Terzan 5: The ancient stellar system hidden in the heart of the Milky Way

Key Points:

• NASA has released a new visualisation tracing a path from the Milky Way's broad central bulge to the compact stellar system Terzan 5, revealing its unique characteristics within the crowded galactic center.
• Terzan 5, located about 22,000 light-years away in Sagittarius, is an unusually dense system with around two million times the Sun's mass, distinguished by its ability to retain multiple generations of stars formed over billions of years.
• Observations from the James Webb and Hubble space telescopes show Terzan 5 hosts four distinct stellar populations, prompting its reclassification from a typical globular cluster to a rare "bulge fossil fragment" that preserves evidence of the Milky Way's early formation.
• Terzan 5's large mass likely enabled it to hold onto gas and heavier elements from stellar explosions, allowing ongoing star formation and survival through the galaxy's assembly, unlike many smaller systems that merged or dispersed.
• The zoom visualisation underscores the scientific importance of Terzan 5, offering a rare window into the Milky Way's formative era and demonstrating how advanced telescopes can reveal detailed histories hidden within dense, dust-obscured regions.