According to researchers published in the journal Nature on Wednesday, a newly discovered star designated S301 is racing around Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy, at speeds reaching roughly 15,534 miles per second. Discovered in data from the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert, the star orbits at close range in an 8.7-year elliptical path, offering astronomers a rare cosmic laboratory to measure invisible gravitational forces and black hole rotation.
Fastest Star in the Milky Way Speeds Past Sagittarius A*
Astronomers using the European Southern Observatory’s Very Large Telescope have mapped the extreme orbit of S301, the fastest star ever observed in our galaxy. According to Stefan Gillessen, an astronomer with the Max Planck Institute for Extraterrestrial Physics in Germany, the star reaches velocities of about 15,534 miles per second—roughly 100,000 times faster than a commercial airplane and just shy of 8 percent of the speed of light.
The star follows a super elongated elliptical path where the supermassive black hole sits at one end. Felix Mang, a Ph.D. student at the Max Planck Institute for Extraterrestrial Physics who first noticed the faint flicker of light in the data, tracked its position over multiple years. “The star comes in in one direction, getting faster and faster and faster, then gets a very sharp turn around the black hole,” Gillessen explains regarding the mechanism that harnesses gravity without pulling the star inside.
Did you know? The supermassive black hole at the center of the Milky Way is roughly four million times the mass of our Sun. Stefan Gillessen notes that its appearance “probably looks like Interstellar,” featuring a dark silhouette surrounded by a shimmering halo of light.
Using Infrared Light to Peer Through Cosmic Dust
Observing objects near the galactic center presents immense challenges due to dense clouds of cosmic dust and gas that block visible wavelengths. To overcome this obstacle, researchers utilized four telescopes at the European Southern Observatory’s Very Large Telescope site in Chile’s Atacama Desert to gather infrared light.
“Just by using infrared light, you can peer into the most central part of the nucleus of the Milky Way,” Felix Mang notes. This technical capability allowed the team to pinpoint S301, which is 10 times closer than the previous record holder. Because of this proximity, the star experiences the direct effects of the black hole’s rotation.
Probing Space-Time and Black Hole Physics
While several hundred stars closely orbit the giant black hole and are sensitive to its gravity, scientists have successfully mapped the orbits of around 50 of them. According to Stefan Gillessen, the primary significance of discovering S301 lies not merely in its velocity, but in its utility as a physical probe.
“Thereby we can use the star [as a probe] to visualize how gravity is acting on space and time,” Gillessen states. Because supermassive black holes lurk in the center of almost every large galaxy and trap even light—so nothing can escape—tracking stars like S301 provides researchers with methods for measuring mysterious properties, including how fast the supermassive black hole spins.
Pro Tip: Advanced telescopes are continuously improving our ability to detect fainter stars near galactic cores. UCLA astronomer Tuan Do, who had no role in the study, points out that “this is just the tip of the iceberg” and anticipates “there should be many more stars like this” as instrument sensitivity increases.
Frequently Asked Questions
How fast is the newly discovered star S301?
According to researchers, S301 reaches speeds of over 15,000 miles per second at its closest approach to the black hole, making it the fastest star ever observed in the galaxy.
How long does it take S301 to complete an orbit?
The star takes just 8.7 years to complete a revolution following a super elongated ellipse path, according to data published in the journal Nature.
Why are scientists studying stars near Sagittarius A*?
Because supermassive black holes trap light and obscure their internal workings, astronomers study stars like this one to help measure those mysterious properties, including how fast the supermassive black hole spins.
Where was the discovery made?
Astronomers made the discovery using data from the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert, analyzed by researchers including Stefan Gillessen and Felix Mang at the Max Planck Institute for Extraterrestrial Physics.
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