Revised element abundances for WC-type central stars

TL;DR

This paper reevaluates the elemental abundances of WC-type central stars using advanced non-LTE models to resolve previous discrepancies in carbon-to-helium ratios and compares these findings with stellar evolution predictions.

Contribution

It applies the latest non-LTE models with line-blanketing and wind clumping to analyze WC star abundances, addressing systematic errors in prior analyses.

Findings

Discrepancy in carbon-to-helium ratios persists despite new models

Determined abundances of H, N, Fe for comparison with evolutionary models

Results challenge previous assumptions about WC star evolution

Abstract

According to previous spectral analyses of Wolf-Rayet type central stars, late [WC] subtypes show systematically higher carbon-to-helium abundance ratios than early [WC] subtypes. If this were true, it would rule out that these stars form an evolutionary sequence. However, due to the different parameter domains and diagnostic lines, one might suspect systematic errors being the source of this discrepancy. In an ongoing project we are therefore checking the [WC] analyses by means of the last generation of non-LTE models for expanding stellar atmospheres which account for line-blanketing and wind clumping. So far, the abundance discrepancy is not resolved. Further element abundances (H, N, Fe) are determined and compared with evolutionary predictions.