College Physics ›› 2018, Vol. 37 ›› Issue (5): 49-51.doi: 10.16854 /j.cnki.1000-0712.170546

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Einstein’s ring of a distant star formed by the sun’s gravity

ZHAO Fan2,HE Feng2,REN Wen-hui3   

  1. 1. Orient Science and Technology College,Hunan Agricultural University,Changsha,Hunan 410128,China; 2. College of Physics and Electronic Science,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China; 3. College of Science,Hunan Agricultural University,Changsha,Hunan 410128,China
  • Received:2017-09-28 Revised:2017-12-14 Online:2018-05-20 Published:2018-05-20

Abstract: When a distant star,the sun and the observer are in a line,the Einstein’s ring can be viewed. Ignoring rotation of the sun,the gravitational field of solar system is described by Schwarzschild metric and then the null geodesic equation is solved exactly by elliptic integral.It must be apart from the sun at least 547.7 AU to observe the Einstein’s ring. However,the diameter of Einstein’s ring and the sun’s edge almost overlap each other so that it is very difficult to distinguish them under current technology.

Key words: null geodesic, exact solution, Einstein’s ring