• Nearest bright “hypervelocity star” found: study


    WASHINGTON: Researchers from the United States and China said Wednesday they have discovered the closest known “hypervelocity star” that is moving away from the center of the Milky Way at more than 1.6 million km per hour.

    “The hypervelocity star can help us know our Milky Way better, ranging from the supermassive black hole at its heart to the halo of dark matter surrounding our galaxy,” Zheng Zheng, lead author and assistant professor of physics and astronomy from the University of Utah, told Xinhua.

    Hypervelocity stars are stars that travel fast enough to escape the gravitational grasp of the Milky Way galaxy. Finally, they could leave the galaxy, Zheng said.

    Such stars are thought to have been formed when the supermassive black hole at the center of a galaxy captures one star in a binary system and ejects the other, he said.

    In the past decade, astronomers have found about 20 of these odd stars.

    In the new study, Zheng and his colleagues discovered the new hypervelocity star using the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) located at the Xinglong Observing Station of the National Astronomical Observatories of China, about 170 km northeast of Beijing.

    The star, named LAMOST-HVS1, is nine times more massive, four times hotter and about 3,400 times brighter than our sun, about 42, 400 light years from us and about 62,000 light years from the galactic center, Zheng said.

    “Although we cannot see it with the naked eye because of the distance, it is the nearest and second-brightest hypervelocity star discovered so far,” Zheng said.

    He said that the star’s speed is 620 km per second relative to our solar system, and about 477 km per second relative to the center of the Milky Way.

    “The star travels about 16,000 times faster than a car, about 1, 600 times faster than a plane. If we could fly at such a speed, we could circle around the Earth in just 90 seconds, and fly to the moon from our Earth in less than 15 minutes,” he said.

    Compared with the 4.6-billion-year-old Sun, the newly discovered star is a youngster born only 32 million years ago, based on its speed and position, he added.

    The study was published in the U.S. journal Astrophysical Journal Letters and also involved researchers from the Chinese Academy of Sciences and the University of Science and Technology of China. PNA


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