Star to Reveal Milky Way’s Black Hole Spin
A star zooming around our galaxy's black hole at incredible speeds may reveal how the black hole spins.
The update
Astronomers have discovered a star named S301 that orbits the Milky Way’s supermassive black hole, Sagittarius A*, at extraordinary speeds—reaching 15,500 miles per second (25,000 kilometers per second), or more than 8% the speed of light. This star follows an extremely tight orbit, completing it in just 8.7 years while approaching the black hole at just 12 times the Earth-sun distance.
Why it matters
S301’s close orbit provides a unique opportunity to measure the black hole’s spin. According to Einstein’s theory of general relativity, a rotating black hole drags spacetime around with it, gradually altering the orbit of nearby objects. By tracking how S301’s orbit changes over time—within about a decade—scientists could directly measure the spin of Sagittarius A* for the first time, providing a crucial test of our understanding of black hole physics.
What to watch
Watch for astronomers to continue monitoring S301’s orbit over the coming years as they attempt to detect the subtle changes caused by the black hole’s rotation. This could lead to the first direct measurement of a supermassive black hole’s spin, potentially confirming or challenging aspects of Einstein’s theory of gravity.
Sources
- sciencenews.org — Details about S301's discovery and potential to reveal black hole spin
- space.com — Specific velocity measurements and orbital characteristics of S301
- livescience.com — Context about the environment near Sagittarius A*
