​Astronomers using the James Webb Space Telescope have identified the first population of young brown dwarf candidates outside the Milky Way, located in the star cluster NGC 602. This cluster is situated near the outskirts of the Small Magellanic Cloud, a satellite galaxy about 200,000 light-years from Earth.

NGC 602's environment mirrors conditions of the early Universe, with low abundances of elements heavier than hydrogen and helium. The cluster's dark dust clouds and ionised gas indicate ongoing star formation. This makes NGC 602 an ideal site to study star formation under conditions different from those in our own galaxy.

The international team used JWST's advanced capabilities to detect these brown dwarf candidates. Brown dwarfs are massive objects, ranging from 13 to 75 times the mass of gas giants like Jupiter, and are not gravitationally bound to stars like exoplanets.

Previously, about 3,000 brown dwarfs were known, all within our galaxy. This discovery, made possible by JWST's sensitivity and spatial resolution, marks a significant milestone in understanding substellar mass formation in young stellar clusters.

Dr Olivia Jones, STFC Webb Fellow at UK ATC and co-author on the new paper in The Astrophysical Journal, said: “Hubble had observed NGC 602 but JWST allows us to see even more detail, peering through the cosmic dust to reveal these brown dwarf candidates. This discovery brings us closer to understanding star and planet formation in the early Universe."

Find out more.

Read the Astrophysical Journal paper.