It’s like the shockwave from a nuclear bomb, only much bigger, and no one gets hurt.
Dr. Brad Tucker from the Australian National University (ANU) Research School of Astronomy and Astrophysics gave that description after leading the team that became the first ever to witness the shockwave generated when a dying star collapsed upon itself, creating a supernova.
Supernovae are huge galactic events. When an old star dies, its core collapses to form a neutron star – the smallest and densest type. The collapse creates a massive explosion that can be seen from other galaxies. The nuclear fusion of this explosion forms gold, silver, uranium, iron, zinc and other heavy metals. That energy is from a shockwave that travels out from the core at 30,000 to 40,000 kilometers per second. Until now, the brightness of the supernova has blocked the view of the shockwave.
According to their report in the Astrophysical Journal, Tucker and astronomers from ANU, the University of Notre Dame, the Space Telescope Science Institute, the University of California Berkeley and University of Maryland were digging through three years of pre-2011 data from the Kepler space telescope when they spotted two old red supergiants – KSN2011a and KSN2011d.
As they watched the two star die, they saw something unusual in KSN 2011a, the smaller one (270 times the radius of the Sun) located 700 million light-years away. As the supernova’s explosive brightness began, they witnessed the shockwave’s visible light wavelengths emerging from the core to its surface. This was a blink-of-the-eye find, as the shockwave only lasted 20 minutes while the supernova took 14 days to reach maximum brightness.
KSN 2011d, 1.2 billion light-years away with a radius 460 times that of the Sun, did not have a visible shockwave because the star was too big for it to reach the surface before the brightness blocked it out, according to Dr. Tucker.
This discovery is a redemption of sorts for the Kepler space telescope after the failure of two of its four reaction wheels failed in 2013, preventing it from rotating and ending its extended mission. Peter Garnavich, an astrophysics professor at the University of Notre Dame in Indiana, describes Kepler’s contribution.
You look at two supernovae and see two different things. That’s maximum diversity. 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. 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.
Now that they know what to look for, Tucker expects to see more supernova shockwaves as the team pours over the past Kepler data and new information from the K2 “Second Light” mission which takes advantage of Kepler’s remaining capabilities to watch over 5,000 galaxies.
In the meantime, Supernova Shockwave would make a great name for an energy drink.