Scientists believe that shock breakouts, the shockwave that rocks a star before it turns supernova, allow stars to finally explode and release heavy atoms.

Witnessing the process occur and seeing how it happens, however, have been elusive, leaving scientists with mere guesses as to how this celestial event exactly happens.

By using NASA's Kepler space telescope, scientists have finally seen how this shock breakout happens, a breakthrough that can shed light on how chemicals and life itself were scattered in the Milky Way galaxy.

Peter Garnavich, from the University of Notre Dame in Indiana, and colleagues observed 50 trillion stars in hundreds of galaxies over a three year period examining the light captured by the now half-broken Kepler telescope every half an hour to hunt for signs of supernovae.

Supernova starts when the star runs out of nuclear fuel. This causes the star's core to collapse once gravity takes over.

Stars that are between 10 to 20 times more massive than our sun tend to expand to supergiants before they end up their lives as supernovae.

Once these stars run out of fuel in the center, their core collapses into a neutron star, which is followed by a supersonic shockwave. A shock break out is expected to occur when the shock wave reaches the star's surface.

In 2011, two red supergiants exploded and were captured by Kepler. The first star called KSN 2011a is about 300 times the size of the sun while the second star KSN 2011d is about 500 times the size of the sun.

Using Kepler, astronomers finally saw a supernova shockwave as it reaches the surface of one of the stars with the shock breakout observed to last for 20 minutes.

"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. "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."

Only one of the supernovae had the shock breakout, which according to the researchers could mean that the bigger star that they did not see a shockwave may not have been strong enough for the shockwave to get out.

"No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar interaction suspected in the fast rising light curve," the researchers wrote in their study. "The early light curve of KSN2011d does show excess emission consistent with model predictions of a shock breakout. This is the first optical detection of a shock breakout from a type II-P supernova."

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