Using the Hubble telescope (along with the natural "zoom lens" of gravitational lensing) researchers over at NASA spotted this odd star structure, which they're describing as similar to both a spiral bridge and a corkscrew-shaped string of pearls. Close-ups after the jump.
The structure measures in at 100,000 light-years long and is made up of a series of interspersed young star clusters, evenly spaced at every 3,000 light-years. While this star-chain phenomenon is often seen in the arms of spiral galaxies, this is the first time it's ever been observed in two merging galaxies.
So just what's going on? The appearance is due to a phenomenon called Jeans instability, which NASA explains could have unfolded several different ways:
The underlying physical processes that give rise to the "string of pearls" structure are related to the Jeans instability, a physics phenomenon that occurs when the internal pressure of an interstellar gas cloud is not strong enough to prevent gravitational collapse of a region filled with matter, resulting in star formation. This process is analogous to that which causes a column of water falling from a rain cloud to disrupt, and rain to fall in drops rather than in continuous streams. Scientists currently are working on a better understanding of the star chain's origin. One possibility is that the cold molecular gas fueling the burst of star formation may have been native to the two merging galaxies. Another possibility is a so-called "cooling flow" scenario, where gas cools from the ultra-hot atmosphere of plasma that surrounds the galaxies, forming pools of cold molecular gas that starts to form stars. The third possibility is that the cold gas fueling the chain of star formation originates from a high-temperature shock wave created when the two giant elliptical galaxies crash together. This collision compresses the gas and creates a sheet of dense cooling plasma.