Friday, June 22, 2012

Far-Out Fridays: Supernovae

NASA Image - Public Domain
This is what is left of a star that was once observed by Johannes Kepler, the 17th century German astronomer. He called it "the new star in (the constellation) Ophiuchus' foot". The star was visible by the naked eye for 18 months, then vanished. What could cause a star to wink out in so short a frame of time?

As I've explained before, long-distance viewing is effectively time travel. However, that aspect of physics wouldn't extend or compress the amount of time a phenomenon took to observe. How could a star spring into being, and then flair back out, in 18 months, when stars have lifespans measured not in millions but billions of years?

The simple answer is that it didn't. What Kepler saw was not the birth of a new star, but its cataclysmic death. A phenomenon known as a supernova - an explosion of such force that it produced light many times its ordinary glow, and expelled most of the star's mass outward at the incredible speed of .10c ... over 30,000 kilometres per second. The composite image above is of the remaining stellar gas and dust that is centred around the original location of the star that spawned it.

Here's the weird thing. We know that certain stars are going to go supernova, and certain stars aren't. We understand the general process of a supernova occurring. What we don't understand is how the collapse of the star becomes such a grand explosion. It's an unsolved problem in astrophysics.

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