GARCHING — Astronomers announced on Wednesday, August 19, 2026, the discovery of a record-breaking star traveling at velocities reaching 25,000 kilometers per second, equivalent to roughly 8 percent the speed of light, near the center of the Milky Way.
The star, designated S301, represents the closest known stellar body orbiting Sagittarius A*, the supermassive black hole situated at the center of our galaxy. Identified by the international GRAVITY+ collaboration, researchers utilized the European Southern Observatory's Very Large Telescope Interferometer in Garching, Germany, to detect and map the object. S301 is approximately 50 percent larger than the sun and follows an extremely elongated 8.7-year orbit that brings it within 1.7 billion kilometers of the black hole, a distance roughly comparable to the span between Saturn and the sun.
Unlocking Black Hole Spin Mechanics
The discovery provides researchers with a vital instrument to measure the spin of Sagittarius A*, an elusive characteristic that has long remained difficult to calculate. While previous stellar observations successfully established the black hole's mass at approximately 4 million times that of the sun, determining its rotational spin requires tracking an object operating within extreme gravitational gradients.
Stefan Gillessen, an astronomer at the Max Planck Institute for Extraterrestrial Physics, noted that as the massive black hole rotates, it should subtly alter the trajectory of S301 over successive orbital cycles. By combining historical astrometric data collected since 2017 with recent observations, the research team aims to model these relativistic shifts.
Observational Techniques and Future Data Collection
Detecting S301 required advanced interferometric capabilities capable of isolating objects faint in comparison to surrounding galactic dust and dense stellar clusters. The GRAVITY+ instrument merges light from multiple telescope mirrors to achieve high-resolution imaging performance.
Astrophysicists plan to continue monitoring the star's velocity profile and positional coordinates as it navigates its closest approach window. Additional data collection cycles are scheduled to run through the end of the observation period ending on November 15, 2026.
Why is the newly discovered star S301 important for astronomy?
The newly discovered star S301 is important because its exceptionally close orbit around Sagittarius A* allows scientists to measure the supermassive black hole's elusive spin and understand its growth history.
The discovery was formally reported by astronomers on August 19, 2026, using the Very Large Telescope Interferometer.
Ongoing tracking of the star's orbital progression is scheduled to continue through November 15, 2026.