后来所言仙女座云云的数据就不严谨了,不但忘了"缩小一万亿分之一来观察"的定语,290万光年的数据来自的资料应该比较老,最新的数据是250万光年,不过随着人类技术的不断进步,这个距离的测量值还会更加精确的.波江座ncc 13OO应为 NGC 1300 的扫描错误或排版错误,
NGC 1300 is often touted as being the most spectacular example of a barred spiral galaxy- and for good reason, the bar in the central portion of this galaxy is larger than the diameter of our own galaxy at an incredible length of 150,000 light years across. This galaxy is approximately 75 million light years away. However, even at this remote distance astronomers have studied this galaxy intensely since it reveals information about the nature of our galaxy, the Milky Way. Measurements of the speeds at which clouds of gas (and stars) orbit the galaxy were taken in order to determine how a barred spiral galaxy develops. The Milky Way has a small bar; however, studying an external face-on barred spiral like NGC 1300 is easier than looking through the intervening gas and dust of our own galaxy towards the center. Also note the handful of background galaxies that may be 5 times as distant (or more).
大熊座M18
Messier 18 or M18 (also designated NGC 6613) is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Sagittarius Star Cloud (M24). Its age is estimated at 32 million years. It is 4,900 light-years away. |