cold front in the Perseus galaxy cluster

Credit: NASA/CXC/GSFC/S. Walker, ESA/XMM, ROSAT

A gigantic cold front in the Perseus galaxy cluster has been observed by a trio of X-ray telescopes.

The ancient cold front can be seen at the left of the image, drifting away from the much inner, younger front closer to the centre. Galactic cold fronts are nothing like the cold fronts we experience on Earth – instead they are caused by galaxy clusters colliding into one another. The gravitational pull of a larger cluster tugs a smaller cluster closer, resulting in gas in the core of the cluster being sloshed around like liquid in a glass. This creates a cold front in a spiral pattern moving outwards from the core and these sloshing cold fronts can provide a probe of the intercluster medium.

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Source / Image Courtesy

Winter often brings many intense and powerful storms, with cold fronts sweeping across many parts of the globe. There are, however, even bigger weather systems. For example, astronomers have discovered cold fronts in space that are millions of light years in extent and older than the Solar System.

For example, researchers used NASA's Chandra X-ray Observatory to study a cold front located in the Perseus galaxy cluster that extends for about two million light years, or about 10 billion billion miles.

Galaxy clusters are the largest and most massive objects in the Universe that are held together by gravity. In between the hundreds or even thousands of galaxies in a cluster, there are vast reservoirs of super-heated gas that glow brightly in X-ray light.

The cold front in the Perseus cluster consists of a relatively dense band of gas with a "cool" temperature of about 30 million degrees moving through lower density hot gas of about 80 million degrees. The enormous cold front formed about 5 billion years ago and has been traveling at speeds of about 300,000 miles per hour ever since.

Not only has it survived for so long, the cold front has also remained surprisingly sharp and split into two different pieces.

This suggests that magnetic fields are wrapped around the cold front, which formed before the birth of our Solar System, preserving it.