And finally, 100 million-year-old galactic mystery solved by Hubble

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The Independent Online

Images taken by the Hubble Space Telescope of the Perseus cluster of stars have helped scientists to solve a 100 million-year-old mystery of how giant structures in deep space are prevented from disintegrating. The spectacular pictures show vast, thread-like "filaments" of gas which emerge from the centre of a galaxy known as NGC 1275, situated some 235 million light years away from Earth.

Astronomers have tried to explain how these beautiful structures can have survived for so long, given that the filaments reach out from their home galaxy into the Perseus cluster, which is a hostile, high-energy environment with a strong, tidal pull of gravity.

These combined forces should have ripped apart the filaments in a very short time, causing them to collapse into stars. Instead, they have withstood this immense destructive force for more than 100 million years, scientists said. Now, for the first time, images from Hubble have allowed researchers to observe the filamentary structure in detail. Using such data, they were able to demonstrate that the strong magnetic fields in the region give the filaments a skeletal structure which is enough to enable them to resist gravitational collapse.

Professor Andrew Fabian of the University of Cambridge, who led the study published in the journal Nature, said that the unprecedented detail revealed by the Hubble telescope was the key factor.

"We can see that the magnetic fields are crucial for these complex filaments, both for their survival and integrity. Without them, these beautiful structures would be unable to withstand their surroundings and would collapse into stars," Professor Fabian said yesterday.

The filaments are a by-product of a supermassive black hole at the core of NGC 1275 interacting with gases in the Perseus cluster. This immense black hole blows out bubbles of radio-wave emitting material into the Perseus cluster. In the wake of these bubbles, cold gas from the heart of the galaxy is also dragged out into long streams to form the filaments.

Using the Hubble Space Telescope advanced camera for surveys, the scientists were able to differentiate individual threads of gas and determine their physical properties. By using the Hubble data to determine the filamentary structure, the researchers were able to estimate the strength of the magnetic fields around them and demonstrate how it is this which has maintained their structure against collapse. The study will enable the team to interpret observations of similar networks of filaments in other, even more remote central cluster galaxies.

The threads are also the only visible manifestation of the intricate relationship between the central black hole and the surrounding gas of the Perseus Cluster, making the data an important asset in the study of black holes as well.