Overview
- The GRAVITY+ collaboration announced Wednesday that they discovered S301 and published the result in Nature after fitting its orbit with VLTI data extending back to 2017.
- S301 follows an extremely elongated 8.7‑year orbit that brings it roughly 12 astronomical units from Sagittarius A* and drives speeds near 25,000 km/s, about 8 percent of light speed.
- Astrometric positions already reveal a strong general‑relativistic Schwarzschild precession of about 2 degrees per orbit but the team lacks the star’s radial velocity, leaving two mirror-image orbital solutions.
- The star’s close passage probes the region where a spinning black hole would drag spacetime, so combined spectroscopic follow‑up and decade‑scale monitoring could let scientists constrain Sgr A*’s spin within roughly ten to twenty years.
- The discovery depended on the GRAVITY+ sensitivity upgrade at ESO’s VLTI, S301 is likely a compact ~1.5‑solar‑mass main‑sequence star that may have been captured after a binary was torn apart, and more similarly faint stars may lie hidden near the Galactic Center.