The Kepler Telescope may no longer be operational, but it is still providing invaluable information to astronomers. Using data gathered by Kepler, researchers have been examining a dying star called SN 2018oh to learn about how, at the end of their lives, stars explode in a huge burst of light. The SN 2018oh supernova died around 170 million years ago, but because it is so far away it has taken until now for the light from the event to reach us.
The death of a star occurs fairly rarely in our galaxy, with an estimated one supernova occurring in a galaxy the size of the Milky Way every 50 years. But there are many other galaxies in the universe, and experts estimate that a star dies somewhere in the universe once every second or so. By looking beyond our galaxy and into other galaxies beyond, scientists can study the process of star death even millions of years after it has happened.
Now a team from the Australian National University (ANU) has combined data from both the Kepler telescope and ground-based telescopes to find out more about SN 2018oh. For starters, it’s a Type Ia supernova, a class found in certain binary systems (where two stars orbit around each other) in which one of the stars is a white dwarf. White dwarf stars are limited in how much mass they can absorb from their fellow binary stars, especially when they rotate slowly, and if they absorb too much mass they explode when their core temperature reaches the ignition temperature for carbon fusion.
Researchers believe that in the case of SN 2018oh, this explosion process was even more dramatic than usual. Normally, a Type Ia supernova will brighten for around three weeks before fading away; with SN 2018oh this process happened much more quickly — brightening and fading within just a few days. A lead researcher in the study, Dr. Brad Tucker, speculated that the other star in the binary system could be responsible for this unusual outcome: “It’s possible in the case of SN 2018oh that the shock wave from the exploding white dwarf ran into the companion star, creating an extremely hot and bright halo that accounts for the added brightness and heat we observed.”
Dr. Tucker also emphasized the importance of the Kepler data to their project: “The now retired Kepler Space telescope changed our view of the Universe — showing just how common planets around other stars are. It has also now revolutionized what we know about how stars end their lives in brilliant explosions.”
