2008年12月11日:银河中心-（At the Center of the Milky Way）--原图下载
Credit: ESO,Stefan Gillessen (MPE),F. Eisenhauer, S. Trippe, T. Alexander, R. Genzel, F. Martins, T.Ott
说明: 我们银河系中心有一颗超大质量的黑洞。上面这个论述，曾经饱受争议，不过经过16年观测追蹤28颗靠近银河中心恒星的轨道运动后，它现在有了稳固的观测基础。使用欧洲南天文台的天文望远镜及先进的近红外光相机，天文学家耐心地量测这些恒星位置如何随着时间变化，而其中一个编号为S2的恒星，因为以不到一光时的距离绕行银河中心，因此更观测到它完整的运行轨道。成果明确地证明，S2是受到一个不可见但具有强大引力的緻密天体之影响，因而推算出这个黑洞的质量高达太阳之四百万倍。他们除了能够追蹤这么靠近银河中心的恒星，量测出黑洞的质量，也定出银河中心离我们有27,000光年。上面这幅近红外光深空影像，呈现了三光年範围内的拥挤银河中心。这些离银河中心数光年内恒星运动的精彩时序动画，可在此处找到。
原文：
Credit: ESO,Stefan Gillessen (MPE),F. Eisenhauer, S. Trippe, T. Alexander, R. Genzel, F. Martins, T.Ott
Explanation: At the center of our Milky Way Galaxy lies asupermassive black hole.Once a controversial claim, this conclusion is now solidly basedon 16 years of observationsthat map the orbits of 28 stars very nearthe galactic center.Using European Southern Observatorytelescopes and sophisticatednear infrared cameras, astronomers patiently measured the positionsof the stars over time, following one star, designated S2, througha complete orbit as it came within about 1 light-day of the center of the Milky Way.Their resultsconvincingly show that S2 is moving under the influence of theenormous gravity of a compact, unseen object -- a black holewith 4 million times the massofthe Sun.Their ability to track stars so close to thegalactic centeraccurately measures the black hole's mass and also determines thedistance to the center to be 27,000 light-years.This deep, near-infrared image shows the crowded inner 3light-years of the central Milky Way.Spectacular time-lapse animations of the stars orbitingwithin light-days of the galactic centercan be found here.
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