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CHICAGO — Giant magnetic tentacles are the force that keeps a lacy pattern of glowing gas filaments in the giant elliptical galaxy NGC 1275 from evaporating in the surrounding hot gas or collapsing under the weight of their own gravity, British astronomers say.
The discovery, courtesy of images captured by NASA'S Hubble Space Telescope, helps explain how this delicate pattern has held up for more than 100 million years, and may prove useful in understanding similar structures in even more distant galaxies, they said Wednesday.
NGC 1275 is one of the closest giant elliptical galaxies and lies at the centre of the Perseus Cluster of galaxies about 250 million light years from Earth. A light year is the distance light travels in one year – 9.5 trillion kilometres.
At its core is a massive black hole that spews out radio-wave emitting material into the surrounding cluster of gas. As the black hole belches out jets of supercharged particles, it drags along cold gas from the galaxy's core and these trails form the tendrils – just 200 light-years wide – that make up the galaxy's decorative pattern.
This composite image provided by NASA shows the active galaxy NGC 1275 (Perseus A). X-ray data from the Chandra's Advanced CCD imaging spectrometer and radio data from NRAO's Very Large Array were combined with optical wavelengths in the red, green and blue from Hubble's Advanced Camera for Surveys. In the composite image, the X-ray data contribute to the soft violet shells around the outside of the centre. The pinkish lobes toward the middle of the galaxy are from radio frequencies. The radio emission, tracing jets from the black hole, fills the X-ray cavities. Dust lanes, star-forming regions, hydrogen filaments, foreground stars, and background galaxies are contributions from the Hubble optical data. (NASA/The Associated Press)
A team of astronomers led by Andy Fabian from the University of Cambridge think they know how these delicate filaments stay intact.
Using colour images from Hubble, Dr. Fabian and colleagues detected underlying magnetic fields that hold the whole thing together.
"We can see that the magnetic fields are crucial for these complex filaments – both for their survival and for their integrity," Dr. Fabian, who reported his findings in the journal Nature, said in a statement.
The new images also showed that the thinner, more fragile filaments were held in place by stronger magnetic fields.
Images of NGC 1275 can be found at: http://hubblesite.org/news/2008/28.
