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职称英语理工类考试考前每日一练 Black holes trigger stars selfdestruction Scientists have long understood that supermasvive black holes weighing.Millions or billions of suns can tear apart stars that come too close.The black holegravity pulis harder on the neatest 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 JeanPierre Luminet of the Observatoire of the Paris in Meudon，France，carried out computer simulations of the final moments of such an unfortunate stars 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 he complicated by shock waves generated during the flattening process and that not nuclear explosion should occur. The new simulations investigated the effects of shock waves in detail.and fund 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 de- | 
