超新星 1987A 二十年

400年来最亮的超新星1987A(SN 1987A)发现已20年.国际上在2007年举行了多次学术会议，美国宇航局（NASA）发布了哈勃空间望远镜(HST)拍摄的漂亮照片，美国还为此发行了纪念邮票.文章介绍了SN1987A的发现过程和它的最初的光度，阐明了它的光谱观测以及它的前身星的特性，综述了哈勃空间望远镜长期监测获得的丰富资料（特别是它的三环结构）以及钱德拉X射线天文台取得的一系列新结果，指出了至今仍未发现它的中心致密天体，还有许多谜团未解开.最后对未来的研究作了展望.

Supernova 1987A: 20 years later

It is 20 years since supernova 1987A, the brightest supernova in more than 400 years, was discovered. Several international symposiums were held in 2007, NASA released a special and beautiful SN1987A color photograph taken by the Hubble space telescope, and commemorative stamps were issued by the USA, all for celebrating SN1987A. We present an overview of its discovery, the spectra and character of its progenitor, the rich data accumulated over long term observations by the Hubble telescope, especially the three-ring structure, and the results of the Chandra X-ray observatory. Although SN1987A has been observed continuously, its central compact object has still not been discovered and certain mysteries remain unexplained. Finally, we look into the future.