CNO cycle

How Massive Stars Die

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When people think of star death, they most often think of supernovae (plural for supernova). So why haven’t I spent the past bunch of posts on star death talking about them?

Because supernovae are not actually the most common fate to await a star. Only a small fraction of the stars in our universe are massive enough to go supernova. Most stars die fairly quietly, gently expelling their outer layers and contracting to form white dwarfs.

No such gentle fate awaits the most massive stars.

But why do massive stars go supernova?

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What About Binary Systems?

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In the constellation of Perseus, there is a star named Algol that exists in a binary system. The binary consists of two stars: a massive main-sequence star and a less massive giant.

According to what we’ve explored so far…that doesn’t make any sense.

More massive stars evolve faster than less massive ones. They expand into giants before less massive stars do. In any one binary system out there, we should observe a more massive giant and a less massive main-sequence star, not the other way around.

But the Algol system is not alone in this peculiarity. Over half the stars in the universe are binaries, and in a number of those, the more massive star is still on the main sequence.

Why?

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The Adult Life of a Star

/ Emma / 1 Comment

Stars are like cars. They need fuel to go. And also like cars, they don’t have an infinite supply.

But here’s where the metaphor breaks down. They can never refuel.

Yup. That’s right. For their entire lives, stars are stuck with only the amount of fuel they formed with. They can’t get more.

What happens when you’re driving, and you run out of gas?

Well, if you can’t refuel, you’re gonna have to call a tow truck. But stars don’t have tow trucks, and for them, it’s not a matter of moving or not—it’s a matter of life and death, such as it is.

But how does that work?

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What Goes On Inside a Star?

/ Emma / 5 Comments

Our sun is undoubtedly the star we know the best. It’s only 93 million miles away—which might seem far, but isn’t that large a distance when you realize that the nearest neighboring star is a whole 4.3 light-years away.

As in, it takes light—yeah, that same stuff that hits the ground from your flashlight in a split second—a whole 4.3 years to get here.

We’re pretty familiar with our star’s interior. We know it produces most of its energy in its core, a relatively small but very hot region at its center. We also know that energy then radiates outward until it hits the convective layer.

There, the energy gets stuck in circulation for a bit until it finally manages to leave the sun’s surface.

But…how normal is that? Is it the same for all stars, or just the sun?

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