Adithi Ramakrishnan
Astronomers using a giant telescope in Chile have discovered the fastest known star in the Milky Way, zipping around the supermassive black hole at the centre of our galaxy at breathtaking speeds.
The star reaches velocities of roughly 25,000 km per second (15,534 miles per second) — roughly 100,000 times faster than a commercial passenger aircraft.
"That star is really, extremely fast," said Stefan Gillessen, an astronomer with the Max Planck Institute for Extraterrestrial Physics in Germany and co-author of the study.
The newly tracked star completes a full orbit around the central black hole in just 8.7 years, taking it closer to the monster gravity well than any star previously observed. It relies on the black hole’s immense gravitational pull to slingshot around at extreme speeds without falling past the point of no return.
Gillessen and his research team uncovered the record-breaking star after analysing data gathered by the European Southern Observatory’s Very Large Telescope, located in Chile’s Atacama Desert. The findings were published in the journal Nature.
Scientists estimate there are several hundred stars orbiting closely around the Milky Way's central supermassive black hole, all influenced by its intense gravitational force. To date, researchers have mapped the paths of about 50 of them. However, this newly identified star passes 10 times closer than the previous record holder, making it close enough to feel the physical effects of the black hole's rotation.
Supermassive black holes lurk at the heart of almost every massive galaxy. Because their gravitational pull is so powerful that nothing — including light — can escape them, observing the region directly is notoriously difficult.
Studying stars that venture this close offers scientists a rare tool to measure the elusive properties of these cosmic monsters, including the exact rate at which the central black hole spins.
As optical technology advances, modern telescopes are allowing astronomers to spot much fainter objects that previously evaded detection. Scientists expect even faster candidates to emerge in the near future.
"This is just the tip of the iceberg," said Tuan Do, an astronomer with the University of California, Los Angeles, who was not involved in the study. "As we get fainter, there should be many more stars like this."