For the first time ever, scientists have seen a star go supernova via visual light. The massively destructive process happened to the star KSN 2011d, a previously red giant star that was about 500 times the size of our sun and situated about 1.2 billion light years away. The light from the destruction of the star reached us in 2011, and an international team of scientists, led by Notre Dame astrophysics professor Peter Garnavich, uncovered it while searching through data captured by the Kepler space telescope. What is awe inspiring about the event is that the explosion lasted 20 minutes. That’s a long period of time when one thinks of explosions, but an insanely short amount of time compared to the billions of years the star was in existence.
“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich in a NASA press release. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”
What is a Supernova?
As a star uses up its fuel and its core grows in mass, the core cannot support its own weight and it collapses in on itself. The result is a massive explosion that blows apart the star, including its outer layers, forming a very bright cloud that can last for months before losing its luminosity. The chart below shows the brightness of the KSN 2011d star before, during and after the explosion.
You can see that it’s just motoring along like it had for billions of years, then right before what is showing as day 4 on the chart, there is a spike before the brightness grows as the cloud expands. That spike is the explosion – called a shock breakout – that took “just” – or a “whopping,” depending on your perspective – 20 minutes. NASA put together a youtube clip showing an animation of what the star might have looked like during the explosion, matched up against the timeline of the event.
Are Supernova’s Good or Bad?
“All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center in California’s Silicon Valley. “Life exists because of supernovae.”
Supernova’s are part of the natural cycle of some stars. To date, we have seen one about once every 50 years, but Kepler is opening up trillions of stars for analysis which means more are likely to come.