Kinematics, turbulence and evolution of planetary nebulae
Gesicki K., Zjilstra A.A., Acker A., 2003, A&A, 400, 957
Abstract
This paper discusses the location of a sample of planetary nebulae on
the HR diagram. We determine the internal velocity fields of 14
planetary nebulae from high-resolution echelle spectroscopy, with the
help of photoionization models. The mass averaged velocity is shown to
be a robust, simple parameter describing the outflow. The expansion
velocity and radius are used to define the dynamical age; together with
the stellar temperature, this gives a measurement of the luminosity and
core mass of the central star. The same technique is applied to other
planetary nebulae with previously measured expansion velocities, giving
a total sample of 73 objects. The objects cluster closely around the
Schönberner track of 0.61 Msun, with a very narrow
distribution of core masses. The masses are higher than found for local
white dwarfs. The luminosities determined in this way tend to be higher
by a factor of a few than those derived from the nebular luminosities. The
discrepancy is highest for the hottest (most evolved) stars. We suggest
photon leakage as the likely cause. The innermost regions of the non-[WC]
nebulae tend to show strong acceleration. Together with the acceleration
at the ionization front, the velocity field becomes ``U''-shaped. The
presence of strong turbulent motions in [WC] nebulae is confirmed.
Except for this, we find that the [WC] stars evolve on the same tracks
as non-[WC] stars.
paper (pdf 1.3 Mb)
Last update: June 10, 2003