UNUSUAL DUST EMISSION FROM PLANETARY NEBULAE IN THE MAGELLANIC CLOUDS

被引:77
作者
Bernard-Salas, J. [1 ]
Peeters, E. [2 ,3 ]
Sloan, G. C. [1 ]
Gutenkunst, S. [1 ]
Matsuura, M. [4 ,5 ]
Tielens, A. G. G. M. [6 ]
Zijlstra, A. A. [7 ]
Houck, J. R. [1 ]
机构
[1] Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA
[2] Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada
[3] SETI Inst, Mountain View, CA 94043 USA
[4] Natl Inst Nat Sci, Natl Astron Observ Japan, Mitaka, Tokyo 1818588, Japan
[5] UCL, Dept Phys & Astron, London WC1E 6BT, England
[6] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA
[7] Univ Manchester, Jodrell Bank, Ctr Astrophys, Manchester M13 9PL, Lancs, England
关键词
dust; extinction; infrared: general; Magellanic Clouds; planetary nebulae: general; POLYCYCLIC AROMATIC-HYDROCARBONS; MU-M; INFRARED-SPECTRA; PHOTODISSOCIATION REGIONS; SPITZER SPECTROSCOPY; CHEMICAL-COMPOSITION; EVOLVED STARS; CARBON STARS; HII-REGIONS; FEATURES;
D O I
10.1088/0004-637X/699/2/1541
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present a Spitzer Space Telescope spectroscopic study of a sample of 25 planetary nebulae (PNe) in the Magellanic Clouds (MCs). The low-resolution modules are used to analyze the dust features present in the infrared spectra. This study complements a previous work by the same authors where the same sample was analyzed in terms of neon and sulfur abundances. Over half of the objects (14) show emission of polycyclic aromatic hydrocarbons, typical of carbon-rich dust environments. We compare the hydrocarbon emission in our objects to those of Galactic H II regions and PNe, and Large Magellanic Cloud/Small Magellanic Cloud H II regions. Amorphous silicates are seen in just two objects, enforcing the now well known fact that oxygen-rich dust is less common at low metallicities. Besides these common features, some PNe show very unusual dust. Nine objects show a strong silicon carbide feature at 11 mu m and 12 of them show magnesium sulfide emission starting at 25 mu m. The high percentage of spectra with silicon carbide in the MCs is not common. Two objects show a broadband which may be attributed to hydrogenated amorphous carbon and weak low-excitation atomic lines. It is likely that these nebulae are very young. The spectra of the remaining eight nebulae are dominated by the emission of fine-structure lines with a weak continuum due to thermal emission of dust, although in a few cases the signal-to-noise ratio in the spectra is low, and weak dust features may not have been detected.
引用
收藏
页码:1541 / 1552
页数:12
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