Overview
- Researchers report oMEGACat BH-2 as the first confirmed stellar-mass black hole inside the massive Omega Centauri globular cluster based on combined Hubble (2002–2023) and JWST (2024–2025) astrometric data.
- The team derives a best-fit mass of about 4.46 times the Sun and an approximate 94-year orbital period for the visible star–dark companion pair, which is the longest-period black hole–star binary yet measured.
- The detection used astrometry—the precise tracking of a star’s tiny position shifts over more than two decades—to infer the unseen companion’s mass from the star’s motion rather than from X-rays or radio emission.
- Important caveats remain because the observations cover less than half of the fitted orbit and the mass depends on assumptions about the visible star, so further JWST, Gaia, and Roman measurements are expected to refine the period and mass.
- The black hole’s unexpectedly low mass in a metal-poor cluster has implications for models of stellar collapse, the so-called mass gap between neutron stars and black holes, and the role of dense clusters in producing gravitational-wave sources.