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arXiv 1105.2822astro-ph.GA
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线导出的朝向银河系中心的红外消光

Line derived infrared extinction towards the Galactic Center

Tobias K. Fritz, Stefan Gillessen, Katie Dodds-Eden, Dieter Lutz, Reinhard Genzel, Walfried Raab, Thomas Ott, Oliver Pfuhl, Frank Eisenhauer, Farhad Yusef-Zadeh

摘要:

我们推导出了从1到19微米的朝向银河系中心的消光曲线。我们使用ISO-SWS和SINFONI观测到的小螺旋的氢发射谱线。消光自由通量参考是由VLA观察到的2 cm连续发射。朝向内部14”* 20”,我们发现消光系数为A(2.166微米)=2.62 +/- 0.11,幂律斜率为α =-2.11 +/- 0.06,短波长为2.8微米,与最近文献中的平均近红外斜率一致。然而,在较长的波长下,我们发现消光比2.8微米的短波长更灰色。我们发现,这是不可能的,以适应所观察到的消光曲线与尘埃模型组成的纯碳和硅酸盐颗粒,并添加复合颗粒,包括冰,需要解释的意见。结合距离相关消光和距离无关消光,我们得出到GC的距离为R_0=7.94 +/- 0.65 kpc。对于Sgr A*(r<0.5”),我们得到A_H=4.21 +/- 0.10,A_Ks=2.42 +/- 0.10和A_L '= 1.09 +/- 0.13。

英文摘要:

We derive the extinction curve towards the Galactic Center from 1 to 19 micron. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction free flux reference is the 2 cm continuum emission observed by the VLA. Towards the inner 14" * 20" we find an extinction of A(2.166 micron)=2.62 +/- 0.11, with a power-law slope of alpha=-2.11 +/- 0.06 shortward of 2.8 micron, consistent with the average near infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 micron. We find it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance dependent extinction with our distance independent extinction we derive the distance to the GC to be R_0=7.94 +/- 0.65 kpc. Towards Sgr A* (r<0.5") we obtain A_H=4.21 +/- 0.10, A_Ks=2.42 +/- 0.10 and A_L'=1.09 +/- 0.13.

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