Ruins of Ancient Star Cluster Discovered at Our Galaxy

Gemini Observatory helps reveal that a stream of old stars at the Milky Way’s edge is a shredded star Cluster.A primordial stellar stream discovered in the outer reaches of the Milky Way has a lower proportion of heavy elements than any known stellar system in our galaxy.

Observations with the Gemini Observatory showed that the stars in this stream were torn from an ancient star Cluster and are relics from the early days of the Milky Way, which could provide insights into the formation of the first stars. An international team of researchers including members from Europe, Canada, and Russia has discovered a unique stream of stars orbiting the Milky Way.

It is called C-19, the stellar stream is south of the spiral of the Milky Way, and its orbit extends about 20,000 light-years from the Galactic Center at its closest approach and roughly 90,000 light-years at its farthest. The stellar stream stretches across an expanse of the night sky roughly 30 times the width of the full Moon although it isn’t visible to the naked eye.

Gemini North telescope located in Hawai‘i as part of the international Gemini Observatory, a Program of NSF’s NOIRLab and the GRACES instrument the team realized that C-19 is a remnant of a globular Cluster.  The stars in the stream possess a uniquely low proportion of heavy elements, or as astronomers phrase it, low “metallicity.” Globular Cluster were thought to have metallicities no lower than 0.2%, but C-19 has an unprecedentedly low metallicity of less than 0.05% lower than has ever been observed for a stellar system in the Milky Way or its surroundings.