Fastest Star S301 | How It Maps Black Hole Gravity

A Record-Breaking Orbit Near Sagittarius A*

Astronomers have identified a star named S301 that orbits the Milky Way’s central supermassive black hole at unprecedented speeds. Discovered by a team at the Max Planck Institute for Extraterrestrial Physics, this celestial body hits a top speed of 15,500 miles per second. That translates to roughly 55.8 million miles per hour as it rounds Sagittarius A*. It stands as the fastest stellar object ever recorded by human observers.

Most celestial motion is slow by comparison. Our solar system travels through the galaxy at about 140 miles per second. Even the Parker Solar Probe, the fastest object humans have ever built, reaches top speeds of 430,000 miles per hour during its closest passes by the Sun. S301 dwarfs these figures. It gains this momentum by slingshotting around the extreme gravitational pull at the galaxy's center before slowing down to complete its wider orbital path.

Scientific Value of Close Proximity

S301 is not just a statistical curiosity. Its primary significance lies in its proximity to the black hole. It sits 10 times closer to Sagittarius A* than S2, the previously recorded closest star. Because light cannot escape a black hole, scientists rely on tracking the movement of nearby objects to infer the properties of the black hole itself. S301 acts as a probe for the most intense gravity in our galaxy.

Researchers plan to monitor this star over the next ten years to gather data on spacetime distortion. One primary goal is the observation of the Lense-Thirring effect, also known as frame-dragging. Albert Einstein predicted that massive rotating objects pull the fabric of spacetime along with them. S301 is the first known object near Sagittarius A* that orbits within a region where this distortion is significant enough to measure with existing technology.

Future Research and Observational Challenges

Studying S301 presents a major technical hurdle. The star is exceptionally faint, appearing roughly two billion times dimmer than Betelgeuse. To detect and track it, the Max Planck team used the Gravity instrument at the Very Large Telescope and the Micado instrument at the Extremely Large Telescope. Both facilities are located in Chile under the management of the European Southern Observatory.

Felix Mang, a Ph.D. student and lead author of the study, noted the unique nature of these findings. According to Mang, they are not merely observing spacetime curvature. Instead, they are witnessing how the black hole’s rotation warps the fabric of the galaxy. This provides a direct test for general relativity that was previously impossible. As researchers continue to track S301, they expect to reveal how rotating black holes influence their immediate surroundings.