Australian National University researchers found a white dwarf - the dense remains of a star, that our sun will be in billions of years - gorging on a brown dwarf companion which is 10 times smaller.

Astronomer Ryan Ridden-Harper unexpectedly found the supernova event while sifting through archived data from the Kepler space telescope, which was launched by NASA in 2009 to find earth-sized planets and retired in 2018.

Mr Ridden-Harper had written a program to look at the Kepler data "using peripheral vision for stuff that was missed" according to his supervisor, ANU astrophysicist and cosmologist Dr Brad Tucker.

"It is almost reminiscent of what would happen if the sun and Jupiter in five billion years collided," Dr Tucker told AAP.

"Our sun, in five billion years will grow and turn into red giant that puffs out and starts to swallow Mercury, Venus and earth."

The research adds to knowledge about the average lifetimes of stars by observing them in old age, and how they perish.

Stars have a 'recycling system' in that when they die, they explode to create new stars and then new solar systems, Dr Tucker said.

Our sun is a third-generation 'grandchild' star created when a former star exploded, which was itself created when an older star blew up.

For people that are uncomfortable at the notion that our sun will die, Dr Tucker said: "We don't have a choice."

"Ultimately there is a greater process at work: us, me, you, the reader are made up of this same star stuff," he said.

"When we see it in real time, the explosions tell us what materials were there to go and create new stars and new planets, so it is really finding the full life cycle of a solar system.

"It tells us then what could have happened to create us. This is the big question: why are we here, why did life form on this planet, why are the ingredients the right ratio that they are that lead to this experiment we call life?"

Scientists believe human beings - or homo sapiens - have existed for about 300,000 years and the earth for some 4.5 billion years, and that these future events are a long way off.

The 'vampire' star Mr Ridden-Harper saw was thousands of light years away, meaning it happened thousands of years ago.

"It is kind of amazing to think ancient civilisations of people were on earth when this thing actually exploded, that's happening all the time in our skies," Dr Tucker said.

The new program acts like a detective to find rare astronomical events such as mystery explosions and learn about black holes. Researchers will continue using the program to analyse data from Kepler and satellites.

The research by Mr Ridden-Harper - with colleagues at ANU, the Space Telescope Science Institute and University of Notre Dame in the US - is published in the Monthly Notices of the Royal Astronomical Society.

Australian Associated Press