On the robustness of H-deficient post-AGB tracks

Abstract

We analyze the robustness of H--deficient post--AGB tracks regarding previous evolution of their progenitor stars and the constitutive physics of the remnants. Our motivation is a recent suggestion of Werner & Herwig (2006) that previous evolution should be important in shaping the final post--AGB track and the persisting discrepancy between asteroseismological and spectroscopical mass determinations. This work is thus complementary to our previous work (Miller Bertolami & Althaus 2006) and intends to shed some light on the uncertainty behind the evolutionary tracks presented there. We compute full evolutionary models for PG1159 stars taking into account different extramixing (overshooting) efficiencies and lifetimes on the TP-AGB during the progenitor evolution. We also assess the effect of possible differences in the opacities and equation of state by artificially changing them before the PG1159 stage. Also comparisons are made with the few H-deficient post--AGB tracks available in the literature. Contrary to our expectations, we found that previous evolution is not a main factor in shaping H--deficient post--AGB tracks. Interestingly enough, we find that only an increase of $\sim 50$ in the intershell opacities at high effective temperatures may affect the tracks as to reconcile spectroscopic and asteroseismologic mass determinations. This forces us to conclude that our previous tracks (Miller Bertolami & Althaus 2006) are robust enough as to be used for spectroscopic mass determinations, unless opacities in the intershell region are substantially different. Our results, then, call for an analysis of possible systematics in the usually adopted asteroseismological mass determination methods.

Accepted for publication in Astronomy and Astrophyscs

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Cited by in corpus (12)

• On helium-dominated stellar evolution: the mysterious role of the O(He)-type stars
• Asteroseismological measurements on PG 1159-035, the prototype of the GW Vir variable stars
• Asteroseismological constraints on the coolest GW Vir variable star (PG 1159-type)PG 0122+200
• Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS: I. Asteroseismology of the GW Vir stars RX J2117+3412, HS 2324+3944, NGC 6905, NGC 1501, NGC 2371, and K 1-16
• Asteroseismology of hot pre-white dwarf stars: the case of the DOV stars PG 2131+066 and PG 1707+427, and the PNNV star NGC 1501
• On the systematics of asteroseismological mass determinations of PG1159 stars
• Spectral analysis of the hybrid PG 1159-type central stars of the planetary nebulae Abell 43 and NGC 7094
• Hidden IR structures in NGC 40: signpost of an ancient born-again event
• Asteroseismology of the GW Virginis stars SDSS J0349-0059 and VV 47
• Kepler and TESS Observations of PG 1159-035
• Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS -- IV. Discovery of two new GW Vir stars: TIC0403800675 and TIC1989122424
• Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS VI. Asteroseismology of the GW Vir-type central star of the Planetary Nebula NGC 246