Astronomers say they've demonstrated how stars can form on the treacherous edge of a supermassive black hole. When a cloud of gas swirls towards a black hole, they say, a combination of complex forces push some parts of the cloud into a disk that orbits the black hole at a safe distance, allowing stars to be born in the gas. The researchers
developed a simulation that demonstrates how clouds of gas can be captured by massive black holes to form eccentric disks, which then fragment to become a necklace of massive stars.... Their findings are in accordance with actual observations in our Milky Way galaxy that indicate the presence of a massive black hole, surrounded by an elliptical necklace of massive stars [Telegraph].
The edge of a supermassive black hole doesn't sound like a promising environment for a star nursery; black holes, which are usually the remains of collapsed stars, are so dense that their gravity drags in anything that crosses the "event horizon." Says astronomer Ian Bonnell:
"The high tidal shear from the black hole should tear apart the molecular clouds that form stars" [National Geographic].
In the simulation, much of the gas cloud is torn apart, but shock waves and other turbulence sucks some of the gas into a spiral,
causing it to take up orbit around the black hole and giving time for stars to form [Scientific American].
While researchers say that the simulation produced a plausible scenario, there's only indirect evidence that this star formation process is indeed playing out around black holes throughout the universe. The simulation, published in the journal Science [subscription required],
showed that the stars that formed were very massive. This result reflects what astronomers see close to the galactic centre, where there seem to be very few lightweight stars [New Scientist].
DISCOVER recently published breathtaking images of the turbulent gases involved in star formation with its photo gallery, "Turbulence: How to Visualize the Invisible."