UNUSUAL DUST EMISSION FROM PLANETARY NEBULAE IN THE MAGELLANIC CLOUDS
UNUSUAL DUST EMISSION FROM PLANETARY NEBULAE IN THE MAGELLANIC CLOUDS
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DOI：
10.1088/0004-637x/699/2/1541
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
J. Bernard-Salas;Els Peeters;Els Peeters;G. Sloan;S. Gutenkunst;M. Matsuura;A. Tielens;A. Zijlstra;J. Houck
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作者：
J. Bernard-Salas;Els Peeters;Els Peeters;G. Sloan;S. Gutenkunst;M. Matsuura;A. Tielens;A. Zijlstra;J. Houck
我们提出了一个斯皮策太空望远镜对麦哲伦星云（MCs）中25个行星状星云（PNe）样本的光谱研究。低分辨率模块用于分析红外光谱中存在的尘埃特征。这项研究补充了同一作者之前的一项工作，即根据氖和硫丰度分析同一样品。超过一半的物体（14个）显示出多环芳烃的排放，这是典型的富碳粉尘环境。我们将这些天体的碳氢化合物排放与银河系H区、星云状星云、大麦哲伦星云H区和小麦哲伦星云H区进行了比较。无定形硅酸盐只在两个物体中被发现，这加强了现在众所周知的事实，即富氧尘埃在低金属丰度的地方不太常见。除了这些共同的特征，一些星云星云还显示出非常不寻常的尘埃。9个物体在11 μm处表现出强烈的碳化硅特征，12个物体在25 μm处表现出硫化镁发射。碳化硅在mc中的高比例光谱并不常见。两个物体显示出可能归因于氢化非晶碳和弱低激发原子线的宽带。这些星云很可能非常年轻。其余8个星云的光谱主要是由于尘埃的热发射而发出的带有弱连续体的精细结构线，尽管在少数情况下光谱中的信噪比很低，并且可能没有检测到弱尘埃特征。
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 μm and 12 of them show magnesium sulfide emission starting at 25 μm. 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.