天文学家目睹中子星逃离银河系

环球科学编译

翻译  Steed


        
    利用NASA的钱德拉X射线天文卫星，天文学家发现一颗中子星正在高速逃逸，就像一颗被击球手强力击出的棒球。这颗中子星似乎是一场不对称的超新星爆炸的结果，它正以超过480万千米/小时的速度逃离银河系。它注定会逃出银河系，一去不复返。



    这颗中子星位于一个名叫船尾座A的超新星遗迹之中。天文学家认为，这个超新星遗迹是在大约3,700年前诞生的，当时一颗大质量恒星在一场超新星爆炸中分崩离析。不过与通常的对称爆炸不同，这颗恒星的爆炸是不对称的。一大团物质被炸向某一个方向，于是恒星爆炸产生的中子星就被炸向了相反的方向——就像天然形成的火箭一样。





    1999年12月，天文学家测量了这颗中子星的位置，2005年4月又再次进行了测量。根据它在这段时间内的移动的距离，天文学家可以精确计算出它的速度。这颗中子星的速度如此之快，本来应该很容易发现它的移动，但是这颗中子星距离地球非常遥远（超过7000光年），从地球上看过去，它的位移就变得非常细微。事实上，钱德拉X射线天文卫星能够测量出这个位移实属不易。






    在这张中子星附近区域的光学/X射线合成照片上，可以清楚地看到一大团氧气体云正在飘离天文学家认定的爆炸中心。这团气体云移动的方向与中子星的逃逸方向相反。



    船尾座A的中子星给天文学家留下了一个谜团。即使是最精巧、最复杂、最成熟的超新星爆炸模型，也无法解释这颗恒星的速度和它所发出的辐射。



    美国佛蒙特州米德尔布里学院（Middlebury College）的弗兰克·温克勒（Frank Winkler）说：“这颗‘宇宙炮弹’给我们带来的困扰在于，我们不知道怎么解释那门‘宇宙大炮’为什么会有如此巨大的威力。也许一场能量高得异乎寻常的爆炸可以解释这样的高速度，但那种模型太过复杂，很难套用到真实的恒星爆炸之中。”

有没有轨道预测呢？

不知道，好像没说。原文地址可以去看一下http://www.sciam.cn/article.php?articleid=1697

原帖也没有关于轨道预测的报道，观测都那么困难轨道预测就更难了吧

在钱德拉X射线空间望远镜网站找到原文了:http://chandra.harvard.edu/photo/2007/puppis/


    这是部分原文: This graphic shows a wide-field view of the Puppis A supernova remnant along with a close-up image of the neutron star, known as RX J0822-4300, that is moving at a blistering pace. The larger field-of-view is a composite of X-ray data from the ROSAT satellite (pink) and optical data (purple), from the Cerro Tololo Inter-American Observatory 0.9-meter telescope, which highlights oxygen emission. Astronomers think Puppis A was created when a massive star ended its life in a supernova explosion about 3,700 years ago, forming an incredibly dense object called a neutron star and releasing debris into space.

      
The neutron star was ejected by the explosion. The inset box shows two observations of this neutron star obtained with the Chandra X-ray Observatory over the span of five years, between December 1999 and April 2005. By combining how far it has moved across the sky with its distance from Earth, astronomers determined the cosmic cannonball is moving at over 3 million miles per hour, one of the fastest moving stars ever observed. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far.
   

       The results from this study suggest the supernova explosion was lop-sided, kicking the neutron star in one direction and much of the debris from the explosion in the other. The estimated location of the explosion is shown in a labeled version of the composite image. The direction of motion of the cannonball, shown by an arrow, is in the opposite direction to the overall motion of the oxygen debris, seen in the upper left. In each case, the arrows show the estimated motion over the next 1,000 years. The oxygen clumps are believed to be massive enough so that momentum is conserved in the aftermath of the explosion, as required by fundamental physics.

原帖也没有关于轨道预测的报道，观测都那么困难轨道预测就更难了吧    是啊