Astronomers have discovered a 13-billion-year-old galaxy cluster that is the earliest ever observed, according to a paper released Friday, a finding that may hold clues about how the universe developed.
Such an early-stage cluster -- called a protocluster -- is "not easy to find", Yuichi Harikane, a researcher at the National Astronomical Observatory of Japan who led the international team, said in a press release.
"A protocluster is a rare and special system with an extremely high density," Harikane said, adding that the researchers used the wide viewing field of the Subaru telescope in Hawaii to "map a large area of the sky" in their search.
The discovery of the protocluster, a collection of 12 galaxies, suggests that large cosmic structures were present in the very early stages of the universe, which scientists believe was born 13.8 billion years ago.
One of the 12 galaxies is known as Himiko, a giant gas cloud found in 2009 by using the same telescope.
"It is reasonable to find a protocluster near a massive object, such as Himiko. However, we're surprised to see that Himiko was located... on the edge 500 million light-years away from the center," the paper's co-author Masami Ouchi said.
Home to our own solar system, the Milky Way galaxy has captivated the imagination since the dawn of cosmology. Named after the dim ‘milky’ glow generated by the indistinguishable mass of stars that it’s made from, when the Milky Way is observed from Earth, it appears like a band, due to its disc shape, but is actually a barred spiral galaxy.
Facts and figures around the Milky Way’s size and constituents vary, with the galaxy’s diameter believed to be between 120,000 and 150,000 light-years. Within the Milky Way there could be as many as a trillion stars and 100 billion planets. With such incredible numbers, it’s easy to understand why until 1920 it was believed that the Milky Way contained all the stars in the universe, but we now know it to be just one of around 200 billion galaxies that we can observe.
"It is still not understood why Himiko is not located in the centre," he said.
"These results will be key for understanding the relationship between clusters and massive galaxies.
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