Astronomy: Probably the first brown dwarfs outside the Milky Way discovered

For 30 years, celestial bodies have been discovered that have not made it to the stars – but so far only in the Milky Way. That seems to have changed now.

The star cluster NGC 602

(Image: ESA/Webb, NASA & CSA, P. Zeidler, E. Sabbi, A. Nota, M. Zamani (ESA/Webb))

Oct 25, 2024 at 9:58 am CEST

2 min. read

By

Martin Holland

With the discovery of brown dwarfs in the Small Magellanic Cloud, an international research team may have succeeded in finding the first evidence of substellar celestial bodies outside our solar system. This has now been announced by the European Space Agency ESA. The "failed stars" were found thanks to the interaction of the Hubble and James Webb space telescopes. The celestial bodies, which have not yet been confirmed as such, are located in a star cluster in which stars are formed under completely different conditions than in our cosmic neighborhood.

A powerful duo

Brown dwarfs are celestial bodies that are not massive enough to ignite nuclear fusion as in stars, but at the same time are significantly more massive than (exo-)planets. They have some characteristics in common with both; in a sense, they form an in-between. Since the first discovery of a brown dwarf almost 30 years ago, around 3000 have been discovered, all of them in the Milky Way. The fact that the first candidates for brown dwarfs have now been found outside the Milky Way underlines the power of the two space telescopes. They form an "amazingly powerful duo", explains Antonella Nota from the research team.

The discovery of the brown dwarfs now fits very well with the theory that the mass distribution of objects that do not ignite nuclear fusion is simply a downward continuation of that of the stars, adds Peter Zeidler from ESA. Because there are comparatively few elements heavier than hydrogen and helium in the region where the objects are located, the conditions there are similar to those in the early universe. Thanks to this research, we are now getting closer to understanding the formation of stars in this period. The research paper on the discovery of brown dwarfs has been published in The Astrophysical Journal.