One for the record books 🏅
Our Very Large Telescope Interferometer has discovered the fastest known star in our galaxy. Named S301, it orbits Sagittarius A* — the supermassive black hole at the centre of the Milky Way — reaching speeds of 25 000 kilometres per second, over 8% the speed of light.
📷 ESO/GRAVITY collaboration
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S301 also comes closer to Sagittarius A* than any other known star, at around the distance of Saturn to the Sun.
This is close enough for the orbit of S301 to be influenced by the black hole's rotation.
General Relativity predicts that a rotating object drags and twists spacetime around it. S301 gets close enough to Sgr A* that it could be affected by this phenomenon,.
📷 ESO/M. Kornmesser
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This effect would nudge the S301 star every time it passes close to the black hole, slowly changing its orbit in a subtle but measurable way within the next few years.
Read the full story: https://www.eso.org/public/news/eso2612/
📷 ESO/GRAVITY collaboration/L. Calçada
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Is that relativistic apsidal precession that I see? Or just the result of the orbit being inside other masses?
Is that relativistic apsidal precession that I see, or are you just happy to be able to detect frame dragging by Sgr A*?
@rjblaskiewicz @martinvermeer What you see here is the normal Schwarzschild precession that happens regardless of whether the black hole rotates or not. This had already been measured a few years ago using another star called S2: https://www.eso.org/public/news/eso2006/
But S301 gets much closer to the black hole, and therefore it may feel the frame-dragging in addition to the Schwarzschild precession: https://www.eso.org/public/images/eso2612e/
@esoastronomy @martinvermeer Awesome.
@esoastronomy @rjblaskiewicz @martinvermeer
Truly awestruck. Thanks for sharing.i often wonder if the grass is greener, albeit stretched out, on the other side.
@esoastronomy For readers not familiar with the topic, a non rotating black hole will also change an orbit from that predicted by Newtonian gravity. Frame dragging adds an additional change, one that is normally very difficult to detect, making this a very nice test of general relativity. Satellite experiments have detected frame dragging, but only in a weak gravitational field.
@esoastronomy I wonder what the universe would look like from a planet orbiting that star. I imagine it would look very different.
(I wonder how long a planet could orbit that star, or whether the black hole and surroundings would make that unstable)
@ShadSterling It would be quite a view! For instance, the event horizon of Sagittarius A* would appear about 60% wider than the full Moon (0.8 degrees vs 0.5 for the Moon).
Aug 19, 2026, 4:28 PM@esoastronomy Thanks! That's really exciting - best data of the day!