EVIDENCE FOR DUST EVOLUTION WITHIN THE TAURUS COMPLEX FROM SPITZER IMAGES
EVIDENCE FOR DUST EVOLUTION WITHIN THE TAURUS COMPLEX FROM SPITZER IMAGES
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斯皮策图像中金牛座复合体内尘埃演化的证据
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Jet propulsion Laboratory
中科院分区：
文献类型：
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作者：
N. Flagey;A. Noriega;F. Boulanger;S. Carey;T. Brooke;E. Falgarone;T. Huard;C. McCabe;M. Miville;D. Padgett;R. Paladini;L. M. R. S. S. C. C. I. Technology;I. D. Spatiale;Lermalra;Smithsonian Astrophysical Observatory;Jet propulsion Laboratory
我们目前的金牛座复合体（TC）的斯皮策图像。我们利用观测的灵敏度和空间分辨率来表征整个云的漫红外（IR）发射。这项工作突出了尘埃演化的证据内的原型参考静止分子云研究的半透明部分。我们联合收割机Spitzer 160 μm和IRAS 100 μm的观测数据，得到了5′分辨率的尘埃温度图和远红外（FIR）尘埃不透明度图。尘埃的平均温度约为14.5 K，在整个云中的离散度为±1 K。远红外区尘埃不透明度与来自两微米全天巡天恒星颜色的消光密切相关，比弥漫星际介质的平均值大2倍。这种不透明度的增加和辐射场的衰减都有助于解释大颗粒的较低发射温度。在中红外（MIR）图像中，TC的结构发生了显着变化，跟踪多环芳烃（PAHs）和非常小的颗粒（VSGs）的排放。我们集中我们的分析的MIR发射到一个范围内的黄道纬度远离黄道带和黄道光残差小。在这个云区中，没有8和24 μm对应于最亮的160 μm发射特征。相反，8 μ m和24 μm的图像显示了在160 μm和消光图中非常不明显的沉积结构。在这种丝状结构中，红外颜色在亚秒差距的距离上变化。我们比较了观测到的颜色与模型计算量化的辐射场强度和随机加热粒子的丰度对尘埃光谱能量分布的影响。为了匹配观测到的颜色范围，我们必须调用星际辐射场和多环芳烃和VSGs丰度的几个因子的变化。我们的结论是，在这种结构的尘埃质量循环的一个显着的部分，在小尺寸的尘埃尺寸分布的一端。
We present Spitzer images of the Taurus Complex (TC). We take advantage of the sensitivity and the spatial resolution of the observations to characterize the diffuse infrared (IR) emission across the cloud. This work highlights evidence of dust evolution within the translucent sections of the archetype reference for studies of quiescent molecular clouds. We combine the Spitzer 160 μm and IRAS 100 μm observations to produce a dust temperature map and a far-IR (FIR) dust opacity map at 5′ resolution. The average dust temperature is about 14.5 K with a dispersion of ±1 K across the cloud. The FIR dust opacity is tightly correlated with the extinction derived from Two Micron All Sky Survey stellar colors and is a factor of 2 larger than the average value for the diffuse interstellar medium. This opacity increase and the attenuation of the radiation field both contribute to account for the lower emission temperature of the large grains. The structure of the TC significantly changes in the mid-IR (MIR) images that trace emission from polycyclic aromatic hydrocarbons (PAHs) and very small grains (VSGs). We focus our analysis of the MIR emission to a range of ecliptic latitudes away from the zodiacal bands and where the zodiacal light residuals are small. Within this cloud area, there are no 8 and 24 μm counterparts to the brightest 160 μm emission features. Conversely, the 8 and 24 μm images reveal filamentary structure that is strikingly inconspicuous in the 160 μm and extinction maps. The IR colors vary over subparsec distances across this filamentary structure. We compare the observed colors with model calculations quantifying the impact of the radiation field intensity and the abundance of stochastically heated particles on the dust spectral energy distribution. To match the range of observed colors, we have to invoke variations by a factor of a few of both the interstellar radiation field and the abundance of PAHs and VSGs. We conclude that within this filamentary structure a significant fraction of the dust mass cycles in and out the small-size end of the dust size distribution.