SIMBAD references

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 H II regions and Magellanic Cloud H II 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 H II 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 photoionization models.