Nine “monster” stars which are 30 million times brighter than the Sun have been spotted by British astronomers using the Hubble Space Telescope.

• The cluster of stars around 170,000 light years from Earth is the largest group of very massive stars ever identified.
• They were discovered by an international team led by astronomers from Sheffield University.
• The Hubble Space Telescope was launched into orbit in 1990 and is nearing the end of its life, but is still proving useful.
• The cluster is called R136, and measures a few light years across.
• It sits in the Tarantula Nebula inside the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way. It is extremely large, hot and bright stars whose energy is radiated mainly in the ultra violet.
• Nine of the stars are more than 100 times the mass of the Sun – and were described as “monster” on the Hubble Twitter account – while dozens are 50 times larger. But while they are huge, none of them are larger than R126a1 – also in the Tarantula Nebula – which is the most massive star in the known universe and 250 times larger than our Sun.
• The discovery of five more huge solar masses could pose questions about how they all formed.