In the heart of the Perseus galaxy cluster lies a remarkable galaxy known as NGC 1275, which has long "filaments"of glowing gas that snake out from its center.
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 [The Independent].
Now, thanks to images from the Hubble Space Telescope, astronomers say they understand how the filaments have held their shape for over 100 million years: Magnetic fields are keeping the filaments together, they say.
The magnetic fields ... hold onto the filaments because they wield influence over charged particles – such as protons and electrons – in the filaments' gas [New Scientist].
NGC 1275 is a galaxy built around a massive black hole, which helps explain its unusual structure: The filaments may represent the most visible effect of the galaxy's central black hole on its gaseous surroundings. The black hole's high-energy jets have heated up the gas to about 70 million degrees Fahrenheit (40 million Kelvin), which in turn produces glowing bubbles that float outward from the galaxy center. The bubbles pull colder gas outward behind them in the form of the trailing filaments
The study, reported in the journal Nature [subscription required], shows that the filaments are up to 20,000 light-years long, yet only 200 light-years wide. Lead researcher Andy Fabian calculates that the magnetic fields holding them together are only 0.01% as strong as the field on the Earth's surface, yet says that's enough to insure the "survival and integrity" of the filaments:
"Without them, these beautiful structures would be unable to withstand their surroundings and would collapse into stars" [Telegraph].
Image: Fabian et al./NASA