A star that appeared and then vanished in A.D. 1437 was an explosion in a binary star system—which now reveals clues about the life cycle of certain stars. Christopher Intagliata reports.

1437年突然出现又神秘消失的一颗恒星其实是发生在一个双星系统里的一次爆炸，这些现象向我们透露出某些恒星生命周期的信息。

撰文/播音：克里斯托弗·因塔利亚塔(Christopher Intagliata)

On March 11, 1437, Korean royal astronomers noticed something out of the ordinary in the night sky. "There was a brand new star they'd never seen before, between two of the well-known stars in the tail of Scorpius. That star was only seen for 14 days and then it disappeared and was never seen again.”

1437年3月11日，朝鲜皇家天文学家注意到当天的夜空有一点不寻常。“在天蝎座尾巴上，两颗著名恒星中间有一颗他们从来没看到过的新恒星。这颗恒星只出现了14天，之后就消失不见了。”

Michael Shara, an astronomer at the American Museum of Natural History in New York. He’s spent more than two decades puzzling over this star that winked at astronomers nearly 600 years ago. "It's a many-sided jigsaw puzzle and I won't say we've filled in all the pieces, but at least I think we've got the corners and the boundaries pretty much in place now.”

纽约美国自然历史博物馆的天文学家迈克尔·沙拉（Michael Shara）如是说。他花了二十多年的时间来解密这颗在600多年前超天文学家闪烁的恒星。“这就像是一副多面拼图，我不敢说我们已经拼好了所有的板块，但是至少我想我们已经把一些角落和边界拼凑到位。”

What he and his colleagues have determined is this: the "disappearing star" the Korean astronomers spotted was in fact a massive explosion produced by a special type of binary star system, known as a 'cataclysmic variable.’

他和他的同事认为：朝鲜天文学家观察到的这颗“消失的恒星”实际上是由被称为“激变变星”的特殊双星系统所产生的一次大爆炸。

The system consists of two stars. One's a white dwarf—“the corpse of something that used to be a star in the distant past." And its companion is a hydrogen-rich star, pretty much like our sun.

这个特殊的系统包含了两颗恒星。其中一颗是白矮星——“远古时期一颗恒星的尸体。”而它的同伴则是一颗与太阳十分相似的富含氢的恒星。

"The white dwarf's gravity is so powerful it can suck hydrogen off of that companion. So in essence it's cannibalizing its companion hydrogen-rich star. That hydrogen flows into a ring around the white dwarf, and then every few months or few years the ring builds up, becomes more and more massive and collapses down onto the white dwarf. That gives rise to dwarf nova eruptions.”

“白矮星的引力十分强，它可以把氢从‘同伴’那里吸走。所以，本质上它是在蚕食它的伙伴。氢元素在白矮星周围形成一个环带，然后每过几个月或者几年，环带就会变大，并变得越来越重，最后向白矮星坍塌。这就造成了矮新星爆发。”

But every couple of hundred thousand years, those dwarf eruptions are punctuated by much bigger bangs, as more and more hydrogen builds up. "You blow up as a gigantic hydrogen bomb, that's a thermonuclear event. And that classical nova is what happened in 1437 to this star.”

但是每过几十万年，随着氢越来越多，这些矮行星的爆发会被更强的爆炸打断。“它就像一个巨大氢弹一样爆炸，这就是一个热核爆炸事件。而那个新星就是1437年发生在这个恒星上的爆炸。”

Shara's team located the cosmic remains of that huge explosion. And they were able to determine that the nova of 1437—and smaller dwarf nova eruptions photographed in that same square of sky in the 1930s and '40s—were actually hiccups of light from the same binary star…in different phases of its life cycle.

沙拉的团队找到了那次大爆炸的宇宙残骸。而且他们还能确定，1437年的那颗新星和上世纪三十四年代在天空中同一个角落里拍到的较小矮新星的爆发，其实来自于同一个双子星，只是在它的不同生命阶段。

"And hence dwarf novae and old novae are the same things. Just like butterflies and caterpillars are the same things." The study is in the journal Nature. [M. M. Shara et al., Proper-motion age dating of the progeny of Nova Scorpii A.D. 1437]

“所以就像蝴蝶和毛毛虫其实是同一种生物一样，矮新星和旧新星也是同一种东西。”这项研究成果发表在《自然》杂志上。（论文信息：[M. M. Shara et al., Proper-motion age dating of the progeny of Nova Scorpii A.D. 1437]）

Shara says 50 of these novalike fireworks explode every year in the Milky Way…illuminating the galaxy, and perhaps, our understanding of the evolution of stars.

沙拉表示，银河系每年大概都有50多个类新星爆发，它们照亮了银河系，也许，同时也照亮了我们对恒星演化史的认知。