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Astron. Astrophys. 321, 898-906 (1997)


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Improved simulations of the planetary nebula luminosity function

R.H. Méndez and T. Soffner

Institut für Astronomie und Astrophysik der Universität München, Scheinerstr. 1, D-81679 München, Germany

Received 19 September 1996 / Accepted 8 November 1996

Abstract

We have developed a new procedure for the generation of a planetary nebula luminosity function (PNLF), improving on previous work (Méndez et al. 1993). The procedure is based, as before, on an exponential central star mass distribution, on H-burning post-AGB evolutionary tracks, and on the avoidance of nebular models for the calculation of nebular fluxes. We have added new post-AGB evolutionary tracks and introduced the following improvements: (1) the imperfect analytical representation of post-AGB evolutionary tracks has been replaced by an interpolation routine giving a better approximation; (2) we have modified the distribution of the intensities of [O III ] [FORMULA] 5007 relative to H [FORMULA], so that it better imitates the observed distribution, which we have taken from data in the Strasbourg-ESO catalogue of Galactic PNs and other sources; (3) we have adjusted the absorbing factor µ along the white dwarf cooling tracks, so as to reproduce the observed PNLF of the Magellanic Clouds and M 31 at fainter magnitudes. In this way we have produced a PNLF which is more consistent with observed PN properties. We use this randomly generated PNLF to: (1) show as convincingly as possible that most PNs in any real population must leak stellar H-ionizing photons; (2) revise our determinations of the parameter [FORMULA] ; (3) discuss the shape of the PNLF, hinting at the possible existence of a distinct feature 2 magnitudes fainter than the brightest PNs; (4) attempt estimates of maximum final masses from fits to the PNLFs of the LMC and M 31. There is marginal evidence of a higher maximum final mass in the LMC, but this should be confirmed in other galaxies with recent star formation. A convincing confirmation will require to increase the sample sizes and to extend the PNLFs to at least 1.5 mag fainter than the brightest PNs.

Key words: planetary nebulae: general – stars: post-AGB – galaxies: distances – methods: numerical – galaxies: M 31 – Magellanic Clouds

Send offprint requests to: R.H. Méndez

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998

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