James Webb Telescope captures a star factory with failed suns

The discovery provides valuable insights into star formation processes under conditions similar to the early universe.

In Short

• NGC 602's environment is characterized by low abundances of heavy elements
• It is an ideal laboratory for studying cosmic evolution
• Webb's capabilities allowed for the detection of substellar objects

An international team of astronomers has made a new discovery using the James Webb Space Telescope, detecting the first rich population of brown dwarf candidates outside the Milky Way.

The findings, published in The Astrophysical Journal, focus on the young star cluster NGC 602 in the Small Magellanic Cloud, a satellite galaxy approximately 200,000 light-years from Earth.

Brown dwarf stars are celestial objects that fall in a unique category between the largest planets and the smallest stars. Often called “failed stars,” they are too massive to be considered planets but lack the mass needed to sustain nuclear fusion—the process that powers stars and causes them to shine.

Led by Peter Zeidler of AURA/STScI, the team identified 64 candidate brown dwarfs within NGC 602. These objects, often described as "failed stars," are more massive than gas giants but lack sufficient mass to sustain hydrogen fusion like true stars.

"Only with the incredible sensitivity and spatial resolution in the correct wavelength regime is it possible to detect these objects at such great distances," Zeidler explained. This achievement marks a significant milestone, as all previously known brown dwarfs were located within our galaxy.

The discovery provides valuable insights into star formation processes under conditions similar to the early universe. NGC 602's environment is characterized by low abundances of heavy elements and ongoing star formation, making it an ideal laboratory for studying cosmic evolution.

Elena Manjavacas, a team member, emphasised the significance of this find: "Until now, we've known of about 3000 brown dwarfs, but they all live inside our own galaxy".

The detection of extragalactic brown dwarfs opens new avenues for understanding the formation and distribution of these objects across the cosmos.

The research also highlights the synergy between the Hubble and Webb telescopes. Antonella Nota, executive director of the International Space Science Institute, noted that while Hubble revealed young low-mass stars in NGC 602, Webb's capabilities allowed for the detection of substellar objects.

These observations not only expand our understanding of brown dwarf formation but also provide clues about the early universe.

Elena Sabbi of NSF's NOIRLab added, "By studying the young metal-poor brown dwarfs newly discovered in NGC602, we are getting closer to unlocking the secrets of how stars and planets formed in the harsh conditions of the early Universe".

As astronomers continue to analyse this groundbreaking data, the discovery paves the way for further exploration of substellar objects beyond our galaxy, potentially revolutionising our understanding of cosmic evolution and star formation processes.