The most massive black holes in the Universe detected by the ripples they make in space time were not born directly from collapsing stars, according to a new study.

These cosmic giants instead build up through a series of repeated and extremely violent collision events in very densely populated star clusters, an international team of researchers argue.

Using data from both the James Webb and Hubble space telescopes, an international team of astronomers, including the University of Massachusetts Amherst’s Distinguished Professor Daniela Calzetti, have been able to, for the first time, glimpse one of the most mysterious parts of a star’s life: the moments just after birth, when the star is still wrapped in its “natal cloud.” This glimpse does more than shine a bright light on stars’ lifecycle; it also answers one of the thorniest questions from the early universe: how did the early universe manage to re-ionize itself after it cooled down from the Big Bang?

The Hubble and James Webb Space Telescopes have revealed thousands of young star clusters emerging from their birth clouds. The observations, published in Nature Astronomy, show that more massive clusters clear away their natal gas faster than lower-mass clusters. The result has important implications for our understanding of star formation and how the young stars affect their surroundings.