The most massive galaxies in the young Universe contain far more small stars than previously assumed. This “hidden” stellar population makes some early galaxies three to four times more massive than earlier estimates – according to a new study using the James Webb Space Telescope (JWST).
The finding
An international team led by Leiden University studied nine massive galaxies that had already passed their main phase of star formation. By combining extremely deep JWST spectra with earlier observations from the Very Large Telescope, they were able to determine for the first time how many small, faint stars these distant galaxies actually contain.
Why it matters
The result makes it even harder to explain how such massive, “mature” galaxies could form so soon after the Big Bang. It also suggests that planets around low-mass stars may have been more common in the early Universe than previously thought. The study was published on 18 August 2026 in the journal Nature Astronomy.
Sources: Leiden University, phys.org.
