06/17/2026
The James Webb and Hubble Space Telescopes teamed up to study Terzan 5, a stellar system 22,000 light-years away in the constellation Sagittarius, and what they found rewrote the classification books. 🔭
New research uncovered strong evidence for four distinct stellar populations, with formation ages spanning from 12.5 billion to just 2.5 billion years ago. That extraordinary age range means Terzan 5 is not a globular star cluster as originally thought, but something far rarer: a bulge fossil fragment, a self-enriching stellar system embedded in the densely packed core of the Milky Way. Packed with roughly 2 million times the Sun's mass into just a few tens of light-years, it's one of the most massive, densely populated systems in our galaxy.
Image source: NASA, ESA, CSA, STScI, G. Zullo (University of Bologna), F. R. Ferraro (University of Bologna). Image Processing: A. Pagan (STScI)