Scientists have made an astronomical discovery that could change our understanding of the most mysterious objects in the universe. A star, named S301, has been detected orbiting the supermassive black hole Sagittarius A*, located at the center of the Milky Way, at an unprecedented speed. The study, published on August 19, 2026 in the journal Nature, points out that the identification of this ultrafast star could be fundamental to measuring, for the first time, the rotation of the black hole itself.
A star with surprising speed
The newly identified star S301 stands out for its unique characteristics. With a mass and brightness greater than that of the Sun, it reaches speeds estimated at up to 90 million kilometers per hour as it revolves around Sagittarius A*. This mark represents around 8% of the speed of light, exceeding the speed of a jet plane by 100,000 times. No other stellar body, both in our galaxy and in others, has been recorded so quickly to date.
The challenging orbit at the heart of the Milky Way
The star S301 follows a highly elliptical trajectory, completing one revolution around Sagittarius A* every 8.7 years. At its closest point, it is at an average orbital distance equivalent to 11.5 times the distance between the Earth and the Sun. This proximity is crucial, as Sagittarius A* is a supermassive black hole with a mass approximately 4 million times greater than that of the Sun, and is 26 thousand light-years from our planet.
It is vital to understand the scale: one light year is equivalent to 9.5 trillion kilometers, illustrating the vastness of the distances involved. Despite its state of “quiescence” – meaning it is not actively devouring matter at the moment – Sgr A*’s gravitational pull is immense, capable of swallowing stars or any material that comes dangerously close. However, researchers guarantee that S301 should continue its orbit safely, without the risk of being swallowed.
Unraveling the origin of S301
Researchers believe that S301 was not born alone, but was part of a binary star system. At some point in their cosmic journey, this duo got too close to the gigantic Sagittarius A*. The intense gravitational interaction between the three bodies resulted in a dramatic event.
One of the stars was thrown out of the center of the Milky Way, and could even leave the galaxy, while the other, S301, was “trapped” in an orbit close to the black hole. Stefan Gillessen, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics, in Germany, and one of the authors of the research, reassured about the star’s future: “The orientation of the orbit will change, but the star is not at risk of being swallowed.”
Advanced technology for the cosmic gaze
The detailed observation of S301 was made possible by the Very Large Telescope Interferometer (VLTI), an advanced structure operated by the European Southern Observatory in Chile. The VLTI is a feat of astronomical engineering, combining light from four eight-meter telescopes.
This union creates a “virtual telescope” with a spatial resolution 15 times greater than that of a single telescope. This unique capability allowed scientists to capture S301’s precise movements, which are essential for research.
The role of S301 in measuring Sagittarius A* rotation
The discovery of S301 offers an unprecedented opportunity to unravel one of the greatest astrophysical mysteries: the rotation of black holes. According to Felix Mang, co-author of the study and doctoral candidate at the Max Planck Institute for Extraterrestrial Physics, “to date, we know very little about the rotation of Sgr A*.”
Black holes are theorized to spin to the point of distorting spacetime itself around them, a phenomenon predicted by Albert Einstein’s Theory of General Relativity that has profound implications for our understanding of gravity and the universe at extreme scales. However, confirming this rotation is extremely challenging as these objects neither emit nor reflect light, making them virtually invisible to direct observation methods.
S301’s motion is continually influenced by Sgr A*, which allows researchers to map the tiny but significant perturbations in its orbit, as if the star were a natural laboratory for studying extreme gravitational effects. “We can only observe its rotation through the effects it has on the surrounding space,” explained Gillessen, emphasizing the indirect nature of the observation.
The implications and future of observations
The proximity of S301 to Sagittarius A* makes it directly “feel” the rotation of the black hole. Stefan Gillessen described the phenomenon: “It is not a wobble, like a back-and-forth motion, but rather the star being deflected into a slightly different orbit each time it passes through the black hole.”
This subtle change in the S301’s trajectory is key. “If we observe this change in orbit for another decade, we should be able to directly determine the rotation of the black hole. To date, it has never been possible to make a measurement of this type”, concluded the astrophysicist. Astronomers will keep their attention focused on S301, which will make its next critical pass through the closest point to the black hole in 2031, an event eagerly awaited by the scientific community.
