仙后座A撞击喷出物中的核合成层
Nucleosynthetic Layers in the Shocked Ejecta of Cassiopeia A
摘要：
我们提出了一个三维分析的超新星遗迹仙后座A使用高分辨率光谱从斯皮策太空望远镜。我们观察超新星喷出物之前和期间的冲击-喷出物相互作用。我们确定残骸的反向冲击波是球形的，误差在7%以内，尽管这个球形的中心与残骸的几何中心偏移了810 km/s。我们确定在4000平方角秒的区域内，核合成层的速度宽度约为1000 km/s，尽管沿着任何单独视线的层的速度宽度<250 km/s。Si和O，来自不同的核合成层的祖星，被观察到是一致的速度空间中的某些方向，但隔离高达约500公里/秒的其他方向。我们比较这些观测的核合成层预测超新星爆炸模型，试图约束这样的模型。最后，我们观察到小规模的，波纹状的速度结构，这可能是在超新星爆炸本身，而不是数百年后，在遗迹的反向冲击动力学不稳定性造成的。
英文摘要：
We present a 3-dimensional analysis of the supernova remnant Cassiopeia A using high resolution spectra from the Spitzer Space Telescope. We observe supernova ejecta both immediately before and during the shock-ejecta interaction. We determine that the reverse shock of the remnant is spherical to within 7%, although the center of this sphere is offset from the geometric center of the remnant by 810 km/s. We determine that the velocity width of the nucleosynthetic layers is approximately 1000 km/s over 4000 square arcsecond regions, although the velocity width of a layer along any individual line of sight is <250 km/s. Si and O, which come from different nucleosynthetic layers in the progenitor star, are observed to be coincident in velocity space in some directions, but segregated by up to approximately 500 km/s in other directions. We compare these observations of the nucleosynthetic layers to predictions from supernova explosion models in an attempt to constrain such models. Finally, we observe small-scale, corrugated velocity structures that are likely caused during the supernova explosion itself, rather than hundreds of years later by dynamical instabilities at the remnant's reverse shock.
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