Level 1 - Absolute Beginner
Scientists found a very fast star. It moves faster than any other star we know about.
This star is called S301. It moves around a black hole at the center of our galaxy.
A black hole is a place in space with very strong pulling power. Nothing can escape it, not even light.
S301 gets very close to the black hole. Scientists want to use it to learn new things about the black hole.
- star
- a huge, hot ball of gas in space that gives off light
- fast
- moving at a very high speed
- galaxy
- a huge group of stars, like the Milky Way, held together in space
- black hole
- a place in space with such strong pulling power that nothing, not even light, can escape
- center
- the middle point of something
- close
- near to something, not far away
- spin
- to turn around and around
- scientist
- a person who studies the world using careful research
Level 2 - Elementary
Astronomers have discovered the fastest star ever recorded in our galaxy. Named S301, it races around the supermassive black hole at the center of the Milky Way at an incredible 25,000 kilometers per second.
The black hole, called Sagittarius A*, has a mass about four million times greater than our Sun. S301 orbits it on a tight, 8.7 year path, coming closer to the black hole than any other star ever observed.
S301 gets so close, about 136 times the black hole's Schwarzschild radius, a measurement of the point of no return around a black hole, that it can actually feel the effects of the black hole spinning.
This close approach makes S301 extremely valuable to scientists. By watching the star's path carefully over its next few orbits, astronomers hope to measure the spin of Sagittarius A* for the first time, something that has never been directly confirmed before.
- astronomer
- a scientist who studies stars, planets, and other objects in space
- supermassive
- having an extremely large mass, much greater than normal
- mass
- the amount of matter an object contains
- orbit
- the curved path an object follows around another object in space
- Schwarzschild radius
- the distance from a black hole's center beyond which nothing can escape
- approach
- the act of coming near to something
- valuable
- very useful or important
- confirm
- to prove that something is true
Level 3 - Intermediate
Astronomers using the European Southern Observatory's Very Large Telescope Interferometer have identified the fastest star ever recorded in the Milky Way, a discovery that could finally allow scientists to measure the spin of the supermassive black hole at our galaxy's center.
The star, designated S301, was first spotted in the spring of 2023 using the GRAVITY instrument and reaches speeds of roughly 25,000 kilometers per second as it traces an extraordinarily elongated orbit around Sagittarius A*, a black hole with a mass approximately four million times that of the Sun.
S301 completes a full orbit in just 8.7 years, swinging as close as 136 to 142 Schwarzschild radii at its nearest approach, about ten times closer than the previous record holder, a well studied star known as S2. That proximity is scientifically significant, since it places S301 close enough to feel measurable effects from the black hole's own rotation, a phenomenon known as frame dragging.
Because no star has ever been observed near enough to a black hole to detect this effect directly, researchers say that tracking S301 through its next close pass, expected in 2031, could yield the first direct measurement of Sagittarius A*'s spin, a fundamental property that has so far only been inferred indirectly.
- interferometer
- an instrument that combines light from multiple telescopes to achieve very high resolution
- designated
- officially given a name or label
- elongated
- stretched out, longer than it is wide
- proximity
- the state of being near or close to something
- frame dragging
- the effect in which a spinning massive object twists the space and time around it
- phenomenon
- a fact or event that can be observed and studied
- inferred
- worked out or concluded from evidence, rather than observed directly
- fundamental
- forming a basic, essential part of something
Level 4 - Advanced
Astronomers working with the European Southern Observatory's Very Large Telescope Interferometer have identified S301, a star tracing the tightest and fastest orbit yet observed around the supermassive black hole anchoring the Milky Way's center, a discovery poised to deliver the first direct constraint on the black hole's spin.
First detected in the spring of 2023 through the GRAVITY instrument, S301 reaches velocities of approximately 25,000 kilometers per second along a highly eccentric 8.7 year orbit around Sagittarius A*, a black hole of roughly four million solar masses. Its closest approach, at 136 to 142 Schwarzschild radii, surpasses the proximity of the previously closest known star, S2, by a factor of roughly ten, placing S301 within a regime where general relativistic effects beyond simple gravitational attraction become detectable.
Chief among these is frame dragging, the phenomenon by which a rotating massive body twists the surrounding spacetime, subtly perturbing the orbits of nearby objects in a manner that depends directly on the black hole's angular momentum. Until now, no star has approached Sagittarius A* closely enough for this effect to leave a measurable imprint on its trajectory, leaving the black hole's spin, a fundamental parameter alongside its mass, known only through indirect inference from accretion models and jet observations.
Astronomers now plan to track S301 through its next perihelion passage in 2031, when relativistic precession in its orbit should become measurable with sufficient precision to extract a spin value directly, a result that would mark the first empirical determination of the rotation of our galaxy's central black hole and offer a stringent new test of general relativity in the strong field regime.
- eccentric orbit
- an orbit that is elongated rather than nearly circular
- general relativistic
- relating to Einstein's theory of general relativity, which describes gravity as the curvature of spacetime
- angular momentum
- a measure of the amount of rotation an object has, based on its mass, shape, and spin rate
- accretion
- the gradual accumulation of matter onto an object, such as a black hole, by gravitational attraction
- perihelion
- the point in an orbit at which an object is closest to the body it orbits
- precession
- a gradual shift in the orientation of an orbit or rotational axis over time
- empirical
- based on observation or direct experiment rather than theory alone
- strong field regime
- conditions of extremely intense gravity, such as those near a black hole, where relativistic effects are most pronounced
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