#416: Cosmic Conundrums & Astral Assemblies: Tackling the Universe's Toughest Questions

Hi there, Thanks for joining us on this Q and A edition of Space Nuts. Andrew Dunkley here, your host. Hope you're well. Coming up on this particular show, we're going to be focused on black holes. We've got two questions independently that basically ask a similar thing about black holes and magnetic fields, and I think we've had similar questions in the past, so we'll tackle that one probably again. We're also going to look at different kinds of stars, how many of each there might be, and do those proportions agree across galaxies and if it's different. Why personal projects? Someone wants to know what Fred's favorite personal project has been over the years. Oh gosh, that goes back well when Galileo and I were sitting on the beach. You know, we'll find out. And Rusty has asked why fog bows are white. That's all coming up on this edition of Space Nuts fifteen, Channel ten nine ignition sequence Space Nuts three two. Nice as when I report it real good And here he is Professor Freedwards, an astronomer at large. Hello Fred, Hello, I believe when you were sitting on the beach with Galileo that you were talking about the gravity of world affairs. We were drinking a cup of gravity each. Actually it was really nice. Ye, good stuff, that's good stuff. How are you going? You're good? Yes, well, thank you. I'm good to see you too. I hope you're well as well and taking your gravity seriously. I think I have we have to sack our laundry. We're both wearing the same shirts as last week. So it's a bit of a worried. It is shocking, isn't it. Yeah, I should have it's not good. Yeah, well we could. We could stretch that joke for a long long time, but we're not going to. No, that's probably not really worth it, and probably nobody would have noticed. I did not mention, Probably not the lady. The ladies would probably notice before the men. My wife notices things about my attire that I don't even think about. So yes, it's another story that just shows they're so much more fashionable than we are. Shall we do some questions for no, let's just at the show. That's probably well, yeah, just that was quick and easy. Until next time. How about we talk about black holes and magnetic fields. This is a question from Robert, and I'll follow it up with a text question. We got from Lachlan. Here we go, Andrew, this is Robert from the Evidence. I have a question about black holes on my favorite subjects. This is not dark matter, right. Apparently black holes do not have a sucking everything everything that's something to the black hole. However, we do see these enormous jets being ejected from quasards one hundreds of thousand bagsish long. Obviously they do have some sort of poles. Of these poles. The only time I see that the reality is with neutron stars, white Horse. The Tory stars a sort of thing and it's always due to a magnetic field. So how can this be? Maybe black holes do have magnetic field, and you know the sertains that are disc around it would be able to create this thing. However, that would not be responsible for poles on the object itself, I would think. However, maybe I'm wrong. So what do you think, guys? The MA they of any hole in it? Where is it a hole in one? I'll hear it, uh jokes jud jokes from all corners. Thank you, Robert. And in conjunction with that, we've got a text email, a quick one from Lachlan saying, is black hole radiation the electromagnetic field. This SEMs to be a point of contention. We get a lot, We've had a lot of questions about black holes, but this one seems to come up semi regularly for it. Yeah, it does, and it's kind of connected with if I remember rightly, it's called the no hair theorem, which I really like, actually the no hair theme I'm sure you do, which is that there's only a few parameters that you can learn about a black hole. And I did write about the no yeah, no hair theorem in Cosmic Chronicles. I should read it again and find out what I said. But yes, because you know, there's just a very few parameters, and the idea of magnetism is that magnetism isn't one of them, which is kind of what Robert is alluding to. So if you have, you know, no hair black the fact that there's no hair there tells you that there's no magnetism. However, however, clearly do have magnetic fields, because that is what focuses the jets of radiation and material that are exactly the cause, as Roberts alluded to, of quasars. Active galaxies Delinquent galaxies are sometimes called them because they're all youthful galaxies. We're looking back in time a long way and see the seeing these quasars. So there is clearly some way in which magnetism can occur. And you basically what you do to get the magnetic field of your black hole is you rotate it. So it's got to be a rotating black hole and give it an electric charge. And those two things together, an electric charge and angular moments, which is just a fancy word for rotation, produce what is known as a ker Newman black hole k double R Newman black hole. A curR black hole is one that routates. I think a black hole is probably one with electric charge. One with both of those things is a kur Newman black hole, and it does have a magnetic diephole, which tells you it's got a magnetic field. So yes, a black hole can have a magnetic field, all right. And Laplin's question, is black hole radiation the electromagnetic field that's somewhat different angle on it? It is. That's partly true because what happens is that you know, you've got a Kerr Newman black hole that's got a strong magnetic field, it's got an accretion disc of material around it, stuff that's been gobbled into the black hole. That material is swept up or some of it is swept up by the magnetic field and squirted out at the poles of the black hole, the rotation poles to make these jets of material, which themselves also generate radiation because you've got highly energetic particles moving through you know, a medium, non vacuum medium. And so yes, the jets are basically the radiation that arises because of the magnetic field of the black hole. Question. I think so yes, but I don't really know. We just get so many questions about them. I note that there's been a new image released of a black hole at which was revealed in the last few weeks. Actually, so they've got a bit of a better understand ending of it from the image of environment and that was I think was James Webb image, if I remember rightly. But yeah, that's we're starting to get more and more information about them, so maybe more of their secrets will start to be unraveled. Or was it Sagittarius a star that we're talking about. There was one that that published information about earlier this year. It was the twentieth of March and it is Sagittarius, so there is a marvelous rendering. And again it comes back to something we talked about in the last main issue of Space Arts about polarized light. How you detect magnetism via polarized light. The Event Horizon Telescope collaboration, which looks at the structure of black black hole accretion discs, has indeed detected the polarization of that doughnut shaped disc around the black hole at the center of our galaxy. And it's a picture that you can find online. It's pretty easy to find, but dated day March this year. Space dot com is a good place to start, but there are plenty of articles on it, but space dot com. Thanks Robert and thanks Lachlan. I hope we helped you out there. Let's move on to our next question. This one comes from Pete. Hello, Fred and Andrew. This is Pete Alinga from Sunny Sheffield in the UK. I have three questions for you, all related to the mnemonic obi A fine Girl kiss Me, which I use to remember the different types of stars. Question one, what are the proportions of these star types in the Milky Way? Question two? Do these proportions hold through for all galaxies. Questions three, If the proportions are different across the universe, what does that tell us? Thank you for the great show, which is all the better for splitting out the Q and AS into a separate recording All the best, Eat Manager Pete. It is lovely to hear from you. Thanks for the endorsement on doing two shows a week instead of one. It seems to be well accepted, so that's good. Different kinds of stars, yes, we know there are. How many of each in the milky way? Do those proportions correlate across galaxies? And if they're different? Why? I think that's a price of his entire question load. It is, that's right, so you know what we're looking at here is the be a fine girl kiss me is well known actually these days is also be a fine guy kiss me. It was a mnemonic that was conjured up back in the day for the what we call the spectral classes of Just a minute, let me deal with this. I find the phone. That's no good. I'm not going to say that's. Get rid of that. Yes, sorry about that. I don't know who that was from somewhere, probably trying to sell you cladding or solar pals while they're in Queensland, so it could be either of those. As you can tell you, I do apologize for that, apologize to all our listeners. I meant to put the phone on silent and I clearly forgot. I actually forget to do it on the radio sometimes, so yeah, I can sympathize, Yeah, but I won't. So we were unless it was somebody responding to my exhortation or be a fine girl, kiss me. It could have been that, I guess, coming in by phone. But it's a mnemonic for the spectra classes of stars. And the reason why it's so totally counter intuitive. You know why isn't it in straightforward alphabetical order, is because it goes back to the very early days at the beginning of the last century of people doing this spectral classification working out what the different kinds of spectra of stars meant. So when you look at the spectrum of a star, you get this barcode of information and they're different, and that we now know a lot of the difference depends on temperature, some of it depends on age. These are all factors that are in that and so they did classify them originally A, B, C, D, E, F, G, et cetera. And then eventually it was worked out what it was that these things were telling you. And it's now in temperature order going downward, so O stars are the very very hot ones surface temperatures twenty thirty thousand degrees kelvin down to the M stars the me of the mnemonic so ob A f G k M M stars are the red dwarfs with surface temperatures region of three thousand degrees kelvin, that sort of sort of temperature. And so that distribution has been you know, we know that those are the classes. And Pete tasking an ip fellow Yorkshireman, Pete asking about what the relative numbers are of those, and it's pretty easy to find them on the interweb. I just d good so you can answer the question. The bottom line is, you know the essentially that obfgk M is out the A. I think it is an order of decreasing temperature and its order of decreasing numbers, sorry, increasing numbers, because the stars are the rarest and the M stars are the commonest. In fact, they're by far theless common type of stars in our galaxy. Sou and as as is is as a G, so they sort of rank in the middle to higher end of numbers. Yes, but they're nowhere near as common. M stars are ms accounting for seventy six and a half percent of all stars, and G is seven point six, so it's a lot less, whereas O stars are rare still aren't they point zero zero zero zero three percent of all stars? There you go, So that's the perfect answer to the question. You see, you don't really need me, however you might need yes, yes, which was about whether you know this. The same is true for other galaxies, and there are subtle differences. Basically it's the same distribution, but there are some subtle differences. And in Pete's next question was if there are differences, what causes them, and it's things like differences in the amount of metals which are in those stars. So metallicity the amount of basically the amount of iron in a star, although as you know, Andrew, astronomers think of everything except hydrogen and helium as being a metal, which ismical, but anyway, so the metallicity can vary in a galaxy and that would give slightly different numbers, but really the marginal by far the communist types of stars in the universe or Amy stars, these dwarf stars type the am of kiss me indeed, so yeah, easy to find on the internet if you want to have a look at those various star types and the well, all these statistics, their vital statistics, I think would be the best way to describe it. Pete, thank you. I love those questions because they sort of get into the nuts and bolts of stars and it sounds like it's pretty much the same across galaxies, give or take, which is good because that would have been if they weren't, it would have been a much longer explanation. This is space Nuts. Andrew Dunkley here with Professor Fred Nuts. Okay, Fred, let's move on to our next question, which comes from Michael. I. Just Michael from Kent to the UK. Just a question you guys. If there was a project that you could have worked on past or president, what would it be more exclusively Professor Watson, what projects stood up for you the most that you've worked on and why enjoy your show? Guys? Thank you so much. Maybe a bit selfish, but I enjoy your long episodes because it helped makes my micro shifts a lot of you. Thank you so much and enjoy it. Thank you, Michael. We just said someone saying we love he you split them up, and now Michaels saying I like them when they're long. You could save it up and just running back to back. It would be my advice because you can do that. Personal projects, I mean for me, I mean I work in radio and so I haven't had direct involvement with astronomy except with Fred, but gosh, and I think for me it'd be more space, space science related. I'd want to be working on maybe a mission to the Moon. I would love to have been involved in if I was old enough and clever enough working on the Apollo missions, actually being hands on getting those missions off the ground. If there was some way of turning back the clock and being in the right place at the right time, that would be something I would have adored working on, probably because it was so very much synonymous with my childhood. It all started when I was pretty well. When I was born, I could send home from school to watch the moonwalk Apollo eleven Moonwalk on TV, which happened in the early afternoon our time, if I recall correctly, on my families black and white TV. That to me was probably one of the most inspiring things that I saw as a kid, and it's still with me today. Going down after the missions to Parliament House in Canberra with my family on holiday and walking into the foyer and they had a glass cabinet, a glass box and inside the box was a little claw, and on the top of the claw was a rock. And that was a rock they brought back from the Moon. And I was absolutely mesmerized by that. I couldn't believe that I was seeing a rock from another world. It was just a piece of basshold, but that's beside the point. There was a piece of another world, and that just blew the lid off my brain. So if I could do anything again, or do anything in the past astronomy, space science related, that would probably be one that I would want to work on, a bit more sort of nuts and bolts than something Fred might be about to talk about. But I went over and I saw the Apilow eight control room that they set up in Florida at the NASA base there, got to see the Satin five rocket hanging from the ceiling, got to see Neil Armstrong's uniform, his spacesuit. Yeah, all of that is it's probably what tickles my fancy most of all in terms of space sen So that would be it for me. Michael Paul Shaw. What about you, Fred, Well, yeah, I mean I endorsed all that completely, but just to come a little bit further down to earth, if I may. I do have friends who have worked on projects which really we're milestone projects, and one of them is the Kirby Mission, the Cosmic Background Explorer, which was a base mission designed to measure for the first time the cosmic microwave background radiation. It's that was I think in the nineties. Yes, it was the nineties where that was happening. It's been superseded by since then by W. Matt the Wilkinson Microwave and Issotropy Probe and PLANK and a European spacecraft that measured the cosmic microwave background. So what we're doing here is putting a satellite into space to look for the after glow of the Big Bang, which is a pretty neat thing to do, you know, the cosmic wallpaper, the thing beyond which we can see because we're looking back in time so far that we can see the glow of the Big Bang, and it's got this structure on it, which was imposed on it by sound waves in the early universe. That's the really, you know, almost spooky bit of this. But the colleague guy had who worked on that, I always thought, what a way to start your career. I think it was his PhD topic. He was part of the Kobe team, and he did a lot of work on that. He's now an astrobiologist, so he changed tech completely. And then the other one, it's a similar sort of thing and epoch making discovery and maybe there are two. Actually yes, One would be imagine being part of the team that first detected gravitational waves back in twenty fifteen, Attigo. You know, you really be absolutely blown away by the fact that for the first time you've detected a gravitational wave from impact. I think it was neutron star collisions that first one, if I remember rightly, it was. It's a date that I can easily remember, fourteenth of September twenty fifteen, because that's Marny's birthday. So it's stuck in my mind that it was on her birthday. And the other one guests similar because it involves a huge, huge collaboration. It would have been great to have worked on the event horizon telescope to produce that very first picture of a black hole event horizon, the one from eighty seven just a few years ago as well. So those are really big ticket projects which it would have been great to work on. The big projects that I've worked on, in a way, the one that I had most to do with in it was actually my project which was developing wide angle spectroscopic instruments for the United Kingdom. Siret Telescopture's a wide angle telescope one point two meter diameter aperture, and I built three generations with a lot of help, of course, of fiber optic instruments, three or four. It was three. The fourth generation was actually nothing to do with me, but I was kind of cheering it on. So what that meant using this fiber optic technology was that you could measure the spectrum of many objects simultaneously, up to one hundred and fifty in the end, and we in fact it was four generations. The fifth generation was the one I wasn't involved with, so I did a lot of work on this. The fourth generation one we did surveys of stars in our galaxy, half a million stars and also surveys of about one hundred and sixty thousand galaxies. We made a map of the nearby universe with these galaxies. And those two surveys were also big projects that I worked on. One was called the sixty f Galaxy Survey sixty FGS, which wound up actually in two thousand and three. The other was the RAVE Survey, the Radial Velocity Experiment, which wound up two well, they observing wound up in twenty thirteen. So they were big projects which gave me a lot of a lot of anks, I can tell you. That's why i've hairstyle here. But nevertheless, they were also very very rewarding and you know, made me think. I think they did quite a lot for my astronomical street credit booth of them. Yeah. Indeed, another one I remember, and you and I did a little documentary piece on this was the two degree field instrument that that was a big sort of leap forward and it was a sort of an add on to the existing telescope as far as I remember, wasn't it, Fred. It's a bit like it is add on to the Angle Australian Telescope HPPY that we're talking about in the last episode. Yeah, yeah, yes, thank you, Michael. I hope that filled the breach in terms of personal projects that we would love to have worked on. Final question, Fred comes from Rusty and Johnny Brook. I've paraphrased this because Rusty asks questions in chapters, but I'll break it down. Why a fog bow's white? Now? When I first read his question, I thought, what's a fog bow? I'd never heard the term before. I know that sounds strange, but I've never heard a reference to a fog bow before. So I had to have a close look at his photo and try to figure out what he meant. And he's talking about a rainbow effect in fog. But they're not a rainbow because they're white. They're just white. He is suggesting that it's water droplet size that might be a factor here. What are we talking about, Fred, Yeah, So sunlights lighting up a bank of fog, and I'm supposed you've never seen one, because I used to see them a lot when I was driving to your town back in the day when I used to commute from kinder Burbon to talk on the NBC. So sunlight, it illuminates a bank of fog, and if you're at a position where the sun's behind you, it forms what amounts to a rainbow. But exactly as you say, the colors are washed out. They're just white. Now, Rusty did send an image of a fog bow, which was a beautiful image, and yes it's white, but if you look carefully, you can just see a slight red tinge on the outside of it and a slight bluish tinge on the inside of it. And that's Those are the colors that you see in an normal rainbow. So it's a kind of rainbow, but with the colors washed out. And that's exactly what happens. What's happening, and Rusty is perfectly right. It's called it's all to do with droplet size. So fog bow droplets are much much smaller than rain drops that form a rainbow. The raindrops forming a rainbow could be half a millimeter in diameter. The ones for a fog bow much smaller. It's an aerosol almost where you're talking about your fifty microns or something like that, rather than half a millimeter, so much smaller, so there is a rainbow effect. Rainbows are caused by refract refraction and dispersion of light in a globe of water, dispersion being the spreading out into the spectrum that happens in a fog boat droplet as well, but because they're so small, it's swamped out by another effect called diffraction, and diffraction is to do with the wave nature of light. Because these things are so small, you got to take the fact that light is a wave motion into account. And what it does is it just washes out the colors. So every color, rather than being a single color in a specific part of the rainbow, just gets washed out to be much broader. So the colors are all there, but they're swamped by each other until they become white, exactly like you know, if you're pushing it back through a prism, all these colors they will turn white. That's not the reason. It's because of diffractions spreading out the being, but they look white. So yeah, a lovely photograph from Rusty. We should put that one on the website. I think I will send it to Hugh so that he's got something to do. Yeah, I'll do that, Yes, yes, thanks Rusty, and always good to hear from you. Rusty often sends photos through of his astronomical images and it gives me photographic tips. I haven't tried them yet, but I will when I get into some dark space. It's a bit too much light around my new place, so I don't have much luck with astrophotography in my backyard. But forgbos, yes, I can't believe I've never heard that term before. Maybe I was just so ignorant to it it never stuck in my brain, which is basically my entire education. So thank you, Rusty. Lovely to hear from you, and Michael and Pete and Lachlan and Robert. Thanks for sending your questions in, and don't forget. If you've got questions, we'd love to get them from you, send them in right now. We'll wait or we'll look later. You can send them via our website, spacenuts podcast dot com or space nuts dot io. Just click on the links on the page and you can send us audio or text questions. Text questions through the AMA tab, audio questions through AMA and the send us your audio question on the right hand side under that weird purple color. That's it, Fred, Thanks again so much, lovely to catch up. We'll see you soon, so great. Take care on you you too, Fred Watson Astronomer at Large, and thanks to Hue in the studio for not asking us any questions at all ever, and from me Andrew uncle, it is goodbye until next time on Space Nuts see you then bye bye snus. You'll be to the Space Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You can also stream on demand at bites dot com. This has been another quality podcast production from nights dot com.