NASA and the European Space Agency’s (ESA) Hubble Space Telescope recently shared a stunning photo of a globular cluster filled with old stars that date back to the Big Bang. According to the agencies, the stars within the cluster have unique characteristics that set them apart from other cosmic objects in the universe.

The globular cluster spotted by Hubble has been identified as NGC 1866, which is located within a small neighboring galaxy of Milky Way known as the Large Magellanic Cloud. It was first discovered by Scottish astronomer James Dunlop in 1826.

According to the ESA, NGC 1866 is so close to Earth that astronomers can study its stars individually. Through previous and current observations, it was concluded that the stars residing within the cluster are very old.

Astronomers were able to determine the age of the stars in NGC 1866 due to their composition. As explained by the ESA, the stars within the cluster have low metallicity, which means they do not contain as many metal elements as young stars do.

Because of this, astronomers believe that NGC 1866’s stars could be some of the first cosmic objects that were formed following the Big Bang.

“There is still debate over how globular clusters form, but observations such as this have revealed that most of their stars are old and have a low metallicity,” the ESA said in a statement.

“In astronomy, “metals” are any elements other than hydrogen and helium; since stars form heavier elements within their core as they carry out nuclear fusion throughout their lifetimes, a low metallicity indicates that a star is very old, as the material from which it formed was not enriched with many heavy elements,” the agency added.

Although the stars within the cluster are very old, the ESA noted that NGC 1866 still features multi-generational star formations. According to the ESA, the few young stars of the globular cluster may have formed after NGC 1866 encountered a giant cosmic cloud filled with gas.

The interaction between the cluster and the gas cloud triggered a series of cosmic reactions within NGC 1866 that led to the formation of young stars among the old ones.

NGC 1866
Star clusters are common structures throughout the universe, each made up of hundreds of thousands of stars all bound together by gravity. This star-filled image, taken with the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3), shows one of them: NGC 1866. ESA/Hubble & NASA