By Dean Murray
An explosive new space image reveals a star’s inner conflict hours before it blew up.
The picture shows the inside of a star turning on itself in the short time before it spectacularly exploded, according to a new study from NASA’s Chandra X-ray Observatory.
The shattered star, known as the Cassiopeia A supernova remnant, is one of the best-known, well-studied objects in the sky.
NASA explains: “Over three hundred years ago, however, it was a giant star on the brink of self-destruction.
“The new Chandra study reveals that just hours before it exploded, the star’s interior violently rearranged itself.
“This last-minute shuffling of its stellar belly has profound implications for understanding how massive stars explode and how their remains behave afterwards.”
Cassiopeia A (Cas A for short) was one of the first objects the telescope looked at after its launch in 1999, and astronomers have repeatedly returned to observe it.
“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said Toshiki Sato of Meiji University in Japan who led the study. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”
The new research with Chandra data reveals a change that happened deep within the star at the very last moments of its life. After more than a million years, Cas A underwent major changes in its final hours before exploding.
“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” said co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”
The strong turbulent flows created by the star’s internal changes may have promoted the development of the supernova blast wave, facilitating the star’s explosion.
“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said co-author Hiroyuki Uchida, also of Kyoto University. “Such final internal activity of a star may change its fate — whether it will shine as a supernova or not.”
The results have been published in the latest issue of The Astrophysical Journal.
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