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Planetary Nebulae and White Dwarfs

Published online by Cambridge University Press:  22 September 2016

V. Weidemann*
Affiliation:
Inst. Theor. Phys. u. Sternwarte, Univ. Kiel, W. Germany

Extract

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The present-day birth rate of planetary nebulae, 5·10−12 PN/pc3yr according to Cahn and Wyatt (1976), seems somewhat high compared to white dwarfs, for which a redetermination, including the statistics of Sion and Liebert (1977), yields 2·10−12 WD/pc3yr to within a factor of two. However, an increase of the distance scale for PN by a factor of 1.3 compared to Seaton (1968) - necessary in order to shift the extremum of PN radial velocities to the distance of the galactic center (9 kpc), and to increase the luminosities of the central stars from the position given by Pottasch et al. (1977) to a minimum value compatible with evolutionary constraints (Weidemann, 1977a) - brings birth rates of PN and WD into almost complete agreements.

Type
Session VIII: Planetary Nebulae and Their Influence on the Galaxy
Copyright
Copyright © Reidel 1978