The image above shows a visible picture of the inner 20 degrees of the Milky Way as seen from Earth (for comparison, the Moon is roughly 1/2 a degree on the sky). This part of the sky is extremely crowded due to the high density of the central regions of the Galaxy as well as the presence of many stars between Earth and the galactic centre. Dark patches are due to absorption of visible light by dense dust clouds. Alex Mellinger/Liverpool John Moores University

Astronomers announced Tuesday they had discovered a family of nitrogen-rich stars near the center of the Milky Way. The stars, found as part of a project known as Apache Point Observatory Galactic Evolution Experiment (APOGEE), may well be the oldest stars in the galaxy, and could provide invaluable information about its evolution.

"This is a very exciting finding that helps us address fascinating questions such as what is the nature of the stars in the inner regions of the Milky Way, how globular clusters formed and what role they played in the formation of the early Milky Way — and by extension the formation of other galaxies," lead researcher Ricardo Schiavon from the U.K.'s Liverpool John Moores University, said in a statement.

Globular clusters are densely packed clumps of thousands, and occasionally millions, of stars that orbit the center of a galaxy. The Milky Way is currently known to have at least 150 such clusters — most of which are roughly 10 billion years old, making them the most ancient stars in the galaxy.

However, astronomers believe that when the galaxy was young, there may have been up to 10 times more globular clusters orbiting its center. The chemical composition of the newly-discovered stars — older stars have higher concentration of heavier elements such as nitrogen — suggests this family may once have been part of these no-longer-extant clusters.

"While not certain, we suspect that these stars resulted from globular cluster destruction," Schiavon said. "They could also be the byproducts of the first episodes of star formation taking place at the beginning of the Galaxy's history. We are conducting further observations to test these hypotheses."