Astronomers observed the remains of a globular cluster destroyed by the Milky Way 2 billion years ago.
A globular cluster is a spherical collection of millions of stars bound together by gravity and orbiting the galaxy’s core. Our Milky Way contains about 150 such clusters. They are all ancient structures that have seen the development of galaxies over billions of years.
Using the Anglo-Australia ground telescope at the Siding Spring Observatory in the state of New South Wales, astronomers at the University of Sydney recently discovered a remnant of a new globular cluster in the constellation Phoenix, was destroyed by the Milky Way’s gravity about 2 billion years ago.
Simulation of the rest of the newly discovered globular cluster. Photo: University of Sydney.
“Cluster remnants make up today’s Phoenix Stream. It holds memories of cluster formation in the early universe, based on the chemistry of stars”, study’s lead author Alexander Ji emphasized.
Ji and his colleagues focused on measuring the abundance of elements heavier than hydrogen and helium – the so-called metallic properties of a star – to find information about the gas clouds where it is born. . The older the stars, the lower the abundance of heavy elements.
“We were really surprised that the Phoenix Stream has a very low metallic properties, which sets it apart from all the known globular clusters in the Milky Way,” said graduate student Dr Zhen Wan, co-author of project for more.
Astronomers believe that the Phoenix Stream is the last remnant of ancient globular clusters formed from the dawn of the universe. Its stars were weakened before the spherical structure was torn apart by the galaxy’s gravity.
Details of the study were published on July 29 in the journal Nature.