First failed star candidates outside the Milky Way

Oct. 23 () –

Observations with the NASA/ESA/CSA James Webb Space Telescope have detected the first candidates for brown dwarfs, also known as ‘failed’ starsoutside the Milky Way.

Halfway between gas giants and stars, brown dwarfs are substellar objects that are not massive enough to maintain continuous hydrogen-1 nuclear fusion reactions in their core, unlike main sequence stars.

Specifically, its location is in the star cluster NGC 602, in the Small Magellanic Cloud, a satellite galaxy of our Milky Way, about 200,000 light years from Earth.

The local environment of this cluster is similar to that of the early Universe, with a low abundance of elements heavier than hydrogen and helium. The existence of dark clouds of dense dust and the fact that the cluster is rich in ionized gas also suggest that a star is forming. Together with its associated diffuse region N90, which contains clouds of ionized atomic hydrogen, this cluster provides a valuable opportunity to examine how stars They can form under conditions radically different from those found in the solar neighborhood.

An international team of astronomers, including Peter Zeidler, Elena Sabbi, Elena Manjavacas and Antonella Nota, used the Webb telescope to observe NGC 602 and discover candidates for the first young brown dwarfs outside our Milky Way.

“Only thanks to the incredible sensitivity and resolution in the right wavelength range can we detect these objects at such great distances,” he explained. in a statement from ESA lead author Peter Zeidler from AURA/STScI. “This has never been possible before and will also remain impossible with ground-based telescopes for the foreseeable future.”

THE MASSIVE COUSINS OF THE GAS GIANTS

Brown dwarfs are the more massive cousins ​​of the gas giant planets (they are typically between 13 and 75 Jupiter masses, and sometimes less). They are floating, meaning they are not gravitationally bound to a star like exoplanets are. However, some of them share characteristics with exoplanets, such as their atmospheric composition and storm patterns.

“Until now, we knew about 3,000 brown dwarfs, but they all live within our own galaxy“added Elena Manjavacas, member of the AURA/STScI team for ESA.

“Brown dwarfs appear to form in the same way as stars, they just don’t capture enough mass to become a fully grown star. “Our results fit well with this theory,” commented Ziedler.