Overview
- The team published its analysis on July 1 in The Astrophysical Journal Letters, confirming Gaia23bra b is about 1.63 times the mass of Jupiter orbiting an orange dwarf roughly 0.8 times the Sun’s mass at a Jupiter-like distance about 40,000 light-years away.
- ESA’s Gaia first flagged a brightening in 2023 and researchers then found the same event in archived TESS observations, where TESS’s denser ~200-second cadence revealed short-lived features that indicate a planetary companion.
- Gravitational microlensing works when a foreground star and its planet bend the light of a more distant background star, producing a brief magnification whose shape can give the planet’s mass ratio and orbital separation.
- TESS was built to spot transits but its repeated, high-cadence monitoring captured this microlensing signal, leading researchers to say more microlensing planets likely lurk in nearly eight years of TESS data.
- The detection provides a pathfinder case for the Nancy Grace Roman Space Telescope’s microlensing survey planned for late 2026 and could help fill gaps in our census of wide-orbit giants and Earth-distance planets that transits miss.