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Astron. Astrophys. 334, 239-246 (1998)

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4. Conclusions

We have made an attempt to present a so called general picture for PNe which is based on the assumption that the PN and CSPN characteristics must be understood in the global frame of the theories applied in this case. These theories are: (i) the RDW model; (ii) the theory for evolution of an AGB-post-AGB star; (iii) the ISW wind for PNe. We used in our study the one-dimensional two-winds model of Zhekov & Perinotto (1996) applied to two PNe (NGC  6543 and NGC  6826) and the main results can be summarized as follow:

  • NGC  6543: The CSPN age (according to the 0.605  [FORMULA] mass track) and the age of the nebula are consistent (given by the ISW mode) with a value of about 4000 years. The model predicted (ISW model) X-ray characteristics of this object are in accordance with those deduced from observations. The general PNe picture gives preference to a distance value of 1.4  kpc.
  • NGC  6826: A self-consistent general picture of PNe is possible along the evolutionary track of 0.565  [FORMULA] mass for the CSPN in NGC  6826. As a result a value close to 2  kpc looks appropriate for the distance to this object. Future X-ray observations are of great importance for proper confrontation with predictions from the theory in this case.
  • For both objects, the general PNe picture suggests that the so-called super-wind had a mass loss of 1-2 orders of magnitude smaller than the traditionally accepted value of [FORMULA]   [FORMULA]  yr-1.
  • The force multiplier parameters (from the RDW model) play important role for the general picture of PNe. A development of the RDW theory towards higher photospheric temperature is highly desired.
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© European Southern Observatory (ESO) 1998

Online publication: May 12, 1998