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Racing star could prove Einstein's theory

Artist concept of matter swirling around a black hole

Black holes have a gravitational force so strong that even light cannot escape (Source: NASA/Dana Berry/SkyWorks Digital)


The University of California, Los Angeles researchers say the discovery, reported in the journal Science, will help them test Albert Einstein's theory of general relativity and his predictions of how black holes warp space and time.

The star, S0-102, is orbiting the black hole every 11-and-a-half years, much faster than the 60 years or longer orbit of most of the stars around the Milky Way's black hole centre.

This is only the second star discovered with such a short orbit - the other, S0-2, orbits the black hole every 16 years - thanks to improved imaging techniques.

Lead researcher Andrea Ghez, who has been observing the black hole since she discovered it in 1998, says the second data point is crucial for their research.

"It is the tango of S0-102 and S0-2 that will reveal the true geometry of space and time near a black hole for the first time," she says. "This measurement cannot be done with one star alone."

Like Earth and other planets, stars have elliptical orbits - meaning they regularly move closer and further from the black hole.

Ghez and her team at UCLA hope to see evidence of little wobbles in the orbit when the stars move closer, which would show they are being affected by the curvature of space time, as predicted by Einstein's theory.

Ghez adds it was "phenomenal" to find two stars so close to the black hole.

"This should not be a neighbourhood where stars feel particularly welcome," she says.


They cannot be seen directly, and so are observed through their influence on the things around them.

"Now it's a whole new ballgame," says Ghez, adding that the team's investigations could open a new window into understanding black holes and how the universe evolves.

Tags: astronomy-space, blackholes, stars

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