Latest / Daniel and Kelly’s Extraordinary Universe / What's the biggest star in the Universe?

Transcript

What's the biggest star in the Universe? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, what's the biggest number you can hold in
• 0:11
  Speaker 1: your head? I can think about infinity, I guess, can
• 0:15
  Speaker 1: you do have an infinite number of neurons? No, but
• 0:19
  Speaker 1: it feels like I've eaten an infinite number of cookies
• 0:22
  Speaker 1: during this pandemic. It does feel like it's dragging onto infinity.
• 0:27
  Speaker 1: But you know, even if you ate a hundred cookies
• 0:29
  Speaker 1: a day, that's not even a million cookies a year.
• 0:31
  Speaker 1: Although that's a good goal to happen, you're right, And honestly,
• 0:35
  Speaker 1: it's hard to visualize a number bigger than like a
• 0:38
  Speaker 1: hundred or a thousand anything else. In my head. Frankly,
• 0:42
  Speaker 1: it's just like a lot, a bunch, a zillion. So
• 0:46
  Speaker 1: then how do you think about how big things are
• 0:48
  Speaker 1: out in space, like Jupiter or the Sun or the galaxy? Like,
• 0:52
  Speaker 1: how do you conceive or think about the mass of
• 0:54
  Speaker 1: such huge objects? I just use the unit of cookies.
• 0:58
  Speaker 1: Jupiter is a whole lot of cookies. It's a pandemic
• 1:00
  Speaker 1: bard fool of cookies. It's the biggest cookie jar in
• 1:03
  Speaker 1: the universe. That's my goal in this pandemic. To eat
• 1:05
  Speaker 1: one Jupiter's worth of cookies. Then you look like Jupiter
• 1:10
  Speaker 1: I think we just wrote Jupiter's formation story for the
• 1:13
  Speaker 1: comic book series. I am more hammade cartoonists and the
• 1:30
  Speaker 1: creator of PhD comments. Hi. I'm Daniel. I'm a particle physicist,
• 1:34
  Speaker 1: but I have strong opinions about cookies. Do you really
• 1:38
  Speaker 1: like a positive or negative like you're never ambivalent about cookies.
• 1:42
  Speaker 1: I'm never ambivalent about cookies and very specific taste for
• 1:45
  Speaker 1: what makes a good cookie really according to you? Or
• 1:48
  Speaker 1: do you think you have some sort of universal standard
• 1:51
  Speaker 1: of cookie goodness. I would not want to be the
• 1:54
  Speaker 1: cookie spokesperson for humanity, but I have strong reactions to cookies. Yes, really,
• 1:59
  Speaker 1: What do you think about hips of hoyies? Those are
• 2:01
  Speaker 1: not cookies, My god, those are cardboards simulcrums of cookies. Man, Well,
• 2:09
  Speaker 1: welcome to our podcast. Daniel and Jorge explain the universe
• 2:12
  Speaker 1: of cookies, just the regular universe, the other universe, A
• 2:17
  Speaker 1: production of I Heart Radio, in which we take our
• 2:19
  Speaker 1: cookie fueled brains on a tour of everything in the universe,
• 2:23
  Speaker 1: how it works, how big it is, how small it is.
• 2:26
  Speaker 1: Nothing on this podcast is too vast, too incredibly huge
• 2:30
  Speaker 1: for us to try to wrap our minds around. Nor
• 2:33
  Speaker 1: is it too small for us to try to penetrate
• 2:36
  Speaker 1: with our intellect and get a grasp of what's going
• 2:38
  Speaker 1: on down at the tiniest level. Yeah, because it's pretty
• 2:41
  Speaker 1: hard sometimes to hold the hold universe in your head.
• 2:44
  Speaker 1: I mean, you have to hold not just the tiny
• 2:46
  Speaker 1: microscopic particles that everything is made out of, but you
• 2:49
  Speaker 1: also have to hold the ginormous structures that are out
• 2:51
  Speaker 1: there in space, those huge suns and stars and galaxies
• 2:56
  Speaker 1: and solar systems and clusters of galaxies. It's a big universe.
• 2:59
  Speaker 1: It is a big universe, and often we just rely
• 3:02
  Speaker 1: on math as like a mental scaffolding to take us
• 3:05
  Speaker 1: where our minds have a hard time going. We talk
• 3:08
  Speaker 1: about these numbers, but it's good to understand that these
• 3:11
  Speaker 1: things are real. When we talk about these objects that
• 3:13
  Speaker 1: are out there, they're real. They're out there. There's actually enormous,
• 3:17
  Speaker 1: vast burning plasma balls in the sky. This is not
• 3:21
  Speaker 1: a joke, This is not just notation. It's reality. Yeah,
• 3:24
  Speaker 1: they're giant cookies as well, the size of Jupiter. You know.
• 3:27
  Speaker 1: I always say we shouldn't be surprised by anything we
• 3:29
  Speaker 1: discover in the universe. But if hubble turns up enormous
• 3:33
  Speaker 1: planet sized cookies. I would be surprised and delighted. Depends
• 3:37
  Speaker 1: on what's in the cookie, man, and if they're Jupiter
• 3:40
  Speaker 1: sized chips of hoys, I'm out well. In today's podcast,
• 3:44
  Speaker 1: will be tackling another one of our Extreme Universe series,
• 3:48
  Speaker 1: in which we talk about the biggest things in the universe,
• 3:51
  Speaker 1: the hottest, the coldest, the emptiest bass in the universe.
• 3:56
  Speaker 1: We like to talk about extreme things, Yeah, because the
• 3:58
  Speaker 1: extremes tell us what's a limit are. That's what reveals
• 4:01
  Speaker 1: what the rules are. When you push the universe to
• 4:04
  Speaker 1: the edges of what he can do, you understand why
• 4:06
  Speaker 1: you can do something and why it can't. So the
• 4:08
  Speaker 1: Extreme Universe series is not just fun because it blows
• 4:11
  Speaker 1: your mind, but also it teaches us something about the
• 4:13
  Speaker 1: way the universe works. Yeah, it's extremely educational as well.
• 4:18
  Speaker 1: So on today's podcast will be tackling one of these
• 4:21
  Speaker 1: extreme things in the universe, and we're doing something a
• 4:24
  Speaker 1: little different today. That's right. Today we have a guest
• 4:27
  Speaker 1: who will be asking the question of the episode for us. Yeah,
• 4:30
  Speaker 1: he's kind of a bit of a celebrity online, right, Yeah. Absolutely,
• 4:33
  Speaker 1: he's definitely the youngest host of a science podcast that
• 4:36
  Speaker 1: I'm aware of. Yeah, so here is our special guest
• 4:40
  Speaker 1: to introduce the question. Hello, with my pleasure to welcome
• 4:43
  Speaker 1: to the program. Today's special guest question asker Tie Pool. Hi,
• 4:48
  Speaker 1: say hello to everyone. Hi, I'm really excited to be here.
• 4:52
  Speaker 1: I'm a little bit nervous, but mostly excited. Well, welcome
• 4:56
  Speaker 1: to the program. Why don't you tell us a little
• 4:57
  Speaker 1: bit about yourself and your podcast? Well, I'm fourteen, just
• 5:02
  Speaker 1: started high school. I'm here in Toronto, and I host
• 5:06
  Speaker 1: a CBC podcast called tie Asks Why the Journey of
• 5:09
  Speaker 1: a kid just asking questions because you know, my curiosity
• 5:14
  Speaker 1: got the better of me. You asked so many questions
• 5:18
  Speaker 1: that they decided you should host a podcast about it. Yeah,
• 5:20
  Speaker 1: pretty much. And what kind of topics does your podcast
• 5:24
  Speaker 1: ask about or answer? Well, we have a wide range
• 5:27
  Speaker 1: of stuff. You know, it can get kind of silly
• 5:29
  Speaker 1: stuff like why do we dance? Or how do songs
• 5:33
  Speaker 1: get stuck in your head? But we also deal with
• 5:35
  Speaker 1: deeper ones like what is love and what is death?
• 5:39
  Speaker 1: And then of course we get to some really crazy
• 5:42
  Speaker 1: ones like the end of the universe and a pretty
• 5:45
  Speaker 1: topical one about viruses. Awesome, it sounds like a lot
• 5:49
  Speaker 1: of fun here on the program. We are definitely big
• 5:52
  Speaker 1: fans of curiosity for folks or even down to nine
• 5:56
  Speaker 1: years old. And I've listened to a bunch of episodes
• 5:58
  Speaker 1: of your podcast. It's a lot of fun. So congrats, thanks,
• 6:02
  Speaker 1: I'm really honored. I recently listened to your episode about
• 6:05
  Speaker 1: John von Newman, and I think it's really cool because
• 6:07
  Speaker 1: he's a really cool guy. He just is in the
• 6:09
  Speaker 1: background of a lot of science things, but he did
• 6:11
  Speaker 1: a lot. Yeah, he definitely was a curious person. All right,
• 6:15
  Speaker 1: So then let's dig into today's episode. We have you
• 6:18
  Speaker 1: on to be our guest question asker, So why don't
• 6:21
  Speaker 1: you introduce for our listeners what today's episode is about. Well,
• 6:25
  Speaker 1: I got another question and I decided to be a
• 6:27
  Speaker 1: good idea to ask you guys. So the question for
• 6:29
  Speaker 1: this episode is what is the biggest star in the universe? Awesome?
• 6:34
  Speaker 1: I love that question. But tell me first, what tickles
• 6:37
  Speaker 1: you about that question? What makes you curious about the
• 6:40
  Speaker 1: size of stars? Well, it's just kind of thinking about
• 6:44
  Speaker 1: the sun, and it's a strange thing to think about.
• 6:46
  Speaker 1: It seems like really big and scale of our planets
• 6:49
  Speaker 1: and stuff. But I kind of learned and realized that
• 6:53
  Speaker 1: our son is not very big in comparison to other stars.
• 6:56
  Speaker 1: So it kind of just got me thinking, like how
• 6:58
  Speaker 1: big could we reallyly go? You know, can we get
• 7:01
  Speaker 1: something that's like twice the size of our stunt? Is
• 7:03
  Speaker 1: that the biggest or like a million times we go
• 7:06
  Speaker 1: like really really big? Awesome? Well, I love your expectation
• 7:09
  Speaker 1: that the universe will surprise you, will shock you, because
• 7:12
  Speaker 1: I think there's a lot of examples in history where
• 7:15
  Speaker 1: we learned something about the universe and we are totally
• 7:17
  Speaker 1: surprised at the size of things, about the scale of
• 7:20
  Speaker 1: the crazy stuff that's going on out there in the universe. Yeah,
• 7:24
  Speaker 1: I kind of just was in the mood to get
• 7:25
  Speaker 1: my mind blown. You know, I'm excited to hear the number.
• 7:30
  Speaker 1: It's gonna be crazy. It's gonna be like a billion
• 7:32
  Speaker 1: or something. All right, Well, thanks very much. We'll hope
• 7:36
  Speaker 1: to blow your mind. All right. That was Tie Pool,
• 7:39
  Speaker 1: host of TI ask why, and like him, I think
• 7:43
  Speaker 1: we're all ready to get our mind bloom. That's right.
• 7:45
  Speaker 1: It's a lot of pressure though, right, he's really expecting
• 7:47
  Speaker 1: a big number. Yeah, yeah, because you know, I bet
• 7:50
  Speaker 1: there are huge stars out there in the universe. There
• 7:52
  Speaker 1: are huge stars out there in the universe, and Ty
• 7:55
  Speaker 1: was reaching for what he thought was like a vast
• 7:57
  Speaker 1: number of star, a million times bigger than our son.
• 8:00
  Speaker 1: But actually we're going to deliver something much much bigger
• 8:03
  Speaker 1: than that, bigger than a million times the size of
• 8:05
  Speaker 1: our son. That's right. We're gonna make our son look
• 8:08
  Speaker 1: like a tiny dust spec, a shiny, tiny dustpec. Al right, Well,
• 8:12
  Speaker 1: as usual, you also went out there into the wilds
• 8:14
  Speaker 1: of the Internet to ask regular listeners what they thought
• 8:18
  Speaker 1: of this question. That's right, So thank you to everybody
• 8:20
  Speaker 1: who stretched their minds and tried to imagine an enormous
• 8:23
  Speaker 1: star out there in the universe. And if you would
• 8:25
  Speaker 1: like to respond to tough questions from a physicist without
• 8:28
  Speaker 1: any reference materials, please write to me two questions at
• 8:32
  Speaker 1: Daniel and Jorge dot com. So think about it for
• 8:34
  Speaker 1: a second. If someone asked you what you thought was
• 8:37
  Speaker 1: the biggest star in the universe, what would you say.
• 8:41
  Speaker 1: Here's what people had to say. I think that a
• 8:44
  Speaker 1: big factor for determining how big a star can get.
• 8:48
  Speaker 1: I think it's gravity. Well, one thing for sure, it's
• 8:52
  Speaker 1: they always discovered something that is bigger than they thought
• 8:58
  Speaker 1: it would be. That stars can get much more massive
• 9:02
  Speaker 1: than our own son. I do not know how big
• 9:05
  Speaker 1: a star can get, but I know that at a
• 9:07
  Speaker 1: certain point it, when it passes a certain threshold, it
• 9:11
  Speaker 1: will collapse on itself and from a black hole. All right, Well,
• 9:15
  Speaker 1: the answer seemed to be all over the place, big
• 9:18
  Speaker 1: answers and small answers. Yeah, exactly, definitely. People are prepared
• 9:22
  Speaker 1: to have their minds blown and to be surprised. I
• 9:25
  Speaker 1: think one thing we've learned in our exploration of the
• 9:27
  Speaker 1: universe is that what we expect is very rarely what's
• 9:31
  Speaker 1: actually out there. Yeah. Well, I think maybe to start
• 9:35
  Speaker 1: us off, maybe we should settle this technical question, which
• 9:39
  Speaker 1: is I think is important. What do we mean by
• 9:41
  Speaker 1: biggest star? Do we mean the biggest in volume, like
• 9:44
  Speaker 1: the one that occupies the most space, or the dancest
• 9:48
  Speaker 1: or most massive star. What are we talking about here?
• 9:51
  Speaker 1: Most paparazzi following them around taking pictures? Maybe, yeah, most
• 9:55
  Speaker 1: Instagram followers, biggest box office. That's right, that's what it
• 9:59
  Speaker 1: take to be massive on social media. Though it's a
• 10:02
  Speaker 1: fair question that you can make an argument in either direction.
• 10:05
  Speaker 1: Mass is really important in determining the life cycle of
• 10:08
  Speaker 1: a star, and what it means. But volume is also
• 10:11
  Speaker 1: a big deal. Really in the end, maybe what we're
• 10:13
  Speaker 1: talking about is like the physical size of these things. Yeah,
• 10:16
  Speaker 1: because when you see it, when you're in front of
• 10:18
  Speaker 1: it at this point, you would think about when you
• 10:19
  Speaker 1: think about the word big, like, oh, wow, that's big.
• 10:22
  Speaker 1: But if it was small and dense, you've been impressed,
• 10:24
  Speaker 1: but you wouldn't say, wow, that's big. Yeah. Well it's
• 10:26
  Speaker 1: a big deal, right. It makes a big dent in
• 10:29
  Speaker 1: the structure of the universe. It's like a large gravitational well,
• 10:33
  Speaker 1: I mean, black holes are not a tiny thing to
• 10:34
  Speaker 1: be ignored. And I think initially I would have voted
• 10:38
  Speaker 1: for the mass of the star because that really does
• 10:41
  Speaker 1: tell you about the nature of the star and also
• 10:44
  Speaker 1: like its fate. The entire fate of the star is
• 10:46
  Speaker 1: determined by how much stuff it has. If it has
• 10:49
  Speaker 1: a certain amount of stuff, it's going to end up
• 10:51
  Speaker 1: as a white dwarf that has more, it's gonna become
• 10:52
  Speaker 1: a neutron star or eventually a black hole. All of
• 10:55
  Speaker 1: that is determined by the mass of the star. It's
• 10:57
  Speaker 1: a really important way to categorize stars. And I guess
• 11:01
  Speaker 1: it doesn't change because the volume of a star changes, right,
• 11:04
  Speaker 1: Like stars go through a life cycle and they grow
• 11:07
  Speaker 1: and they shrank and they end up small at the end. Right,
• 11:10
  Speaker 1: it's a varying quantity. But the math doesn't really change,
• 11:13
  Speaker 1: does it. It doesn't change that much. I mean, the
• 11:15
  Speaker 1: end cycle of a star, it does blow off some
• 11:18
  Speaker 1: of its outer layers. So, for example, our sun is
• 11:20
  Speaker 1: going to end up as a white dwarf, and it
• 11:22
  Speaker 1: won't have all the mass that it had in it's
• 11:24
  Speaker 1: early part of its life because it's going to blow
• 11:26
  Speaker 1: out a huge amount of that into like a planetary nebula.
• 11:28
  Speaker 1: So it does sort of change. But you know, you
• 11:30
  Speaker 1: might say that by the time our sun becomes a
• 11:33
  Speaker 1: white dwarf, it's no longer a star, right because it
• 11:35
  Speaker 1: has no more fusion going on inside of it. To
• 11:38
  Speaker 1: see list celebrity now exactly can't even get into the
• 11:43
  Speaker 1: hottest restaurants in l A anymore. It's in dancing with
• 11:46
  Speaker 1: the stars, exactly. But volume, you're right, it's variable. Star
• 11:52
  Speaker 1: can grow a lot during its life cycle. So if
• 11:54
  Speaker 1: we just look out into space and compare two stars,
• 11:57
  Speaker 1: we might be comparing two stars that eventually would have
• 11:59
  Speaker 1: the same size. If you sort of lined them up.
• 12:01
  Speaker 1: But one of them is like a grandpa star that's
• 12:03
  Speaker 1: really big at the end of his life. The other
• 12:05
  Speaker 1: one it's like a baby star that's more condensed. Okay,
• 12:07
  Speaker 1: so then we're really talking about the mass of the
• 12:10
  Speaker 1: star then, like what's the most massive star? Yeah, I
• 12:13
  Speaker 1: don't know. I'm honestly on the fence about it, because
• 12:16
  Speaker 1: the mass of the star is also important for other reasons,
• 12:18
  Speaker 1: Like it tells you about the history of the universe.
• 12:20
  Speaker 1: You know, the very early universe stars were much bigger
• 12:23
  Speaker 1: and hotter and burned faster because there weren't these pockets
• 12:26
  Speaker 1: of metal to collapse smaller stars, and later on the
• 12:29
  Speaker 1: stars that were formed are smaller and lasts longer, So
• 12:33
  Speaker 1: that's really important. On the other hand, what I think
• 12:36
  Speaker 1: about what is the biggest star in the universe, I
• 12:38
  Speaker 1: definitely am thinking about volume. I want my mind blown
• 12:41
  Speaker 1: by the sheer amount of space that this thing takes up. Right,
• 12:45
  Speaker 1: it's a tough call. So why don't we do both?
• 12:47
  Speaker 1: All Right, We're gonna hand out two awards, right, We're
• 12:49
  Speaker 1: just gonna like dilute the value of our prizes by
• 12:52
  Speaker 1: giving out two of them. Make two categories, you know,
• 12:55
  Speaker 1: like the Peace Nobel Prize and the actual Nobel Prizes.
• 13:00
  Speaker 1: You mean the one in chemistry, right, That's exactly what
• 13:03
  Speaker 1: I was thinking. Yes, all right, so let's talk about
• 13:06
  Speaker 1: most massive star and also most I don't know, voluminous star,
• 13:11
  Speaker 1: biggest man, it is just biggest, most volume is just
• 13:14
  Speaker 1: the biggest. All right, so let's jump into it. I
• 13:17
  Speaker 1: guess what we talk about when we talk about mass. Yeah, well,
• 13:20
  Speaker 1: we had a fun podcast a week or so ago
• 13:22
  Speaker 1: about how massive stars can get, how big they can get,
• 13:25
  Speaker 1: how small they can get. And we also talked recently
• 13:28
  Speaker 1: about like where's the threshold between a planet and a star?
• 13:32
  Speaker 1: And really the definition of something that's a star is
• 13:35
  Speaker 1: something that confuse hydrogen, and in order for that to happen,
• 13:39
  Speaker 1: you just have to have enough mass, just like a
• 13:41
  Speaker 1: minimum mass threshold. You don't have enough stuff enough like
• 13:44
  Speaker 1: hydrogen gathered together and then compressed down, then you can't
• 13:48
  Speaker 1: get fusion going. And the minimum threshold there is something
• 13:52
  Speaker 1: like about a hundred times the mass of Jupiter. Doesn't
• 13:55
  Speaker 1: have to be hydrogen though, right, some stars confuse other elements. Yeah,
• 13:59
  Speaker 1: the heavier stuff like helium or carbon or neon or oxygen.
• 14:03
  Speaker 1: That takes even more mass in order to get that started.
• 14:06
  Speaker 1: But you're right, there is like a special category of
• 14:08
  Speaker 1: star called a brown dwarf that doesn't fuse hydrogen itself.
• 14:13
  Speaker 1: Iffuses an isotope of hydrogen called deuterium. So if you
• 14:17
  Speaker 1: have like fifty Jupiter masses or actually anything between about
• 14:20
  Speaker 1: like fifteen to eighty, you can get a form of
• 14:23
  Speaker 1: fusion going. It's called deuterium fusion. It's not like as
• 14:27
  Speaker 1: bright and as hot as normal hydrogen fusion. And so
• 14:30
  Speaker 1: this is I think a disagreement about whether or not
• 14:32
  Speaker 1: you would call this a star. Doesn't have regular hydrogen fusion,
• 14:36
  Speaker 1: so it's called a brown dwarf, also sometimes called a
• 14:38
  Speaker 1: failed star. And so the smallest thing you would really
• 14:42
  Speaker 1: call a star is about hundred times the mass of Jupiter,
• 14:45
  Speaker 1: and it can really fuse hydrogen, and you call these
• 14:48
  Speaker 1: red dwarfs. It's actually the most common kind of star
• 14:51
  Speaker 1: in the universe, these red dwarfs. They're everywhere, meaning like
• 14:54
  Speaker 1: if you take a hundred jupiters and you put them
• 14:56
  Speaker 1: on the same place, they will become a star. Yes,
• 14:59
  Speaker 1: if you took a to jupiters and put them all
• 15:01
  Speaker 1: in the same place, they would collapse and they would
• 15:03
  Speaker 1: start fusion. The interesting thing is that they actually wouldn't
• 15:05
  Speaker 1: be much bigger than Jupiter because there'd be so much
• 15:08
  Speaker 1: gravity would pull it together. So a red dwarf is
• 15:11
  Speaker 1: not actually bigger than Jupiter. It's just much more dense
• 15:14
  Speaker 1: that has a hundred times the mass, and that's enough
• 15:16
  Speaker 1: to get hydrogen fusion going. And what would they look
• 15:19
  Speaker 1: like if you saw them, Like, would they look as
• 15:21
  Speaker 1: bright as Arthen? No, they're not nearly as bright because
• 15:25
  Speaker 1: there's a very strong relationship between the mass of a
• 15:27
  Speaker 1: star and its brightness, and as the mass goes up,
• 15:30
  Speaker 1: the brightness increases by the power of four. So a
• 15:32
  Speaker 1: star that has like a tenth the mass of the
• 15:35
  Speaker 1: Sun has much much less brightness. It's like one ten
• 15:38
  Speaker 1: thousands of the brightness of the Sun. And in fact,
• 15:41
  Speaker 1: the closest red dwarf to Earth is called Bernard's Star,
• 15:44
  Speaker 1: is too dim to see by I even though it's
• 15:46
  Speaker 1: pretty close. Mmmmm, all right, So you take a hundred jupiters,
• 15:50
  Speaker 1: you put in together, you start fusing in the middle.
• 15:52
  Speaker 1: And is it basically like a more like a simmering
• 15:55
  Speaker 1: ball of fire, or is it only happening in the
• 15:57
  Speaker 1: core for example, it's definitely a ball of or like
• 16:00
  Speaker 1: if you were near you would get fried. It's still
• 16:02
  Speaker 1: very hot, it's just not nearly as bright as a
• 16:05
  Speaker 1: larger star, all right. So that's the minimum star. That's
• 16:09
  Speaker 1: the minimum star. And the amazing thing about the minimum
• 16:11
  Speaker 1: star is that remember that big stars burn hotter, and
• 16:14
  Speaker 1: so they burn faster. These small stars they're just sitting
• 16:17
  Speaker 1: there like glowing embers, and they're gonna last a long
• 16:21
  Speaker 1: long time. Like these red dwarves, they could last for
• 16:24
  Speaker 1: ten trillion years, ten trillion years and would never run
• 16:28
  Speaker 1: out of fuel or anything. Yeah, because they're just very
• 16:31
  Speaker 1: slowly burning their fuel. They're much cooler than our sun,
• 16:34
  Speaker 1: which is why they're much less bright, and so they're
• 16:36
  Speaker 1: sort of like conserving our fuel. The biggest, brightest stars
• 16:39
  Speaker 1: will only last like a few million years. The smaller
• 16:42
  Speaker 1: stars that are not as big and not as hot,
• 16:44
  Speaker 1: they can go on for trillions of years, much much
• 16:46
  Speaker 1: longer than the age of our universe so far. They're
• 16:50
  Speaker 1: like those TV actors that get work forever on TV,
• 16:53
  Speaker 1: but they're they're not as they don't shine as brightly
• 16:55
  Speaker 1: on the big screen. That's right, Christopher Walking, for example, No,
• 16:59
  Speaker 1: my Colcaine, that guy is still working, all right. Well,
• 17:02
  Speaker 1: so that's the minimum star, and so let's crank up
• 17:05
  Speaker 1: the mass style and get into more massive stars and
• 17:08
  Speaker 1: then we'll get to the actual biggest stars. But first
• 17:13
  Speaker 1: let's take a quick break, all right, Daniel, we're on
• 17:28
  Speaker 1: the hunt for the most massive stars in the universe,
• 17:31
  Speaker 1: and also the biggest stars in the universe, physical stars,
• 17:35
  Speaker 1: like the shiny kind that's out in space as through
• 17:38
  Speaker 1: physical stars, unless you're suggesting that Hollywood celebrities are non physical,
• 17:42
  Speaker 1: that they're like supernatural. They're very ithereal they transcend physcality,
• 17:49
  Speaker 1: that's right. So the next thing up after red dwarfs
• 17:52
  Speaker 1: are stars like our Sun, would you call a yellow dwarf?
• 17:55
  Speaker 1: And our son Like it's not nearly the biggest or
• 17:59
  Speaker 1: most massive star in the universe, but it's huge, you know,
• 18:02
  Speaker 1: compared to the size of the Earth, which already is
• 18:04
  Speaker 1: like staggeringly large, the Sun is enormous. It's like three
• 18:09
  Speaker 1: hundred thousand times the massive the Earth, and you could
• 18:11
  Speaker 1: fit more than a million earths inside of it. Mm hmmmm.
• 18:15
  Speaker 1: And that one is also fusion, right, definitely, this fusion
• 18:18
  Speaker 1: happening at the core of the Sun. Mm hmmm. Yeah,
• 18:21
  Speaker 1: and it's sort of just right for us though, right, Like,
• 18:23
  Speaker 1: if it was brighter, maybe we wouldn't be a lot
• 18:26
  Speaker 1: were dimmer. Yeah, exactly. If it was a lot brighter
• 18:29
  Speaker 1: than the surface of the Earth would be a lot toastier,
• 18:31
  Speaker 1: and maybe Mars would be a better neighborhood to live in.
• 18:34
  Speaker 1: So it's like three hundred times brighter than those red
• 18:38
  Speaker 1: dwarfs that are nearby, but it's only gonna last about
• 18:41
  Speaker 1: ten billion years. So we're halfway through the life of
• 18:43
  Speaker 1: the Sun. Oh wow, So it's about three hundred times
• 18:47
  Speaker 1: bigger than the red dwarf but will last much much less. Yeah,
• 18:51
  Speaker 1: so it's only about ten times the mass, but it's
• 18:53
  Speaker 1: gonna last a lot less time because if you crank
• 18:56
  Speaker 1: up the temperature, fusion really takes off and starts burning
• 18:58
  Speaker 1: a lot faster. It's very nonlinear. You double the mass,
• 19:02
  Speaker 1: you get much hotter temperatures, and you burn through that
• 19:04
  Speaker 1: mass much faster. So here in our solar system, that
• 19:08
  Speaker 1: means we're sort of on the low end of the
• 19:10
  Speaker 1: massive sun scale, right, our sun is relatively small compared
• 19:14
  Speaker 1: to what's out there. Yes, absolutely, our sun is not
• 19:17
  Speaker 1: impressive compared to the most massive stars that are out there.
• 19:20
  Speaker 1: It's not in the population of the smallest stars, the
• 19:22
  Speaker 1: red dwarfs that are very, very common. But it's not
• 19:24
  Speaker 1: an impressive star at all. We still like it though.
• 19:28
  Speaker 1: It's still our favorite star. It's perfect for us, all right.
• 19:31
  Speaker 1: So let's crack up the mass even more. What happens
• 19:33
  Speaker 1: if you get into thousands of times the mass of
• 19:35
  Speaker 1: our Sun? Well you can't. Actually, it turns out that
• 19:38
  Speaker 1: the biggest stars that are out there are only like
• 19:41
  Speaker 1: a hundred hundred fifty up to maybe about two hundred
• 19:45
  Speaker 1: times the mass of the Sun. I see, because what
• 19:49
  Speaker 1: happens after that. What happens after that is that the
• 19:52
  Speaker 1: Sun gets really big and really hot, and it starts
• 19:55
  Speaker 1: to burn really strongly is core, and that fusion generates
• 19:59
  Speaker 1: a lot of radiation, and so it blows out the
• 20:01
  Speaker 1: outer layers of the star. So there's sort of an
• 20:03
  Speaker 1: upper limit to how much mass you can cram into
• 20:06
  Speaker 1: a star and how it still be stable. Remember, a
• 20:08
  Speaker 1: star is sort of a balance between gravity that's trying
• 20:11
  Speaker 1: to compact it and fusion that's pushing out the glowing
• 20:14
  Speaker 1: the hot energy that's keeping it from compacting. I see.
• 20:18
  Speaker 1: So if you gather more than two hundred times the
• 20:20
  Speaker 1: mass of our Sun together in like a giant hydrogen cloud,
• 20:24
  Speaker 1: it wouldn't all crunch together in the middle because by
• 20:27
  Speaker 1: the time it starts to crunch, the middle starts exploding,
• 20:30
  Speaker 1: and then that blows everything away. Yeah, and first of all,
• 20:32
  Speaker 1: if you have such a huge cloud, it probably wouldn't
• 20:34
  Speaker 1: collapse into just one star. It's more likely to collapse
• 20:37
  Speaker 1: into several smaller stars. But if you somehow arranged like
• 20:41
  Speaker 1: a bunch of really big stars to combine themselves together
• 20:44
  Speaker 1: into something which was two or three hundred times the
• 20:46
  Speaker 1: mass of the Sun, it would blow itself apart because
• 20:49
  Speaker 1: the fusion at its core would be so powerful. All right, well,
• 20:52
  Speaker 1: let's take the next step. Then, what's next step? After
• 20:54
  Speaker 1: our star? After our star? This serious which is actually
• 20:58
  Speaker 1: the brightest star in night sky, and it has two
• 21:01
  Speaker 1: times the mass of our Sun, so it's like two
• 21:04
  Speaker 1: scoops of suns, and it's much bigger actually than our son.
• 21:08
  Speaker 1: It's like eight times the volume. And even though it's
• 21:10
  Speaker 1: only twice the mass, it's like twenty five times brighter
• 21:14
  Speaker 1: than our sun. That's a general thing, or is it
• 21:18
  Speaker 1: just this one star? Now? In general? As you crank
• 21:21
  Speaker 1: up the mass, the brightness goes up much much faster.
• 21:24
  Speaker 1: This is the mass luminosity relationship we talked about in
• 21:26
  Speaker 1: another podcast episode. That's what we use actually to measure
• 21:29
  Speaker 1: the massive stars. We look at their brightness because, as
• 21:31
  Speaker 1: we said before, as you add mass, the temperature increases,
• 21:34
  Speaker 1: and it increases really dramatically, which tips off nuclear fusion,
• 21:37
  Speaker 1: which makes things even brighter. M Yeah. In fact, the
• 21:41
  Speaker 1: brightest star in our night sky is one of these
• 21:43
  Speaker 1: two suns. Starts. Yeah, exactly, that's serious. Are you serious?
• 21:49
  Speaker 1: Surely you're joking and stop calling me Shirlett. Alright, So
• 21:53
  Speaker 1: a star that's two times the massive our sun would
• 21:56
  Speaker 1: only live two and a half billion years. Yeah, wow,
• 21:58
  Speaker 1: it's burned through his fuel, all right, what's the next step?
• 22:01
  Speaker 1: Next step up is Beta Centauri. This thing is twelve
• 22:05
  Speaker 1: times the mass of the Sun and it's about a
• 22:08
  Speaker 1: thousand times as big. So you could take our son
• 22:11
  Speaker 1: and fitted into this star a thousand times. It's hard
• 22:14
  Speaker 1: to hold that idea in your mind. Wow, it's only
• 22:17
  Speaker 1: like ten times more massive, but it creates such a
• 22:20
  Speaker 1: crazy condition of explosions that that sun basically flows up right,
• 22:24
  Speaker 1: It's like a big fire exactly. It's a huge fire,
• 22:27
  Speaker 1: and that's why it's twenty thousand times brighter than our sun.
• 22:31
  Speaker 1: Twenty thousand times. Wow, that's like taking twenty sons and
• 22:36
  Speaker 1: shining it on us. Imagine having twenty thousand sons in
• 22:39
  Speaker 1: the sky like that's a hot day. Yeah, we need
• 22:42
  Speaker 1: twenty thousand SPF at least. And this is a super
• 22:46
  Speaker 1: awesome star because it's only going to live for twenty
• 22:49
  Speaker 1: million years. These things, they are fiery, they're impressive, but
• 22:53
  Speaker 1: they do not stick around. What happens after twenty million years.
• 22:57
  Speaker 1: After twenty million years, it goes into its super giant is.
• 23:00
  Speaker 1: It actually gets much much bigger and then eventually collapses
• 23:03
  Speaker 1: and it's going to form either a neutron star or
• 23:05
  Speaker 1: a black hole, depending exactly on how much mass it has. Wow,
• 23:08
  Speaker 1: don't you mean in years is not a lot of
• 23:10
  Speaker 1: time astronomically speaking, right, you wouldn't have enough time to
• 23:14
  Speaker 1: develop life for really, you know, get all your grocery
• 23:18
  Speaker 1: shopping done. No, you wouldn't. And the other interesting thing
• 23:20
  Speaker 1: is that this is part of a star system that
• 23:22
  Speaker 1: has three stars. You've heard of a binary star system.
• 23:25
  Speaker 1: We have two stars orbiting each other. This one's part
• 23:27
  Speaker 1: of a triple system. So there are two other stars
• 23:30
  Speaker 1: there that are much smaller that will last longer, and
• 23:33
  Speaker 1: you might develop life around one of those, but only
• 23:35
  Speaker 1: if it can survive the cataclysmic end of Bitta Centaur.
• 23:40
  Speaker 1: How common are these types of stars? Are we getting
• 23:42
  Speaker 1: too more rare kinds of stars? These are definitely much
• 23:46
  Speaker 1: more rare. As the mass goes up, the frequency that
• 23:48
  Speaker 1: you'll find these stars drops, not just because it's harder
• 23:51
  Speaker 1: to get a large blob of mass, it's just less
• 23:54
  Speaker 1: likely for it to happen, but also because they don't
• 23:56
  Speaker 1: last very long. Like these red dwarfs, they're gonna be
• 23:59
  Speaker 1: around basically for ever, right, trillions of years. The yellow
• 24:02
  Speaker 1: doors we're talking about billions of years about the lifetime
• 24:04
  Speaker 1: of the universe. Here, we're just talking about millions of years,
• 24:07
  Speaker 1: which astronomically speaking, is like a blink. So these things,
• 24:10
  Speaker 1: when they do happen, they don't stick around very long,
• 24:12
  Speaker 1: and that of course contributes to their rareness. M All right,
• 24:16
  Speaker 1: let's get into the King of all or queen of
• 24:19
  Speaker 1: all massive stars. There is one that you can crown
• 24:22
  Speaker 1: as the most massive star there is, though there is
• 24:24
  Speaker 1: some disagreement. You know, it's hard to measure these things,
• 24:27
  Speaker 1: as we talked about, especially on the very upper edge,
• 24:29
  Speaker 1: and so different astronomers might say that different stars are
• 24:32
  Speaker 1: the most massive. But there's a couple that are like
• 24:35
  Speaker 1: right at the edge. And the one I think that's
• 24:37
  Speaker 1: super cool is this one called are one three six
• 24:40
  Speaker 1: A one. This one's two hundred and fifteen times the
• 24:44
  Speaker 1: mass of the Sun, two hundred and fifteen serving scoops
• 24:48
  Speaker 1: all put together into one star. Wow, And I imagine
• 24:51
  Speaker 1: that's really bright. Yeah, this thing is as bright as
• 24:54
  Speaker 1: nine million sons nine millions Sun's shining all at once. Yeah.
• 25:03
  Speaker 1: And it's so close to this limit at how big
• 25:05
  Speaker 1: a star can be that it's just not going to
• 25:07
  Speaker 1: last very long. It's radiating out so much energy that
• 25:10
  Speaker 1: the fusion happening at its core is pushing out the
• 25:13
  Speaker 1: edges of the star. It's losing mass constantly. It's an explosion.
• 25:17
  Speaker 1: It's falling apart mm because at some point it like
• 25:20
  Speaker 1: pushes things out so far that they just escaped the gravity. Yeah, exactly.
• 25:24
  Speaker 1: The fusion pressure at the surface is greater than the
• 25:27
  Speaker 1: gravitational hold though. Things are getting pushed away from the
• 25:30
  Speaker 1: star like you imagine these really really massive objects in
• 25:33
  Speaker 1: space are going to suck you in. Right, this is
• 25:35
  Speaker 1: the star that pushes you away. The solar wind from
• 25:38
  Speaker 1: this star is so strong that it's actually pushing its
• 25:41
  Speaker 1: own skin off. Wow. That's disgusting but also pretty impressive.
• 25:46
  Speaker 1: Don't be judgmental, man, That's just the way the stars are.
• 25:49
  Speaker 1: And when you say pushing you, you really mean more
• 25:51
  Speaker 1: like frying you, right, Like, if you're there being pushed
• 25:53
  Speaker 1: by the star, it's not like it's pushing you, it's
• 25:55
  Speaker 1: like it's throwing fire at you. Well, both, Like, it's
• 25:58
  Speaker 1: a lot of energy for you to remember, the solar
• 26:01
  Speaker 1: wind has momentum. That's how we talk about like solar sails, right.
• 26:04
  Speaker 1: They can really capture the momentum of the solar wind,
• 26:07
  Speaker 1: and that's why these things are expanding. That's why they're
• 26:10
  Speaker 1: literally blowing up because the solar wind is literally pushing,
• 26:13
  Speaker 1: not just frying and cooking. There's a lot of momentum
• 26:15
  Speaker 1: that's being imparted anything that comes close to this thing,
• 26:18
  Speaker 1: and actually the outer layers, so it's tearing itself apart. Right.
• 26:22
  Speaker 1: I guess what I mean is it wouldn't feel good
• 26:23
  Speaker 1: to be pushed by that much radiation. No, it would
• 26:26
  Speaker 1: not feel good. I don't recommend going like solar surfing
• 26:29
  Speaker 1: or anything sailing. The incredible thing is that this is
• 26:35
  Speaker 1: just one part of an enormous cluster. Like this is
• 26:39
  Speaker 1: maybe the most massive star in the universe, nine million
• 26:42
  Speaker 1: times brighter than the Sun. But actually only recently we
• 26:45
  Speaker 1: figured out that it's one star because it's part of
• 26:48
  Speaker 1: this big blob of stars that together, this huge cluster
• 26:52
  Speaker 1: is called R one three six, is ten thousand times
• 26:55
  Speaker 1: brighter than just this star. Oh wow, this most massive
• 26:59
  Speaker 1: star is really like the minor player in an orchestra
• 27:02
  Speaker 1: of stars. Yeah, it's the biggest one. It's just a
• 27:05
  Speaker 1: huge collection of stars, and this is like the big
• 27:08
  Speaker 1: grand Pappy. But together all those stars outshine this one
• 27:12
  Speaker 1: by ten. So it's a crazy object out there. Is
• 27:16
  Speaker 1: that about as massive as stars can get. What if
• 27:19
  Speaker 1: I have a star that massive and I pumped more
• 27:22
  Speaker 1: hydrogen into it, what would happen? It would blow itself up.
• 27:26
  Speaker 1: As you get it more massive, it's going to increase
• 27:28
  Speaker 1: the temperature and that's going to increase the rate of fusion,
• 27:30
  Speaker 1: which is an increase the radiation and pressure, and so
• 27:33
  Speaker 1: it's going to tear itself apart. It's gonna blow up,
• 27:36
  Speaker 1: It's gonna blow up. Yeah. Somebody actually wrote to me
• 27:38
  Speaker 1: and asked me, like, if you wanted to blow up
• 27:41
  Speaker 1: a star, what would be your go to strategy? And
• 27:45
  Speaker 1: you know, as usual, I thought, is this a supervillain
• 27:48
  Speaker 1: making a plan asking me for physics consulting? But the
• 27:51
  Speaker 1: answer I gave him I thought was pretty impractical, which was, like,
• 27:54
  Speaker 1: just add a lot of mass to the star. That
• 27:56
  Speaker 1: will blow it up. So if he's somehow capable of
• 27:58
  Speaker 1: injecting five times more mass into our sun, for example,
• 28:02
  Speaker 1: that would spell its doom. Right. Well, I mean, obviously
• 28:05
  Speaker 1: it's a lot, but it doesn't sound like a lot.
• 28:06
  Speaker 1: You don't need millions of suns to blow it up.
• 28:09
  Speaker 1: You can just gather a few hundred. Yeah, And it's fascinating.
• 28:11
  Speaker 1: That's why these extremes are really interesting. It tells you
• 28:13
  Speaker 1: that you can't have an arbitrarily sized star, right, You
• 28:16
  Speaker 1: can't just have an enormous galaxy size star. That's why
• 28:19
  Speaker 1: galaxies are filled with stars instead of us having galaxy
• 28:22
  Speaker 1: sized stars, because there's an upper limit. Because stars are
• 28:25
  Speaker 1: not just like blobs of gas floating out in space.
• 28:29
  Speaker 1: There's this push and pull. Gravity squeezing them down, fusion
• 28:32
  Speaker 1: is pushing them out, And there's only certain regimes in
• 28:35
  Speaker 1: which those two things are close enough to being balanced
• 28:38
  Speaker 1: that the thing can exist for very long at all. Right,
• 28:41
  Speaker 1: But I guess also that's only in the star category.
• 28:44
  Speaker 1: You can have objects that are more massive than two
• 28:47
  Speaker 1: or three hundred masses of the Sun, right, Yeah, for example,
• 28:50
  Speaker 1: a black hole. Right, you may have black holes that
• 28:52
  Speaker 1: are billion times the mass of the Sun. And we
• 28:55
  Speaker 1: talked about what's the biggest planet you can have to Yeah,
• 28:58
  Speaker 1: exactly though that's definitional, right, as far as we know, though,
• 29:00
  Speaker 1: there's no physical upper limit on the mass of a
• 29:04
  Speaker 1: black hole. The only limit there is how do you
• 29:06
  Speaker 1: get so much stuff near a black hole so that
• 29:08
  Speaker 1: he can eat it? And how does it actually fall
• 29:10
  Speaker 1: in within the lifetime of the universe, which is why
• 29:12
  Speaker 1: we think the biggest black holes out there are like five, ten,
• 29:16
  Speaker 1: maybe fifteen billion times in the mass of the Sun.
• 29:18
  Speaker 1: We don't see an the outh that there are a
• 29:20
  Speaker 1: trillion times the mass of the Sun, though theoretically there's
• 29:23
  Speaker 1: nothing preventing that from happening. But here, even theoretically, you
• 29:27
  Speaker 1: can't build a star that has five dred times the
• 29:30
  Speaker 1: mass of the Sun and expect it to last more
• 29:32
  Speaker 1: than a few hundred thousand years. Right, What if I
• 29:35
  Speaker 1: take like a harrier element? Can I take five hundred
• 29:38
  Speaker 1: times the mass of the Sun in helium and put
• 29:41
  Speaker 1: that together? Would that give me a star? No, because
• 29:43
  Speaker 1: that would also trigger fusion, and that fusion would be
• 29:46
  Speaker 1: even hotter and more energetic, and so you would also
• 29:50
  Speaker 1: just spell the death of the star. But the elements
• 29:53
  Speaker 1: would be heavier, wouldn't it, wouldn't there be more gravitational pressure. Yeah,
• 29:56
  Speaker 1: And more gravitational pressure is exactly what's driving the fusion. Right.
• 30:00
  Speaker 1: More gravitational pressure means higher temperatures, which means faster fusion,
• 30:04
  Speaker 1: which means more fusion radiation, which means the death of
• 30:06
  Speaker 1: your star. All right, so there's a limit to start them.
• 30:11
  Speaker 1: There is a limit to start them. Exactly about Tom Cruise.
• 30:14
  Speaker 1: You can't get any bigger than that, Tom Hanks, Tom Cruise,
• 30:17
  Speaker 1: Nicole Kidman, that's it. You collapse into an egotistical black
• 30:20
  Speaker 1: hole after that black hole of paparazzis and and tabloids. Exactly.
• 30:25
  Speaker 1: All right, Well that's the most massive stars. Now let's
• 30:28
  Speaker 1: get to the question of what's the biggest star, Like,
• 30:30
  Speaker 1: if you're standing in front of it, what would be
• 30:33
  Speaker 1: the biggest star that you can see or be in
• 30:35
  Speaker 1: the presence of. So let's get into that, but first
• 30:37
  Speaker 1: let's take a quick break. All right, we're talking about
• 30:51
  Speaker 1: the biggest star in the universe, not just here on
• 30:56
  Speaker 1: Earth as a movie star, but in the astronomical sense.
• 31:00
  Speaker 1: What's the largest right, that's what we're talking about now,
• 31:03
  Speaker 1: largest star that you can have, Like, if you're standing
• 31:05
  Speaker 1: in front of it, what's the biggest thing that you
• 31:07
  Speaker 1: could be looking at? What takes up the most space
• 31:10
  Speaker 1: in our universe? I like to imagine, you know, taking
• 31:13
  Speaker 1: a spaceship and going up to the surface of the Sun.
• 31:15
  Speaker 1: It would seem like it filled up your whole horizon, right,
• 31:18
  Speaker 1: It would be so vast, like an ocean of burning plasma.
• 31:22
  Speaker 1: And then it's awesome to think about like that being
• 31:24
  Speaker 1: dwarfed by something even larger, right right, all right, So
• 31:28
  Speaker 1: then let's talk about volume, like what determines the volume
• 31:31
  Speaker 1: of a star. This is a little bit tricky, right,
• 31:34
  Speaker 1: Like how you measure the volume of the star and
• 31:36
  Speaker 1: how you even define it is a little bit tricky.
• 31:39
  Speaker 1: Don't suns have a surface that you can measure off of,
• 31:41
  Speaker 1: like our sons has a surface, right, pictures of it
• 31:43
  Speaker 1: looked like it has an edge. Yeah, but it's sort
• 31:46
  Speaker 1: of like the Earth, like where it is the atmosphere end.
• 31:49
  Speaker 1: It's not a hard cut off. It's sort of like
• 31:51
  Speaker 1: drifts off gradually. So you can say, obviously we have
• 31:54
  Speaker 1: a surface on the Earth, but the Sun doesn't have
• 31:56
  Speaker 1: a rigid surface the same way the Earth does. It
• 31:58
  Speaker 1: sort of has a gradual draw off in density. Then
• 32:01
  Speaker 1: you get to the outer layers, and so it's hard
• 32:03
  Speaker 1: to know exactly where to define the size of the star. Right,
• 32:07
  Speaker 1: It's a little fuzzy, but still I feel like, you know,
• 32:09
  Speaker 1: if you look at a picture of the Sun that
• 32:10
  Speaker 1: they've taken, it does seem to have like a surface
• 32:13
  Speaker 1: of molten something or the surface of fire, after which
• 32:17
  Speaker 1: it's not as defined, or you see the blackness of
• 32:20
  Speaker 1: space behind it. And you can also think about, like
• 32:22
  Speaker 1: what is the part of the star that's actually glowing,
• 32:24
  Speaker 1: that's giving off light. Maybe you could define the edge
• 32:27
  Speaker 1: of it that way, And that's actually useful because that's
• 32:30
  Speaker 1: connected to how we know the size of these stars.
• 32:33
  Speaker 1: Like we're gonna talk about some really big stars that
• 32:35
  Speaker 1: are super far away, and you might wonder, like, well,
• 32:37
  Speaker 1: how do we know this thing is so big and
• 32:40
  Speaker 1: we can't measure it exactly? Only for like really close
• 32:43
  Speaker 1: up stars, can we actually resolve the left side of
• 32:46
  Speaker 1: it and the right side of it make a measurement
• 32:48
  Speaker 1: directly of how big it is. It only works for
• 32:50
  Speaker 1: stars that are very very close to us, where we
• 32:53
  Speaker 1: can use like parallax. Beyond that, we have to have
• 32:55
  Speaker 1: models that say, if the star is this temperature and
• 32:58
  Speaker 1: has this brightness, and that tells us it must have
• 33:01
  Speaker 1: a certain surface area in order to emit that much light,
• 33:04
  Speaker 1: and from that we can deduce the volume of the star.
• 33:08
  Speaker 1: You have to basically sort of guests based on your
• 33:10
  Speaker 1: knowledge of how sounds work. Yeah, we have a model
• 33:13
  Speaker 1: who is not exactly a guess. It's called nuclear physics.
• 33:16
  Speaker 1: But we have a model for what's going on inside
• 33:18
  Speaker 1: the star that connects the brightness of the star with
• 33:20
  Speaker 1: the mass of the star and the temperature of the star,
• 33:22
  Speaker 1: and from all that we can estimate what the radius
• 33:25
  Speaker 1: of the star must be. I feel like I just
• 33:27
  Speaker 1: insulted you. Then you not just me It's okay, It's
• 33:30
  Speaker 1: just a whole field of physics. You mean, a hypothesis
• 33:33
  Speaker 1: without proof is not a guess. It's not without proof.
• 33:36
  Speaker 1: We develop these models and we test them. We look
• 33:38
  Speaker 1: at in the universe and we see do the stars
• 33:40
  Speaker 1: behave the way we expect? And we can only test
• 33:42
  Speaker 1: them in some cases for closer up stars, And the
• 33:44
  Speaker 1: rest of it is extrapolation. But it's not just like,
• 33:47
  Speaker 1: I don't know, let's pick a number. So there are
• 33:49
  Speaker 1: stars that we can measure the size of from here. Yeah,
• 33:53
  Speaker 1: there's stars that are close enough that we can use
• 33:55
  Speaker 1: parallax to directly measure their size, but not very many.
• 34:00
  Speaker 1: Al right. Well, the other tricky thing is that the
• 34:03
  Speaker 1: size of a star changes over its life. You know,
• 34:05
  Speaker 1: it grows and then it shrinks. Yeah, exactly. The star
• 34:09
  Speaker 1: for most of its life is about the same size.
• 34:11
  Speaker 1: It burns happily, it's in that's happy place where fusion
• 34:15
  Speaker 1: and gravity are like in balance with each other. But
• 34:18
  Speaker 1: eventually fusion makes really heavy metals which collected the core
• 34:21
  Speaker 1: of the star and increase the gravity, and then eventually
• 34:25
  Speaker 1: the fusion starts happening sort of more on the outer
• 34:27
  Speaker 1: edges of the star. You only have hydrogen near the
• 34:30
  Speaker 1: outer edges of the star now, and so that's where
• 34:32
  Speaker 1: most of the hydrogen fusion is happening, and that creates
• 34:35
  Speaker 1: more pressure to blow out the star, makes it get
• 34:38
  Speaker 1: much much bigger. Our Sun, for example, is going to
• 34:41
  Speaker 1: get to two hundred times its current volume when it
• 34:44
  Speaker 1: goes into its red super giant phase. Mmm. Right. It
• 34:49
  Speaker 1: gets so hot that it burns brighter and bigger. Basically
• 34:52
  Speaker 1: the flame gets bigger, yeah, exactly, and so it gets
• 34:55
  Speaker 1: really big and fluffy. And like where the Earth is
• 34:58
  Speaker 1: right now is probably gonna be pretty close to the
• 35:01
  Speaker 1: radius of the Sun when it gets near the end
• 35:04
  Speaker 1: of its life cycle. That's in about five billion years,
• 35:06
  Speaker 1: so you still got time to do a lot of stuff.
• 35:09
  Speaker 1: But that's going to happen to our star and to
• 35:11
  Speaker 1: almost every star out there, all right, So I guess
• 35:14
  Speaker 1: maybe we're really talking about what's the peak volume of
• 35:17
  Speaker 1: stars right like at their biggest what's the biggest they
• 35:20
  Speaker 1: can get exactly? Or like when we look out there
• 35:23
  Speaker 1: currently in the universe, what are the biggest stars that
• 35:25
  Speaker 1: are around right now? Some of the most of the
• 35:28
  Speaker 1: ones that are really big are going to be the
• 35:29
  Speaker 1: ones that are about to die because they're in this
• 35:31
  Speaker 1: last stage where they're blowing themselves up before they collapse.
• 35:35
  Speaker 1: Mm hmmm. Al right, well, let's go down the list.
• 35:37
  Speaker 1: What are some of the ones that are huge, you know,
• 35:39
  Speaker 1: just to get a sense of scale. There's a star,
• 35:41
  Speaker 1: for example, called gay Crux, which is like the nearest
• 35:45
  Speaker 1: giant star to the Sun, and it's got only one
• 35:48
  Speaker 1: and a half times the mass the Sun, but the
• 35:51
  Speaker 1: radius of this thing is a hundred and twenty times
• 35:54
  Speaker 1: the radius of the Sun, which makes it much much bigger.
• 35:59
  Speaker 1: And is it a start one point five times the
• 36:02
  Speaker 1: massive arson it's it's a pretty similar kind of star.
• 36:04
  Speaker 1: Then it's a pretty similar kind of star exactly. And
• 36:07
  Speaker 1: it's in the Southern Cross actually, so it's sort of famous.
• 36:10
  Speaker 1: But you know, it's much bigger. It's only got like
• 36:12
  Speaker 1: another fifty percent of the mass, but the volume is
• 36:15
  Speaker 1: like ten thousand times bigger. M m. Yeah, that's huge.
• 36:20
  Speaker 1: But is it just because it's in a different stage
• 36:22
  Speaker 1: than our Sun? Because our son is gonna get that big, right,
• 36:25
  Speaker 1: our stage is also going to get that big. So yeah,
• 36:27
  Speaker 1: this one is, like all the ones on our Biggest
• 36:29
  Speaker 1: Stars list, is near the end of its life. Oh
• 36:32
  Speaker 1: I see that these are like peak peak size. Yeah, exactly.
• 36:35
  Speaker 1: This is when their stars are really reaching, like the
• 36:37
  Speaker 1: peak of their career, you know, when they are the
• 36:39
  Speaker 1: biggest they're ever going to be, right, And so the
• 36:42
  Speaker 1: one we can see right now is this one called
• 36:44
  Speaker 1: gay Crux, which is a hundred times the size of
• 36:47
  Speaker 1: our son. That's huge. Yeah. It's radius is about a
• 36:50
  Speaker 1: hundred times, right, which means the volume is a hundred
• 36:53
  Speaker 1: cubed right, right, So it's huge. Arson was sitting next
• 36:56
  Speaker 1: to it, it would look like one percent. That's big, yeah, exactly.
• 37:00
  Speaker 1: The ratio between the Earth and our Sun is about
• 37:02
  Speaker 1: the same as our sun and this star, So this
• 37:05
  Speaker 1: thing is just enormous alright. So you can see that
• 37:08
  Speaker 1: in the nice sky. If you go out at nine
• 37:10
  Speaker 1: and look up, you can see this, yeah, exactly. If
• 37:12
  Speaker 1: you're in the southern hemisphere and you can see the
• 37:14
  Speaker 1: Southern Cross, then yes, you can see this enormous star.
• 37:18
  Speaker 1: All right. Well, what's the next one on the list?
• 37:20
  Speaker 1: Next one on the list is the Pistol Star. This
• 37:22
  Speaker 1: one is twenty five times the mass the really substantially bigger,
• 37:26
  Speaker 1: but it's got three hundred times the radius, right, And
• 37:30
  Speaker 1: remember the volume goes up by radius cubed, so you
• 37:33
  Speaker 1: double the radius, you're going up in volume by a
• 37:36
  Speaker 1: factor eight. And so this one's like three times the
• 37:39
  Speaker 1: radius of gack Rux, which means it's like almost thirty
• 37:42
  Speaker 1: times the volume of that previous star. Wow, at that size,
• 37:45
  Speaker 1: would that fit, for example, in our solar system or
• 37:48
  Speaker 1: would it take up the whole solar system? That would
• 37:50
  Speaker 1: not fit in our solar system very comfortably, right, it
• 37:53
  Speaker 1: would go out past the radius of the Earth. I
• 37:56
  Speaker 1: think Jupiter Saturn would still survive, but it would not
• 37:59
  Speaker 1: be good for us, Like, you would not want to
• 38:00
  Speaker 1: put this star in our solar system. Too big, it's
• 38:04
  Speaker 1: too big. And you can't even see this star by
• 38:07
  Speaker 1: e super big. It's super bright, but it's actually close
• 38:11
  Speaker 1: to the center of the galaxy where there's a lot
• 38:13
  Speaker 1: of gas and dust going on, so you can't actually
• 38:16
  Speaker 1: see it with the naked eye. It's hidden. Yeah, it's
• 38:19
  Speaker 1: hidden from us by all this interstellar dust. And what
• 38:22
  Speaker 1: to call it? Blue hyper giant? What does that mean? Well,
• 38:24
  Speaker 1: blue just tells you the kind of light that it's emitting,
• 38:28
  Speaker 1: and a hypergiant is just the stage of life that
• 38:30
  Speaker 1: it's in. All these stars when they're done with the
• 38:32
  Speaker 1: main sequence and they're about to blow themselves out. They
• 38:35
  Speaker 1: become giants or supergiants or hypergiants, depending on you know,
• 38:38
  Speaker 1: the radius. All right, well, what else do we know
• 38:42
  Speaker 1: is out there? What's the next biggest star? The next
• 38:44
  Speaker 1: one is Roe Cassiopeia. It's a yellow hypergiant. This one
• 38:48
  Speaker 1: is five hundred times the radius of the Sun. Wow.
• 38:52
  Speaker 1: So this is kind of what would happen to our star.
• 38:55
  Speaker 1: But like a little bigger star, eventually it would grow
• 38:58
  Speaker 1: to this big. This one is forty times the mass
• 39:00
  Speaker 1: of our Sun. Our star is never gonna get this big.
• 39:03
  Speaker 1: And because it's so massive, it also makes it more rare. Like,
• 39:05
  Speaker 1: we don't know very many of these yellow hyper giant
• 39:08
  Speaker 1: stars in the whole galaxy. The only like fifteen of
• 39:11
  Speaker 1: them that have ever been seen. Wow. And this one
• 39:14
  Speaker 1: is definitely bigger than our solar system. This one would
• 39:17
  Speaker 1: definitely like eat Earth and Mars, but actually wouldn't even
• 39:21
  Speaker 1: get out to Jupiter. Jupiter is much further out than
• 39:24
  Speaker 1: all the other planets because the asteroid belt in between.
• 39:28
  Speaker 1: But still that's huge, right, It's huge. I mean, that's
• 39:31
  Speaker 1: it's like fire front of times the radis of our Sun. Yeah.
• 39:34
  Speaker 1: I mean, if you look at the Solar system, for example,
• 39:36
  Speaker 1: zoomed out so you can see all the planets. Even
• 39:39
  Speaker 1: the huge Sun looks really really small. Now replace that
• 39:42
  Speaker 1: with an enormous star that's like the size of the
• 39:45
  Speaker 1: radius of Mars. The whole Solar system would look totally different,
• 39:48
  Speaker 1: right right, And from here on Earth, our Sun was
• 39:51
  Speaker 1: five hundred times bigger, you know, we would see it
• 39:53
  Speaker 1: take up the entire sky and then eventually eat does up. Yeah,
• 39:56
  Speaker 1: that would be really crazy. Imagine living on a planet
• 39:59
  Speaker 1: where the Sun took up the entire sky toast all right, Now,
• 40:05
  Speaker 1: what's the next biggest star that we can see? Next?
• 40:07
  Speaker 1: Is one that's pretty famous. It's actually Beetle Juice. Beetle
• 40:10
  Speaker 1: Juice is about a thousand times the radius of the Sun. Like,
• 40:14
  Speaker 1: it just totally dwarfs our entire solar system. This one
• 40:18
  Speaker 1: would even eat of Jupiter if you put it in
• 40:20
  Speaker 1: the center of the solar system. Interesting, And so again
• 40:23
  Speaker 1: it's a star that's kind of at its peak. It's
• 40:25
  Speaker 1: like it's burning really brightly right now. Yeah, And actually
• 40:27
  Speaker 1: this one is quite interesting recently because it's been dimming.
• 40:31
  Speaker 1: Like remember, Beetle Juice got dim all of a sudden
• 40:34
  Speaker 1: in a way nobody understood, and people thought, it is
• 40:36
  Speaker 1: gonna go supernova? Is it about to blow? And then
• 40:39
  Speaker 1: people thought, maybe it's just a big blob of dust
• 40:41
  Speaker 1: the past in front of beetle Juice, and other people thought,
• 40:43
  Speaker 1: maybe it's an alien superstructure. We really didn't understand it.
• 40:46
  Speaker 1: Maybe this is like a variable star that's like compressing
• 40:49
  Speaker 1: and then glowing, compressing and glowing. We didn't really understand it.
• 40:52
  Speaker 1: But this is definitely a much bigger star than our son. Wow,
• 40:56
  Speaker 1: a thousand times the size for Sun that would be huge. Yeah,
• 41:00
  Speaker 1: if you're sitting in front of it. Yeah, and so
• 41:02
  Speaker 1: a thousand times the radius of the Sun, right means
• 41:06
  Speaker 1: a thousand cubed of the volume, And so that's a
• 41:09
  Speaker 1: billion times the volume of the Sun. Remember, TI was like,
• 41:12
  Speaker 1: I wonder if there are stars out there that are
• 41:14
  Speaker 1: like a million times the volume of the Sun. We're like,
• 41:16
  Speaker 1: here's one that fits a billion sons inside of it. Yeah,
• 41:20
  Speaker 1: that's that's why. Well, I hope we blew your mind.
• 41:21
  Speaker 1: Tie all right, So then let's maybe skip a little
• 41:25
  Speaker 1: bit ahead to what is the biggest star that we
• 41:27
  Speaker 1: know about, like in terms of size that you can
• 41:29
  Speaker 1: see in the night sky. What is the biggest one
• 41:30
  Speaker 1: that you can see, the biggest one out there right now.
• 41:33
  Speaker 1: The current champion is one called Stevenson to eighteen. This
• 41:38
  Speaker 1: one has more than two thousand times the radius of
• 41:42
  Speaker 1: our sun. Wow, two thousand times bigger, which means it's like,
• 41:47
  Speaker 1: you know, a bazillion times more volume. It's yeah, exactly,
• 41:50
  Speaker 1: It's like more than sixteen billion sons could fit inside
• 41:55
  Speaker 1: this thing. If you dropped the sun into this thing,
• 41:58
  Speaker 1: you wouldn't even notice it. Wow. And how much brighter
• 42:00
  Speaker 1: is it? It's a half million times brighter. So you
• 42:04
  Speaker 1: put half a million sons together and you get the
• 42:07
  Speaker 1: brightness of this thing. Five thousand sons in one place.
• 42:10
  Speaker 1: That's crazy in one place. Yeah, it's just it's taking
• 42:13
  Speaker 1: up so much space. It's incredible. Like if you try
• 42:16
  Speaker 1: to fly around this thing in a spaceship, it would
• 42:19
  Speaker 1: take you like nine hours at light speed just to
• 42:23
  Speaker 1: do one orbit around this star. Wow, that's crazy. It
• 42:26
  Speaker 1: takes hours for the light just to leave this star exactly.
• 42:30
  Speaker 1: If you're a photon generated at the heart of this thing,
• 42:33
  Speaker 1: you're not getting out there for a while, all right.
• 42:36
  Speaker 1: So that's that is the biggest star that we can see.
• 42:38
  Speaker 1: It's thousands of times bigger than our sun. Bazillion times
• 42:41
  Speaker 1: bazillion is at the technical term bigger and volume than
• 42:46
  Speaker 1: our star, and it's half a million times brighter. It's
• 42:49
  Speaker 1: really impressive. It definitely deserves some kind of prize. And
• 42:52
  Speaker 1: you can see it in the night sky. Is out
• 42:54
  Speaker 1: there in the night sky. It's near this cluster called
• 42:57
  Speaker 1: Stephenson two, which is why it's called Stevenson two eighteen.
• 43:00
  Speaker 1: And you can't see it by eyes. Actually discovered in
• 43:02
  Speaker 1: around by astronomers using infrared telescopes. Wow, that's wild. That's huge.
• 43:08
  Speaker 1: So you can't see it because it's so far away. Yeah,
• 43:11
  Speaker 1: this thing is like twenty thousand light years from Earth.
• 43:14
  Speaker 1: So remember the brightness of a star falls with like
• 43:16
  Speaker 1: the distance squared, and so if you're twice as far away,
• 43:20
  Speaker 1: it's a quarter of the brightness. And so this one,
• 43:22
  Speaker 1: we're twenty thousand light years away, which is why it's
• 43:25
  Speaker 1: apparently so dim to the naked eye. But I guess
• 43:29
  Speaker 1: if you have a telescope, you can see it and
• 43:31
  Speaker 1: you can sort of model its size. You can model
• 43:33
  Speaker 1: its size by understanding its luminosity and its temperature, and
• 43:36
  Speaker 1: then we can do these calculations but we definitely can't
• 43:38
  Speaker 1: measure directly, and that's a shame, because man, I would
• 43:41
  Speaker 1: love to see this thing close up, Like, what is
• 43:44
  Speaker 1: the surface of this thing look like? Yeah, what would
• 43:46
  Speaker 1: it look like? Is it a different color or is
• 43:48
  Speaker 1: it just a big bright yellow ball. Well, it's a
• 43:51
  Speaker 1: red super giant, so probably would be mostly red. But yeah,
• 43:54
  Speaker 1: you know, if you look at pictures of the sun
• 43:56
  Speaker 1: close up, you notice that there are a lot of
• 43:57
  Speaker 1: like hot spots and cold spots. It's like a lot
• 44:00
  Speaker 1: of stuff going on. So I think you'd see the
• 44:02
  Speaker 1: same thing. But we've never seen one of these things
• 44:04
  Speaker 1: super close up. It would be an awesome opportunity to
• 44:07
  Speaker 1: learn more about how a star gets really big and
• 44:09
  Speaker 1: what it looks like at the end of its life
• 44:11
  Speaker 1: cycle if we could. But you know, it's so far away, right,
• 44:14
  Speaker 1: And what kind of star is this? Is it like
• 44:16
  Speaker 1: our star but you put more hydrogen into it or
• 44:18
  Speaker 1: is it something fundamentally different. No, it's just like a
• 44:21
  Speaker 1: bigger serving of hydrogen. It's just got a lot more
• 44:23
  Speaker 1: mass than our star. Like, we don't have a precise
• 44:25
  Speaker 1: number for how much mass it has. It's not always
• 44:28
  Speaker 1: easy to measure for these really really big, very bright stars.
• 44:32
  Speaker 1: But it just started out with a bigger helping and
• 44:34
  Speaker 1: that's why I ended up a much bigger star. And
• 44:36
  Speaker 1: then you wait sort of for the end of its
• 44:38
  Speaker 1: life cycle. It's like a really massive star also at
• 44:41
  Speaker 1: the peak of its size. Wow, it's hot stuff. It's
• 44:44
  Speaker 1: hot stuff, exactly alright. So we covered the most voluminous
• 44:50
  Speaker 1: star and also the most massive star. So the most
• 44:53
  Speaker 1: massive star is our one three six A one, which
• 44:57
  Speaker 1: is two hundred times the massive our Sun, and the
• 45:01
  Speaker 1: most voluminous the biggest star is about two thousand times
• 45:04
  Speaker 1: the size war Sun. Yeah, two thousand times of radius
• 45:07
  Speaker 1: and then billions of times the volume, all right, and
• 45:10
  Speaker 1: that basically makes me feel small, Daniel. That was the
• 45:13
  Speaker 1: goal of the podcast exactly to think about the size
• 45:16
  Speaker 1: of the stuff that's out there in the universe. And
• 45:18
  Speaker 1: remember that we're pretty tiny compared to the enormous, powerful
• 45:22
  Speaker 1: forces creating these objects out there. Yeah, because they make
• 45:26
  Speaker 1: our star look tiny, and we're super tiny compared to
• 45:29
  Speaker 1: our Sun. Yeah, we're even super tiny compared to our Earth,
• 45:32
  Speaker 1: which is super tiny compared to our Sun, which turns
• 45:35
  Speaker 1: out to be a pip squeak in the universe. Well,
• 45:37
  Speaker 1: It's pretty amazing to sort of think about, because the
• 45:39
  Speaker 1: recipe for all these stars is the same. You know,
• 45:41
  Speaker 1: it's just ad hydrogen, but you know, you get all
• 45:43
  Speaker 1: this huge variation in like what's happening in the processes
• 45:46
  Speaker 1: and the volume and the mass. It's a pretty complex
• 45:50
  Speaker 1: and impressive universe. Yeah. I do like the idea of
• 45:53
  Speaker 1: a star having a recipe which is one ingredient and
• 45:56
  Speaker 1: one step right, but no more right, Like, if you
• 46:02
  Speaker 1: get it off by a little bit, it becomes a
• 46:03
  Speaker 1: totally different star. That's true. If you get it off
• 46:05
  Speaker 1: by a factor of five hundred, then you no longer
• 46:08
  Speaker 1: get a star. But that's also true of cookies. You know,
• 46:10
  Speaker 1: you put in five times too much sugar, they're not
• 46:12
  Speaker 1: really cookies anymore, right, Or five hundred times more chocolate chips,
• 46:16
  Speaker 1: you just get a chocolate chip exactly. That's just a
• 46:19
  Speaker 1: recipe for a chocolate chip. It sounds like a star
• 46:21
  Speaker 1: of a recipe. I have strong opinions, but I would
• 46:23
  Speaker 1: taste it. You would just taste chocolate. It's like, oh, yeah,
• 46:28
  Speaker 1: that's an interesting recipe. Chunk of chocolate with little tiny
• 46:31
  Speaker 1: cookies ambitted in it. A cookie chip. Yeah, all right, Well,
• 46:35
  Speaker 1: We hope you enjoyed that and made you think about
• 46:37
  Speaker 1: the brightness and the amazing things that are shining out
• 46:40
  Speaker 1: during the night sky. And remember that however big you
• 46:43
  Speaker 1: think things are, they're actually much more vast than you
• 46:46
  Speaker 1: could ever possibly imagine. All Right, we hope you enjoyed that.
• 46:50
  Speaker 1: Thanks for joining us, see you next time. Thanks for listening,
• 47:00
  Speaker 1: and remember that Daniel and Jorge Explain the Universe is
• 47:03
  Speaker 1: a production of I Heart Radio. Or more podcast from
• 47:07
  Speaker 1: my heart Radio visit the I heart Radio app, Apple Podcasts,
• 47:11
  Speaker 1: or wherever you listen to your favorite shows. H