Carbon abundance in Small Magellanic Cloud planetary nebulae through Advanced Camera for Surveys prism spectroscopy: constraining stellar evolution at low metallicity

TL;DR

This study uses ultraviolet spectroscopy to measure carbon abundances in Small Magellanic Cloud planetary nebulae, providing insights into stellar evolution at low metallicity and expanding the existing database for such objects.

Contribution

It more than doubles the number of SMC PNe with known carbon abundances, enabling better constraints on stellar evolution models at low metallicity.

Findings

SMC PNe are mostly carbon-rich and have not undergone hot-bottom burning.

Stellar yields at SMC metallicity agree with observations for stars below 3.5 solar masses.

Carbon lines are major coolants in SMC PNe, influenced by metallicity.

Abstract

We perform near ultraviolet ACS prism spectroscopy of 11 Small Magellanic Cloud (SMC) planetary nebulae (PNe) with the main aim of deriving the abundance of carbon. The analysis of the ACS spectra provide reliable atomic carbon abundances for all but a couple of our targets; ionic C^(2+) abundances are calculated for all target PNe. With the present paper we more than double the number of SMC PNe with known carbon abundances, providing a good database to study the elemental evolution in low- and intermediate-mass stars at low metallicity. We study carbon abundances of Magellanic Cloud PNe in the framework of stellar evolution models and the elemental yields. Constraining SMC and LMC stellar evolutionary models is now possible with the present data, through the comparison of the final yields calculated and the CNO abundances observed. We found that SMC PNe are almost exclusively carbon rich, and that for the most part they have not undergone the hot-bottom burning phase, contrary to half of the studied LMC PNe. The yields from stellar evolutionary models with LMC and SMC metallicities broadly agree with the observations. In particular, evolutionary yields for M$_{\rm to}<3.5 {\rm M}_{\odot}$ well encompass the abundances of round and elliptical PNe in the SMC. We found that the carbon emission lines are major coolants for SMC PNe, more so than in their LMC counterparts, indicating that metallicity has an effect on the physics of PNe, as predicted by Stanghellini et al. (2003).