The early universe’s giant galaxies are hiding their true weight in small stars

Using the James Webb Space Telescope, an international team led by Leiden University has, for the first time, reliably measured the mix of tiny and giant stars in nine massive early galaxies — finding their stellar populations are bottom-heavy, packed with far more low-mass stars than galaxies like the Milky Way. As a result, these cosmic titans may be much more massive than thought; one, formed less than 1.5 billion years after the Big Bang, may be up to four times heavier than previous estimates. Published in Nature Astronomy.