Blue Snowball 蓝雪球

Amateur Astronomer - - 宇宙奥秘 -

Andromeda is best known for a single object — the Andromeda galaxy, M31. But that’s not the constellation’s only good “deep-sky” object. One of them is inside our own galaxy: a dying star known as the Blue Snowball Nebula. 仙女座因其独一无二的仙女座大星云M31而知名。但M31并不是仙女座中唯一很棒的深空天体。其中一个是在我们自己的星系内部,一颗被称为“蓝色雪球星云”的垂死恒星。 Even though it’s much closer than the Andromeda galaxy, the Snowball is still a good jaunt from Earth — about 4,000 light-years. It’s a bubble of gas and dust expelled by a dying star. 尽管它比仙女座更近,从地球到“雪球”仍是一次不错的短途旅行,大约有4000光年。它是由一颗垂死的恒星排出的气体和尘埃组成的气泡。 The star’s nuclear reactor — its hot core — is switching off. The core is blowing away the star’s outer layers. That bubble spans about a quarter of a light-year, and it’s expanding at about 60,000 miles per hour. The gas is “energized” by ultraviolet light from the core, causing it to glow. Seen through a telescope, the object looks like a blue snowball. 这颗恒星的核反应区域——它炽热的内核——正在关闭。内核正在将恒星的外层吹走。这个气泡的跨度大约有四分之一光年,并且正以每小时约6万英里的速度膨胀着。这些气体被来自内核的紫外线激发,使其发光。通过望远镜观测,这一天体看起来就像是一个蓝色的雪球。 With the outer layers barreling away from it, the core is exposed to view. It’s tiny — only about one-tenth the diameter of the Sun. But it’s much, much hotter than the surface of the Sun, so it shines more than a thousand times brighter. 外层快速移动离开核心,核心就会暴露在视线中。它很小,直径只有太阳的十分之一。但是它比太阳表面要热得多,所以它的亮度要比太阳亮一千倍。 Before long, though, the core’s nuclear fire will be extinguished. The core will continue to shine, but at a tiny fraction of the Sun’s brilliance. Without a strong energy source to light it up, the blue snowball will melt away. 不久之后,内核的核反应将会熄灭。内核还会继续发光,但只有太阳光辉的很小一部分。没有强大的能量来源来点亮它,蓝色的雪球就会融化而消失掉。

上图画面天空中部模糊的光斑就是M 31,它是我们肉眼能看见的最遥远的天体。M 31也被称为仙女座大星云,仙女座因为M 31而备受观测者的青睐。除了M 31,仙女座中也有其他有趣的天体,我们文中讲述的蓝雪球就是其中之一。图片来源:C ristian Fattinnanzi.

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