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arXiv 1003.5684astro-ph.SRastro-ph.HE
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SN 1987 A内部喷出物的三维结构

The 3-D Structure of SN 1987A's inner Ejecta

K. Kjaer, B. Leibundgut, C. Fransson, A. Jerkstrand, J. Spyromilio

备注：
Above abstract is abridged. 11 pages, 9 figures. Accepted July 1st 2010 by Astronomy and Astrophysics
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摘要：

SN 1987 A爆炸20年后，我们现在能够观察到三维空间分辨的内部喷出物。新合成的物质及其放射性衰变子产物的详细绘图揭示了爆炸机制。这可能揭示爆炸的几何形状及其与SN 1987 A周围的赤道环和外环的联系。我们用积分场光谱法对超新星喷出物和赤道环在[Si I]+[Fe II]和He I发射谱线上成像。光谱信息可以被映射到径向速度图像中，显示出喷出物在天空上和垂直于天空平面的方向上的膨胀。内部喷出物在空间上解决了南北方向，显然是不对称的。我们认为，大部分的喷出物是位于同一平面所定义的赤道环，并没有形成一个双极结构已经建议。喷出物的确切形状建模，我们发现，一个细长的三轴椭球体最适合的意见。从我们的光谱分析的喷出物光谱，我们发现，大部分的He I，[Si I]和[Fe I-II]的排放起源于核心材料，经历了爆炸核合成。He I发射可能是富α冻结的结果，如果正电子能量是局部沉积的。我们的观测清楚地表明SN 1987 A的非对称爆炸机制。伸长和速度的不对称性指向一个大规模的空间非球形分布预测在最近的爆炸模型。喷出物在赤道环平面上的方向反对由于恒星旋转而通过两极引起的喷射爆炸。

英文摘要：

Twenty years after the explosion of SN 1987A, we are now able to observe the three-dimensional spatially resolved inner ejecta. Detailed mapping of newly synthesised material and its radioactive decay daughter products sheds light on the explosion mechanism. This may reveal the geometry of the explosion and its connection to the equatorial ring and the outer rings around SN 1987A. We have used integral field spectroscopy to image the supernova ejecta and the equatorial ring in the emission lines of [Si I]+[Fe II] and He I. The spectral information can be mapped into a radial velocity image revealing the expansion of the ejecta both as projected onto the sky and perpendicular to the sky plane. The inner ejecta are spatially resolved in a North-South direction and are clearly asymmetric. We argue that the bulk of the ejecta is situated in the same plane as defined by the equatorial ring and does not form a bipolar structure as has been suggested. The exact shape of the ejecta is modelled and we find that an elongated triaxial ellipsoid fits the observations best. From our spectral analyses of the ejecta spectrum we find that most of the He I, [Si I] and [Fe I-II] emission originates in the core material which has undergone explosive nucleosynthesis. The He I emission may be the result of alpha-rich freeze-out if the positron energy is deposited locally. Our observations clearly indicate a non-symmetric explosion mechanism for SN 1987A. The elongation and velocity asymmetries point towards a large-scale spatial non-spherical distribution as predicted in recent explosion models. The orientation of the ejecta in the plane of the equatorial ring argues against a jet-induced explosion through the poles due to stellar rotation.

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