Astronomy and Astrophysics – Astrophysics
Scientific paper
Nov 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994a%26a...291..595b&link_type=abstract
Astronomy and Astrophysics (ISSN 0004-6361), vol. 291, no. 2, p. 595-603
Astronomy and Astrophysics
Astrophysics
17
Dimensional Analysis, H Alpha Line, Halos, Main Sequence Stars, Oxygen Spectra, Planetary Nebulae, Precession, Silicon, Image Analysis, Radial Velocity, Shock Waves
Scientific paper
Images of the elliptical planetary nebula NGC 7009 have been obtained with narrow band filters centered in most of the main optical emission lines. The H alpha and (OIII) 5007 A images reveal an extended, high excitation circular halo around the central elliptical body of the planetary. A (SIII) 9069 A image shows a localized outer condensation, previously unreported. Bidimensional plasma diagnostics have been obtained. The halo is entirely excited by photons, whereas gas dynamical effects play an important role in determining the shape and excitation of the inner regions. The existence of bow shocks may be inferred from images of forbidden to Balmer line ratios. If the shape of the inner nebula is due to rotation of the planetary nebula nucleus (PNN), the progenitor of NGC 7009 probably was a main sequence star of about 2 solar mass, and the mass of the halo is approximately 1 solar mass. The inner nebula contains two rings of material, probably related to episodic mass loss events. The rings are not aligned. If this misalignment is due to precession of the PNN, we find a precession period of approximately 30,000 years. If precession is being driven by a companion star, the latter is located approximately 4.5 solar radius from the PNN. No common envelope would be expected at the present stage of evolution of this system.
Aguilar Luis
Bohigas Joaquin
Lopez Jose Alberto
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