Sun Solar Flare Particles coronal mass ejections

恒星的生命周期:如何将我们的太阳能系统m end?

太阳在大约46亿年前形成，将在其当前状态下生存，大致说明了另外4.5至55亿年。尽管我们无法预测未来数十亿年的情况，但了解星星如何发展使天文学家能够广泛推断出太阳的生活可能如何发挥作用。更大的明星可能会在被称为超新星的爆炸中结束他们的生命，但这并不是我们自己的可能的情况。

1. Hydrogen-burning phase

Every secondthe Sun将6亿吨的氢转化为400万吨能量：其余的氢将转换为氦气“灰”。在整个生命中，太阳的能源产量一直在增加，并且据认为在成立以来的46亿年中，它的增长幅度增长了30％。在接下来的十亿年中，随着越来越多的氢转化为氦气，太阳将获得约10％的亮度，从而导致热能增加。如果我们考虑人工制造的效果climate change已经有了我们星球的天气模式，想象一下这样的增加的效果。

不断上升的温度将导致极地冰帽tart to melt and the oceans to warm, sending water vapour into our atmosphere. That water vapour will trap more heat, creating a ‘moist greenhouse’ effect that will raise global temperatures even higher. About 3.5 billion years from now, the Sun will be 40 per cent brighter than it is today, causing our oceans to boil, the ice caps to melt completely and our atmosphere to be stripped away. Earth will become likeVenus：灼热，干旱和毫无生气。

阅读更多：

2.次级阶段

尽管这种情况令人恐惧，但这只是太阳灭亡的开始。从现在起约50亿年，太阳将达到其寿命的主要顺序的末端，并将用尽其核心中的所有氢。

With nofusion process反对gravity, the core will begin to contract and become denser over time. As it does so, its temperature will rise and eventually ignite the remaining hydrogen lying outside the core.

This new source of fuel will generate enormous amounts of energy that will push the outer layers outwards, causing the Sun to expand two to three times its current diameter, turning it into a subgiant star.

Artists illustration of the Sun dying — Illustration of a view from Earth as the Sun dies in around 5 billion years time © Detlev Van Ravenswaay/Science Photo Library

3. Red Giant Phase

As the surface layers of the Sun are pushed further out, they will continue to trap heat from the dense core buried deep within this ever-expanding shell, and the star will develop into a huge, luminous object called a red giant.

These ageing stars can reach sizes between 100 to 1,000 times that of the Sun, and the expanding surface area will cause the temperature of the outer layers to cool to about 3,000°C (the surface of the Sun is around 5,500°C today). The cooler temperature means these stars shine in the redder part of the colour spectrum; hence the name ‘red giant’.

随着太阳经历这一过程，它将延伸到汞和金星的内行星的轨道上，完全吞没它们，甚至可能到达地球的轨道路径。但是，我们的家园可能不会被彻底摧毁，因为在这次膨胀期间，太阳将继续失去质量：一些估计表明，在其最大的情况下，可能只剩下65％至70％。

The gravitational pull will consequently be weakened and the orbits of the remaining planets in the Solar System will begin to drift outwards. Perhaps Earth will make a lucky escape. All the while, the Sun’s core will get smaller and hotter, until 12 billion years after its formation, a new nuclear reaction will occur.

Could we exist on Earth under a red giant star?

4. A new red giant

核心将继续收缩，直到温度达到约1亿°C - 热足以点燃消耗氢的氦气并将其转化为碳和氧气。由于密集的核心将无法扩展以允许增加能量输出，因此氦气将以强烈的凶猛燃烧，从而产生短暂的爆炸，称为“氦闪光灯”。这将降低核心的密度并带来暂时的稳定性，因为氦现在将能够以更控制的速率燃烧。

However, it won’t take long for the new fuel source to be used up; just 100 million years or so. As the helium continues to burn it will generate fierce energy and, just as with the burning of hydrogen, this will cause the Sun to expand once more into a second red giant phase.

5. Planetary nebula

Despite all the expansion and contracting, the loss of mass and the consumption of fuel, the life cycle of the Sun isn’t finished just yet. The red giant will continue to convert helium into carbon and oxygen, yet the core will never reach the 600 million°C required to ignite that carbon, so it will begin to contract once more.

As the helium is used up, the outer layers will be pushed further out and lost to space so that, about 12.5 billion years after its formation, half of the Sun’s mass will remain. The expanding outer layers will be illuminated by the hot core within, creating a glowing cosmic cloud known as a ‘planetary nebula’.

这些现象是天文学家众所周知的，并且是我们太阳质量的衰老之星的典型代表，但与行星无关。他们的名字仅仅是他们圆形膨化形状的结果。

6. White dwarf

With the outer layers of the Sun having finally dissipated, all that will remain is a hot, dense core known as a白矮星。这些物体是宇宙中最浓的，但通常比我们自己的星球大一点。然而，它们可以达到超过100,000°C的温度。

Southern Ring Nebula (MIRI Image) — At the centre of the Southern Ring Nebula is a hot, dense white dwarf star. As it transformed into a white dwarf, the star periodically ejected mass – the shells of material you see here. © NASA/ESA/CSA/STScI

整个太阳衰老过程中核心产生的大部分热量都将被困在这一恒星残留物中，它将需要数十亿甚至数千亿年才能使其冷却。

7.黑矮人

The white dwarf remnant will eventually expend all its remaining heat and light energy and (perhaps in hundreds of billions of years) fade into its final stage: that of a lifeless black dwarf. Currently, black dwarfs are merely hypothesised because the Universe, aged at 13.8 billion years, is not yet old enough to have created any, but it is thought that this will be the final fate of our Sun.

好像要使故事变得更加悲惨，我们曾经强大的明星的低质量将失去其大部分引力吸引力，从而导致行星漂流到更远的地方，只不过是冷冻，烧焦的岩石。

But, as the remnants of our Solar System are lost to space, particles from our own dead Sun could coalesce and begin the process of star formation anew. This may result in the formation of planets with rocky bodies, atmospheres and liquid water primed for new life.