Most galaxies in the universe follow a regular design but there are some rebels that are assertive about rocking a different look. Researchers have just exposed something very exciting about one of them. PGC 1000714 is an incredibly rare galaxy that is surrounded by two rings and has an elliptical core. This galaxy belongs to the exceptionally rare class known as Hoag-type galaxies and is located 359 million light years away from Earth.
The red core of PGC 1000714 is 5.5 billion years old, made by older stars, while the outer ring is only about 130 million years old and is full of young stars. By forming the age difference between the core and the ring, the astronomers discovered something surprising: a diffuse red second inner ring closely surrounding the center of the galaxy. A comprehensive study of the object has been published by the Monthly Notices of the Royal Astronomical Society.
"The different colors of the outer and inner ring suggest that this galaxy has experienced two different formation periods," from the University of Minnesota Duluth, lead author Burcin Mutlu-Pakdil said in a statement. "From these initial single snapshots in time, it's impossible to know how the rings of this particular galaxy were formed." The scientists doubtful the outer ring formed from the gas of a smaller nearby galaxy that was slowly shredded apart. The source of the inner disk instead remains a bit more secretive, and the astrophysicists have stated that higher resolution observations are essential to realize what exactly they are seeing here.
"Whenever we find a strange or unique object to study, it challenges our current assumptions and theories about how the Universe works. It usually tells us that we still have a lot to learn," added co-author Patrick Treuthardt, from the North Carolina Museum of Natural Science. Hoag-type galaxies are less than 0.1 % of all the observed galaxies and the individuality of having a double ring makes this a truly rare discovery.
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