(Image Source: NASA / Space.com)

BY JIM FLINK

ANCHOR CHRISTINA HARTMAN

Twinkle, Twinkle massive star.  How’d you break up from afar.
Astronomers are humming that tune, as they unravel a two-thousand year old mystery.
A dying supernova witnessed by ancient Chinese astronomers.  

Scientists have pieced together this image -- a composite of data from four NASA space telescopes.

Space.com has the back story.

“In 185 A.D., Chinese astronomers witnessed what they called a mysterious ‘guest star’ that appeared in the sky and lingered for about eight months. It wasn’t until the 1960s that scientists determined that this cosmic object was the first documented observation of a supernova that signaled the violent death of a distant star.”

And it was big.  As big as today’s moon -- to the ancient astronomer’s eyes, despite being 8000 light years away.
The BBC notes....

“In more recent times, astronomers have wondered how it grew so large, so fast. Space telescope observations now suggest that before exploding, a wind of material from the star blew a cavity around it, into which the supernova could expand much more quickly.”

Space.com speaks with an astronomer who says the supernova is still two to three times larger than he would expect.
Now, scientists know why.

“...infrared views of the supernova from NASA’s Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE) reveal that the star explosion detonated inside a region of space that was relatively free of gas and dust. This allowed the star’s explosion to travel out much farther and faster than expected...”

And the Astrophysics Journal, which published the findings, notes- there’s still much more to learn.

“We fit the infrared flux ratios with models of collisionally heated ambient dust, finding post-shock gas densities....large amount of iron in the X-ray-emitting ejecta... This would make RCW 86 the first known case of a ... supernova in a wind-blown bubble.  The wind-blown bubble scenario requires a single-degenerate progenitor, which should leave behind a companion star.”