Once or twice a day, a strange object in the Milky Way blinks at us. Now, astronomers think they know why.
The object is called NGTS-7, and to most telescopes it looks like a single star. Researchers at the University of Warwick in England started watching because it seemed to be emitting flares, but on closer examination they noticed that its starlight dims briefly every 16.2 hours. When the astronomers zoomed in, they realized there are actually two similarly sized stars in the system, and that only one of them is dimming briefly in that way — suggesting that there’s something dark circling on or just above the star’s surface. Now, in a paper posted to the preprint journal arXiv, the astronomers offer an explanation: A brown dwarf is orbiting one of the stars, in an orbit so tight that it takes just 16.2 hours to complete.
It’s impressive that the astronomers involved were able to parse the complicated signal from this system, disentangling where the intermixed light from the brown dwarf and the two small, young stars originally came from, said Hugh Osborn, an astronomer at the Laboratoire d’Astrophysique de Marseille in France, who was not involved in the research.
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