Pulsations of Pre-White Dwarfs with Hydrogen-dominated Atmospheres

Abstract

We carried out a fully non-adiabatic analysis for nonradial oscillations of pre-white dwarfs evolved from the post-Asymptotic Giant Branch (AGB) with hydrogen-dominated envelopes. It is shown that nuclear reactions in the hydrogen burning-shell excite low-degree g-modes in the period range of about 40-200 s for the pre-white dwarf models with Teff=40,000 K - 300,000 K. It is also shown that the amount of hydrogen {has} a significant influence on the instability domain of such pre-white dwarfs in the Hertzsprung-Russel (H-R) diagram. Thus, the thickness of hydrogen-dominated envelopes may be well constrained by observing the presence of the g-mode oscillations.

arXiv commentPASJ accepted, 7 pages, 6 figures

References in corpus (9)

• The chemical composition of the Sun
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• Evolutionary and pulsational properties of white dwarf stars
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Gravity-Mode Instabilities in Models of Post-Extreme Horizontal Branch Stars: Another Class of Pulsating Stars?
• On the possible existence of short-period g-mode instabilities powered by nuclear burning shells in post-AGB H-deficient (PG1159-type) stars
• Stability Analysis of Strange-Modes in Hot Massive Stars with Time-Dependent Convection

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