Where does a star end and a brown dwarf begin?
Thanks to the extraordinary capabilities of the James Webb Space Telescope, astronomers are now seeing the answer with unprecedented clarity.
In a new study of 47 Tucanae, researchers discovered a striking discontinuity in the cluster’s stellar sequence precisely where hydrogen-burning stars transition into brown dwarfs. Brown dwarfs are often described as failed stars because they never become massive enough to sustain stable hydrogen fusion in their cores.
Using JWST’s powerful infrared imaging together with precision astrometry, the team traced the cluster’s faintest members and uncovered a distinct break in the observed population. This feature provides an important observational benchmark for models describing the lowest-mass objects capable of forming in stellar systems.
By identifying the boundary between stars and brown dwarfs in one of the Galaxy’s best-studied clusters, the study offers new insight into star formation, stellar structure, and the limits of what constitutes a star.
Paper Information
DOI: https://doi.org/10.1051/0004-6361/202452907
ADS: Abstract and citation record