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

This episode explores the fascinating life cycles of stars, focusing on their birth, evolution, and explosive demise.

1. Stars are born from dense regions of gas and dust known as giant molecular clouds.
2. The fate of a star is heavily influenced by its mass, with larger stars living shorter, more volatile lives.
3. Supernovas mark the spectacular end of massive stars, while smaller stars like our Sun end as white dwarfs.
4. The episode illustrates the process of nuclear fusion, where stars generate energy and heavier elements.
5. Observing stars like Betelgeuse offers insights into the potential future of our own Sun and the universe.

1: Star Birth

Exploring the formation of stars in giant molecular clouds and the role of gravity in creating protostars. Regina Barber: "In order for something to even be a star at all, like nuclear fusion has to happen, turning hydrogen into helium in its core."

2: Stellar Evolution

Detailing the life stages of stars from their fiery beginnings to their stable middle ages. Short Wave Host: "The majority of a star's lifetime is during its middle age."

3: The End of a Star

Discussing the end stages of a star's life, leading up to its final explosive moments as a supernova. Regina Barber: "Betelgeuse will not just fall back in on itself, but then it'll explode as a supernova."

1. Take time to observe the night sky and learn about different stars and constellations.
2. Engage with local astronomy clubs or online forums to deepen your understanding of stellar phenomena.
3. Use apps or websites to track celestial events like supernovas or meteor showers.
4. Consider the broader metaphor of stars' lives—embracing change and the beauty in endings.
5. Educate others about the importance of astronomy for understanding our universe.

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?

People

Regina Barber, Serafina El Badrinance

Guest Name(s):

Serafina El Badrinance

Content Warnings:

None

NPR Sponsor
This message comes from NPR sponsor Greenlight. Want to teach your kids financial literacy with greenlight, kids and teens use a debit card of their own. While parents can keep an eye on kids spending and savings in the app. Get your first month free@greenlight.com. nPR.

Short Wave Host
You're listening to short wave from NPR.

Regina Barber
Hey, short waivers. 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. Thats because T corona Borealis, a star thats usually invisible to the naked eye, is set to experience a nova event anytime between now and September. Up close, its a thermonuclear explosion, kind of like a hydrogen bomb. But here on earth, itll look like a bright new star appearing out of nowhere.

T Corona Borealis is a recurrent nova, which means it flares up repeatedly but doesn't completely destroy itself in the process. The last time we saw it flare up was almost 80 years ago in 1946. But humans have been watching other stars explode for much, much longer.

Short Wave Host
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 caves, drawings. Some of them are on, you know, old records. It's, I mean, it's remarkable to see how civilizations, even at that point, have a record of exploding stars.

Regina Barber
That's Serafina El Badrinance. She's an astrophysicist and an expert in supernovas, the final destroying explosion of massive stars. And she studies one star in particular, Betelgeuse.

Short Wave Host
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.

Regina Barber
If you're looking up at Betelgeuse 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?

Short Wave Host
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.

Regina Barber
A low mass star, stars smaller than our sun, will live longer than high mass stars like betelgeuse. Its 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 dont worry.

Short Wave Host
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 will fizzle out into what we call a white dwarf.

Regina Barber
So today on the show, it's a star party. Serafina 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 short wave, the science podcast from NPR.

NPR Sponsor
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 isles, 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@nature.org solutions support for NPR and.

NPR Sponsor
The following message come from our sponsor, Whole Foods Market host the ultimate backyard barbecue with Whole Foods Market.

Whole Foods Market
It's the hot grill summer event through.

NPR Sponsor
July 16 with sizzling sales on no antibiotics ever. Boneless beef, ribeye steak and beef New York strip steak. Plus, check out sales on sustainable wild caught Alaska sockeye salmon, organic strawberries, and more. 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.

Regina Barber
Okay, Serafina, let's start with the beginning of a star's life. How are stars born?

Short Wave Host
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 they're 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 protostar, which is sort of the nascent star. And then over the course of millions of years, the protostars 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.

Regina Barber
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?

Short Wave Host
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 starlight, 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 protostar to a main sequence star.

Regina Barber
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 will see Taurus, the bull. 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.

Short Wave Host
So the stellar nursery in the Pleiades has basically hundreds of new stars. And they're blue because of the size and the temperature that they're born at.

Regina Barber
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 blowtorch.

Short Wave Host
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.

Regina Barber
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 trinary systems like t corona borealis, which we mentioned earlier.

Short Wave Host
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 more easily form a binary star like Sirius, the.

Regina Barber
Star in the chest of Orions largest hunting dog, Canis Major.

With a quick look, you can probably see Sirius A, the brightest star in the sky, but its part of a binary system with a second, much smaller star, Sirius B.

Okay, so, Serafina, why is Sirius a so bright?

Short Wave Host
Sirius is at the very beginning.

Its 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.

Regina Barber
Yeah. Okay, let's compare Sirius to some older stars in Orion. Right. So what process is happening in the core of these middle aged stars?

Short Wave Host
So, nuclear fusion sets the sort of life stage of the star.

Regina Barber
Middle aged 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.

Short Wave Host
Our sun is middle aged 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 aged stars are relatively stable.

Regina Barber
Okay, so, like, middle aged stars are fusing that hydrogen into helium in a very non chaotic way. Right?

Short Wave Host
Yeah, exactly.

Regina Barber
And they stay there for a while. How long are stars technically middle aged of their lifetime?

Short Wave Host
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 aged, 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.

Regina Barber
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 Betelgeuse, sadly. And that sits in Orion's shoulder, right?

Short Wave Host
Yeah, exactly. I would call Betelgeuse a star that is nearing explosion and is sort of an elderly star that will explode anytime now, astronomically speaking.

Regina Barber
Okay. And we know that because of what's happening in its core. Right. Like, what is changing?

Short Wave Host
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 heavy, heavier elements, but they're still shells of the lighter elements that are undergoing fusion surrounding the core of the star.

Regina Barber
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.

Short Wave Host
So it's a very bloated star, and basically it has swollen as it gets older, Betelgeuse will not just fall back in on itself, but then it'll explode as a supernova.

Regina Barber
And when is the estimate that beetlejuice is going to explode?

Short Wave Host
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?

Regina Barber
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 Betelgeuse and what that might look like if it explodes?

Short Wave Host
Yeah. When Betelgeuse 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, we'll be able to see for quite some time.

Regina Barber
What kind of life lessons can we learn from stars?

Short Wave Host
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.

But change and even violent change, I think in a star, as it nears the ends of its life, it sort of experiences these crazy, rapid mass loss, violent winds. It can burp things, it can eject things, and it might seem as though that is very chaotic and that can 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.

Regina Barber
Serafina, thank you so much for being a guide to the stars with me.

Short Wave Host
Thank you so much for undergoing this journey with me.

Regina Barber
We'll be back tomorrow with our regular short wave 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.

Mike Wong
Hey, Gina, 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.

Short Wave Host
Bye.

Regina Barber
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 Brit Hansen. Special thanks to our friends at the US Space and Rocket center. I'm Regina Barbour, and you're listening to short wave from NPR.

NPR Sponsor
This message comes from NPR sponsor jump into a new perspective on performance apparel. Viori makes products that stand the test of time and hope to inspire others to live vibrant, healthy lives, empowering your best life in clothing that can be worn for just about any activity, from running to yoga. Visit viori.com NPR to receive 20% off your first purchase and enjoy free shipping on any US orders over $75.

NPR Sponsor
Discover the versatility of Viori clothing support.

Whole Foods Market
For NPR and the following message come from Ixl Online. Is your child asking questions on their homework you don't feel equipped to answer? IXL learning uses advanced algorithms to give the right help to each kid, no matter the age or personality. One subscription gets you everything. One site for all the kids in your home, pre k to 12th grade, make an impact on your child's learning. Get IxL now and NPR listeners can get an exclusive 20% off IxL membership when they sign up today@ixl.com.

NPR
Npr black perspectives haven't always been centered in the telling of America's story. Now we're taking center stage, introducing NPR's Black Stories, Black Truths, a collection of black led stories from NPR's podcasts. Search NPR black stories, black truths wherever you get your podcasts.