- The supermassive black hole at the center of the Milky Way suddenly lit up in May.
- Astronomers say the black hole called Sagittarius A* grew 75 times brighter in just two hours.
In mid-May, a supernova black hole at the center of our Milky Way galaxy became 75 times brighter within a span of two hours, and scientists have yet to determine why it happened.
Sagittarius A* (Sgr A*) flares brighter from time to time but nothing quite as bright as the infrared radiation flash that occurred May 13, observed by astronomers using the Keck II Telescope on the summit of Mauna Kea in Hawaii, according to the research paper, which will be published in Astrophysical Journal Letters. Three other flashes, though not quite as bright, were also observed in the days surrounding the May 13 event.
Situated some 26,000 light years from Earth in the center of the Milky Way, the black hole is four million times as massive as the sun, according to NASA. While no light can escape Sgr A*, astronomers can observe interactions of the supernova with other stars, planets and dust clouds that surround it – and the infrared radiation the interactions give off.
Tuan Do, an astronomer at UCLA, was in Hawaii observing the black hole when the event occurred.
“I was pretty surprised at first and then very excited,” Do told ScienceAlert. “The black hole was so bright I at first mistook it for the star S0-2, because I had never seen Sgr A* that bright. Over the next few frames, though, it was clear the source was variable and had to be the black hole. I knew almost right away there was probably something interesting going on with the black hole.”
While the researchers are not sure why the bright flash occurred, Do says he has a few working theories.
“One of the possibilities is that the star S0-2, when it passed close to the black hole last year, changed the way gas flows into the black hole, and so more gas is falling on it, leading it to become more variable,” Do told ScienceAlert.
Another possibility is that the flash is a delayed reaction from a 2014 event, when a gas cloud passed near the black hole.
Other telescopes around the world are continuing to observe the black hole in hopes that more data will help astronomers explain the bright flash.
“I’m eagerly awaiting their results,” Do said in a tweet.
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