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A giant string of pearls is the last thing you'd expect to spot in space.

Astronomers say this 'extraordinary' structure is actually lining two massive galaxies on a collision course.

The unprecedented 100,000-light-year-long structure looks like a string of pearls twisted into a corkscrew shape that winds around the cores of two colliding galaxies.

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The unprecedented 100,000-light-year-long structure looks like a string of pearls twisted into a corkscrew shape that winds around the cores of two colliding galaxies, and bridges them as they collide

Astronomers don't quite know how to explain the origin and ultimate fate of the object, but the answer must be extraordinary, they say.

'We were surprised to find this stunning morphology, which must be very short-lived' (perhaps about 10 million years, which is a fraction of the time it takes for galaxies to merge), said Grant Tremblay of the European Southern Observatory in Garching, Germany.

'We've long known that the 'beads on a string' phenomenon is seen in the arms of spiral galaxies and in tidal bridges between interacting galaxies.

'However, this particular supercluster arrangement has never been seen before in giant merging elliptical galaxies,' he said.

'We have two monsters playing tug-of-war with a necklace, and its ultimate fate is an interesting question in the context of the formation of stellar superclusters and the merger-driven growth of a galaxy's stellar component.'

The Slinky-structure's unique morphology may yield new insights into the formation of stellar superclusters, the merger-driven growth of galaxies, and gas dynamics in the rarely seen merger process of two giant elliptical galaxies.

Like a string of pearls, these young, blue 'super star clusters' are evenly spaced along the chain at separations of 3,000 light-years from one another.

The pair of elliptical galaxies is embedded deep inside the dense galaxy cluster SDSS J1531+3414.

The cluster's powerful gravity warps the image of background galaxies into blue streaks and arcs that give the illusion of being inside the cluster.

NASA's Hubble Space Telescope has photographed the dense galaxy cluster SDSS J1531+3414 in the northern constellation Corona Borealis

The astronomers' first hypothesis was that the 'string of pearls" was actually a lensed image from one of these background galaxies, but their recent follow-up observations with the Nordic Optical Telescope definitively rules this out.

'We were stunned by what we saw in SDSS J1531+3414,' Tremblay said.

'The uniqueness of this source spurred follow-up observations with both ground- and space-based telescopes.

'This is a beautiful demonstration of the profound scale-invariance of the fundamental laws of nature,' Tremblay added.

The underlying physical processes that give rise to the "beads on a string" morphology are related to the Jeans instability, describing the behavior of self-gravitating clumps of gas.

It's analogous to the process that causes a falling column of water to disrupt, explaining why rain falls in drops rather than in continuous filaments from clouds.

Water coming out of the kitchen tap eventually breaks into a series of droplets, and a very similar process is happening in SDSS J1531+3414.

'We see the same physics on 100,000-light-year scales that we see in our kitchen sinks and inkjet printers,' said Tremblay.