2.2.5是这篇吗 找 的我头痛了 几个关键词都有了 有一篇讲黑洞(最后一篇,唯一一篇完全看懂的),先讲了黑洞不能直接观测,只能观测它吸引周围的东西。然后比较了两个星系的情况,一个星系里有星云向中心移动,大部分科学家说星系中心有黑洞,但是有些科学家说星云移动的速度算下来只能算出星座的中心用大堆的星星,导致密度大,不是黑洞。另一个星系里有很多什么天体向中心移动,速度算下来和别的星系不一样,如果中心只是很多星星的话那么中心就太挤了还是怎么样(意思就是应该有黑洞,反正没出题,看得不仔细) (原文)
For example, observations indicate that gas clouds in galaxy M87 are whirling unusually fast about the galaxy’s center. Most astronomers believe that the large concentration of mass at the galaxy’s center is a black hole whose gravity is causing the gas to whirl. A few skeptics have argued that the concentration of mass necessary to explain the speed of the whirling gas is not necessarily a black hole: the concentration in M87 might be a cluster of a billion or so dim stars.The same hypothesis might have been applied to the galaxy NGC 4258,but the notion of such a cluster’s existing in NGC 4258 was severely undermined when astronomers measured the speed of a ring of dust and gas rotating close to the galaxy’s center. From its speed, they calculated that the core’s density is more than 40 times the density estimated for any other galaxy. If the center of NGC 4258 were a star cluster, the stars would be so closely spaced that collisions between individual stars would have long ago torn the cluster apart. 下面是直接由翻译器翻的,大家随便看看 例如,观测表明,星系M87的气体云快速旋转的异常有关星系的中心。大多数天文学家认为,在星系的质心的高度集中,是一个黑洞,其引力是导致气体旋转。一些怀疑论者认为,质量浓度 需要说明的旋转气流速度不一定是黑洞:在M87的浓度可能是一亿左右熄灭同样昏暗的假设有可能被应用到星系NGC 4258群集中,但这种观念群集的现有的NGC 4258受到严重破坏时,天文学家测出的尘埃和气体环的旋转速度接近银河系的 中心。从它的速度,他们计算出核的密度大于40倍的任何其他星系估计密度。如果该中心的NGC 4258是一个星团,恒星会如此密集个别恒星之间的碰撞将早已撕裂集群分开。 -- by 会员 mnch729 (2011/6/11 23:03:08)
说是文章里还有heating和cooling才对…… |