30-不同金属丰度星系中的微米源
30-micron sources in galaxies with different metallicities
摘要：
我们提出了一个分析和比较的30微米的灰尘功能，在斯皮策太空望远镜光谱的207个富碳的渐近巨星分支（AGB）的恒星，后AGB对象，和行星状星云位于银河系，麦哲伦云（MC），或人马座矮球状星系（Sgr dSph），其特点是不同的平均金属丰度。我们研究了30微米特征载体的形成是否可能是金属度的函数。通过这项研究，我们期望更好地了解这些星系中富碳恒星的恒星演化的后期阶段。我们的分析使用“曼彻斯特方法”作为估计样品中富碳AGB星和行星状星云尘埃温度的基础。我们使用了一个黑体函数与一个单一的温度推导出曼彻斯特方法或其修改，以近似连续下的30微米的功能。我们工作的最重要的结论是，30微米特征的形成受到金属丰度的影响。具体来说，与MC中AGB星的金属含量更低的样本相反，该特征在质量损失率较低，温度较高的情况下被发现，并且在银河系碳星中更为突出。AGB、后AGB天体和PNe的平均特征（轮廓）似乎不受金属丰度的影响，至少在五分之一和太阳金属丰度之间，但在PNe的情况下，它被转移到明显更长的波长。
英文摘要：
We present an analysis and comparison of the 30 micron dust features seen in the Spitzer Space Telescope spectra of 207 carbon-rich asymptotic giant branch (AGB) stars, post-AGB objects, and planetary nebulae located in the Milky Way, the Magellanic Clouds (MCs), or the Sagittarius dwarf spheroidal galaxy (Sgr dSph), which are characterised by different average metallicities. We investigated whether the formation of the 30 micron feature carrier may be a function of the metallicity. Through this study we expect to better understand the late stages of stellar evolution of carbon-rich stars in these galaxies. Our analysis uses the `Manchester method' as a basis for estimating the temperature of dust for the carbon-rich AGB stars and the planetary nebulae in our sample. We used a black-body function with a single temperature deduced from the Manchester method or its modification to approximate the continuum under the 30 micron feature. The most important conclusion of our work is the fact that the formation of the 30 micron feature is affected by metallicity. Specifically that, as opposed to more metal-poor samples of AGB stars in the MCs, the feature is seen at lower mass-loss rates, higher temperatures, and has seen to be more prominent in Galactic carbon stars. The averaged feature (profile) in the AGB, post-AGB objects, and PNe seems unaffected by metallicity at least between a fifth and solar metallicity, but in the case of PNe it is shifted to significantly longer wavelengths.
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