This is scientific American 60 second science. I'm Christopher in Tagyatta.

On March 11th, 1437, Korean royal astronomers noticed something out of the ordinary in the night sky.

There was a brand new star they had never seen before that was between two of the well-known stars

in the Tale of Scorpius.

That star was only seen for 14 days and then it disappeared and was never seen again.

Michael Shera, 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.

You know, it's a many-sided jigsaw puzzle, and I won't say we filled in all the pieces, but at least I think we've got the corners and then the boundaries pretty much in place now.

What he and his colleagues have determined is this. The disappearing star the Korean astronomers spotted, it was in fact a massive explosion produced

by a special type of binary star system known as a cataclysmic variable.

That system consists of two stars. One's a white dwarf. So it's the

corpse of something that used to be a star in the distant past. It's what's left

after the star died. And its companion is a hydrogen-rich star,

pretty much like our sun.

And the white dwarf's gravity is so powerful

that 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 then collapses down onto the

white dwarf that gives rise to what we call dwarf nova eruptions.

But every couple hundred thousand years, those dwarf eruptions are punctuated by much bigger banks, as more and more hydrogen builds up.

You blow up as a gigantic hydrogen bomb.

That's a thermonuclear event.

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