present high resolution images and high dispersion spectra of the
planetary nebula IC 4593. Benefiting from superb seeing (0″.4),
the narrowband images reveal the existence of a complex system of
collimated knots in the inner 15″ of the nebula.The knots, which
morphologically resemble outward facing bow-shocks, are located at
different position angles and distances from the centre, present very
low radial velocities, extended tails pointing toward the central star,
as well as peculiar extensions in the outer regions of the nebula. Some
of these properties seem to indicate that the observed structures are
multiple collimated outflows propagating from the central star
throughout the nebula along very different directions. This is a mass
loss scenario, however, that is not predicted or reproduced by any
theoretical model for AGB and post-AGB stars. The origin of the inner
knots remains therefore enigmatic.The isolated, outermost condensations
of the nebula previously detected by various authors are found to be
part of a very faint and large asymmetrical halo.