Neon and Sulfur Abundances of Planetary Nebulae in the Magellanic Clouds

TL;DR

This study measures neon and sulfur abundances in 25 planetary nebulae in the Magellanic Clouds using infrared data, revealing lower abundances compared to the Milky Way and insights into chemical evolution.

Contribution

First infrared-based analysis of neon and sulfur in Magellanic Cloud planetary nebulae, comparing with Galactic data and discussing chemical evolution implications.

Findings

Neon abundances are about 1/3 and 1/6 of Galactic PNe in LMC and SMC.

Ne/S ratio is higher in Magellanic Clouds than in the Milky Way.

Neon abundances in PNe and HII regions are consistent.

Abstract

The chemical abundances of neon and sulfur for 25 planetary nebulae (PNe) in the Magellanic Clouds are presented. These abundances have been derived using mainly infrared data from the Spitzer Space Telescope. The implications for the chemical evolution of these elements are discussed. A comparison with similarly obtained abundances of Galactic PNe and HII regions and Magellanic Clouds HII regions is also given. The average neon abundances are 6.0x10(-5) and 2.7x10(-5) for the PNe in the Large and Small Magellanic Clouds respectively. These are ~1/3 and 1/6 of the average abundances of Galactic planetary nebulae to which we compare. The average sulfur abundances for the LMC and SMC are respectively 2.7x10(-6) and 1.0x10(-6). The Ne/S ratio (23.5) is on average higher than the ratio found in Galactic PNe (16) but the range of values in both data sets is similar for most of the objects. The neon abundances found in PNe and HII regions agree with each other. It is possible that a few (3-4) of the PNe in the sample have experienced some neon enrichment, but for two of these objects the high Ne/S ratio can be explained by their very low sulfur abundances. The neon and sulfur abundances derived in this paper are also compared to previously published abundances using optical data and photo-ionization models.