Cosmic Queries – Starquakes with Conny Aerts

What is a starquake? On this episode, Neil deGrasse Tyson and comic co-host Matt Kirshen explore asteroseismology, the sun, and what’s happening on the insides of stars with astrophysicist Conny Aerts.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  Hey Startalkians, Neil here. You're about to listen to an episode specially drawn from our archives to serve your cosmic curiosities. The archives run deep. If you enjoy this, take a peek at the full catalog on your favorite podcast platform. There's a lot there to tickle your geek underbelly. Check it out.

• 0:24Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk Cosmic Queries Edition. This one is titled "Starquakes." I've got as a co-host here Matt Kirshen. Matt, welcome back to StarTalk.

• 0:48Matt Kirshen?

  Thank you so much for having me. It's nice to be back.

• 0:51Neil deGrasse Tyson?

  Yeah, so you solicited questions about like stars and starquakes from...

• 0:56Matt Kirshen?

  I'm very excited about this topic and so are the listeners. There's been a lot of, a lot of your Patreon patrons have responded to this one and we're gonna try and get through as many of these as possible, but uh...

• 1:05Neil deGrasse Tyson?

  Well, I don't know a damn thing about...

• 1:07Matt Kirshen?

  I will try.

• 1:08Neil deGrasse Tyson?

  I don't know a damn thing about starquakes, so...

• 1:11Matt Kirshen?

  Yeah, I know. I'm excited. I mean, I live in California where earthquakes are a problem, so I know how to deal with those, but I don't, if you're involved in a starquake, is getting under a table still enough or how do we deal with it?

• 1:21Neil deGrasse Tyson?

  Yeah, we're gonna, we're gonna find out for sure. So our guest with the expertise we need is Connie Arts. I think I pronounced that right. Connie, welcome to StarTalk.

• 1:32Speaker 02

  Hi, glad to be here.

• 1:34Neil deGrasse Tyson?

  Excellent. Now, you're in from Belgium and the Netherlands. You have a dual appointment. One as the professor of astrophysics at, let me get this straight, in Luvin, Belgium, and it's KU, that's Catholic University, it's like Catholic University in Luvin, is that correct?

• 1:55Speaker 02

  Yeah, KU Luvin. Just don't worry about it.

• 1:59Neil deGrasse Tyson?

  K U Louven.

• 2:01Speaker 02

  Leuven is a small college town in Belgium, so that's where I'm from.

• 2:04Neil deGrasse Tyson?

  Excellent. And in the Netherlands, you're a professor of astroseismology at Radbouw University in the Netherlands. And so the fact that that's even a title to hold, astroseismology, says how far we've come in just the specification within the broader field of astrophysics. And I think this is just delightful. And your expertise is stellar astrophysics, stellar structure and evolution. These are two favorites of mine professionally. But I never really thought about seismology in anything other than Earth. And so, first, tell us, what is astroseismology?

• 2:48Speaker 02

  Well, it's the study of the seismology of stars. Now, as you say.

• 2:54Neil deGrasse Tyson?

  You're gonna have to do better than that.

• 2:56Speaker 02

  Yeah, I know, I know. Give me a chance, right? Give me a chance. So, we all know earthquakes. The Earth has a whole crust, you know. It's not pleasant to have earthquakes, but it's fantastic to have starquakes. Stars are hot, cacious spheres, and they also move up and down. And we can use these starquakes to learn what's inside the star. It's the only way to know how to look inside a star. And that's just like seismologists of the Earth, you know. They are the only happy people. When the Earth is quaking, let's say, why? Because the earthquakes create waves, they travel into the planet, they bounce back at

• 3:39Speaker 02

  the iron core, and seismographers detect it. And then we can do all sorts of fun physics and chemistry of our planet. And we do the same, but then for stars.

• 3:50Neil deGrasse Tyson?

  Okay, Matt, I think Connie just said that while cities are burning and everyone is dying, geologists are delighted that they have earthquakes.

• 3:58Matt Kirshen?

  Absolutely, yeah. I'm hiding under a table while my pets are going crazy, and seismologists are like, the data, what beautiful data we're getting right now.

• 4:08Neil deGrasse Tyson?

  So, but I'm confused though, because when I think of an earthquake, I have a very simple understanding of it, that you have a rigid crust that is under pressure and under tension, and then it spontaneously gives way, and then you get an abrupt shift, and that's an earthquake. But when I think of stars, they're fluids, they're gaseous fluids. So what could possibly be quaking if you don't have anything solid to build up the tension that then gets released?

• 4:39Speaker 02

  Yeah, so that's a bit different, because the starquakes are happening all the time, because it's a gas. And so you have motions, right? Up and down motions, but also more complex motions. And if you, if you, if you, you know, press a gas and then release it, it creates sound waves. That's a bit like music in a theater hall. So for me, stars are three-dimensional musical halls, concert halls, right?

• 5:12Neil deGrasse Tyson?

  Wow.

• 5:13Speaker 02

  And so the nice thing is that starquakes are always there. Luckily for us humans, the earthquakes die out quickly, right?

• 5:21Neil deGrasse Tyson?

  And they're rare, relative, I mean, they're rare in the sense of the ones that do serious damage are rare. But as I understand it, there are actually earthquakes of even very small magnitude almost all the time. I think that's correct.

• 5:33Speaker 02

  Yeah, that's correct, because anybody in nature vibrates, yeah? And so, yeah, stars do that all the time, and they do it permanently, which for us astrophysicists is great, because we can measure the up and down motion. Why? Because it gives changes in the, in the temperature of the star. And so the brightness of the star changes as a function of time. And then we have our seismographs that measure these changes as a function of time.

• 6:02Neil deGrasse Tyson?

  And your seismographs are also, you implied there, that they're sensitive to those Boundaries where temperature changes.

• 6:12Speaker 02

  That's right.

• 6:12Neil deGrasse Tyson?

  Because your sound would get reflected or your pressure wave, which we're calling sound, would would get reflected or bent in a different way. And you use that to model the total interior structure of the star. Is that correct?

• 6:25Speaker 02

  Yeah, that's correct. But yeah, like, um, we cannot hear these sound waves with our ears. So we see the brightness variations because the sound is only propagating there where there is gas and between us and the star, you know, there's nothing, it's empty, right? So we can't literally hear the the frequencies of the waves, but we see the up and down motion. And so that is actually connected. The frequency of these sound waves created by these up and down motions is connected to the physics and also the chemical composition of the star in its interior. So we can't literally dive into the stellar concert hall, but we can measure the frequencies from a distance, let's say.

• 7:09Neil deGrasse Tyson?

  But but if you could, you would hear all of these.

• 7:11Speaker 02

  Yeah, yeah, yeah, yeah, that's that's fantastic. Sometimes I give lectures for musical artists and then they are all totally fascinated about this, about these sounds like, you know.

• 7:22Neil deGrasse Tyson?

  So let me test this on Matt. So Matt, NASA is going to plan a mission to send astronauts to the sun to listen to these sounds, but it's dangerous, obviously, so they're going to go at night.

• 7:36Matt Kirshen?

  You'd need your earplugs as well. I, you know, I like to allow concerts sometimes. I don't take any chances now. I'm getting old and my hearing's going. That, by the way, I know, I know we haven't got into the questions yet, but that actually is one of our questions from Lucas, from listener Lucas, was actually about whether you can make that the heartbeat of stars into music.

• 7:54Speaker 02

  Yes.

• 7:55Matt Kirshen?

  And so you're saying, yes, that you can absolutely do that.

• 7:58Neil deGrasse Tyson?

  Oh, my goodness. So has have people done so you so you have a a portfolio of frequencies going on at different times in different locations. And so you get a clever musician to sort of take all of that base material.

• 8:10Speaker 02

  Yeah.

• 8:11Neil deGrasse Tyson?

  And figure out a way to listen to it. That'd be interesting.

• 8:13Speaker 02

  Yeah, yeah, so we we actually just. Shift the, I mean, each star has its own symphony, right? Depending on how big it is, how how much mass it has, how old it is. It has its own symphony. But then we shift that global symphony into the audible range of humans. That's that's called somification. It's a whole field by itself. And actually, it allows blind people to be astronomers. I find that I'm a very, for me, inclusion is very important. So in this way, we can reach people who can't see, but they can hear the stars. But we have to help them a little bit by shifting to the audible range.

• 8:53Neil deGrasse Tyson?

  Yeah. We have finally achieved the goals of the ancients by celebrating the music of the spheres.

• 8:59Speaker 02

  Yeah, exactly. That's true.

• 9:01Neil deGrasse Tyson?

  Oh, man. OK. So that so that question already got asked, Matt. So that was who asked that?

• 9:07Matt Kirshen?

  That was that was Lucas from New West who asked that question.

• 9:10Neil deGrasse Tyson?

  Where is what is New West? What is that?

• 9:11Matt Kirshen?

  I I don't know. It just says New West. I'm not sure exactly, but Lucas also proceeds it by saying, I have a geek kind of question, which I don't think you need to proceed any questions to start off with that.

• 9:21Neil deGrasse Tyson?

  This is a geek safe space here, everybody.

• 9:25Neil deGrasse Tyson?

  You don't have to preface it. But New West, I mean, I live in New York and, you know, there's.

• 9:31Matt Kirshen?

  Formerly New Amsterdam.

• 9:32Neil deGrasse Tyson?

  Just south of New England. I don't never heard of New West. I don't know what that is. Maybe that's California after it breaks away from the San Diego's fault.

• 9:41Matt Kirshen?

  Just floating off, just floating off into the Pacific.

• 9:45Neil deGrasse Tyson?

  So why don't we get some more questions here? This is great now that we have some foundation for what.

• 9:49Matt Kirshen?

  Yeah, we've got some awesome ones. Some of them have already, some of them you've already kind of answered, and I'm sure that'll happen as we go along. But I'll try and get as many ones in. So James Smith from Indianapolis says, what is the largest recorded quake not found here on Earth? And also, do all planets have plates that shift like Earth? A couple of people have asked that question as well, whether all other planets.

• 10:07Neil deGrasse Tyson?

  So let's start there first. You know, we know Earth is geologically active because there's like volcanoes and plate tectonics. So where else in the solar system might do that before we get back to the sun?

• 10:19Speaker 02

  Oh, well, you know, all planets will have quakes. I mean, any any body in nature quakes. I was banging, I was about to bang the table here, but I will not do that. But the table would also have, you know.

• 10:33Speaker 02

  Quakes. So they dampen out quickly depending on whether you have a gaseous planet or a crust like planet like Earth. So Jupiter, Saturn, all the big gaseous planets in our solar system, they also have uh quakes.

• 10:48Neil deGrasse Tyson?

  Wait a minute, Connie, you're saying every sound anywhere is a quake to you?

• 10:53Speaker 02

  Yeah.

• 10:53Neil deGrasse Tyson?

  Okay.

• 10:54Speaker 02

  That's true. You do.

• 10:56Matt Kirshen?

  So a guitar is ba- what what we're doing right now is kind of causing the the tiniest to tiniest quakes by making sound.

• 11:03Neil deGrasse Tyson?

  We're creating Earth's atmosphere.

• 11:04Speaker 02

  Of course, you're you're creating sound waves, so.

• 11:07Neil deGrasse Tyson?

  Oh, my God.

• 11:07Matt Kirshen?

  Listener Woody also asked, by the way, on this same topic, what what different would the ice giants experience quakes? I guess you've said the answer is yes. And what possible differences would there be between earth, water, ice, frozen methane and nitrogen quakes?

• 11:18Speaker 02

  Yeah, so so the the.

• 11:20Neil deGrasse Tyson?

  Right, that's a bit way, just a quick thing. So we've got ice in Uranus Neptune, uh, the ice giants, and we've got sort of gases in Jupiter Saturn. We've got Earth's crust here. And so presumably, uh, you've, Connie, you've got some portfolio of who makes what kind of sound under what conditions so that you can decode what you hear. Is that correct?

• 11:51Speaker 02

  That's correct. And so the the the frequency of the sound waves of all these heavenly bodies is really determined by the density of the object, right? And so stars are gases and their density is very different from the density here on Earth.

• 12:08Neil deGrasse Tyson?

  Very low, yeah.

• 12:09Speaker 02

  Or in Jupiter, yeah. So uh, by measuring the frequencies of the quakes, we know quite directly how big the object is and what its density is. And if you know these two, then you know the mass. So that's the basic tools, right?

• 12:27Neil deGrasse Tyson?

  You said you said that on the sun, you you measure the quakes because some parts of the sun get brighter relative to others because they're hotter. How do you do that with just a planet sitting out there in space?

• 12:38Speaker 02

  Yeah, we need to send some space mission

• 12:41Neil deGrasse Tyson?

  Oh.

• 12:42Speaker 02

  there to come closer and to be able to see this. And so for stars, we also, I mean, this, this is a booming research field in astrophysics. Why? Because we recently had the luck of being able to measure the brightness variations with satellites. Yeah, we, we don't have a sasmo graph that we can put there, literally, like for the Earth. But we sent instruments that, that measure these tiny variations in the gas, you know?

• 13:11Neil deGrasse Tyson?

  Okay, so it, I'm a, I'm a, I'm an old, old world astrophysicist. So when you say, we make these measurements by going there, that's cheating.

• 13:21Speaker 02

  Yeah, that's cheating. Yeah, yeah, we can't go there.

• 13:25Neil deGrasse Tyson?

  That's tabletop science at that level.

• 13:27Speaker 02

  Yes.

• 13:28Neil deGrasse Tyson?

  If, if you get to go there.

• 13:29Speaker 02

  Yeah.

• 13:30Neil deGrasse Tyson?

  But, but you're saying it's the same kind of features in a gaseous planet. Some parts will be a little warmer or cooler than others on the surface. And that'll tell you, that, that'll give you seismic information about what's going on inside.

• 13:43Speaker 02

  Yeah, as, as soon as the density changes, for whatever reason, density changes give pressure waves and these are sound waves, right?

• 13:52Neil deGrasse Tyson?

  Okay.

• 13:53Matt Kirshen?

  And, and so, um, the follow-up part from, uh, from James, what's the largest recorded quake not found on Earth?

• 14:01Speaker 02

  Oh, well, we have the, the slowest quake in a star, like it can take several, several months in, in, in period. Well, for the sun, it's five minutes, by the way. For those who don't know, yeah, the solar quakes go up and down, create sound wave with periods of about a few minutes, five minutes at their strongest. So for a very big blue super giant star, it takes months before the quake went up and down.

• 14:28Neil deGrasse Tyson?

  So just to be clear, the normal frequencies we listen to are hundreds and thousands of cycles per second. And that's, that's what our, our eardrum and brain will record. And you're saying these are cycles every five minutes?

• 14:43Speaker 02

  Yes, and that's even fast.

• 14:45Neil deGrasse Tyson?

  Or even every month. So that's why you have to shift it back to our audio range.

• 14:51Speaker 02

  Yeah.

• 14:51Neil deGrasse Tyson?

  Otherwise, we don't, we would never even know what was happening.

• 14:53Speaker 02

  That's right. These are slow waves to human standards.

• 14:57Neil deGrasse Tyson?

  Right. You, you'd vaporize first, but

• 14:59Speaker 02

  Yeah.

• 14:59Matt Kirshen?

  Right.

• 15:00Neil deGrasse Tyson?

  While you're vaporized, you would not know you were in the middle of a starquake, I see.

• 15:03Speaker 02

  That's right.

• 15:03Matt Kirshen?

  That's wild for me. So Incredibly slow, but presumably hugely energetic.

• 15:08Speaker 02

  Uh, yes, that's, that's true. Yeah. So the, the energy of each wave can be quite tremendous, but that also depends on the type of, of waves that you're dealing with.

• 15:21Neil deGrasse Tyson?

  Okay. Wow. All right. Well, let's take a quick break and we're to come back to more star quakes. Something was like, what?

• 15:33Neil deGrasse Tyson?

  But to Connie, everything's a quake. So we'll get more into that in this episode of StarTalk Cosmic Queries when we return.

• 15:48Neil deGrasse Tyson?

  Do we have any good reason to think that aliens would be evil? Where did we get that idea from? Aliens could be the most peace-loving creatures the universe has ever generated, yet our representations of them tend to be diabolical, which gets me to wonder that these representations of evil aliens are not based on how we think they will behave, that maybe they're really based on how we know we have behaved to one another, especially when there's a conflict between a higher technology and a lower technology. So exploring the topic of aliens can not only give us insights into all the ways of being alive

• 16:33Neil deGrasse Tyson?

  in the universe, it can, on occasion, hold up a mirror to our greatest fear, which might in fact be ourselves. That and more in my latest offering, Take Me to Your Leader: Perspectives on Your First Alien Encounter. I narrated the audiobook. That's available with the print version, and I'm kind of thinking you should get it now. It'd be too late if you have your first alien encounter and have not yet read the book. You want to be ready.

• 17:12Neil deGrasse Tyson?

  We're back, StarTalk Cosmic Queries. We're talking about star quakes. And my co-host, Matt Kirshen. Matt, where can I find you on the internet?

• 17:22Matt Kirshen?

  Well, you can find my podcast, Probably Science. I start with the Neil episode. That's always a nice place to start.

• 17:28Neil deGrasse Tyson?

  I was a guest once on your Probably Science. I just thought by now it would have been called Certainly Science. I just, I thought it was evolutionary, but apparently not.

• 17:38Matt Kirshen?

  The longer we do the show, the more probably it gets. It's gonna descend through possibly to, ah, science.

• 17:47Neil deGrasse Tyson?

  To probably not.

• 17:48Matt Kirshen?

  And then I'm on Twitter, @mattkershen, and technically on Instagram, but I'm very rarely there.

• 17:54Neil deGrasse Tyson?

  Okay, Kirshen, K-A-R-S-H-E-N. And we have as our in-house expert right now on star quakes, professor of astroseismology in the Netherlands. But right now, Connie Arz, I think I pronounced that right, is visiting New York City at a place called the Flatiron Institute, which is in the Flatiron section of Manhattan. And very cool science is happening there. All manner of science. It started with sort of math and astrophysics, but it's spilling into biology and computer science, where very deep problems that need high-performance computing and clever people

• 18:36Neil deGrasse Tyson?

  to solve them are invited to then gather their talents and try to solve the secrets of the universe. And Connie Arz is on sabbatical this year. So Connie, we're delighted to have you as part of this podcast.

• 18:52Speaker 02

  Very grateful to be here. Thank you.

• 18:56Neil deGrasse Tyson?

  Yeah, yeah. So we've got some more questions. But before we do that, I just want to be clear that most people's understanding of the word quake is, I think, built in is that it's abrupt and short-lived. That's kind of built into our life experience with a quake. But we're now hearing about quakes on completely different timescales. Should you have invented another word to describe a quake that... Moves on the scale of days or months rather than seconds or minutes?

• 19:32Speaker 02

  Sure, and I use the term star quakes for popular lectures, but actually in in our professional life, we we speak of stellar oscillations. So they're global oscillations, they're smooth, they're properly behaved. So for stars, it's a bit less abrupt than for earthquakes, let's say.

• 19:54Neil deGrasse Tyson?

  Okay, okay. So if on Earth they were Earth oscillations, then Matt, you maybe you wouldn't have to hide under a desk or in the the structural beams of the house.

• 20:05Matt Kirshen?

  I would just ride it out.

• 20:06Neil deGrasse Tyson?

  Just ride it, surf it out.

• 20:08Matt Kirshen?

  Keep the knees perplexed, keep keep your core stable, that's all you need.

• 20:13Speaker 02

  But you would get seasick all the time, you know, because they would always be there, you know.

• 20:18Matt Kirshen?

  Yeah, lies on the horizon, that's the secret, always look out the window, don't try and look at a fixed object inside.

• 20:22Neil deGrasse Tyson?

  Take me surfing one day out in Los Angeles and teach me.

• 20:26Matt Kirshen?

  Oh, I I'm a terrible surfer, but.

• 20:28Neil deGrasse Tyson?

  Okay, so Matt, what do we else do we have for Connie?

• 20:31Matt Kirshen?

  We've got some great questions. By the way, I just side note, I I love when we have topics like this, when it's something that is close to Neil's wheelhouse, but just outside it, when it's when it's like in your field of astrophysics, but something that you've never really encountered, they're my favorite episodes, because.

• 20:43Neil deGrasse Tyson?

  Because you like looking how much of an idiot I am, that's what you're saying.

• 20:47Matt Kirshen?

  I love it, yeah, we're just just at the edge of Neil's knowledge, it's my favorite. It's it's it's the best.

• 20:54Neil deGrasse Tyson?

  Well, those are my favorite episodes where I learn stuff, so.

• 20:56Matt Kirshen?

  Absolutely, absolutely.

• 20:58Neil deGrasse Tyson?

  This is good.

• 20:59Matt Kirshen?

  So I'm going to combine these two questions, I like to do this, because.

• 21:03Neil deGrasse Tyson?

  I want to hear their names anyway.

• 21:04Matt Kirshen?

  Absolutely, Dylan and from NAU in Flagstaff and Alejandro Reynoso from Monterey have both asked about what we can actually learn from the oscillation of stars. Dylan says, can we predict its age and or understand the core? And also, do all stars oscillate or just dying stars, supermassive stars, main sequence stars? And then Alejandro says, what have you learned from analyzing star quakes that you couldn't learn with other methods? So basically, they're both asking, what specifically is it that we can learn from these quakes?

• 21:32Neil deGrasse Tyson?

  I'm going to tighten that question and say, what are you learning that we didn't otherwise?

• 21:39Neil deGrasse Tyson?

  Figure out through other means.

• 21:42Speaker 02

  Okay, if there's one word that I have to ask to that question, it is rotation of stars. That's more than one word, but internal rotation of stars, you know, and why is that? Let me give the analogy with music again. So we have sound waves that are happening inside a star, but the the gas in the star is rotating around, right? And what do you get when you put a musician in a theater play? And you make the podium rotate just for the fun of it as a surprise to the musician?

• 22:13Neil deGrasse Tyson?

  You get pissed off musicians, that's what you get.

• 22:17Speaker 02

  Exactly. I like that experiment, actually, you can really hear that. But the symphony is destroyed. That's what the audience would say. Now, for me, as an astrophysicologist, the frequencies of the waves get shifted, right?

• 22:33Neil deGrasse Tyson?

  The Doppler shift.

• 22:35Speaker 02

  Yeah, they get shifted because of the extra motion you to the rotation. And we can measure that. And we're not measuring that at the surface of the star, but in the inside the star where the the starquake has its strongest energy, right? And so what we have come to realize is that the theory of how stars evolve, relying on how they rotate in their interior, it is quite off. It's it's not very good. And that's not surprising, right? Because we could only measure before we had starquakes. We could only measure the rotation of the star at its external layer. Like for the sun, you see the you see the tiny little dark spots of the sun rotating around.

• 23:18Speaker 02

  If you're patient, every twenty six days, you see them back in your line of sight. But so the sun rotates with a period of about twenty six days. But that's just the outer layers. It doesn't say at all how it rotates in its interior. So if you have no information, what can you do? Well, you think, well, it won't be that different.

• 23:37Neil deGrasse Tyson?

  You just assume it's the same, right?

• 23:39Speaker 02

  You assume it's the same.

• 23:40Neil deGrasse Tyson?

  Everything else rotates as an as a kind of a unified object. Why would I even think some lower level would rotate at a different rate?

• 23:48Speaker 02

  Well, the stars have many more surprises than us.

• 23:53Speaker 02

  Astrophysicists have imagination.

• 23:57Neil deGrasse Tyson?

  What a smack. Oh, Matt, did you hear? Matt? Did I just hear this woman correctly here?

• 24:03Matt Kirshen?

  Yeah, I stand by it. I'm on team star on this one.

• 24:07Speaker 02

  And.

• 24:08Neil deGrasse Tyson?

  That was a smackdown right there, okay?

• 24:10Speaker 02

  Yes, I always say the stars are right, the theory is wrong if they, if it doesn't match with each other, right?

• 24:16Neil deGrasse Tyson?

  Uh huh.

• 24:17Speaker 02

  Thanks to the frequency shifts of these waves, we can now measure how stars rotate around. And why is that important? Well, if they rotate faster or slower, then their material gets mixed in a different way. Yeah, uh, that's also something you can imagine if you take the analogy with coffee drinkers, you know? If you, if you like coffee with milk, you pour milk into your coffee and you don't wait until, you know, until everything is mixed because then the coffee is cold and it doesn't taste well anymore. No, you take a spoon and you rotate your coffee. In my terminology, that is saying you bring angular momentum to the coffee cup. And what, why do you do that?

• 24:59Neil deGrasse Tyson?

  That's what everyone says when they're having coffee at Starbucks.

• 25:02Speaker 02

  That's what everybody does without saying it. And that's because everybody prefers well-mixed coffee with milk.

• 25:10Matt Kirshen?

  I'm, I'm assuming at the Flatiron Institute that it, that just the coffee station there has angular momentum implements.

• 25:16Neil deGrasse Tyson?

  Yes.

• 25:18Neil deGrasse Tyson?

  How much angular momentum would you like on your coffee this morning?

• 25:21Matt Kirshen?

  Yeah, just. Do you want, do you want a metal angular momentum implement or one of the wooden straight ones?

• 25:26Speaker 02

  Yeah. Well, we could do an, an experiment of how people do that, huh? But, you know, the diversity of human beings, uh, taking their spoons will be, uh, large. And in stars, there's a whole range of internal rotation frequencies that we have measured. In, we have about 2,000 stars now for which this has been measured by many groups in the world with astrophysicologists. And so the life of the stars is really going, uh, slower if I look at the measurements.

• 26:00Neil deGrasse Tyson?

  You mean our estimates for their life expectancy need to be updated to have them live longer than we originally thought, is that what you're saying?

• 26:08Speaker 02

  Yeah, particularly for the big massive stars.

• 26:11Neil deGrasse Tyson?

  Is that because they're mixing more material into their core?

• 26:14Speaker 02

  Yeah.

• 26:14Neil deGrasse Tyson?

  Giving them a little more lease on life?

• 26:16Speaker 02

  And they they get more material into their inner part, and in the inner part of a star is actually a nuclear reactor for me, because the they're the simplest constituent, which is hydrogen, is turned into helium by nuclear fusion, and stars are masterpieces in that. But if you bring more hydrogen into that area where it's hot and dense enough, then the star can live longer. And so the rotation affects how much nuclear fuel you bring inside its its interior, actually.

• 26:50Matt Kirshen?

  That was about to be the opposite of what I would have guessed, because I was wondering whether the sort of the stirring effect would have sped up the fusion reaction by kind of, you know, you can increase the speed of a chemical reaction, I know that's different from a nuclear reaction, by by stirring the chemicals together or by increasing the energy in there, but you're saying it's the opposite because it's bringing more fuel in from the outside.

• 27:11Speaker 02

  Yeah, that's right. Yeah, so once the nuclear burning is ongoing, the nuclear fusion in stars is stable, stars are can do that very well, we humans can't do that here.

• 27:22Neil deGrasse Tyson?

  Now, everything I know about the nuclear furnace says that it's pretty small relative to the size of the star itself. Do your waves give you enough information about tiny areas like a like the nuclear core?

• 27:35Speaker 02

  Yeah, well, tiny, it's 10% of the mass that they typically takes part in the nuclear fusion, so it's still 10%, it's not that small.

• 27:43Neil deGrasse Tyson?

  Of the mass, even if it's physically small, it's got it's got a lot of mass going on.

• 27:46Speaker 02

  Yeah, because the density is very high, and so if you if you change that 10% to, say, 12%, that sounds like, you know, it's only 2%, you know, but that's a lot of fuel, eh? That you bring into your nuclear reactor, and so then...

• 27:59Neil deGrasse Tyson?

  Right, and increase the life by at least 20% perhaps, or you think maybe?

• 28:03Speaker 02

  Yeah, yeah, yeah, yeah, it can really change the lifetime of the star, so that's that's, so...

• 28:09Neil deGrasse Tyson?

  And Matt, if you were in the center of a star, you'd be dense too, I just wanted to tell you that.

• 28:13Matt Kirshen?

  Oh, thanks. It's one of the nicest things anyone's ever said to me.

• 28:20Neil deGrasse Tyson?

  We've got more questions, Matt, bring them on.

• 28:21Matt Kirshen?

  We do. Aziz from Saudi Arabia says, "I wonder if it's possible for a star to have a starquake so strong caused by, for example, nuclear fission or fusion happening or abnormally fast, or caused by any other reason to lose mass?" I thought I'd ask that one because we're already talking about fusion.

• 28:38Neil deGrasse Tyson?

  You know, in the formation of stars in the galaxy, you can get shock waves across a gas cloud that's otherwise mining its own business, and it can trigger gravitational collapse and other interesting features. So I'd love that question, Connie. So are starquakes just the product of what's going on? Or are they a participant in causing what's going on?

• 28:59Speaker 02

  Yeah, so you can have all sorts of reasons why stars have these oscillations, right? And they can indeed be caused by the fierce turbulence in the core of a very massive star. Because, you know, we call that convection, turbulent motions, and they create waves also. Because, again, they make the gas, you know, compress and expand. But there are also other reasons why stars can have starquakes. Think of the Earth-Moon system and tides. Well, half of the stars, or even more if you go to higher masses, they live together with two, and then they have tidal forces.

• 29:40Neil deGrasse Tyson?

  Binary star system. Just like in that scene in Star Wars, where Luke comes out, is it the sand planet? And he sees a double sunset. That's the only accurate science in the entire series.

• 29:52Speaker 02

  That's okay. That's okay. You know, yeah.

• 29:56Neil deGrasse Tyson?

  Okay, so what happens there? So you have a gravitational tidal dance?

• 30:00Speaker 02

  And they, that's right. They rotate around each other and they pull. They give a tidal pull, right? And so you could also say that, you know, for me, tidal forces are actually forced oscillation. You know, I say everybody oscillates in nature. So when the stars are close enough together, the tidal oscillations, as I call them...

• 30:24Speaker 02

  Uh, are very strong, can be very strong. So that's another reason why stars can have, uh,

• 30:31Neil deGrasse Tyson?

  So these are like a tidal bulge?

• 30:33Speaker 02

  Yeah, exactly.

• 30:34Neil deGrasse Tyson?

  In the direction of the, of the object responsible for it.

• 30:37Speaker 02

  Yeah.

• 30:37Neil deGrasse Tyson?

  See, see, in my older years, I, I have a tidal bulge as well.

• 30:43Neil deGrasse Tyson?

  I'm, I'm watching for that, just to see what I can do about it.

• 30:46Speaker 02

  Yeah. Yeah, you wanna prevent it, but we like it when it started.

• 30:52Neil deGrasse Tyson?

  Yeah. All right, Matt, give me some more.

• 30:53Matt Kirshen?

  Quentin from Switzerland says, uh, and I don't know what, I don't know what, uh, Quentin's referring to. So hopefully one of you two can fill me in. Says, do you need more data to exactly figure out what happened with Betelgeuse recently? Is it pronounced Betelgeuse? Betelgeuse?

• 31:06Speaker 02

  Betelgeuse, yes.

• 31:08Matt Kirshen?

  It is pronounced Betelgeuse, like the film, but spelled differently. It seems pretty unlikely that we will witness a similar event in the near future. So what is it, what did happen?

• 31:15Neil deGrasse Tyson?

  I gotta lead off with this and then we'll get the actual answer from Connie.

• 31:18Speaker 02

  Okay.

• 31:19Neil deGrasse Tyson?

  I heard, but Betelgeuse is one of the brightest stars in the night sky. It's a important star in one of the most dominant constellations of all 88. Dominant in size and, and appearance is Orion. Orion is visible in both the northern and southern hemispheres because it straddles the equator on the sky. And so there's this star, Betelgeuse, one of the biggest, baddest red giants in the known universe. And someone told me, do you realize Betelgeuse is getting dimmer? I said, no. What, what, what? And I looked up and I went, huh?

• 31:56Neil deGrasse Tyson?

  Because my whole life, Betelgeuse was a certain brightness relative to other stars in the constellation. I cannot communicate to you. My loss of breath in the moment I looked up and I say, what is happening? Is this, you know, is this, is the seventh seal broken? Is there some, is this something biblical? So Connie, I want you to know.

• 32:20Speaker 02

  Yeah.

• 32:20Neil deGrasse Tyson?

  I, I, I, I nearly freaked out.

• 32:23Speaker 02

  Oh.

• 32:23Neil deGrasse Tyson?

  So what happened to Betelgeuse a year ago? When it just got mysteriously dim? Like it was, it went to less than half its normal brightness. And that had never been observed ever in any time anybody's been looking at the star. So we're gonna blame you for this, Connie. What, what happened?

• 32:41Speaker 02

  Well, Betelgeuse is behaving normally at the start. It's, you know, it's a supergiant, right? It's a very big star. And so these stars are nearing the end of their life. And so they're, they're puffing up their material and they're blowing it away, so to speak. Right? And so when material gets lost from the star, well, then for us, it, the star is obscured because it's in between the supergiant and us. There's material that is being expelled. Now, for me, as an astrophysicologist, that's a bit annoying, that behavior. Because Betelgeuse has star quakes, but all that material that's being expelled makes it hard to still measure them.

• 33:23Neil deGrasse Tyson?

  It's blocking your view.

• 33:25Speaker 02

  It's blocking the view. And that's also the reason why, for us, it's difficult to do astrophysics from ground based telescopes, you know? The stars are up there, they, people say they twinkle, right? But that twinkling that you see with your eyes, that's not the star. That's actually the starlight that is being perturbed by the earth atmosphere. Right? And so it's a bit similar, but then, then the twinkling of Betelgeuse is caused by the material it has expelled. But it does have also oscillations. And these oscillations can tell us how old it is and how big it is, et cetera.

• 34:02Neil deGrasse Tyson?

  All right, is Betelgeuse ready to blow? Because we think that's a supernova category star. Is it? That people, I, I said, oh my gosh, that something, something bad is gonna happen.

• 34:11Speaker 02

  It's gonna happen. It's gonna, it's not bad. No, it's not bad. Because it will explode eventually, but that can take still some while. So, you know, you don't wanna go and look every day because you may need to have some patience, like.

• 34:26Neil deGrasse Tyson?

  Connie, we're trained to think that if something blows up, it's bad. Okay, I'm sorry.

• 34:31Matt Kirshen?

  Yeah, but these guys are like, it's exciting. This is more data.

• 34:34Speaker 02

  Yes.

• 34:34Neil deGrasse Tyson?

  It's more data, okay. All right. This is like the, the, this is like the rocket launchers who, the rocket blows up on the launch pad. You say, oh, are you upset by that failure? No, that was an experiment rich in data.

• 34:46Speaker 02

  Yeah.

• 34:48Speaker 02

  Well, but I'm saying it's good because it enriches the galaxy with metals, with carbon, with oxygen, with iron and, you know. We need that as human beings. So.

• 35:03Neil deGrasse Tyson?

  Okay, just to be clear, Matt, astrophysicists are, we are very lazy with regard to the periodic table of elements. And so, any element that's not hydrogen or helium, we call it a metal. But this freaks out chemists. We're self-aware of this bad vernacular. But the point is, ninety-eight percent of the universe is hydrogen and helium. And so, and the rest is just other stuff. So, we just.

• 35:31Matt Kirshen?

  It's just experimental error. It's just.

• 35:33Neil deGrasse Tyson?

  Yeah. So, we just call them metals. And I'm just covering Connie's ass right here.

• 35:37Matt Kirshen?

  Yeah.

• 35:38Neil deGrasse Tyson?

  When she said, the metals such as carbon. Right. No, she's being fully astrophysical in in the referencing. So, but Connie, you speak of this, this, this blockage of ejected gas. Like, of course, it would do that. Yet, it hasn't done it in the thousands of years we've been observing the night sky and mapping its brightness relative to other stars. So, do you have an account for why it's doing it now and it's not doing it regularly?

• 36:08Speaker 02

  Oh, but you see, we astrophysicists have to be very patient. Because the time scales, when for stars to do this kind of stuff, you know, that's like hundreds of thousands of years, you know, and.

• 36:24Neil deGrasse Tyson?

  Okay, so you're saying if we see it only once in a few thousand years.

• 36:28Speaker 02

  Yeah, that's normal.

• 36:29Neil deGrasse Tyson?

  That could be a regular interval.

• 36:30Speaker 02

  Yeah, yeah.

• 36:32Neil deGrasse Tyson?

  Okay. All right. She got out of that one, Matt, I think.

• 36:35Speaker 02

  It's just annoying that we human beings only live for like one hundred years, like.

• 36:40Neil deGrasse Tyson?

  At most, yeah.

• 36:41Speaker 02

  If we are lucky.

• 36:42Neil deGrasse Tyson?

  Yeah, we're very lucky.

• 36:43Speaker 02

  So, that's in an astronomical time scale, that's instantaneous. That's very, very short. Yeah.

• 36:49Neil deGrasse Tyson?

  All right, we got to take our last break. And when we come back, more astroseismology with a professor of astroseismology, Connie Arts, on StarTalk Cosmic Queries.

• 37:08Speaker 03

  This is Ken the Nerd Neck Zabera from Michigan and I support StarTalk on Patreon. This is StarTalk Radio with Neil deGrasse Tyson.

• 37:20Neil deGrasse Tyson?

  We're back for the third and final segment of StarTalk Cosmic Queries, the Astroseismology Edition with our expert, a professor of astroseismology Connie Arts, and she's on sabbatical now at the Flatiron Institute in New York City, which has gathered all manner of computational scientists in multiple fields, where they not only compare notes with each other in their own field, but across disciplines, perhaps there's some cross-pollination that can lead to discoveries that wouldn't otherwise happen. And Connie, you are based in the Netherlands and in Belgium. You have two different appointments. Yes.

• 38:05Neil deGrasse Tyson?

  That, of course, there's strong overlap in what they are, but this is very cool that we have you here. We're borrowing you from Europe and great to have you here in my hometown, New York City. So Matt, we have a few minutes for a few more questions. Let's see how many more we can slip in. And these questions are from our Patreon members, still, correct?

• 38:23Matt Kirshen?

  They are, yeah. So Kevin the Sommelier asks, "Does astroseismology coincide with the data we can get from the James Webb Space Telescope? Are we able to see those quakes in infrared?"

• 38:37Neil deGrasse Tyson?

  Ooh, I like that.

• 38:38Matt Kirshen?

  Yeah, and also then gives a wine recommendation.

• 38:40Neil deGrasse Tyson?

  Oh yeah, because I told him I would not allow him to ask another question. If he's going to bill himself as a sommelier, there's got to be a recommendation in this question.

• 38:49Matt Kirshen?

  So he recommends specifically for our Belgian guest, says, "With Moulfrite, Kevin recommends a bottle of Muscadet sur les Lagranges." So there we go. Thank you, Kevin, for that.

• 38:59Neil deGrasse Tyson?

  Okay, that sounds like a dessert wine. All right. Let the world know. We've got the recommendation. So I love that question, Connie. I didn't even think to think about this because I'm I love stellar evolution, but I'm primarily a galaxies guy and a large scale structure guy, which which the James Webb telescope is exquisitely tuned to observe the early universe. And it would never occur to me to imagine if it could be of use to you in thinking about star quakes. So what how does how is your field put your sort of hooks into the data of that telescope?

• 39:35Speaker 02

  Well, the James Webb is fantastic, but I would not spend its time on star quakes. And so let me explain why, you know, James Webb can pierce very deep into the early universe in the infrared. What I need as a seismologist is really long term measurements. And that's why we love the Kepler mission of NASA and now the test mission and the future Plato mission, because they're staring at stars for years without interruption. And so you don't want to spend James Webb on that because it has, as you say, so much other fantastic extragalactic science to do. So I

• 40:15Neil deGrasse Tyson?

  Interesting.

• 40:16Speaker 02

  don't want to hook on James Webb, right?

• 40:19Neil deGrasse Tyson?

  Of course, at all times in in our field, Matt, we're always judging whether you need one particular telescope for that task versus another telescope that might be either more available or less a cutting edge, because you want the cutting edge telescope for the cutting edge science that's going to break open whole new fields typically. So, yeah, that's a very important point that you're mentioning there, Connie. And but I want to also ask, that's part of the great computational challenge, because if you have a lot of quakes of all different frequencies. Short measurements cannot distinguish one from the other, correct?

• 41:02Neil deGrasse Tyson?

  You need a very long baseline so that you can tease out of the data frequencies that are represented enough to know that they're real. Did I characterize that accurately?

• 41:14Speaker 02

  Yeah, that's, that's, that's very well described. And in practice, you know, the, the precision of the frequency goes as one over the total time base of the measurements. Yeah. So if Kepler measures four years, well, that's one over four years in, in, in frequency resolution, as we call it, capacity to unravel these, these starquake frequencies. So we, we, we need, we need to be very, astrophysicologists are very patient people.

• 41:46Neil deGrasse Tyson?

  So what you're saying is if you, uh, so I like that. So if you measure something for four years, you can't really say much about frequencies that occur on two-year time scales.

• 41:59Speaker 02

  That's right.

• 42:00Neil deGrasse Tyson?

  You would have only had one or two cycles in there.

• 42:03Speaker 02

  Yeah.

• 42:03Neil deGrasse Tyson?

  And that's not enough to even know if they're real.

• 42:05Speaker 02

  Yes.

• 42:06Neil deGrasse Tyson?

  So you need enough cycles in your baseline of data to be able to say, yeah, that's real. Yes, it's repeating and it's reliable.

• 42:13Speaker 02

  Yeah, that's right. And so that's why we need these long time series and we can only do the work once we achieve that. So we need dedicated space missions to achieve that. And James Webb is just not one of them.

• 42:26Neil deGrasse Tyson?

  I got it.

• 42:27Speaker 02

  Again.

• 42:27Neil deGrasse Tyson?

  Interesting.

• 42:28Speaker 02

  Please, uh, leave James Webb to the people who need it. And I'm not one of them, all right?

• 42:32Neil deGrasse Tyson?

  That's very magnanimous of you, yes.

• 42:34Speaker 02

  Yeah.

• 42:35Neil deGrasse Tyson?

  So, so just to up, update people. So Kepler was a telescope that looked in one part of the sky, looking for, um, for Earth-like planets around sun-like stars, studying them for a long period of time. TESS, that, what's that? That's an acronym for what? I forgot. Uh, transiting.

• 42:55Speaker 02

  Exoplanet.

• 42:56Neil deGrasse Tyson?

  Exoplanet Survey.

• 42:58Speaker 02

  Satellite.

• 42:59Neil deGrasse Tyson?

  Satellite, thank you.

• 43:00Speaker 02

  Yeah.

• 43:00Neil deGrasse Tyson?

  So TESS will see the entire sky, but not quite to the depth in space that Kepler did. And so now, what is Plato gonna do? And is that also an acronym?

• 43:10Speaker 02

  Yeah, well, Plato stands for planetary transits and oscillations of stars. And Plato is actually gonna, from, from, from construction, combines the best of both worlds of the Kepler mission and the TESS mission. In the sense that we need long-term observations, but we also need the whole, not the whole sky, but a very, very big part of it. To have copies of the Earth in our line of sight that rotate around copies of the sun. It takes a year for us to evolve. And so Plato has that built in. It's actually, it's twenty-four telescopes on one big platform.

• 43:48Neil deGrasse Tyson?

  Oh, my gosh, okay, I didn't know that about it.

• 43:50Speaker 02

  Yeah, so, so it's, it's a multi-telescope instrument that is being built by the European Space Agency right now. I tend to call it my third child, because I've been.

• 44:01Neil deGrasse Tyson?

  Oh, you're, you're deep with, involved in the design and objectives of it. Well, congratulations for that.

• 44:06Speaker 02

  Yeah, yeah, so that's exciting. I wanna see the data before I retire, yeah.

• 44:10Neil deGrasse Tyson?

  Kepler was a famous German mathematician who coincided with Galileo, actually, in time. And we all heard of Plato, but I, I don't know any TESS. So TESS was an acronym, but not an acronym of a famous scientist of the past.

• 44:26Speaker 02

  Exactly, exactly, yeah.

• 44:28Neil deGrasse Tyson?

  So you do, they don't always work out the way you need to.

• 44:31Speaker 02

  Yeah, just as long as the machinery works for us, TESS.

• 44:34Neil deGrasse Tyson?

  You don't care what the hell you call it?

• 44:38Neil deGrasse Tyson?

  All right, so Matt, keep it going, what do you have?

• 44:40Matt Kirshen?

  I am gonna, to try and get through as many of these questions as possible, I am gonna try and combine four different.

• 44:45Neil deGrasse Tyson?

  See if she can do a lightning round.

• 44:46Matt Kirshen?

  Here we are, we're finding four questions. They said it couldn't be done, but four different questioners between, because a lot of people have asked about the effect of sunspots on star quakes. And how they affect Earth. So Charles Maco asks how they affect star quakes. Trevor Mills says, how close would a nearby star have to be for a starquake to be considered dangerous for Earth? And then Sarah Rosen says, how big of a CME would it take for the sun's gravity to be negatively affected? And Gina Martin says, why didn't the one, the starquake back in two thousand and four wipe us out? I've read that it released more energy than our own sun would admit in a hundred and fifty thousand years.

• 45:24Neil deGrasse Tyson?

  Okay, so let me tighten all those up. So Connie, clearly there are quakes going on all the time, and I presume that a CME, a coronal mass ejection, is itself detectable as some kind of quake activity. So, and of course, sunspots are measures of the activity of the sun. So, but you haven't mentioned solar flares, or coronal mass ejections, or sunspots yet, not much in this conversation. So, what role do they play in all of this?

• 45:55Speaker 02

  Oh, well, the role they play is they disturb the periodic oscillations of the sun, but it's not bad for us. Why not? Because coronal mass ejection, or star spots that rotate around, you know, they do not give the same signal in the periodicity of the quakes. I'm quaking my microphone right now. So, you know, a coronal mass ejection is an abrupt event. It's more like an earthquake, you could say. It happens and it disappears, right? But it doesn't disturb us finding the five-minute oscillations of the sun, which

• 46:37Speaker 02

  are always there. Yeah? They get disturbed abruptly, but then they continue, and they continue, and they continue all the time. So for us, you know, we can unravel the signal of star spots, of mass ejections, even for stars other than the sun, from the always smooth periodic oscillation.

• 47:00Neil deGrasse Tyson?

  So how about the dangers that they might pose if you do have a coronal mass ejection that happens to head towards us?

• 47:05Speaker 02

  Yeah, so the earth is protected by a magnetic field that protects us from all these high energetic particles falling in on our planet. And other stars are too far away. So, I mean, it's only a matter of the solar quakes. They are not dangerous for us. The coronal mass ejections, they disturb our electronics every once in a while, right? But you know, that's not a periodic oscillation that I would call solar quakes.

• 47:37Neil deGrasse Tyson?

  Yeah, I forgot that you enjoy events like that, even if they mess with our computers.

• 47:41Speaker 02

  That's how we started.

• 47:43Neil deGrasse Tyson?

  I forgot that. I learned that earlier in this podcast.

• 47:46Speaker 02

  Yeah, yeah, that's true.

• 47:47Neil deGrasse Tyson?

  So that almost counts as a lightning round, Matt, because she answered three questions in one reply.

• 47:52Matt Kirshen?

  Yes, she did.

• 47:53Neil deGrasse Tyson?

  So let's see if we can get a few more in before we call it a day.

• 47:56Matt Kirshen?

  Yeah, James Allen from Brisbane in Australia says, "Could a starquake large enough theoretically cause a star to tear apart? And would descend a high radiation blast like a supernova? What could we learn such things from our own star?"

• 48:10Speaker 02

  A starquake would not rip apart a star because it's really a smooth, nice periodic variability. You know, the biggest starquakes in terms of expansion and contraction, let's say, can make the star become bigger and smaller by about 10% in its radius, let's say. But not make it explode. That's another phenomenon.

• 48:32Neil deGrasse Tyson?

  Okay. Again, that's people thinking that a quake is a spontaneous bad thing.

• 48:36Speaker 02

  No, it's a fantastic smooth thing.

• 48:39Neil deGrasse Tyson?

  It's fantastic smooth thing.

• 48:42Matt Kirshen?

  Well, on that same note, Connor Home from Squim, Washington, says, "Is it possible to predict where and when a starquake will occur? And if so, what's the largest predicted starquake? And how much bigger is it compared to the largest recorded one?"

• 48:55Speaker 02

  Well, starquakes happen all the time. I keep repeating that.

• 48:58Neil deGrasse Tyson?

  So let me ask it differently then. What variety of your oscillations carries the most energy?

• 49:04Speaker 02

  Well, the simplest starquakes are radial oscillations, you know, up and down and up and down. So everything is...

• 49:17Speaker 02

  Expanding and contracting while keeping spherical symmetry. So that's about the, you know, the largest energetic it can get. And that's for me, just a simple oscillation because it's.

• 49:30Neil deGrasse Tyson?

  And that's what gives us variable stars, I guess, right?

• 49:33Speaker 02

  Yeah, yeah, yeah, yeah. So Cephalies, Oortoli, Ray.

• 49:35Neil deGrasse Tyson?

  Yeah, I mean, it's half a star. I mean, some huge fraction of stars in the night sky are variable, presumably for this reason. And I heard when I was in graduate school, Connie, that if you looked at every star close enough with sharp enough data, they're all variable.

• 49:55Speaker 02

  Of course they are. Everything oscillates, of course.

• 49:59Neil deGrasse Tyson?

  So we just have to draw some arbitrary line of what we categor- what we catalog as a variable star relative to other stars. But really, to you, everybody's got action.

• 50:10Speaker 02

  Well, we're measuring the action up to parts per million.

• 50:14Neil deGrasse Tyson?

  Yeah, there it is.

• 50:15Speaker 02

  Right?

• 50:15Neil deGrasse Tyson?

  You got it.

• 50:16Speaker 02

  Parts per million.

• 50:18Neil deGrasse Tyson?

  You got it. All right. Matt, let's get one more- slip one more in before we got a call.

• 50:22Matt Kirshen?

  All right. Margaret Defoe from Milwaukee says, why didn't our solar system go binary? And what is the smallest and largest a star can get? So we're on more general questions about stars, I think.

• 50:32Neil deGrasse Tyson?

  Yeah, let's do it. Hold aside the largest and smallest. That's a whole other astrophysics question. But Connie, what do you say about why the sun is alone when so many stars in the night sky are binary in multiple systems?

• 50:43Speaker 02

  Yeah, well, if you look at the star with the mass of the sun, then half of them are in binary. So that means that half of them are alone. So it's a toss. It's an equal toss, right? Yeah, so that's not so exceptional. But if you, if you go to stars.

• 51:01Neil deGrasse Tyson?

  That's not the answer we were looking for. We wanted you to say, we might have had a double and then it blew up. We want a more sci-fi answer.

• 51:09Matt Kirshen?

  We lost, it was originally a twin. We lost one of them. It ate the other one in the womb.

• 51:13Neil deGrasse Tyson?

  It ate the other one.

• 51:14Speaker 02

  I don't think so. I don't think so. But that happens frequently when you go to higher masses, huh? If your star is born with 10 to 100 times more mass than the sun was born with, well, then about 80% of the stars are multiple, double stars. Yeah, so for the sun, I think it's just a logical consequence of there only being half of them that live their life together, right?

• 51:40Neil deGrasse Tyson?

  Okay.

• 51:41Speaker 02

  Luckily for us, it wouldn't have been so nice here if it would have had been living next to a star that has exploded already.

• 51:49Neil deGrasse Tyson?

  Yeah, yeah, it has issues, but that's definitely a yet to be written sci-fi drama, I think, sci-fi action film. Whatever happened to the sun's twin? You got it. Well, Connie, it's been a delight to have you on StarTalk. And like I said, my city, my town is your town, so I'm a native of New York City. You're visiting for the sabbatical. Maybe we can get you up to the museum and give you a tour and possibly extract, extort a seminar from you for our National Physics Group.

• 52:21Speaker 02

  Yeah, I love this city, so I'm very grateful that you're hosting me.

• 52:26Neil deGrasse Tyson?

  Excellent, excellent. Matt, always good to have you, man.

• 52:28Matt Kirshen?

  It's a pleasure to be here. Thanks for having me, and this has been great. I've loved hearing about this stuff.

• 52:32Neil deGrasse Tyson?

  We got to land this plane. So thanks for joining us on this episode of StarTalk Cosmic Queries: Starquakes. I'm Neil deGrasse Tyson, as always, bidding you to keep looking up.