Astronomers discovered a fascinatin

Astronomers discovered a fascinating mystery when they studied the movementof stars in the Milky Way. The galaxy had a radius of about 50000 light-years, andaccording to Kepler's law, the speeds of stars or gases more than 50,000 light-yearsaway from the center of the Milky Way would decrease with increasing distances.But astronomers had found that their speeds did not decrease even when they weremore than a hundred thousand light-years away. This indicated that there had to bematter even in this distance but this matter did not give out any electromagneticwaves. Hence it had been named “dark matter. It was estimated that dark matterformed a halo of about 300,000 light-years in radius, which surrounded the visiblepart of the Milky Way galaxy, with a mass of more than ten times the visible part. What is that dark matter? Since it has little effect on the ordinary matter, theyare very difficult to identify, but astronomers had suggested a lot of possibilities.For example, they could be “brown dwarfs” with mass between Jupiter and theSun, or “black dwarfs”. Another possibility is that of exotic particles, such asmassive neutrinos, axions, or supersymmetric particles. However, up to now, theobservations are still not conclusive. Another mystery of the Milky Way galaxy is in its center. Stars in the galacticcenter are very densely distributed. In 1959 the astronomer Drake used radiotelescopes to measure the core density of the Milky Way and found it to be around30 stars per cubic light-year. This is 1000 times the density of stars in the regionnear the Sun. Later in the 70's, the space X-ray detectors, Uhuru and Einstein,observed very strong X-ray signals from the center of the Milky Way, and theregion was only three light-years across. From the Doppler effect of the infraredspectrum in the same region, it was found that the gas in the center formed avortex. It was spinning very fast and this represented that the mass of the centerwas that of several million solar masses. Being extremely massive and within avery small region, astronomers thought that it was a black hole, that is, one at thegalactic center of less than a few light-years across and of several million solarmasses. Similar results were found in other galaxies, such as the Andromedagalaxy. It is possible that there is a black hole at the center of every galaxy

結果 (英文) 1:

Astronomers discovered a fascinating mystery when they studied the movementof stars in the Milky Way. The galaxy had a radius of about 50000 light-years, andaccording to Kepler's law, the speeds of stars or gases more than 50,000 light-yearsaway from the center of the Milky Way would decrease with increasing distances.But astronomers had found that their speeds did not decrease even when they weremore than a hundred thousand light-years away. This indicated that there had to bematter even in this distance but this matter did not give out any electromagneticwaves. Hence it had been named “dark matter. It was estimated that dark matterformed a halo of about 300,000 light-years in radius, which surrounded the visiblepart of the Milky Way galaxy, with a mass of more than ten times the visible part. What is that dark matter? Since it has little effect on the ordinary matter, theyare very difficult to identify, but astronomers had suggested a lot of possibilities.For example, they could be “brown dwarfs” with mass between Jupiter and theSun, or “black dwarfs”. Another possibility is that of exotic particles, such as
massive neutrinos, axions, or supersymmetric particles. However, up to now, theobservations are still not conclusive. Another mystery of the Milky Way galaxy is in its center. Stars in the galacticcenter are very densely distributed. In 1959 the astronomer Drake used radiotelescopes to measure the core density of the Milky Way and found it to be around30 stars per cubic light-year. This is 1000 times the density of stars in the regionnear the Sun. Later in the 70's, the space X-ray detectors, Uhuru and Einstein,observed very strong X-ray signals from the center of the Milky Way, and theregion was only three light-years across. From the Doppler effect of the infraredspectrum in the same region, it was found that the gas in the center formed avortex. It was spinning very fast and this represented that the mass of the centerwas that of several million solar masses. Being extremely massive and within avery small region, astronomers thought that it was a black hole, that is, one at thegalactic center of less than a few light-years across and of several million solarmasses. Similar results were found in other galaxies, such as the Andromedagalaxy. It is possible that there is a black hole at the center of every galaxy

結果 (英文) 3:

天文学家在研究银河系中恒星的运动时发现了一个迷人的谜。银河系的半径约为5万光年，根据开普勒定律，距离银河系中心5万光年以上的恒星或气体的速度会随着距离的增加而降低，但天文学家发现，即使距离银河系中心10万光年以上，它们的速度也不会降低。这表明即使在这个距离内也必须有物质存在，但这个物质并没有发出任何电磁波。因此它被命名为“暗物质”。据估计，暗物质形成了一个半径约30万光年的光晕，围绕着银河系的可见部分，质量是可见部分的10倍以上。那暗物质是什么？由于它对普通物质的影响很小，所以很难识别，但是天文学家提出了很多可能性，例如，它们可能是质量介于木星和太阳之间的“褐矮星”，也可能是“黑矮星”。另一种可能性是外来粒子，例如
大量的中微子、公理或超对称粒子。然而，到目前为止，观测结果还没有定论。银河系的另一个谜团在它的中心。星系中心的恒星分布非常密集。1959年，天文学家德雷克用射电望远镜测量了银河系的核心密度，发现它大约是每立方光年30颗恒星。这是太阳区域恒星密度的1000倍。70年代后期，空间X射线探测器乌胡鲁和爱因斯坦观测到来自银河系中心的非常强的X射线信号，而这个区域只有3光年宽。根据同一区域红外光谱的多普勒效应，发现中心气体形成avortex。它旋转得非常快，这表明中心的质量是几百万个太阳质量。天文学家认为它是一个黑洞，即一个位于银河系中心的黑洞，直径不到几光年，有几百万个太阳活动区。在其他星系中也发现了类似的结果，例如Andromedagalaxy。可能每个星系的中心都有一个黑洞