标题： 超新星1987A：旋转和双星伴星 显示英文标题

标题： Supernova 1987A: Rotation and a Binary Companion

摘要： 在本文中，我们提供了一种可能的联系，将围绕SN1987A的双极星云结构与其前身星的特性联系起来。采用了一种风吹泡（WBB）情景，在这种情景中，来自蓝超巨星的快速稀薄风扩展到先前红超巨星阶段释放的慢速致密风中。双极形状是由于慢风中的极区到赤道密度对比（即，慢风形成一个慢环）。我们使用Bjorkman和Cassinelli（1992）的风压缩盘（WCD）模型来确定慢环的形状。在WCD情景中，环的形状由前身星的旋转决定。然后，我们使用一种自相似的半解析方法来研究风吹泡的演化，以确定 resulting 双极星云的形状。我们发现，风压缩盘和双极风吹泡模型的结合使我们能够恢复SN1987A周围星云的主要特性。特别是，SN1987A内部环的大小、速度和密度在我们的计算中很容易再现。参数空间的探索表明，红超巨星前身星必须以大于其破坏速度0.3的速度旋转。我们得出结论，前身星很可能是通过与双星伴星的合并而被加速的。使用一个简单的双星合并模型，我们发现伴星很可能具有大于0.5 M_sun的质量。 显示英文摘要

摘要： In this paper we provide a possible link between the structure of the bipolar nebula surrounding SN1987A and the properties of its progenitor star. A Wind Blwon Bubble (WBB) scenario is emplyed, in which a fast, tenuous wind from a Blue Supergiant expands into a slow, dense wind, expelled during an earlier Red Supergiant phase. The bipolar shapre develops due to a pole-to-equator density contrast in the slow wind (ie, the slow wind forms a slow torus). We use the Wind Compressed Disk (WCD) model of Bjorkman & Cassinelli (1992) to determine the shape of the slow torus. In the WCD scenario, the shape of the torus is determined by the rotation of the progenitor star. We then use a self-similar semi-analytical method for wind blown bubble evolution to determine the shape of the resulting bipolar nebula. We find that the union of the wind-compressed-disk and bipolar-wind-blown- bubble models allows us to recover the salient properties of SN1987A's circumstellar nebula. In particular, the size, speed and density of SN1987A's inner ring are easily reproduced in our calculations. An exploration of parameter space shows the the red supergiant progenitor must be been rotating at > 0.3 of its breakup speed. We conclude that the progenitor was most likely spun up by a merger with a binary companion. Using a simple model for the binary merger we find that the companion is likely to have had a mass > 0.5 M_sun.