C/O ABUNDANCE RATIOS, IRON DEPLETIONS, AND INFRARED DUST FEATURES IN GALACTIC PLANETARY NEBULAE
C/O ABUNDANCE RATIOS, IRON DEPLETIONS, AND INFRARED DUST FEATURES IN GALACTIC PLANETARY NEBULAE
复制标题
银河行星状星云中的 C/O 丰度比、铁贫乏和红外尘埃特征
DOI：
10.1088/0004-637x/784/2/173
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Mónica I. Rodríguez
中科院分区：
文献类型：
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作者：
G. Delgado;Mónica I. Rodríguez
我们研究了56个银河系行星状星云（PNe）中存在的尘埃，通过它们的铁耗尽因子，它们的C/O丰度比（51个天体），以及它们的红外光谱（33个天体）中出现的尘埃特征。我们的样品物体具有高质量的深光谱，其中大多数还具有紫外线观测。我们利用这些观测结果得出所有天体的铁丰度和C/O丰度比是均匀的。我们从文献中收集了红外尘埃的特征，并分析了可用的斯皮策/IRS光谱。大部分PNe的碳氧比低于1，在其红外光谱中显示出结晶硅酸盐。除Cn 1 ~ 5外，含硅酸盐的PNe的C/O值均<1。大多数具有富C环境粉尘特征（SiC或通常与mg相关的30 μm特征）的PNe的C/O≥0.8。在整个C/O值范围内检测到多环芳烃，包括6个也显示硅酸盐的物体。所有天体的铁含量都很低，这意味着它们90%以上的铁原子都沉积在了尘埃颗粒中。样品中铁的损耗范围约为两个数量级，富c、含SiC或30 μm红外光谱特征的样品损耗因子最高，而富o、含硅酸盐的样品损耗因子最低。
We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O ≳ 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.