Stars don’t shine forever. The life of a star is incredibly long by our standards, they can live for millions to billions of years. Our own Sun, a star just like any other, has only 5 billion years left before it runs out of fuel and dies.
Small stars like the Sun die with a slow puff of material into space, but stars much more massive than the sun don’t go gently. Massive stars live fast, die young and go out with an incredible bang known as a supernova. A new observation has caught a massive star going supernova, right from the beginning, giving us an unprecedented glimpse into its death.
Kepler and K2
This supernova was caught by the Kepler Space Telescope. How this detection was made is fascinating in itself, because Kepler was supposed to be a planet hunting telescope. Kepler’s mission was to stare at the same 150,000 stars in the hope of seeing an exoplanet cross in front of its parent star, making it temporarily dimmer. Supernova were not part of the plan.
The plan changed in 2013 when a second reaction wheel failed barely a year after another had already failed. Being left with only two reaction wheels, Kepler was unable to stare steadily enough into space to search for exoplanets. It almost seemed like that was it for Kepler until a group of astronomers came up with an incredible new plan.
The new plan K2 utilises the unique design of Kepler and the pressure of light. The solar panels on Kepler are arranged to form a ridge along one side of the telescope. If the ridge is pointed at just the right angle towards the sun, then light coming from the sun would bounce off the solar panels and stabilize the telescope. It’s like the Sun is firing billions of little billiard balls which pummel the solar panels and keep Kepler pointing stable.
The only catch to this plan is that Kepler will need to reorient and stare at another patch in the sky every 80 days. This might not be so good for planet hunters, but it does mean that Kepler can now look for exoplanets, supernova and much more. This amazing plan has been running from 2014, keeping Kepler hunting for planets and now supernovae.
It’s not often in astronomy that sunlight is useful!
With the new K2 mission Kepler spotted a red giant star that went supernova. The supernova is affectionately called Kepler Supernova 2011d or KSN2011d for short. This giant star had reached the end of its life and without nuclear fusion to push out against gravity, the star’s core collapsed and the star went boom. The type of supernova this star exploded in is known as a type II-P supernova. Since Kepler, by chance, watched this unfold astronomers were able to see something called the shock breakout light up the supernova. But what is a shock breakout?
A shocking collapse
At the beginning of KSN2011d when the core of the star collapsed a massive shockwave tore its way to the surface from the core. At the surface the shock breakout released an enormous amount of energy greatly increasing the dying stars brightness for about an hour. After the breakout the dying star dims again momentarily before the rest of the star went supernova. In this violent death throws, this star will outshine a galaxy of stars.
A shock breakout has been detected before in other wavelengths and with this discovery in visible light, astronomers are happy to confirm this phenomena. This discovery brings us closer to understanding what happens in a core collapse supernova, but there is still much left to learn about supernova. Astronomers will keep hunting for supernova with Kepler and other instruments, to further our understanding of these important and violent events. Let’s just hope they don’t find one close by!