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Black Holes Trigger Stars to Self-Destruct

Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close．The black hotels gravity pulls harder on the nearest part of the star，an imbalance that pulls the star apart over a period of minutes or hours，once it gets close enough．

Scientists say this Uneven pulling is not the only hazard facing the star．The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within．Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon，F(xiàn)rance1,carried out computer simulations of the final moments of such an unfortunate star’s life，as it veered towards a supermassive black hole．

When the star gets close enough，the uneven forces flatten it into a pancake shape．Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart．But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur．

The new simulations investigated the effects of shock waves in detail，and found that even when their effects are included，the conditions favor a nuclear explosion．“There will be an explosion of the star — it will be completely destroyed,” Brassart says． Although the explosion obliterates the star，it saves some of the star’s matter from being devoured by the black hole．The explosion is powerful enough to hurl much of the star’s matter out of the black hole’s reach，he says．

The devouring of stars by black holes may already have been observed，although at a much later stage．It is thought that several months after the event that rips the star apart，its matter starts swirling into the hole itself．It heats up as it does so，releasing ultraviolet light and X-rays．

If stars disrupted near black holes really do explode，then they could in principle allow these events to be detected at a much earlier stage，says Jules Hatpern of Columbia University in New York，US2．“It may make it possible to see the disruption of that star immediately if it gets hot enough,” he says．

Brassart agrees．“Perhaps it can be observed in the X-rays and gamma rays，but it’s something that needs to be more studied,” he says．Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos，New Mexico，US3，says the deaths of these stars are difficult to simulate，and he is not sure whether the researchers have proven their case that they explode in the process．

詞匯：

supermassive adj．特大質(zhì)量的

imbalance/im5bAlEns/n．不平衡，不平衡

veer/ viE/v．轉(zhuǎn)向，改變方向

flatten/5flAtn/v．使成扁平，夷平

pancake/5pAnkeik/n．薄煎餅

obliterate/E5blitEreit/v．抹去，除去，消除

devour/di5vauE(r)/v．吞沒；毀滅

swirl/swE:l/打旋，旋動

gamma rays γ 射線

supernova/7sju:pE5nEuvE/n．超新星

注釋：

1． the Observatoire de Paris in Meudon，F(xiàn)rance：位于法國默頓的巴黎天文臺。Observatoire de Paris：法文，即observatory of Paris。默頓位于巴黎西南部郊區(qū)。

2． Columbia University in New York，US：美國紐約哥倫比亞大學(xué)，長青藤聯(lián)盟校之一。創(chuàng)建于1756年，當(dāng)時名為“國王學(xué)院”。美國獨(dú)立后，為了紀(jì)念發(fā)現(xiàn)美洲新大陸的哥倫比亞就改為哥倫比亞學(xué)院，直到1921年成為一所綜合大學(xué)。1897年，該校遷址曼哈頓上城區(qū)校區(qū)。

3． the Los Alamos National Laboratory in Los Alamos，Mexico，US：位于美國新墨西哥州洛斯阿拉莫斯的洛斯阿拉莫斯國家實驗室。洛斯阿拉莫斯是世界上第一顆原子彈和第一顆氫彈的誕生地，它占地110平方公里，擁有1萬多名雇員，其中研究人員3 500名。

練習(xí)：

1． Something destructive could happen to a star that gets too close to a black hole．Which of the following destructive statements is NOT mentioned in the passage?

A The black hole could tear apart the star．

B The black hole could trigger a nuclear explosion in the star．

C The black hole could dwindle its size considerably．

D The black hole could devour the star．

2． According to the third paragraph，researchers differed from each other in the problem of

A whether nuclear reaction would occur．

B whether the stars would increase its density and temperature．

C whether shock waves would occur．

D whether the uneven forces would flatten the stars．

3． According to the fourth paragraph，which of the following is NOT true?

A No nuclear explosion would be triggered inside the star．

B The star would be destroyed completely．

C Much of the star’s matter thrown by the explosion would be beyond the black hole’s reach．

D The black hole would completely devour the star．

4． What will happen several months after the explosion of the star?

A The star’s matter will move further away from by the black hole．

B The black hole’s matter will heat up．

C The torn star’s matter will swirl into the black hole．

D The black hole’s matter will release ultraviolet light and X-rays．

5． According to the context，the word “disruption” in Paragraph 6 means

A “Confusion．”

B “Tearing apart．”

C “Interruption．”

D “Flattening．”

答案與題解：

1． C 短文的第一和第二段提供了答案。第一段第一句說，特大質(zhì)量的黑洞能夠撕裂靠近它們的恒星；第二段的第二句說，由于它們之間力量的懸殊，恒星內(nèi)部會發(fā)生核爆炸。第五段提及黑洞吞噬恒星的問題。C的內(nèi)容文章中沒有找到，所以應(yīng)該選擇C。

2． A 該段告訴我們，兩種研究的焦點(diǎn)在于是否會引起核爆炸。所以，A是正確選擇。

3． D 第四段告訴我們，模擬實驗發(fā)現(xiàn)，整個的條件會引起核爆炸，這將徹底毀滅恒星，但恒星的一些物質(zhì)會被強(qiáng)力的爆炸拋出黑洞。所以，A、B、C三個選擇的內(nèi)容都是正確的說法，而D不是。

4． C 第五段中its matter starts swirling into the hole itself，這里的its matter指的是the star’smatter，即被爆炸拋出黑洞的恒星物質(zhì)。所以應(yīng)選C。

5． B 根據(jù)全篇語境，disruption在這里的意思是第一段提到的tearing apart。