科学美国人60秒 SSS Winking Star Six Centuries Ago Explained（在线收听）

Winking Star Six Centuries Ago Explained

揭秘600年前那颗一闪即逝的恒星

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，朝鲜皇家天文学家夜观星象，发现了一种非比寻常的现象。“他们在天蝎座其中两个知名恒星之间，发现了一个以前从未见过的全新的恒星。”那颗恒星只出现了14天便消失了，再也没有出现过。

\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."

迈克尔·萨拉是纽约美国自然历史博物馆的一名天文学家。他花了二十多年的时间，苦思研究这颗曾于600年前在天文学家眼前闪现过的恒星。“它就像个多面拼图游戏，我不敢说我们已经填充了所有的板块，但至少各个角落、边界已经拼好了，可以说目前已经拼得非常到位了。”

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.'

他和他的同事们已经确定了一点：那颗朝鲜天文学家发现的“消失的恒星”，实际上是由一种被称为“激变变星”的特殊的双星系统产生的巨大爆炸。

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.

该系统由两颗恒星组成。一颗是白矮星——“远古时期某个曾是恒星的物体的尸体”。另一颗是与我们的太阳非常像的一颗富含氢的恒星。

"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."

“那颗白矮星的引力强大到会吸取另一颗恒星体上的氢。所以本质上来说，它在吞食那一颗富含氢的恒星伙伴。那些被吸取的氢围绕白矮星形成一个环带，然后每隔几个月或几年的时间，环带就会聚集变强，变得越来越大，直至聚落到白矮星上，并因此导致矮新星爆发。”

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."

但每隔几十万年，随着聚集的氢越来越多，这些矮星爆发就会被更强大的冲击打断。“它就像一个巨大的氢弹爆炸，是一种热核爆炸事件。而1437年发生在该恒星体上的就是那个经典新星。”

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.

萨拉的团队找到了那次巨大爆炸事件的宇宙残骸。而且他们能够确定，1437的新星和上世纪三四十年代天文学家在同一片天空中拍下的较小的矮新星爆发，竟然同属于同一个双子星在不同生命阶段的光逆……

"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.

“因此，就像蝴蝶和毛毛虫是同一种东西一样，矮新星和老新星也是同一种东西。”这项研究发表在《自然》杂志上。

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

萨拉表示，每年银河都有50多个类新星爆发烟火照亮银河系……或许，它也在照亮我们对恒星进化史的认知。