Rapid evolution of [WC] stars in the Magellanic Clouds

TL;DR

This study investigates the evolution of [WC] central stars in Magellanic Cloud planetary nebulae by spectroscopic observations, confirming that these stars evolve faster than H-burning stars and originate from more massive progenitors.

Contribution

It provides new spectral data and confirms that [WC] central stars in the Magellanic Clouds evolve faster than H-burning stars, aligning with evolutionary models.

Findings

Five nebulae showed increased excitation over time.

Four [WC] central stars were newly identified.

[WC] stars evolve faster and come from more massive progenitors.

Abstract

We obtained new spectra of fourteen Magellanic Cloud planetary nebulae with the South African Large Telescope to determine heating rates of their central stars and to verify evolutionary models of post-asymptotic giant branch stars. We compared new spectra with observations made in previous years. Five planetary nebulae showed an increase in excitation over time. Four of their central stars exhibit [WC] features in their spectra, including three new detections. This raises the total number of [WC] central stars of PNe in the Magellanic Clouds to ten. We compared determined heating rates of the four [WC] central stars with the He-burning post-asymptotic giant branch evolutionary tracks and the remaining star with the H-burning tracks. Determined heating rates are consistent with the evolutionary models for both H and He-burning post-asymptotic giant branch stars. The central stars of the PNe that show the fastest increase of excitation are also the most luminous in the sample. This indicates that [WC] central stars in the Magellanic Clouds evolve faster than H-burning central stars, and they originate from more massive progenitors.