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首页> 外文期刊>The Astrophysical journal >The Magellanic Zoo: Mid-infrared Spitzer Spectroscopy Of Evolved Stars And Circumstellar Dust In The Magellanic Clouds
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The Magellanic Zoo: Mid-infrared Spitzer Spectroscopy Of Evolved Stars And Circumstellar Dust In The Magellanic Clouds

机译：麦哲伦动物园：麦哲伦星云中演化中的恒星和星尘的中红外Spitzer光谱

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摘要

We observed a sample of evolved stars in the Large and Small Magellanic Clouds (LMC and SMC) with the Infrared Spectrograph on the Spitzer Space Telescope. Comparing samples from the SMC, LMC, and the Galaxy reveals that the dust production rate depends on metallicity for oxygen-rich stars, but carbon stars with similar pulsation properties produce similar quantities of dust, regardless of their initial metallicity. Other properties of the oxygen-rich stars also depend on metallicity. As the metallicity decreases, the fraction of naked (i.e., dust-free) stars increases, and among the naked stars, the strength of the 8 μm absorption band from SiO decreases. Our sample includes several massive stars in the LMC with long pulsation periods that produce significant amounts of dust, probably because they are young and relatively metal-rich. Little alumina dust is seen in circumstellar shells in the SMC and LMC, unlike in Galactic samples. Three oxygen-rich sources also show emission from magnesium-rich crystalline silicates. Many also show an emission feature at 14 μm. The one S star in our sample shows a newly detected emission feature centered at 13.5 μm. At lower metallicity, carbon stars with similar amounts of amorphous carbon in their shells have stronger absorption from molecular acetylene (C_2H_2) and weaker emission from SiC and MgS dust, as discovered in previous studies.
机译：我们用Spitzer太空望远镜上的红外光谱仪观察了大小麦哲伦星云（LMC和SMC）中恒星的样本。比较来自SMC，LMC和Galaxy的样品后发现，富氧星的粉尘产生速率取决于金属性，但是具有相似脉动特性的碳星会产生相似数量的粉尘，而不论其初始金属性如何。富氧恒星的其他特性也取决于金属性。随着金属性的降低，裸露的（即无尘）恒星的比例增加，而在裸露的恒星中，来自SiO的8μm吸收带的强度降低。我们的样本包括LMC中几颗质量大的恒星，它们具有较长的脉动周期，会产生大量的尘埃，这可能是因为它们很年轻并且金属含量相对较高。与银河系样本不同，在SMC和LMC的星际壳中几乎看不到氧化铝粉尘。三种富氧源也显示出富镁结晶硅酸盐的排放。许多还显示出14μm的发射特征。我们样本中的一颗S星显示出一个新检测到的发射特征，其中心为13.5μm。如先前的研究发现，在较低的金属度下，壳中具有相似量的无定形碳的碳星对分子乙炔（C_2H_2）的吸收更强，而SiC和MgS粉尘的发射更弱。

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