NASA/ESA哈勃空间望远镜，利用天然的放大“变焦透镜”，已经掌握了关于一个拥有有意义红移值超7的遥远星系最强有力的证据。
这个星系好象是至尽看到的从宇宙“黑暗时代”以来最年轻，最明亮的星系之一，仅仅在宇宙诞生后7亿年就形成了（红移7.6）
来自哈勃近红外波段照相机和NICMOS的细节照展现了一个婴儿星系，被称为A1689-zD1，经历了作为来自黑暗时代的恒星诞生的大火之后，一个在宇宙大爆炸后不久的时段，但又是在第一个恒星完成寒冷的再加热之前，黑暗宇宙。来自NASA的SPITZER空间望远镜的红外照相机拍摄的图片提供了附加的证据证明年轻的恒星-在黑暗时代就构成了星系。
“我们理所当然的惊讶于找到130亿年前这么年轻的亮星系”加利福尼亚大学的Garth Illingworth天文学家、圣克鲁斯和一位研究小组成员说到。这是一张到目前为止最富细节的图片。
通过作者了解，这个测量结果是非常可靠的。“这个物体是迄今为止最有实力的一位最遥远星系的候选者”来自ESO的小组成员Piero Rosati（德国人） 陈述到。
“哈勃在对于星系结构高洞察力的出图效率上是其他任何望远镜不能媲美的”来自加利福尼亚大学的天文学家Rychard Bouwens和Santa Cruz，另一位星系的发现者说到。
一张新图要能够提供在星系形成的时间和演化的和更多关于这个天体类型等足以用来出版黑暗时代终结的信息。在剩余的时间里，哈勃望远镜已经被前所未有过的被注视着，观察星系在年轻阶段的演化。这些快照已经帮助天文学家制作了一本关于星系从婴儿期到成年期的杂项集。哈勃和SPITZER新拍的A1689-zD1 展示了星系在其婴儿期的一个时间状态。
最近的理论表明黑暗时代开始于大爆炸后的400000年，根据宇宙膨胀冷却和星云中冷氢的形成。这些寒冷的星云象雾一样遍及宇宙。在这个纪元的一些关键时刻，恒星和星系开始形成了。他们集合的光加热和清洁了冷氢云，并在大爆炸的10亿年后结束了黑暗时代。
“这个星系大概是在黑暗时代结束时被保留下来众多星系中的一个”Johns Hopkins大学的天文学家Larry Bradley和研究组中主持人说到。天文学家完完全全的确定高能天体象类星体这样的并不能提供足够的能量结束宇宙的黑暗时代。但是许多拥有年轻恒星的星系可以产生足够的能量去结束他
星系太过遥远以至于无法在可见光波段被哈勃先进的测量照相机拍摄到，因为由于宇宙膨胀他的光波已经伸长红外波段。他利用哈勃的NICMOS，SPITZER和一个自然小技巧被叫做引力透镜才观察到了这么遥远的星系。
天文学家通过附近巨大星系团的比较粗略的得知Abell 1689的距离为22亿光年，把来自其后面更遥远星系的光直接放大。这个天文的望远镜就是引力透镜。Abell 1689是最引人注意的引力望远镜中的一个，他的引力特性已经被非常好的了解到。
The NASA/ESA Hubble Space Telescope, with a boost from a natural "zoom lens", has found the strongest evidence so far for a galaxy with a redshift significantly above 7.
It is likely to be one of the youngest and brightest galaxies ever seen right after the cosmic "dark ages", just 700 million years after the beginning of our Universe (redshift 7.6).
Detailed images from Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) reveal an infant galaxy, dubbed A1689-zD1, undergoing a firestorm of star birth as it comes out of the dark ages, a time shortly after the Big Bang, but before the first stars completed the reheating of the cold, dark Universe. Images from NASA's Spitzer Space Telescope's Infrared Array Camera provided strong additional evidence that it was a young star-forming galaxy in the dark ages.
"We certainly were surprised to find such a bright young galaxy 13 billion years in the past", said astronomer Garth Illingworth of the University of California, Santa Cruz, USA and a member of the research team. "This is the most detailed look to date at an object so far back in time."
According to the authors, the measurements are "highly reliable". "This object is the strongest candidate for the most distant galaxy so far", states team member Piero Rosati from ESO, Germany.
"The Hubble images yield insight into the galaxy's structure that we cannot get with any other telescope," added astronomer Rychard Bouwens of the University of California, Santa Cruz, one of the co-discoverers of this galaxy.
The new images should offer insights into the formative years of galaxy birth and evolution and yield information on the types of objects that may have contributed to ending the dark ages. During its lifetime the Hubble telescope has peered ever farther back in time, viewing galaxies at successively younger stages of evolution. These snapshots have helped astronomers create a scrapbook of galaxies from infancy to adulthood. The new Hubble and Spitzer images of A1689-zD1 show a time when galaxies were in their infancy.
Current theory holds that the dark ages began about 400,000 years after the Big Bang, as matter in the expanding Universe cooled and formed clouds of cold hydrogen. These cold clouds pervaded the Universe like a thick fog. At some point during this era, stars and galaxies started to form. Their collective light heated and cleared the fog of cold hydrogen, and ended the dark ages about a billion years after the Big Bang.
"This galaxy presumably is one of the many galaxies that helped end the dark ages", said astronomer Larry Bradley of Johns Hopkins University in Baltimore, USA, and leader of the study. "Astronomers are fairly certain that high-energy objects such as quasars did not provide enough energy to end the dark ages of the Universe. But many young star-forming galaxies may have produced enough energy to end it."
The galaxy is so far away it did not appear in visible light images taken with Hubble's Advanced Camera for Surveys, because its light is stretched to infrared wavelengths by the Universe's expansion. It took Hubble's NICMOS, Spitzer and a trick of nature called gravitational lensing to see the faraway galaxy.
The astronomers used a relatively nearby massive cluster of galaxies known as Abell 1689, roughly 2.2 billion light-years away, to magnify the light from the more distant galaxy directly behind it. This natural telescope is a gravitational lens. Abell 1689 is one of the most spectacular gravitational telescopes known and its gravitational properties are very well known.
自翻+3大图
URL：http://spacespin.org/article.php ... zer-galaxy-distance
Credit: NASA; ESA; L. Bradley (Johns Hopkins University); R. Bouwens (University of California, Santa Cruz); H. Ford (Johns Hopkins University); and G. Illingworth (University of California, Santa Cruz).
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Credit: NASA, ESA, and G. Bacon (Space Telescope Science Institute).
4000*3000
Credit: NASA, ESA, and A. Feild (STScI)
3000*1977
[ 本帖最后由 江涛 于 2008-2-24 19:07 编辑 ] |
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置顶卡
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千斤顶
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江兄又有出手了
这么漂亮的大图前两天居然没看见
好！
