Unusual Dust Emission from Planetary Nebulae in the Magellanic Clouds - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




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Abstract: We present a Spitzer Space Telescope spectroscopic study of a sample of 25planetary nebulae in the Magellanic Clouds. The low-resolution modules are usedto analyze the dust features present in the infrared spectra. This studycomplements a previous work by the same authors where the same sample wasanalyzed in terms of neon and sulfur abundances. Over half of the objects 14show emission of polycyclic aromatic hydrocarbons, typical of carbon-rich dustenvironments. We compare the hydrocarbon emission in our objects to those ofGalactic HII regions and planetary nebulae, and LMC-SMC HII regions. Amorphoussilicates are seen in just two objects, enforcing the now well-known-fact thatoxygen-rich dust is less common at low metallicities. Besides these commonfeatures, some planetary nebulae show very unusual dust. Nine objects show astrong silicon carbide feature at 11um and twelve of them show magnesiumsulfide emission starting at 25um. The high percentage of spectra with siliconcarbide in the Magellanic Clouds is not common. Two objects show a broad bandwhich may be attributed to hydrogenated amorphous carbon and weaklow-excitation atomic lines. It is likely that these nebulae are very young.The spectra of the remaining eight nebulae are dominated by the emission offine-structure lines with a weak continuum due to thermal emission of dust,although in a few cases the S-N in the spectra is low, and weak dust featuresmay not have been detected.



Author: J. Bernard-Salas, E. Peeters, G.C. Sloan, S. Gutenkunst, M. Matsuura, A.G.G.M. Tielens, A.A. Zijlstra, J.R. Houck

Source: https://arxiv.org/



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