Astron. Astrophys. 334, 239-246 (1998)
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
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
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
- 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.
© European Southern Observatory (ESO) 1998
Online publication: May 12, 1998