Overview
- A peer‑reviewed study published July 1 confirmed that TESS captured the microlensing signature of Gaia23bra b by recording short-lived features that, when combined with Gaia’s alert, revealed a planet.
- Gaia23bra b is about 1.6 times the mass of Jupiter and orbits an orange‑dwarf star roughly 40,000 light‑years from Earth at a distance similar to Jupiter’s orbit.
- The detection relied on gravitational microlensing, a one‑time brightening caused when a foreground star and its planet bend and magnify light from a background star, leaving brief ripples in the light curve that TESS’s dense ~200‑second sampling recorded.
- Gaia first noticed the April 2023 brightening but its sparse cadence missed the planetary signal, which sat unnoticed in TESS’s archive for nearly three years before researchers connected the datasets and began searching TESS archives for more hidden microlensing events.
- The result fills a gap in exoplanet searches by reaching wide or distant planets that transits miss and acts as a pathfinder for the Nancy Grace Roman Telescope, which NASA predicts could find roughly 1,000 microlensing exoplanets.