海山二：现知最危险恒星的3D模型
Eta Car: 3D Model of the Most Dangerous Star Known
Video Credit: NASA, CXC, April Hobart; Text: Michael F. Corcoran (NASA, Catholic U., HEAPOW)
Explanation: What’s the most dangerous star near earth? Many believe it’s Eta Carinae, a binary star system about 100 times the mass of the Sun, just 10,000 light years from earth. Eta Carinae is a ticking time bomb, set to explode as a supernova in only a few million years, when it may bathe the earth in dangerous gamma rays. The star suffered a notorious outburst in the 1840s when it became the brightest star in the southern sky, only to fade to obscurity within decades. The star was not destroyed, but lies hidden behind a thick, expanding, double-lobed structure called the Homunculus which now surrounds the binary. Studies of this ejecta provide forensic clues about the explosion. Using observations from NASA satellites we can now visualize the 3D distribution of the shrapnel, all the way from the infrared, through optical and UV, to the outermost shell of million-degree material, visible only in X-rays.
Tomorrow’s picture: open space
海山二：现知最危险恒星的3D模型
影片提供: NASA, CXC, April Hobart; 文稿: Michael F. Corcoran (NASA, Catholic U., HEAPOW)
说明: 地球附近最危险的恒星是那颗？很多人认为是海山二，一个离地球只有10,000光年，总质量约为太阳质量100倍的双星系统。海山二是颗定时炸弹，将在短短的数百万年内发生超新星爆炸，届时地球或许会沐浴在高危害的伽玛射线辐射里。这个恒星系统在1840年代，发生过非常猛烈的爆发变成南天最明亮的恒星，然后在短短数十年内就变暗成为不起眼的繁星之一。不过这颗星并未毁灭，而是隐藏在浓密的双瓣结构里，而这个名为侏儒星云的扩张云气已完全包住此恒星系统。研究这团喷溅物质，或可找到还原此爆发事件的法医学线索。从NASA布署的多部人造卫星之观测数据，我们得以在红外光、可见光和紫外光等波段，都把碎片的三维分布视像化，其中最外围、温度高达百万度的物质层，只有在X射线波段才得见。
明日的图片: open space
