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Asteroids Help Scientists to Measure the Diameters of Far Away Stars

18 Apr 2019, 12:30 UTC
Asteroids Help Scientists to Measure the Diameters of Far Away Stars
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Using the unique capabilities of telescopes specialized on cosmic gamma rays, scientists have measured the smallest apparent size of a star on the night sky to date. The measurements with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) reveal the diameters of a giant star 2674 light-years away and of a sun-like star at a distance of 700 light-years. The study establishes a new method for astronomers to determine the size of stars, as the international team led by Tarek Hassan from DESY and Michael Daniel from the Smithsonian Astrophysical Observatory (SAO) reports in the journal Nature Astronomy.Almost any star in the sky is too far away to be resolved by even the best optical telescopes. To overcome this limitation, the scientists used an optical phenomenon called diffraction to measure the star’s diameter. This effect illustrates the wave nature of light, and occurs when an object, such as an asteroid from our own solar system, passes in front of a star. “The incredibly faint shadows of asteroids pass over us everyday,” explained Hassan. “But the rim of their shadow isn't perfectly sharp. Instead, wrinkles of light surround the central shadow, like water ripples.” This is a general optical phenomenon ...

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