advanced: stellar evolution
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What are Variable Stars?
What if I told you that the “two” stars you see here are actually one and the same? This star, known as L Carinae after its location in the southern constellation Carina, is actually what we call a variable star.…
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Story of a Star Cluster
Meet M13, one of my favorite globular star clusters. M13, also known as Messier 13 or the Hercules Cluster, is found — surprise surprise — in the constellation Hercules in the northern hemisphere. The really cool thing about star clusters…
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What Happens After Helium Fusion?
Back in August — sorry I took so long! — we talked about the helium flash, an explosion that occurs within stars when helium nuclei begin to fuse within a degenerate core. So…this is not what the helium flash would…
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Helium Ignition in Stars
When I first began learning about stars, I expected them to be violent and chaotic places. And to an extent, they certainly are. Pressures are unbelievably high in their cores — high enough to smash protons together, and this is…
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What Happens in an Expanding Star’s Core?
Depending on their mass, stars can remain stable for millions and even billions of years. The most massive stars live for “only” about 10 million years, but models predict that the least massive live for much longer — longer than…
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How a Star Expands
Meet Betelgeuse, a bright star in the winter constellation Orion. Betelgeuse is a cool red supergiant that we’ll talk about a lot more in just a couple weeks, when we cover variable stars. Not too long ago, it was the…
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The Adult Life of a Star
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…
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Stars: The Limits of “Normal”
How big — or small — can a star get? As with most questions in astronomy, the answer to that is not definitive. But stellar models can give us a pretty good idea. Mathematical models of stars tell us that…
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What is a “Normal” Star?
If we were talking about people, I’d say there’s no such thing as a “normal” person. We’re all weird in our own way — that’s what makes us unique and ourselves. However, there’s such a thing as a functional human…
