英语科普小知识 天文学家发现新的超新星

海量资料下载 免费学习英语 www.englishvip.com/xinlw.htm （申请网址） Supernovae were always thought to occur in two main varieties. But a team of astronomers including Carnegie's Wendy Freedman, Mark Phillips and Eric Persson is reporting the discovery of a new type of supernova called Type Iax. This research has been accepted for publication in The Astrophysical Journal.   Previously, supernovae were divided into either core-collapse or Type Ia categories. Core-collapse supernovae are the explosion of a star about 10 to 100 times as massive as our sun. Type Ia supernovae are the complete disruption of a tiny white dwarf.   This new type, Iax, is fainter（微弱的） and less energetic than Type Ia. Although both types come from exploding white dwarfs, Type Iax supernovas may not completely destroy the white dwarf. "A Type Iax supernova is essentially a mini supernova," says lead author Ryan Foley, Clay Fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). "It's the runt of the supernova litter."   The research team--which also included Max Stritzinger, formerly of Carnegie--identified 25 examples of the new type of supernova. None of them appeared in elliptical galaxies, which are filled with old stars. This suggests that Type Iax supernovas come from young star systems.   Based on a variety of observational data, the team concluded that a Type Iax supernova comes from a binary star system containing a white dwarf and a companion star that has lost its outer hydrogen, leaving it helium dominated. The white dwarf collects helium from the normal star.   Researchers aren't sure what triggers a Type Iax. It's possible that the outer helium layer ignites first, sending a shock wave into the white dwarf. Alternatively, the white dwarf might ignite first due to the influence of the overlying helium shell.   Either way, it appears that in many cases the white dwarf survives the explosion, unlike in a Type Ia supernova where the white dwarf is completely destroyed.   The team calculates that Type Iax supernovae are about a third as common as Type Ia supernovae. The reason so few have been detected is that the faintest are only one-hundredth as bright as a Type Ia supernova.   "The closer we look, the more ways we find for stars to explode," Phillips said.   The Large Synoptic Survey Telescope could discover thousands of Type Iax supernovas over its lifetime. 超新星总是被认为是发生在两个主要品种。但一个团队的天文学家，包括卡内基的温迪弗里德曼，马克·菲利普斯和埃里克·佩尔松报告发现了一种新型的超新星称为类型IAX。这项研究已经发 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 在“天体物理学杂志”接受。   此前，超新星被分为两种核心塌缩或Ia型类别。核心坍缩超新星的爆炸我们的太阳质量的恒星大约10到100倍。Ia型超新星是一个很小的白矮星完全中断。   这种新的类型，IAX，是微弱的（微弱的）和比Ia型精力不足。虽然这两种类型的来自爆炸的白矮星，IAX型超新星可能无法完全摧毁白矮星。“IAX A型超新星本质上是一个小型的超新星，”主要作者，粘土哈佛-史密森天体物理中心（CfA）的研究员瑞安福莱说。“这是侏儒的超新星产仔。”   该研究小组 - 其中还包括最大Stritzinger，原卡内基 - 确定了25个新类型的超新星的例子。他们没有出现在椭圆星系，这是充满了年老的恒星。这表明，型的IAX超新星来自年轻恒星系统。   基于各种观测数据，研究小组得出结论，IAX型超新星来自含有一颗白矮星和伴星，已经失去了它的外氢的一个双星系统，把它留给氦为主。收集氦白矮星从正常恒星。   研究人员不知道什么触发型IAX。这可能是外氦层点燃成白矮星，发送一个冲击波。另外，白矮星可能会先点燃由于覆氦外壳的影响。   无论哪种方式，它的出现，在许多情况下，白矮星的生存彻底摧毁白矮星Ia型超新星爆炸，不像。   该小组计算，的IAX型超新星大约三分之一作为常见的Ia型超新星。如此之少的原因已检测是最微弱的只有百分之一明亮的Ia型超新星。   ，“菲利普斯说：”我们期待，更多的方式，我们发现恒星爆炸。   大型综合巡天望远镜可以发现数千的IAX型超新星在其生命周期。 “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务