A star that exploded in 2007 was probably the heaviest that astronomers have ever detected.

Experts say that the exploding star, known as a supernova, contained 200 times more material than our sun. Before now, scientists thought that stars could not get more than about 150 times heavier than the sun.

The supernova was given the name SN2007bi, and was unusual because it lasted for so long. Instead of fading after a few weeks, it stayed bright for more than five months.

Researchers say that this is proof that a special new type of supernova exists. They say that these results could help scientists to investigate what happened after the Big Bang, and give us clues about the early universe.