Hydrogen-poor planetary nebulae
Abstract
Five planetary nebulae are known to show hydrogen-poor material near the central star. In the case of A58, this gas was ejected following a late thermal pulse similar to Sakurai's Object. In this paper I will review these five objects. One of them, IRAS 183332357, may not be a true PN. I will show that there is a strong case for a relation to the [WC] stars and their relatives, the weak emission-line stars. The surface abundances of the [WC] stars are explained via diffuse overshoot into the helium layer. The hydrogen-poor PNe do not support this: their abundances indicate a change of abundance with depth in the helium layer. A short-lived phase of very high mass loss, the r-AGB, is indicated. Sakurai's Object may be at the start of such a phase, and may evolve to very low stellar temperatures.
Cite
@article{arxiv.astro-ph/0105448,
title = {Hydrogen-poor planetary nebulae},
author = {Albert A. Zijlstra},
journal= {arXiv preprint arXiv:astro-ph/0105448},
year = {2007}
}
Comments
12 pages, 3 figures. Invited review: Sakurai's object: What have we learned in the first five years?(Keele, UK). To be published in Astrophysics & Space Science