Imagine looking out into endless space and discovering a hidden population of brown dwarfs deep within a distant star cluster called NGC 602.

Located at the outskirts of the Small Magellanic Cloud, a companion galaxy to the Milky Way, about 200,000 light-years from Earth, the cluster of brown dwarfs is unlike anything seen in the region. Its surroundings reflect an early universe dominated by dark clouds of dense dust, with limited elements heavier than hydrogen and helium. This unique pattern, combined with abundant ionized gas, signals ongoing star formation.

Chasing young brown dwarfs

An international group of astronomers began searching for this star cluster using the James Webb Space Telescope. The aim was to detect young brown dwarf candidates outside the Milky Way, a feat never seen before.

“With incredible sensitivity and resolution in just the right wavelength range, we can detect these objects from such great distances,” said the study’s lead author Peter Seidler, an expert at the European Space Agency.

“This has never been possible before and will continue to be impossible with ground-based telescopes for the foreseeable future.”

The world of brown dwarfs

What are brown dwarfs? Think of them as the more substantial siblings of the gas giant planets. Their masses are generally about 13-75 times that of Jupiter and they are not gravitationally bound to any star. Brown dwarfs are quite similar to exoplanets and have similar atmospheric composition and storm patterns.

“We know about 3,000 brown dwarfs so far, but they all live in our galaxy,” said astronomer Elena Manyavakas of the European Space Agency.

Duo of dynamic telescopes: Hubble and Webb

This discovery highlights the synergy between the Hubble and Webb telescopes in unraveling the mysteries of young star clusters. Antonella Nota, Executive Director of the International Astronautical Institute in Switzerland and ESA’s former Webb Project Scientist, emphasized the importance of this collaboration.

“Hubble has shown that NGC602 contains very young, low-mass stars, but only thanks to Webb can we finally see the extent and significance of substellar mass formation in this cluster. Hubble and Webb are an extremely powerful telescope duo!” said Nota.

“Brown dwarfs appear to form in the same way as stars, but they fail to capture enough mass to become a full-fledged star. Our results are in good agreement with this theory,” Seidler said.

Incredible image of a star cluster

The team’s data includes a new image of NGC 602 obtained by the Webb Near Infrared Camera (NIRCam). The image shows cluster stars, young stellar objects, and surrounding ridges of gas and dust. It captured many background galaxies and stars in the Small Magellanic Cloud. This achievement is the first detection of analogues of giant exoplanets outside the Milky Way.

“We must be ready for groundbreaking discoveries in these new facilities!” – said Manyavakas.

Future research on brown dwarfs

The discovery marks the beginning of a new chapter in brown dwarf research.

“Although more detailed studies are needed to quantify the initial mass function and confirm the true nature of the brown dwarf candidates, this discovery is particularly relevant in trying to improve our understanding of the subsolar mass function at very low metallicities and young ages.” researchers wrote.

As astronomers push the boundaries of space exploration, the next steps include studying the atmosphere and composition of these mysterious objects. Brown dwarfs fill the gap between stars and planets, helping scientists better understand the formation of both.

Thanks to the capabilities of the James Webb Space Telescope, scientists can observe these objects in extraordinary detail. The power of JWST will allow researchers to confirm the existence of brown dwarfs in the Small Magellanic Cloud and discover additional substellar objects beyond the Milky Way.

This research could greatly expand our knowledge of how stars, planets, and their exoplanet counterparts form and evolve in the universe. The study was published on: Astrophysical Journal.