Gravitational Doppler effect in the orbit of the star S2 around the massive black hole Sgr A * at the center of the Milky Way Galaxy

Abstract In 2018 it was announced that the star S2, which had been monitored since 1992, orbiting the massive black hole Sgr A * in the center of the Milky Way galaxy, obeyed as programmed by Einstein's Theory of General Relativity. The orbital movements of this star and dozens more in orbit of the black hole Sgr A * reveal that the mass of the black hole is greater than four million solar masses. The intense gravity of the black hole Sgr A * causes a gravitational Doppler effect predicted in the Theory of General Relativity and which was observed in the light emitted by the star S2. We didactically discuss the phenomena involved in these observations made for the star S2.

摘要：2018年，研究人员宣布，自1992年起被持续观测的恒星S2，在环绕银河系中心超大质量黑洞人马座A*（Sgr A*）运行时，其轨道运动完全符合爱因斯坦广义相对论（General Relativity）的预言。对该恒星以及其他数十颗环绕人马座A*运行的天体的轨道运动观测结果表明，该黑洞的质量超过400万倍太阳质量。人马座A*的极强引力会产生广义相对论所预言的引力多普勒效应（gravitational Doppler effect），这一效应已在恒星S2发出的光线中被观测到。本文以教学阐释的方式，讨论了针对恒星S2的上述观测所涉及的各类物理现象。