Waiting for supernova
|Catching a nearby supernova would be a once-in-a-lifetime experience that could give scientists a glimpse into physics they could never recreate on Earth. Image: Sandbox Studio with Shawna X
Thousands of years ago, when a stargazer noticed a bright, new speck in the sky, one that wasn't there the night before, he likely would have been mystified. For early astronomers, stars were eternal, appearing faithfully on the dark firmament night after night since the beginning of time. What message might the gods be sending by throwing this newcomer into the familiar pattern?
"If stars developed on a faster time scale, then people might have been able to figure out sooner, 'Gee, they're not just points painted on the ceiling,'" says John Beacom, a physicist at The Ohio State University. "They didn't know how to decode it when a new star appeared, and they couldn't guess it was a star exploding."
Nowadays physicists not only are aware of these celestial explosions, they eagerly await the next one to happen nearby. An exploding star's intense conditions could provide us with a glimpse of physics that we could never recreate on Earth.
Supernovae are not rare. Every second, a few stars in the universe expire as supernovae. But it's a big universe, and in our own Milky Way, only two or three go off every hundred years, scientists estimate. The last observed supernova went off in the Large Magellanic Cloud, just outside the Milky Way at a distance of 163,000 light-years from Earth. That was seen in 1987. The last observed supernova in our own galaxy was Kepler's Star, spotted in 1604. It was 20,000 light-years away.
Supernovae come in two types. One type of supernova is born when two white dwarfs merge or when, in a binary star system consisting of a white dwarf and another type of star, the white dwarf accretes too much material from the other. The overwhelming mass of the merged star compresses it to the point that the resulting heat ignites a thermonuclear runaway.