The life cycle of a neutron star - David Lunney

翻译人员: Christina Wang 校对人员: rong wang

About once every century,

大约每个世纪一次，

a massive star somewhere in our galaxy

在我们银河中的某处 一个巨大的星体

runs out of fuel.

会用光燃料。

This happens after millions of years of heat and pressure

这种情况发生是因为 百万年来的高温与高压

have fused the star’s hydrogen

把星体的氢合成了

into heavier elements like helium, carbon, and nitrogen— all the way to iron.

更重的元素， 像是氦、碳、氮——一直到铁。

No longer able to produce sufficient energy to maintain its structure,

无法再产生足够的能量 来维持其结构，

it collapses under its own gravitational pressure and explodes in a supernova.

星体会因自身的引力坍塌， 爆炸成超新星。

The star shoots most of its innards into space,

星体会将其 大部分的物质射入宇宙中

seeding the galaxy with heavy elements.

把重元素散播到星系中。

But what this cataclysmic eruption leaves behind might be even more remarkable:

不过这剧烈爆炸留下来的东西 可能更惊人：

a ball of matter so dense that atomic electrons

一团物质，其密度高到 原子中的电子

collapse from their quantum orbits into the depths of atomic nuclei.

会从量子轨道坍缩到原子核的深处。

The death of that star is the birth of a neutron star:

这个星体的死亡 成了一颗中子星的诞生：

one of the densest known objects in the universe,

宇宙中已知密度最大的物体之一，

and a laboratory for the strange physics of supercondensed matter.

它还是有关超凝聚体的 奇异物理的实验室。

But what is a neutron star?

但中子星到底是什么？

Think of a compact ball inside of which protons and electrons fuse into neutrons

想象一个紧实的球，在它里面 质子和电子融合成中子

and form a frictionless liquid called a superfluid—

形成一种零摩擦力的流体， 叫做超流体——

surrounded by a crust.

被一层外壳包起来。

This material is incredibly dense –

这种材料有非常高的密度——

the equivalent of the mass of a fully-loaded container ship

相当于把一个满载的货船的质量

squeezed into a human hair,

挤到一根人的头发上，

or the mass of Mount Everest in a space of a sugar cube.

或者把珠穆朗玛峰的质量 挤到一块方糖的大小中。

Deeper in the crust, the neutron superfluid forms different phases

在外壳的更深处，中子超流体 构成不同的形态

that physicists call “nuclear pasta,”

物理学家管它叫“核面食”，

as it’s squeezed from lasagna to spaghetti-like shapes.

因为它被压缩成 千层面到意大利面的形状。

The massive precursors to neutron stars often spin.

中子星巨大的前身通常会旋转。

When they collapse,

当它们坍塌时，

stars that are typically millions of kilometers wide

典型的有几百万公里宽的星体

compress down to neutron stars that are only about 25 kilometers across.

压缩成只有 25 公里宽的中子星。

But the original star’s angular momentum is preserved.

但是原始星体的角动量不会改变。

So for the same reason that a figure skater’s spin accelerates

所以就像花样滑冰运动员

把手臂收进来就能 加速旋转的道理一样，

when they bring in their arms,

the neutron star spins much more rapidly than its parent.

中子星的旋转速度 会比它的母体快很多。

The fastest neutron star on record rotates over 700 times every second,

记录中最快的中子星 每秒会旋转超过 700 次

which means that a point on its surface whirls through space

意味着它的表面上的一个点 在太空中的移动速度

at more than a fifth of the speed of light.

比光速的五分之一还要快。

Neutron stars also have the strongest magnetic field of any known object.

中子星还有 所有已知物体中最强的磁场。

This magnetic concentration forms vortexes

这种磁力的集中会形成漩涡

that radiate beams from the magnetic poles.

它会从磁极发射出光束。

Since the poles aren’t always aligned with the rotational axis of the star,

因为磁极并不一定 和星体旋转轴对齐，

the beams spin like lighthouse beacons,

这些光束会像灯塔指示灯一样旋转，

which appear to blink when viewed from Earth.

从地球看就像是在闪烁。

We call those pulsars.

我们称这些天体为脉冲星。

The detection of one of these tantalizing flashing signals

1967 年天体物理家乔瑟琳 · 贝尔

by astrophysicist Jocelyn Bell in 1967

探测到的这激动人心的闪烁信号

was in fact the way we indirectly discovered neutron stars

实际上是我们最一开始 间接发现中子星的方法。

in the first place.

An aging neutron star’s furious rotation slows over a period of billions of years

衰老的中子星的激烈旋转会 在数十亿年的时间里减慢

as it radiates away its energy in the form of electromagnetic and gravity waves.

因为它以电磁波和引力波的形式 辐射出它的能量。

But not all neutron stars disappear so quietly.

但不是所有中子星 都会这么安静的消失。

For example, we’ve observed binary systems

比如，我们曾经观测到双星系统

where a neutron star co-orbits another star.

其中一颗中子星 和另一颗绕着同一中心。

A neutron star can feed on a lighter companion,

一个中子星可以蚕食轻一点的同伴，

gorging on its more loosely bound atmosphere

吞食它没有紧密吸引住的大气层，

before eventually collapsing cataclysmically into a black hole.

然后最终剧烈坍塌成为黑洞。

While many stars exist as binary systems,

虽然很多星体都存在于双星系统中，

only a small percentage of those end up as neutron-star binaries,

但只有一小部分 会形成中子星双星系统，

where two neutron stars circle each other in a waltz doomed to end as a merger.

其中两颗中子星像 跳着华尔兹一样绕着彼此

直至注定的合并。

When they finally collide, they send gravity waves through space-time

当它们最终相撞，它们会向时空中 发射引力波

like ripples from a stone thrown into a calm lake.

像投进平静湖面的 一块石头造成的涟漪。

Einstein’s theory of General Relativity

爱因斯坦的广义相对论

predicted this phenomenon over 100 years ago, but it wasn't directly verified

一百多年前就预测了这种现象， 但是直到 2017 年

until 2017,

它并未被直接证明，

when gravitational-wave observatories LIGO and VIRGO

当引力波探测器 LIGO 和 VIRGO

observed a neutron star collision.

观测到了中子星碰撞。

Other telescopes picked up a burst of gamma rays and a flash of light,

其他望远镜探测到了 一阵伽玛射线和一道闪光

and, later, x-rays and radio signals, all from the same impact.

之后是 X 射线和无线电信号， 都是从同一个碰撞而来。

That became the most studied event in the history of astronomy.

这变成了天文史上 被研究最多的事件。

It yielded a treasure trove of data

它提供了一众珍贵的数据

that’s helped pin down the speed of gravity,

帮助我们确定了引力的速度，

bolster important theories in astrophysics,

支持天体物理中重要的理论，

and provide evidence for the origin of heavy elements like gold and platinum.

并为像金和铂 这些重元素的来源提供了证据。

Neutron stars haven’t given up all their secrets yet.

中子星还并未吐露出 它们所有的秘密。

LIGO and VIRGO are being upgraded to detect more collisions.

LIGO 和 VIRGO 正在被升级来检测更多碰撞。

That’ll help us learn what else

这会帮助我们了解

the spectacular demise of these dense, pulsating, spinning magnets

这些高密度的、脉动的、旋转的磁铁 壮观的消亡

can tell us about the universe.

还能告诉我们什么 其他关于宇宙的知识。