W. J. Maciel -
Abstract #126
AGE DISTRIBUTION OF THE CENTRAL STARS OF GALACTIC DISK PLANETARY NEBULAE
W. J. Maciel, R. D. D. Costa, T. E. P. Idiart
Astronomy and Astrophysics 512, A19 (2010)
The determination of ages of central stars of planetary nebulae (CSPN) is a complex
problem, and there is presently no single method that can be generally applied. We
have developed several methods to estimate the ages of CSPN, based both on the observed
nebular properties and in some properties of the stars themselves.Our aim is to estimate
the ages and the age distribution of CSPN and to compare the derived results with mass
and age determinations of CSPN and white dwarfs based on empirical determinations of
these quantities. We discuss several methods to derive the age distribution of CSPN,
namely, (i) the use of an age-metallicity relation that also depends on the galactocentric
distance, (ii) the use of an age-metallicity relation obtained for the galactic disk, and
(iii) the determination of ages from the central star masses obtained from the observed
nitrogen abundances. We consider a sample of planetary nebulae in the galactic disk,
most of which ($\sim$ 69%) are located in the solar neighbourhood, within 3 kpc from the
Sun. We estimate the age distribution of CSPN with average uncertainties of 1-2 Gyr,
and compare our results with the expected distribution based both on the observed
mass distribution of white dwarfs and on the age distribution derived from available
mass distributions of CSPN. We conclude most CSPN in the galactic disk have ages under
6 Gyr, and that the age distribution is peaked around 2-4 Gyr.
