Star S301 orbits Milky Way's black hole closer than any known star, revealing black hole spin
Astronomers detect a star in an extreme orbit around Sagittarius A*, reaching 8.3% light speed and enabling measurement of the black hole's rotation.
What to know
- S301 is the closest-orbiting star yet observed around Sagittarius A*, reaching speeds of 25,000 km/s (8.3% light speed) at closest approach.
- Its 8.7-year orbit exhibits extreme eccentricity and is directly linked to the black hole's rotation, enabling astronomers to measure this previously difficult-to-detect property.
- The discovery allows scientists to observe relativistic effects of spacetime dragging and frame-dragging caused by the spinning black hole.
The extreme orbit produces dramatic relativistic effects that would be visibly detectable by observers, including Doppler shifts and time dilation.
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“you would notice things like the regular flash of quasars would slow and speed up as the star whips around.”
Correct_Inspection25 · Reddit ↗
Time dilation near the black hole means processes on or around S301 would advance much more slowly relative to the wider universe.
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“Could entire civilizations play out on relatively small time scales compared to the outside universe? Wouldn't the star and planet live an incredibly long time at those forces?”
cameron4200 · Reddit ↗
“At periapsis—its closest approach to the black hole—it reaches about: 25,000 km/s = 15,500 miles per second = 55.9 million mph = 8.3% of the speed of light.”
StepYaGameUp, Reddit commenter · Reddit
S301 Star orbiting Sagittarius A*Sagittarius A* Central black hole of the Milky Way
The record 3 articles and posts · last 30 days
What people are saying 6 voices from 1 site · verbatim
- What would the subjective experience be for an observer on or near S301 as it orbits the black hole?
- Could time dilation effects allow civilizations on S301 to persist for cosmologically significant durations?
- Aug 20
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So obviously S301’s speed is not constant because its 8.7-year orbit around Sagittarius A* is extremely eccentric. But at periapsis—its closest approach to the black hole—it reaches about: 25,000 km/s = 15,500 miles per second = 55.9 million mph = 8.3% of the speed of light . That’s hauling some ass.
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If you had a telescope to watch them develop from far away I think so, also noticeably dynamic Doppler effects like red/blue shifting spectra from stars
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That’s kinda what I meant. Like one civilization lasting as long as ours would still have a relatively young universe.
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It's the opposite, actually. More mass means slower clock compared to the outside universe.
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Due to relativistic effects. Could entire civilizations play out on relatively small time scales compared to the outside universe? Wouldn’t the star and planet live an incredibly long time at those forces?
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Lots of organ music! But really subjective experience of the observer isn’t going to change much, except maybe extreme tidal forces causing earth quakes/etc. you would notice things like the regular flash of quasars would slow and speed up as the star whips around.