本帖最后由 gohomeman1 于 2009-12-30 21:27 编辑
In the new ESO image, Barnard’s Galaxy glows beneath a sea of foreground stars in the direction of the constellation of Sagittarius(the Archer). At the relatively close distance of about 1.6 million light-years, Barnard’s Galaxy is a member of the Local Group (ESO 11/96),the archipelago of galaxies that includes our home, the Milky Way. The nickname of NGC 6822 comes from its discoverer, the American astronomer Edward Emerson Barnard, who first spied this visually elusive cosmic islet using a 125-millimetre aperture refractor in 1884.
在欧洲南方天文台（ESO）的新图中，巴纳德星系位于人马座方向银河系无数前景星后方，离我们约160万光年，算是相当的近，是本星系群一员（相关资料参考这个链接：http://www.eso.org/public/outreach/press-rel/pr-1996/pr-11-96.html）。本星系群是包括我们银河系在内的一群宇宙岛的总称。NGC 6822被俗称为巴纳德星系，是为了纪念美国天文学家爱德华.艾默生.巴纳德于1884年，首次用125mm折射望远镜辨析出这个黯淡的宇宙岛。
Astronomers obtained this latest portrait using the Wide Field Imager (WFI) attached to the 2.2-metre MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Even though Barnard’s Galaxy lacksthe majestic spiral arms and glowing, central bulge that grace its big galactic neighbours, the Milky Way, the Andromeda and the Triangulum galaxies, this dwarf galaxy has no shortage of stellar splendour and pyrotechnics. Reddish nebulae in this image reveal regions of active star formation, where young, hot stars heat up nearby gas clouds. Also prominent in the upper left of this new image is a striking bubble-shaped nebula. At the nebula’s centre, a clutch of massive,scorching stars send waves of matter smashing into the surrounding interstellar material, generating a glowing structure that appears ring-like from our perspective. Other similar ripples of heated matter thrown out by feisty young stars are dotted across Barnard’s Galaxy.
天文学家使用安装在2.2米望远镜后的广域相机（WFI）拍摄了这张最新照片，该望远镜是德国马普研究所/ESO共有的，位于智利北部的拉斯拉天文台。尽管巴纳德星系缺少它的那些庞大邻居银河系、仙女座大星系(M31)和三角座星系（M33）等所具有的壮丽旋臂和璀璨的核球，它却不乏恒星焰火效果（星暴现象）。图中泛红的星云透露出活跃的恒星形成区域，在那里年轻的灼热恒星辐射激发了附近的气体云发光。图中左上方就有这样令人瞩目的水泡状星云，在星云中央，一群炽热巨星的恒星风高速冲入周围的星际物质中，从我们远方看来，就激起环形的发光结构。其他由不安分的年轻恒星的高温星风所激起的涟漪点缀在巴纳德星系的各处。
The image was made from data obtained through four different filters(B, V, R, and H-alpha). The field of view is 35 x 34 arcmin.
本图图像合成采用了4个滤光波段（红、绿、蓝和H-α）的数据，图像视场为35X34角分。
At only about a tenth of the Milky Way's size, Barnard’s Galaxy fits its dwarfish classification. All told, it contains about 10 million stars — a far cry from the Milky Way’s estimated 400 billion. In the Local Group, as elsewhere in the Universe, however, dwarf galaxies outnumber their larger, shapelier cousins.
巴纳德星系直径约为银河系的1/10，因此其属于矮星系。它仅包含约1000万颗恒星，远远小于银河系4000亿颗的估计。在本星系群或者宇宙的其他地方，矮星系都多于形状规则的大型星系同辈。
Irregular dwarf galaxies like Barnard’s Galaxy get their random,blob-like forms from close encounters with or "digestion" by other galaxies. Like everything else in the Universe, galaxies are in motion,and they often make close passes or even go through one another. The density of stars in galaxies is quite low, meaning that few stars physically collide during these cosmic dust-ups. Gravity's fatal attraction, however, can dramatically warp and scramble the shapes of the passing or crashing galaxies. Whole bunches of stars are pulled or flung from their galactic home, in turn forming irregularly shaped dwarf galaxies like NGC 6822.
像巴纳德星系那样的不规则矮星系，其星团形成受制于与其他星系的邂逅或者被吞并。就像宇宙中所有物质一样，星系是运动的，它们常常与其他星系擦身而过甚至互相穿过。星系中的恒星密度是相当低的，即使这种碰撞时，由气体尘埃构成的星云会像在，而恒星碰撞相当罕见。期间，万有引力会戏剧性扭曲擦过或碰撞星系的外形，成串的恒星团被抛出或扯出原先的星系，就形成了类似NGC 6822这样的不规则外形。
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