Hubble Spies Colliding Galaxies Tied in Stellar Pearls

The Hubble Space Telescope has spotted an unprecedented 100,000 light-year long structure wrapped around two colliding galaxies. Continue reading →

The Hubble Space Telescope has spotted an unprecedented 100,000 light-year long structure wrapped around two colliding galaxies. The structure resembles a pearl necklace, with the ‘pearls' being individual super-clusters of young blue stars evenly spaced 3,000 light-years apart.

The stellar pearls were likely spawned by the increase in density of material as the two galaxies collided. The galaxies are located inside the dense galaxy cluster SDSS J1531+3414 approximately 4.5 billion light-years away.

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"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, in a Hubble news release. "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."

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The interesting thing about this discovery is that it was made completely by chance. Hubble was carrying out a survey of 23 galaxy superclusers to observe the gravitational lensing effect of these massive objects. As can be seen in this observation, large arcs of light surround the cluster, caused by the light of more distant galaxies behind the supercluster becoming warped and focused by extreme spacetime curvature.

Hubble's observing power can be boosted by observing these arcs, which provide an amplifying effect on distant galaxies' light that would otherwise be too weak to discern. But on analysis of SDSS J1531+3414, the researchers spotted the strange formation of stars wrapped around the colliding galaxies like a Slinky.

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Though unprecedented, astronomers have an idea as to the physical process that spurred their strange morphology. The Jeans instability, which describes the behavior of self-gravitating clumps of material, likely spurred the formation of these huge stellar beads. On Earth, the same process dominates the formation of rain. Rather than falling as a continuous stream of water, rain falls as small droplets - a small-scale phenomena driven by the Jeans instability that can also be applied to structures hundreds of thousands of light-years across.

"This is a beautiful demonstration of the profound scale-invariance of the fundamental laws of nature," said Tremblay. "We see the same physics on 100,000-light-year scales that we see in our kitchen sinks and inkjet printers."

Using data from the Hubble Space Telescope's famous Ultra-Deep Field (UDF) observation,

astronomers have been able to deduce at what age spiral galaxies acquire their spiral structure

. Since its launch in 1990, the veteran observatory has studied countless galaxies, but some of the most striking images are that of the majestic spirals that pervade the entire observable universe. In this celebration of spiral galaxies and Hubble's prowess at imaging them, we've collected some of our favorite galactic views from the space telescope's archives.

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In this majestic image, phenomenal detail in galaxy

NGC 2841

's spiraling dust lanes have been captured.

Spiral galaxy

NGC 5866

as seen nearly edge-on from Hubble's perspective. The dark galactic dust silhouettes the bright galactic core.


unnamed spiral galaxy

located deep within the Coma Cluster of galaxies, around 320 million light-years away in the northern constellation Coma Berenices, shows off some intricate detail in its arms.

The famous

Sombrero galaxy

(Messier 104) is an edge-on spiral galaxy -- the "rim" of the sombrero is thick lanes of dust obscuring the galaxy's starlight.


is another spiral galaxy not too dissimilar to our Milky Way. Young, bluish stars track along the galaxy's majestic arms, while older, redder stars cluster in its bright core.

This unique view of


is a combination of Hubble data and photographs taken by astrophotographer Robert Gendler.

The 'classic' spiral

Whirlpool Galaxy

gravitationally interacts with a neighboring galaxy, refining its very clear spiral arms.

To celebrate Hubble's 21st year in space, astronomers released this striking image of a pair of interacting galaxies called

Arp 273

. (Image rotated)

The 3 galaxies of

Arp 274

appear to be very close to one another, but astronomers believe that they are far apart and only overlapping from our perspective.


UGC 10214

is undergoing some violent gravitational disturbances after a suspected galactic collision. The creation of the stream of stars post-collision appear as a tail, giving the galaxy "The Tadpole" moniker.

To see full-resolution images and more detail on the galaxies showcased here, browse the mindblowing online Hubble album.