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Explorer telescope finally earns its keep

发布时间:2019-03-07 09:02:08来源:未知点击:

By Jeff Hecht NASA has managed to retrieve something from a bungled space telescope mission. Its faulty WIRE satellite has revealed an ordinary star vibrating or “ringing” beyond the Solar System, and the observations of the star have allowed astronomers to measure its mass more accurately than ever before. Like seismic waves passing through the Earth, vibrations in stars can reveal details of their interiors—and even their masses. A few unusual stars ring with vibrations that make their luminosities vary by up to a few per cent, but normal stars such as the Sun fluctuate by only up to one part in 10 000. Spotting these variations isn’t easy. “You can’t do it from the ground, and you need observations for a month,” says Derek Buzasi of the University of California at Berkeley. He realised NASA’s $73-million Wide-Field Infrared Explorer (WIRE) might be able to do the job. The satellite had been launched on 4 March but its infrared telescope became useless when a defect exposed a vital coolant to the Sun. Buzasi knew WIRE also carries a star tracker to help the satellite maintain the correct orientation. The instrument is linked to a star camera that can make 10 brightness measurements a second. In a paper submitted to the The Astrophysical Journal, Buzasi says observations using the camera have pinned down the mass of Dubhe,