Name: 宇宙中最大的恆星！比太陽還誇張的尺寸比較 🤯 (The Largest Star in the Universe – Size Comparison)
Uploaded: 2026-01-29T17:06:27.000Z
Duration: 11 min 59 s

What is the largest star in the universe and why is it that large?

宇宙中最大的恆星是什麼？為什麼它會那麼大？

We begin our journey with Earth not to learn anything, just to get a vague sense of scale.

我們從地球開始旅程，不是為了學什麼，只是想對尺度有個大概的概念。

The smallest things that have some star like properties are large gas giants or sub brown dwarfs like Jupiter, the most massive planet in the solar system.

具有一些類恆星特徵的最小天體是大型氣體巨行星，或是像木星這樣的次棕矮星，木星是太陽系中質量最大的行星。

11 times larger and 317 times more massive than Earth.

And more or less made of the same stuff as our sun, just much, much less of it.

而且它們的組成和我們的太陽差不多，只是質量少得多得多。

The transition towards stars begins with brown dwarfs, failed stars that are a huge disappointment to their moms.

邁向恆星的過渡始於棕矮星，這些失敗的恆星讓它們的媽媽們非常失望。

They have between 13 and 90 times the mass of Jupiter.

它們的質量介於木星的13到90倍之間。

So even if we took 90 Jupiters and threw them at each other, although fun to watch, it wouldn't be enough to create a star.

所以，即使我們把90個木星丟來丟去，雖然看著很有趣，但這還不足以形成一顆恆星。

Interestingly, adding lots of mass to a brown dwarf doesn't make it much bigger, just its insides denser.

有趣的是，增加很多質量給棕矮星並不會讓它變大多少，只會讓它內部更密集。

This increases the pressure in the core enough to make certain nuclear fusion reactions happen slowly and the object glow a little.

這會增加核心的壓力，足以讓某些核融合反應緩慢發生，物體也會稍微發光。

So brown dwarfs are a sort of glowy gas giant that don't fit into any category very well.

所以棕矮星有點像是發光的氣體巨行星，不太符合任何類別。

But we want to talk about stars, not failed wannabe stars, so let's move on.

但我們想聊的是恆星，不是那些失敗的準恆星，所以我們繼續往下看。

Main Sequence STAR Once large gas balls pass a certain mass threshold, their cores become hot and dense enough to ignite.

Main Sequence STAR 一旦巨大的氣體球超過一定的質量門檻，它們的核心就會變得夠熱、夠密集，足以點燃。

Hydrogen is fused to helium in their cores, releasing tremendous amounts of energy.

氫會在它們的核心中融合成氦，釋放出巨大的能量。

Stars that do that are called main sequence stars.

進行這些反應的恆星就叫做 main sequence star。

The more massive a main sequence star is, the hotter and brighter it burns and the shorter its life is.

main sequence star 質量越大，燃燒得越熱、越亮，壽命也越短。

Once the hydrogen burning phase is over, stars grow up to hundreds of thousands of times their original size.

一旦氫燃燒階段結束，恆星會膨脹到原本大小的數十萬倍。

But these giant phases only last for a fraction of their lifespan.

但這些巨大的階段只會持續它們壽命的一小部分。

So we'll be comparing stars at drastically different stages in their lives.

所以我們會比較恆星生命週期中，差異非常大的幾個階段。

This doesn't make them less impressive, but

這並不代表它們比較不令人驚豔，但

maybe it's good to keep in mind that we'll be comparing babies to adults.

或許可以記住，我們是在比較嬰兒和成人。

The smallest real stars are red dwarfs, about 100 times the mass of Jupiter, barely massive enough to fuse hydrogen to helium.

最小的真正恆星是 red dwarfs，質量大約是木星的 100 倍，勉強夠質量來將氫融合成氦。

Because they are not very massive, they are small, not very hot, and shine pretty dimly.

因為它們質量不大，所以體積小，溫度不高，而且亮度也很暗淡。

They are the only stars in the main sequence that don't grow once they die, but

它們是 main sequence 中唯一不會在死亡後膨脹，而是

Red dwarfs are by far the most abundant type in the universe.

red dwarfs 是宇宙中最常見的恆星類型。

Because they burn their fuel very slowly.

因為它們燃燒燃料的速度非常慢。

It lasts them up to 10 trillion years, a thousand times the current age of the universe.

它們的壽命可長達 10 兆年，是宇宙現有年齡的一千倍。

For example, one of the closest stars to Earth is a red dwarf star star.

舉例來說，離地球最近的恆星之一就是一顆 red dwarf star。

But it shines too dimly to be seen without a telescope.

但它太暗淡了，沒有望遠鏡根本看不到。

我們做了一整支關於 red dwarfs 的影片。

下一個階段是像我們的太陽一樣的恆星。

To say the sun dominates the solar system is not doing it justice.

說太陽主宰著 solar system 其實還不夠貼切。

Since it makes up 99.86% of all its mass, it burns far hotter and brighter than red dwarfs, which reduces its lifetime to about 10 billion years.

因為它佔了整個 solar system 總質量的 99.86%，燃燒的溫度遠比 red dwarfs 來得高且明亮，這將它的壽命縮短到約 100 億年。

The sun is seven times more massive than Barnard's star, but

太陽的質量是巴納德星的七倍，但

that makes it nearly 300 times brighter with twice its surface temperature.

這讓它的亮度接近 300 倍，表面溫度也高出一倍。

Small changes in mass produce enormous changes in a main sequence star's brightness.

主序星質量的微小差異，會造成亮度上巨大的變化。

The brightest star in the night sky, Sirius, is two solar masses with a radius 1.7 times that of the Sun.

夜空中最亮的恆星天狼星，質量是太陽的兩倍，半徑是太陽的 1.7 倍。

But its surface is nearly 10,000 degrees Celsius, making it shine 25 times brighter.

但它的表面溫度接近攝氏一萬度，亮度是太陽的 25 倍。

Burning that hot reduces its total lifespan by 4 times to 2.5 billion.

燃燒如此高溫，將總壽命縮短了 4 倍，只剩下 25 億年。

Stars close to 10 times the mass of our sun have surface temperatures near 25,000 degrees Celsius.

質量接近太陽十倍的恆星，表面溫度約攝氏兩萬五千度。

Beta Centauri contains two of these massive stars, each shining with about 20,000 times the power of the Sun.

南門二包含兩顆這樣的巨大恆星，每顆都比太陽亮約兩萬倍。

That's a lot of power coming from something only 13 times larger.

這麼大的能量，竟然只來自 13 倍大的體積。

But they'll only burn for about 20 million years.

但它們的壽命只有大約兩千萬年。

Entire generations of these blue stars die in the time it takes the sun to orbit the galaxy once.

這些藍色恆星的整個世代，在太陽繞行銀河系一圈的時間裡就已經消亡了。

The most massive star that we know is R136A1.

我們知道質量最大的恆星是 R136A1。

It has 315 solar masses and is nearly 9 million times brighter than the Sun.

它的質量是太陽的 315 倍，亮度是太陽的近 900 萬倍。

And yet, despite its tremendous mass and power, it's barely 30 times the size of the Sun.

然而，儘管它質量巨大、能量驚人，體積卻只比太陽大約 30 倍。

The star is so extreme and barely held together by gravity that it loses 321,000 billion tons of material through its stellar wind every single second.

這顆恆星極端到幾乎只靠重力維繫，每秒透過恆星風流失 321 兆噸的物質。

Stars of this sort are extremely rare because they break the rules of star formation a tiny bit.

這種恆星極為罕見，因為它們稍微打破了恆星形成的規則。

When supermassive stars are born, they burn extremely hot and bright.

超大質量恆星誕生時，燃燒得極度熾熱且明亮。

And this blows away any extra gas that could make them more massive.

這會吹散任何可能讓它們更巨大的額外氣體。

So the mass limit for such a star is around 150 times the Sun.

所以這種恆星的質量上限大約是太陽的 150 倍。

Stars like R136A1 are probably formed through the merger of several high mass stars in dense star forming regions burn their core hydrogen in only a few million years.

像 R136A1 這樣的恆星，很可能是因為在密集的恆星形成區內，好幾顆大質量恆星合併而成的，它們的核心氫只燃燒了幾百萬年。

So this means they are rare and short lived.

所以這表示它們很稀有，壽命也很短。

From here, the trick to going bigger isn't adding more mass.

從這裡來看，要變得更大，關鍵不在於增加更多質量。

To make the biggest stars, we have to kill them red giants.

要製造出最大的恆星，我們得讓它們變成紅巨星。

When main sequence stars begin to exhaust the hydrogen in their core, it contracts, making it hotter and denser.

當 main sequence star 開始耗盡核心的氫時，核心會收縮，變得更熱、更密集。

This leads to hotter and faster fusion, which pushes back against gravity and makes the outer layers swell in a giant phase, and

這會導致更熱、更快的核融合反應，這會對抗重力，並讓外層膨脹進入巨星階段，

這些恆星確實會變得非常巨大。

For example, only 30% more massive than the Sun.

舉例來說，質量只比太陽多 30%。

It has swollen to about 84 times its radius.

它已經膨脹到大約是原本半徑的 84 倍。

Still, when the sun enters the last stage of its life, it will swell and become even bigger, 200 times its current radius.

不過，當太陽進入生命的最後階段時，它也會膨脹，變得更大，達到現有半徑的 200 倍。

In this final phase of its life, it will swallow the inner planets.

在生命的最後階段，它會吞噬內行星。

And if you think that's impressive, let's finally introduce the largest stars in the universe.

如果你覺得這很厲害，那我們就來介紹一下宇宙中最大的恆星。

Hypergiants are the giant phase of the most massive stars in the universe.

超巨星是宇宙中最巨大恆星的巨星階段。

They have an enormous surface area that can radiate an insane amount of light.

它們有巨大的表面積，可以輻射出驚人的光量。

Being so large, they're basically blowing themselves apart as gravity at the surface is too weak to hold on to the hot mass, which is lifted away in powerful stellar winds.

因為體積太大了，它們基本上是在自我毀滅，因為表面的重力太弱，無法束縛住熾熱的質量，這些質量會以強大的恆星風被帶走。

Pistol star is 25 solar masses, but 300 times the radius of the Sun.

手槍星質量是太陽的 25 倍，但半徑是太陽的 300 倍。

A blue hypergiant, aptly named for its energetic blue starlight.

一顆藍色超巨星，以其充滿活力的藍色星光命名，非常貼切。

It's hard to say exactly how long Pistol Star will live, but probably just a few million years.

很難確切知道手槍星能活多久，但可能只有幾百萬年。

Even larger than the blue hypergiants are the yellow hypergiants.

比藍色超巨星更大的，是黃色超巨星。

The most well studied is Rho Cassiopeia, a star so bright it can be seen with the naked eye.

其中研究得最透徹的是仙后座 ρ 星，這顆星亮到肉眼就看得到。

Although it's thousands of light years from Earth.

At 40 solar masses, this star is around 500 times the radius of the sun and 500,000 times brighter.

這顆恆星的質量是太陽的 40 倍，半徑大約是太陽的 500 倍，亮度則是太陽的 50 萬倍。

If the Earth were as close to Rho Cassiopeia as it is to the sun, it'd be inside it and you would be very dead.

如果地球離仙后座 ρ 星的距離和離太陽一樣近，那地球就會在它裡面，而你早就死透了。

Yellow hypergiants are very rare, though only 15 are known.

黃色超巨星非常稀有，目前只知道有 15 顆。

This means they're likely just a short lived intermediate state as a star grows or shrinks between other phases of hypergiantness.

這表示它們很可能只是恆星在超巨星階段之間成長或縮小過程中的短暫過渡期。

With red hypergiants, we reach the largest stars known to us, probably the largest stars even possible.

說到紅色超巨星，我們就來到了已知最大的恆星，甚至可能是宇宙中可能存在的最大恆星。

So who's the winner of this insane contest?

那麼，這場瘋狂競賽的贏家是誰呢？

Red hypergiants are extremely bright and far away, which means that even tiny uncertainties in our measurements can give us a huge margin of error for their size.

紅色超巨星非常明亮且距離遙遠，這意味著即使我們測量上有一點點不確定性，也可能導致我們對它們大小的估計有很大的誤差範圍。

Worse still, red hypergiants are solar system sized behemoths that are blowing themselves apart, which makes them harder to measure.

更糟的是，紅色超巨星是太陽系大小的龐然大物，它們正在自我解體，這使得測量它們更加困難。

As we do more science and our instruments improve, whatever the largest star is will change.

隨著我們進行更多科學研究，儀器不斷進步，目前最大的恆星也會隨之改變。

The star that is currently thought to be among the largest we've found is Stevenson 218.

目前被認為是我們發現的最大恆星之一是 Stevenson 218。

It was probably born as a main sequence star, a few tens of times the mass of the sun, and

它很可能是一顆 main sequence star，質量是太陽的幾十倍，

has likely lost about half its mass by now.

而且到目前為止，可能已經損失了約一半的質量。

While typical red hypergiants are 1,500 times the size of the Sun.

而一般的紅色超巨星是太陽的 1,500 倍大。

The largest rough estimate places Stevenson 218@2150 solar radii and shining with almost half a million times the power of the Sun.

最大的粗略估計顯示 Stevenson 218 的半徑是太陽的 2150 倍，光度是太陽的近五十萬倍。

By comparison, the sun seems like a grain of dust.

相比之下，太陽看起來就像一粒塵埃。

Our brains don't really have a way of grasping this kind of scale.

我們的大腦其實無法真正理解這種尺度。

Even at light speed, it would take you 8.7 hours to travel around it.

即使以光速旅行，繞著它一圈也需要 8.7 小時。