LOOK: Stellar ‘Tsunami’ Forms a Pair of Space Eyelids

A "tsunami" of stars and gas collided with a spiral galaxy's disk to form a dazzling pair of stellar eyelids.

According to astronomers, the stellar arcs were formed when the spiral galaxy called IC 2163 was sideswiped by another spiral galaxy named NGC 2207. The galaxies first brushed past each other and scraped the edges of their outer spiral arms, forming an eyelid-like structure that could be the first phase of an eventual merger.

The interacting pair of galaxies is located approximately 114 million light-years from Earth in the direction of the constellation Canis Major and was discovered by scientists through the Atacama Large Millimeter/submillimeter Array (ALMA), which is a large radio observatory in Chile.

"Although galaxy collisions of this type are not uncommon, only a few galaxies with eye-like, or ocular, structures are known to exist," Michele Kaufman, an astronomer formerly with the Ohio State University and lead author of the study, said in a statement.

"Galactic eyelids last only a few tens of millions of years, which is incredibly brief in the lifespan of a galaxy. Finding one in such a newly formed state gives us an exceptional opportunity to study what happens when one galaxy grazes another," Kaufman added.

The researchers used ALMA's fine resolution to observe the motion of carbon monoxide gas, which is a fuel for star formation, in the galaxy's narrow eyelid features. The researchers also found that the gas in the outer portion of IC 2163's eyelids is moving inward at about 100 kilometers per second.

However, the motion was chaotic. The gas quickly decelerates as it moves to the inside, eventually changing direction and aligning itself with the rotation of the galaxy rather than heading at the center.

Scientists have also observed that the faster the gas decelerates, the denser it becomes. The encounter between the two galaxies drives gas to gather together to create a potential hotspot for star formation, the researchers said.

Astronomers believe that collisions of this nature were common in the early universe when galaxies were close to each other. However, galactic disks were generally clumpy and irregular, which likely overwhelmed the formation of similar eyelid-like features.

The paper was based on a research published in the Astrophysical Journal.