A Supernova pairing

Astrophysicists first caught sight of an unusual-looking supernova in January 2011. It was around 675 million light-years away in the constellation Lynx.

Until its telltale flashy burst,a future supernova is indistinguishable from other stars.

Its really not possible to look at them before they explode, said the papers lead author,Benjamin Dilday,an astrophysicist at Las Cumbres Observatory Global Telescope Network in Goleta,California.

From the behaviour of gas in the area after the explosion,Dilday and colleagues were able to deduce that their supernova had originally been a white dwarf orbiting a red giant.

Gas from the red giant had blown onto the white dwarf,repeatedly igniting its surface and causing explosions called novas. Eventually the star ignited at its center,leading to the supernova.

Astrophysicists use Type 1a supernovas,which are highly consistent in their brightness,as standard measures of distance in the universe. They help underpin the study of dark energy and how the universe expands.

Kate Yandell