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| Version 0 | Version 1 |
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| Black hole star mystery 'solved' | Black hole star mystery 'solved' |
| (about 6 hours later) | |
| Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom. | Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom. |
| Scientists have long wondered how stars develop in such extreme conditions. | |
| Molecular clouds - the normal birth places of stars - would be ripped apart by the immense gravity, a team explains in Science magazine. | Molecular clouds - the normal birth places of stars - would be ripped apart by the immense gravity, a team explains in Science magazine. |
| But the researchers say that stars can form from elliptical discs - the relics of giant gas clouds torn apart by encounters with black holes. | But the researchers say that stars can form from elliptical discs - the relics of giant gas clouds torn apart by encounters with black holes. |
| They made the discovery after developing computer simulations of giant gas clouds being sucked into black holes like water spiralling down a plughole. | They made the discovery after developing computer simulations of giant gas clouds being sucked into black holes like water spiralling down a plughole. |
| "These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the galaxy," said co-author Ian Bonnell from St Andrews University, UK. | "These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the galaxy," said co-author Ian Bonnell from St Andrews University, UK. |
| Ripped apart | Ripped apart |
| Their findings are in accordance with actual observations in our Milky Way galaxy that indicate the presence of a massive black hole, surrounded by huge stars with eccentric orbits. | Their findings are in accordance with actual observations in our Milky Way galaxy that indicate the presence of a massive black hole, surrounded by huge stars with eccentric orbits. |
| The simulations, performed on a supercomputer - and taking over a year of computing time - followed the evolution of two separate giant gas clouds up to 100,000 times the mass of the Sun, as they fell towards the supermassive black hole. | The simulations, performed on a supercomputer - and taking over a year of computing time - followed the evolution of two separate giant gas clouds up to 100,000 times the mass of the Sun, as they fell towards the supermassive black hole. |
| The simulations show how the clouds are pulled apart by the immense gravitational pull of the black hole. | The simulations show how the clouds are pulled apart by the immense gravitational pull of the black hole. |
| The disrupted clouds form into spiral patterns as they orbit the black hole; the spiral patterns remove motion energy from gas that passes close to the black hole and transfers it to gas that passes further out. | The disrupted clouds form into spiral patterns as they orbit the black hole; the spiral patterns remove motion energy from gas that passes close to the black hole and transfers it to gas that passes further out. |
| This allows part of the cloud to be captured by the black hole while the rest escapes. | This allows part of the cloud to be captured by the black hole while the rest escapes. |
| In these conditions, only high mass stars are able to form and these stars inherit the eccentric orbits from the elliptical disc. | In these conditions, only high mass stars are able to form and these stars inherit the eccentric orbits from the elliptical disc. |
| These results match the two primary properties of the young stars in the centre of our galaxy: their high mass and their eccentric orbits around the supermassive black hole. | These results match the two primary properties of the young stars in the centre of our galaxy: their high mass and their eccentric orbits around the supermassive black hole. |
| "That the stars currently present around the galaxy's supermassive black hole have relatively short lifetimes of [about] 10 million years, which suggests that this process is likely to be repetitive," Professor Bonnell explained. | "That the stars currently present around the galaxy's supermassive black hole have relatively short lifetimes of [about] 10 million years, which suggests that this process is likely to be repetitive," Professor Bonnell explained. |
| "Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may help us understand the origin of supermassive black holes in our and other galaxies in the Universe." | "Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may help us understand the origin of supermassive black holes in our and other galaxies in the Universe." |