Some Stars Explode As They Die. We Look At Their Life Cycle - podcast episode cover

Some Stars Explode As They Die. We Look At Their Life Cycle

Jun 25, 202415 minEp. 1083
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Episode description

This summer, scientists have their eyes and telescopes trained on the small constellation system T Coronae Borealis. They think it will explode as part of a periodic nova — a once-in-a-lifetime event according to NASA scientists. And so, with the help of astrophysicist Sarafina El-Badry Nance, we continue our journey farther and deeper into spacetime with a look at the stars: How they're born and how they die. Sarafina has always been drawn to one particular star: Betelgeuse, a red supergiant in the shoulder of the constellation Orion that is nearing the end of its life. What stages of life did Betelgeuse — or any star — go through before it reached this moment?

This episode is part of our series Space Camp — all abut the weird, wonderful phenomena in our universe. Check it out here: https://npr.org/spacecamp

Curious about the night sky? Email us at [email protected] — we'd love to hear from you!

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Transcript

This Message Comes From NPR Sponsored Green Light Want to Teach Your Kids Financial Literacy? With Green Light, Kids and Teens Use A Debit Card Of Their Own While Parents Can Keep an Eye in Kids Spending In Savings in the App. Get Your First Month Free at Greenlight.com slash NPR. This Message Comes From NPR Sponsored Grammarly You Use Multiple Platforms Every Day at Work. Writing is Involved For Most Of Them. That's why Grammarly Works Where You Work. 96% of Grammarly Users Say It Helps Them Create More Impact

It Works Across 500,000 Apps and Websites With One Click Go From Editing Drafts and Hours to Seconds. Sign Up and Download For Free at Grammarly.com slash podcast. That's g-r-a-m-m-a-r-l-y.com slash podcast. Easy Year Said? Done. You're Listening To Short Wave From NPR. Hey, it's Regina Barber, your resident astrophysicist. Here with the next installment of Space Camp, all about the life and death of stars. And this summer in particular is a very exciting time to keep your eyes on the stars.

That's because T. Corona Borealis, a star that's usually invisible to the naked eye, is set to experience a Nova event anytime between now and September. Up close, it's a thermal nuclear explosion. Kind of like a hydrogen bomb. But here on Earth, it'll look like a bright new star appearing out of nowhere. T. Corona Borealis is a recurrent Nova, which means that flare is up repeatedly, but doesn't completely destroy itself in the process.

The last time we saw a flare-up was almost 80 years ago, in 1946. But humans have been watching other stars explode for much, much longer. So humans have seen stars exploding with the naked eye for centuries. And there are records of these explosions. Some of them are literally etched into cave drawings. Some of them are on old records. It's, I mean, it's remarkable to see how civilizations, even at that point, have a record of exploding stars.

That's Sarah Fina El-Baudry-Nance. She's an astrophysicist and an expert in supernovas, the final destroying explosion of massive stars. And she studies one star in particular, Beetlejuice. It's the upper left shoulder of Orion. It is a red supergiant, so it literally looks red to the naked eye, which makes it really easily found when you're looking for the star. And it's particularly interesting because it is very close, and it is nearing the end of its life when it will explode as a supernova.

If you're looking up at Beetlejuice, coming to the end of its life, you might wonder, how did it get there? What stages of life does a star go through before it dies? The life cycle of a star is primarily determined by the mass of the star. So low mass stars have very different fates than high mass stars do. A low mass star, star smaller than our sun, will live longer than high mass stars, like Beetlejuice. It's kind of like dogs. Smaller dogs tend to live longer than big ones.

And these really massive stars explode at the end of their lives. But don't worry. Our sun is not massive enough to explode at the end of its life. Instead, it will sort of get really big as a red giant, and then we'll fizzle out into what we call a white dwarf. So today on the show, it's a star party. Seraphine and I walk you through three constellations as we journey through the life of a star. I'm Regina Barber, and you're listening to Shortwave, the science podcast from NPR.

This message comes from NPR sponsor, the Nature Conservancy, dedicated to addressing climate change and species loss for humanity. By working across communities, oceans, and ills, the Nature Conservancy is delivering solutions for the planet and building a future where people and nature thrive. The Nature Conservancy, together we find a way. Learn more at nature.org slash solutions.

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In a hurry, choose grab and go favorites like picnic salads and sushi plus plenty of cooler friendly beverages, make it a hot grill summer at Whole Foods Market. This episode is brought to you by Synchrony Bank. There's talking about saving, and there's doing it. Synchrony Bank empowers you to tackle your savings goals with a newsworthy 4.75% APY on their high yield savings account. Enjoy flexible access to your money and knowing it's earning a great rate. With no monthly fees or minimums,

it's never been easier to take control of your financial future. Go to Synchrony Bank dot com slash NPR. Remember FDIC. Okay, Sarah Fina, let's start with the beginning of a star's life. How are stars born? So basically stars are born in these stellar nurseries that we call giant molecular clouds. And they're sort of like the cradles of newborn stars. And basically there are regions of gas and dust that clump together because of gravity.

And as the density of these regions pulls more and more gas and dust towards it, that pressure can cause them to collapse under their own weight and create what we call a proto star, which is sort of the nascent star. And then over the course of millions of years, the proto stars will sort of settle down and ignite fusion in their cores, which sort of sets the star on its life cycle as a real main sequence star or hydrogen burning star.

Right. So in order for something to even be a star at all, like nuclear fusion has to happen, right, turning hydrogen into helium in its core. Right, exactly. Once it ignites hydrogen, the star becomes quote unquote alive. Nuclear fusion is the lifeblood of a star. And basically what happens in the cores of stars is that elements and molecules collide with each other.

And create heavier and heavier elements as they do so. And their energy is released in the form of light that sort of shines through the star and that we see as star light or in the case of our sun sunlight. So that nuclear fusion basically sets the tone of the star and that nuclear fusion ignites once the star transitions from a proto star to a main sequence star. Once stars start to fuse those elements in their core, they wink into existence. And this doesn't usually happen in isolation.

Groups of stars are born from the same molecular cloud. And if you zoom back out to the larger scene of these constellations and look to the right of Orion, you'll see tourists the bowl. And within that constellation, you can catch a glimpse of the Pleiades sisters running from Orion and his dogs. It's an area with baby stars. So the stellar nursery and the Pleiades has basically hundreds of new stars and their blue because of the size and the temperature that they're born at.

These baby stars and Pleiades, they're blue because they're born very hot. This makes sense if you think about fire like a campfire is really red, maybe yellow, but it's not as hot as the blue flame that comes out of a blow torch. So blue stars are hotter than red stars and new forming stars are sort of at the hottest parts of their existence. So they look very blue.

And as the Pleiades or any stars form and move around, some stars will split off from their siblings, but those that stick together, they can form binary or even triinary systems like T. Corona Borealis, which we mentioned earlier. So it's really dependent on what region of the giant molecular cloud that it's formed from, like how close that nearest dense region is. So if two dense regions sort of form close together, then you, you know, more easily form a binary star.

Like serious, the star in the chest of Orion's largest hunting dog, Canis Major, with a quick look, you can probably see serious a, the brightest star in the sky. So part of a binary system with a second much smaller star, serious B. Okay, so Seraphina, why is serious a so bright? Serious is at the very beginning. It's a very young star compared to, you know, sort of the evolution of stars. So it's one of the closest stars to Earth. I think it's something like eight or nine light years away.

Yeah, okay, let's compare serious to some older stars in Orion, right? So what process is happening in the core of these middle age stars? So nuclear fusion sets the sort of life stage of the star. Middle age stars, like the Sun, have hydrogen fusing into helium in their cores. And they'll do that until the hydrogen in the center of the star runs out. And then the hydrogen is middle age star. It's fusing hydrogen to helium.

And as a byproduct of that fusion, it emits sunlight or starlight that we sort of experience every day. And yeah, middle age stars are relatively stable. Okay, so like middle age stars are fusing that hydrogen into helium in a very non-chaotic way, right? Exactly. And they stay there for a while. How long are stars technically middle-aged of their lifetime? The majority of a star's lifetime is during its middle age. So something like 90% of a star's life is spent in middle age.

And then the last 10% is sort of this like violent upheaval at the end. So our Sun is fusing hydrogen to helium for something like 10 billion years. So it's a very long, stable part of a star's life. Yeah. Just like me, just 90% of my life is in middle age. Yep. But one day I will be in that final 10% right, like Beetlejuice, sadly. And that sits in Orion shoulder, right?

Yeah, exactly. I would call Beetlejuice a star that is nearing explosion and is sort of an elderly star that will explode anytime now, astronomically speaking. Okay. And we know that because of what's happening in its core, right? Like what is changing? So a dying star has reached the point beyond which it can no longer fuse heavy elements in its core.

It cannot get hot enough to fuse any heavier elements, but there are still shells of the lighter elements that are undergoing fusion surrounding the core of the star. And there's more to learn about the end of a star from Beetlejuice because it's so big it's going to have this dramatic death. So it's a very bloated star. And basically it has swollen as it gets older. Beetlejuice will not just fall back in on itself, but then it'll explode as a supernova.

And when is the estimate that Beetlejuice is going to explode? There have been lots of discussions around when that might happen. Some people anticipate it could be tomorrow night. And some people think more conservatively, I think studies are sort of pointing at 100,000 years or so, which might seem like a very long time, but astronomically speaking, that's quite quick. And I think we're all just sort of crossing our fingers and hoping that it goes off within our lifetimes, but who knows.

We actually have an example of something like this in 1054 AD. A star exploded. And what was left over was so bright, you could see it in the daytime for about a month. And as it dimmed, you could see the debris from the explosion at night for almost two years. So can you tell us about Beetlejuice and what that might look like if it explodes?

Yeah, when Beetlejuice explodes, it'll be visible during the day and the night for about a month and will continuously be visible throughout the next, I think, year. So it'll be something that won't harm us here on earth. The explosion is far enough away that we won't actually feel any sort of physical ramifications, but it'll be a beautiful light show that, you know, will be able to see for quite some time. What kind of life lessons can we learn from stars?

First and foremost, everything changes, right? There's nothing static in the universe really, even though it might feel that way because those timescales are so much longer than our own. And that change and even violent change, I think in the in a star, you know, as it nears the ends of its life, it sort of experiences these crazy rapid mass loss, violent wins, it can burp things, it can eject things, and it might seem as though that is, you know, very chaotic and.

We have a negative connotation, but I think actually it's very normal, right? We all sort of undergo these periods of turbulence and chaos and out of that can come something really beautiful. So I find a lot of comfort in knowing that even these enormous stars experience something that we all experience at some points in our lives. Sarah Fina, thank you so much for being a guide to the stars with me. Thank you so much for undergoing this journey with me.

We'll be back tomorrow with our regular shortwave and back Tuesday with our next installment of the Space Camp series. And it's going to feature the closest stars to Earth now that we've had this explainer on the life cycle of stars. Here's a sneak peek from one of our experts. And it's Mike Wong, your science officer, back on Earth. I hope you're safely traveling all the way between our solar system and Alpha Centauri.

Just to give you a heads up for what you'll find when you get there. Alpha Centauri is a three star system with Alpha Centauri A, B, and C. C is sometimes called Proxima Centauri because it's technically the closest star to Earth and it's a dim red dwarf with an Earth-sized planet going around it in its Goldilocks zone. Please send pictures home. Thanks. Bye. The Space Camp version of this episode was produced and fact checked by Hannah Chin. It was engineered by Valentina Rodriguez Sanchez.

The original episode was produced by Rachel Carlson edited by our showrunner Rebecca Ramirez and fact checked by Britt Hansen. Special thanks to our friends at the US Space and Rocket Center. I'm Regina Barber and you're listening to Shortwave from NPR. This message comes from NPR Sponsor Mint Mobile. From the gas pump to the grocery store, inflation is everywhere. So Mint Mobile is offering premium wireless starting at just $15 a month.

To get your new phone plan for just $15, go to MintMobile.com slash switch. This message comes from NPR Sponsor VCU Massi Comprehensive Cancer Center, who as an NCI-designated Comprehensive Cancer Center in the country's top 4% is unconditionally committed to keeping loved ones in their lives. MassiCancerCensor.org slash Comprehensive. All that sitting and swiping your body is adapting to your technology. Learn how and what you can do about it.

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