原文：
One of the largest Hubble Space Telescope images ever made of a complete galaxy is being unveiled today at the American Astronomical Society meeting in San Diego, Calif.The Hubble telescope captured a display of starlight, glowing gas, and silhouetted dark clouds of interstellar dust in this 4-foot-by-8-foot image of the barred spiral galaxy NGC 1300.
NGC 1300 is considered to be prototypical of barred spiral galaxies. Barred spirals differ from normal spiral galaxies in that the arms of the galaxy do not spiral all the way into the center, but are connected to the two ends of a straight bar of stars containing the nucleus at its center.At Hubble's resolution, a myriad of fine details, some of which have never before been seen, is seen throughout the galaxy's arms, disk, bulge, and nucleus. Blue and red supergiant stars, star clusters, and star-forming regions are well resolved across the spiral arms, and dust lanes trace out
fine structures in the disk and bar. Numerous more distant galaxies are visible in the background, and are seen even through the densest regions of NGC 1300.In the core of the larger spiral structure of NGC 1300, the nucleus shows its own extraordinary and distinct "grand-design" spiral structure that is about 3,300 light-years (1 kiloparsec) long. Only galaxies with large-scale bars appear to have these grand-design inner disks — a spiral within a spiral.
Models suggest that the gas in a bar can be funneled inwards, and then spiral into the center through the grand-design disk, where it can potentially fuel a central black hole. NGC 1300 is not known to have an active nucleus, however, indicating either that there is no black hole, or that it is not accreting matter.
The image was constructed from exposures taken in September 2004 by the Advanced Camera for Surveys onboard Hubble in four filters. Starlight and dust are seen in blue, visible, and infrared light. Bright star clusters are highlighted in red by their associated emission from glowing hydrogen gas. Due to the galaxy's large size, two adjacent pointings of the telescope were necessary to cover the extent of the spiral arms. The galaxy lies roughly 69 million light-years away (21 megaparsecs) in the direction of the constellation Eridanus.
Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
www.hubblesite.org
译文：
加州圣地亚哥市，美国天文学会今天在会议上公布了一副完整的星系图片，这是由哈勃太空望远镜拍摄制作而成的尺寸最大的图片之一。在这幅高4英尺宽8英尺的图像中，哈勃为我们展示了一个星光闪耀，充满热气体和暗星际尘埃云的棒旋星系NGC1300，这个星系距离我们大约6900万光年（2100万秒差距），位于波江座.
和正常旋涡星系不同，棒旋星系的旋臂连接贯穿星系核的棒壮结构两端，而不直接从星系中心螺旋张开。NGC1300被视为棒旋星系的典型之一。在哈勃太空望远镜的高分辨率下，从该星系的旋臂，星系盘和凸出的星系核中我们可以看到无数前所未见的细节。红超巨星，蓝超巨星，星团和恒星形成区在旋臂中清晰可辨，尘埃带则描绘出了星系盘和旋棒的详细结构，甚至透过致密区域都能看得到众多遥远的背景星系。在NGC1300更大的旋涡星系核中心，显示出长达3300光年（1千秒差距）的独特而明显的大尺度旋涡结构，只有那些拥有大型旋棒的星系，才会表现出星系盘内部的大尺度旋涡结构 — 一个旋涡套着另一个旋涡。模型揭示了旋棒中的气体可以被向内吸入，经过星系盘螺旋进入中心区域，为可能存在该区域的一个黑洞提供动力。
现在已知NGC1300没有活动星系核，不过也有迹象表明没有黑洞，或存在吸积物质。这幅图片由哈勃太空望远镜上的高级巡天照相仪在2004年9月份用四种滤光镜曝光合成，从中可以看到蓝色光，可见光及红外线波段的星光和尘埃。明亮的星团被炽热氢气的伴生辐射照亮成红色。由于NGC1300的直径较大，哈勃太空望远镜必须拍摄一系列相邻的照片以拼接成一个完整的星系图像。 |
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