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Kinematics, turbulence and evolution of planetary nebulae

By SpaceRef Editor
January 21, 2003
Filed under , ,

Astrophysics, abstract
astro-ph/0301393


From: Krzysztof Gesicki <[email protected]>
Date: Mon, 20 Jan 2003 18:26:50 GMT (190kb)

Kinematics, turbulence and evolution of planetary nebulae


Authors:
Krzysztof Gesicki,
Agnes Acker,
Albert A. Zijlstra

Comments: 15 pages, 19 figures, accepted for publication in “Astronomy &
Astrophysics”


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 Schoenberner
track of 0.61 M_sun, 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.

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