2010年07月07日04:32
來源：人民網-《人民日報》
宇宙全景新華社巴黎７月５日電 （記者李學梅）歐洲航天局５日宣布，該機構的宇宙探測衛星“普朗克”根據此前收集的數據，繪出了首幅宇宙全景。它將有助於科學家了解宇宙大爆炸后各種天體的形成過程。
歐航局當天發表公報說，這幅圖的珍貴之處在於捕捉到宇宙微波背景輻射，它形成於宇宙大爆炸時期，經過１３７億年的漫長旅行才到達地球，對研究人員而言，它就是研究星系起源的活化石。
圖像正中是地球所在的銀河系，其周圍布滿了冷塵埃形成的纖維狀物質，研究人員分析說，這片區域正是恆星形成的地方，而“普朗克”衛星拍下正在誕生的星體以及尚處在萌芽狀的恆星。
歐航局科學和自動探測負責人戴維·索思伍德認為，“普朗克”衛星為人們開啟了一扇“寶庫之門”，天文學家根據它提供的數據，可以更好地了解宇宙的起源及其現在的運行方式。
http://scitech.people.com.cn/BIG5/12072092.html
我們的宇宙揭露：戲劇性的'全天空照片給出新的線索大爆炸之後發生什麼事
Our Universe revealed: Dramatic 'all-sky' photo that gives new clues about what happened after the Big Bang
By Daily Mail Reporter
Last updated at 2:42 PM on 5th July 2010
This is the oldest light in the Universe.
This incredible image shows the remains of the fireball out of which our Universe sprang into existence 13.7 billion years ago.
It provides scientists with new insight into the way stars and galaxies form but also tells us how the Universe itself came to life after the Big Bang.
It was produced by a European space telescope called Planck and is the mission's first 'all-sky' image which took six months to create.
While the Milky Way shows us what the local Universe looks like now, the microwaves in the background of this image show us what the Universe probably looked like close to its time of creation, before there were stars or galaxies.
The stunning all-sky image taken by Planck is dominated by the brightness from our own Milky Way galaxy由普朗克拍的令人驚嘆全天空圖像，被來自從我們自己的銀河系的亮度所主導
'This is the moment that Planck was conceived for,' says ESA Director of Science and Robotic Exploration, David Southwood.
'We’re not giving the answer. We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our Universe came to be and how it works now.
'The image itself and its remarkable quality is a tribute to the engineers who built and have operated Planck. Now the scientific harvest must begin.'
From the closest portions of the Milky Way to the furthest reaches of space and time, the new all-sky Planck image is an extraordinary treasure chest of new data for astronomers.
The main disc of our Galaxy runs across the centre of the image. Immediately striking are the streamers of cold dust reaching above and below the Milky Way.
This galactic web is where new stars are being formed, and Planck has found many locations where individual stars are edging toward birth or just beginning their cycle of development.
Less spectacular but perhaps more intriguing is the mottled backdrop at the top and bottom. This is the 'cosmic microwave background radiation' (CMBR).
The familiar constellation Orion can be seen in the far-right corner, while the mottled texture of the Universe's background radiation will give astronomers new clues about the formation of the Universe熟悉的獵戶星座可在遠的右下角看到，而宇宙背景輻射的斑駁紋理將給天文學家對宇宙的形成有新的線索
The microwave pattern is the cosmic blueprint from which today's clusters and superclusters of galaxies were built. The different colours represent minute differences in the temperature and density of matter across the sky.
Somehow these small irregularities evolved into denser regions that became the galaxies of today.
The CMBR covers the entire sky but most of it is hidden in this image by the Milky Way's emission, which must be digitally removed from the final data in order to see the microwave background in its entirety.
When this work is completed, Planck will show us the most precise picture of the microwave background ever obtained. The big question will be whether the data will reveal the cosmic signature of the primordial period called inflation.
This era is believed to have taken place just after the Big Bang and resulted in the Universe expanding enormously in size over an extremely short period.
Planck continues to map the Universe. By the end of its mission in 2012, it will have completed four all-sky scans. The first full data release of the CMBR is planned for 2012.
'This image is just a glimpse of what Planck will ultimately see,'says Jan Tauber, ESA's Planck Project Scientist.
http://www.dailymail.co.uk/sciencetech/article-1292104/Our-Universe-revealed-Dramatic-sky-photo-gives-new-clues-happened-Big-Bang.html
宇宙結構進化再揭面紗 首批恆星誕生快於先前預測
2010年07月07日08:38
來源：《科學時報》
在大爆炸后的數億年間，宇宙一片漆黑。大量的熱氫原子與負氫離子遍布在整個宇宙空間。據我們所知，宇宙的形成起始於原子和離子配對生成氫分子，后者將氣體雲中的熱量排出，使它們能夠逐漸冷卻，從而形成第一批行星。
然而分子氫的形成到底需要多長時間？宇宙歷史的這一篇章一直不為人們所知。如今，通過在實驗室中再次還原這些早期氣態雲的化學反應，研究人員終於確定了氫原子與負氫離子在這鍋“原湯”中的結合速度。這一結果為天體物理學家探尋第一批恆星的質量提供了有力支持，將恆星質量評估中的不確定性從20倍降到了2倍。研究人員在7月2日出版的美國《科學》雜志上報告了這一研究成果。
美國哈佛大學的理論物理學家Avi Loeb表示，這項試驗“排除了對第一批氣體雲的化學與冷卻速度的理論模擬的一個最主要的不確定性”。Loeb說，如今，理論學家對於化學反應有了一個更好的理解，他們可以將這些信息輸入計算機模型，從而探究第一批恆星的特性。
文章作者之一、哥倫比亞大學天體物理學實驗室的研究人員Daniel Savin指出，盡管氫原子與負氫離子的結合只是一個“令人驚訝的簡單反應，但對它的理解卻相當匱乏”，這是因為很難在實驗室中生成這兩種元素。為了使這一切成為可能，Savin和他的同事，包括現今在美國伊利諾伊大學厄巴納-香檳分校任職的Holger Kreckel，首次制造出一個負氫離子束，並將其送入一段管道。隨后，這束負氫離子通過一個腔室，在這裡一束激光將7%的負氫離子的額外電子敲掉，從而讓混合的氫原子與負氫離子在管道的更遠處彼此反應。在該儀器的最末端，研究人員統計了這一反應到底生成了多少氫分子。
Savin表示：“結果表明分子氫的形成速度要快於之前的估計。”他說：“這可能也意味著第一批恆星的形成要快於之前的預測。”搞清反應發生的速度是非常重要的，但是還不足以確定第一批恆星的質量。Savin說：“這是因為我們並不確切知道第一批恆星生成時的初始條件，我們還沒有確實地了解質量的分配情況。”
在一篇相關的評論文章中，美國奧斯汀市得克薩斯大學的天體物理學家Volker Bromm寫道，搞清分子氫的形成有多快將幫助科學家模擬第一批恆星的形成，以及宇宙結構隨著時間流逝的進化情況。這是因為第一批恆星的特性、行為和命運會影響隨后發生的宇宙事件，例如原始星系的形成與分布。Bromm寫道：“實際上，這是此項研究非常迷人的一面，微觀物理學進程竟然能夠擁有如此大規模的宇宙學含義。”
（責任編輯：魏艷）
http://scitech.people.com.cn/BIG5/12074226.html
沒有留言:
發佈留言