Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / #416: Cosmic Conundrums & Astral Assemblies: Tackling the Universe's Toughest Questions

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#416: Cosmic Conundrums & Astral Assemblies: Tackling the Universe's Toughest Questions · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Hi there, Thanks for joining us on this Q and A edition of Space
0:03
Nuts. Andrew Dunkley here, your host. Hope you're well. Coming up
0:07
on this particular show, we're going to be focused on black holes. We've
0:10
got two questions independently that basically ask a similar thing about black holes and magnetic
0:17
fields, and I think we've had similar questions in the past, so we'll
0:21
tackle that one probably again. We're also going to look at different kinds of
0:25
stars, how many of each there might be, and do those proportions agree
0:29
across galaxies and if it's different. Why personal projects? Someone wants to know
0:36
what Fred's favorite personal project has been over the years. Oh gosh, that
0:40
goes back well when Galileo and I were sitting on the beach. You know,
0:45
we'll find out. And Rusty has asked why fog bows are white.
0:50
That's all coming up on this edition of Space Nuts fifteen, Channel ten nine
0:58
ignition sequence Space Nuts three two. Nice as when I report it real good
1:10
And here he is Professor Freedwards, an astronomer at large. Hello Fred,
1:14
Hello, I believe when you were sitting on the beach with Galileo that you
1:19
were talking about the gravity of world affairs. We were drinking a cup of
1:23
gravity each. Actually it was really nice. Ye, good stuff, that's
1:29
good stuff. How are you going? You're good? Yes, well,
1:32
thank you. I'm good to see you too. I hope you're well as
1:36
well and taking your gravity seriously. I think I have we have to sack
1:41
our laundry. We're both wearing the same shirts as last week. So it's
1:46
a bit of a worried. It is shocking, isn't it. Yeah,
1:49
I should have it's not good. Yeah, well we could. We could
1:56
stretch that joke for a long long time, but we're not going to.
2:00
No, that's probably not really worth it, and probably nobody would have noticed.
2:04
I did not mention, Probably not the lady. The ladies would probably
2:08
notice before the men. My wife notices things about my attire that I don't
2:14
even think about. So yes, it's another story that just shows they're so
2:20
much more fashionable than we are. Shall we do some questions for no,
2:24
let's just at the show. That's probably well, yeah, just that was
2:30
quick and easy. Until next time. How about we talk about black holes
2:35
and magnetic fields. This is a question from Robert, and I'll follow it
2:38
up with a text question. We got from Lachlan. Here we go,
2:42
Andrew, this is Robert from the Evidence. I have a question about black
2:46
holes on my favorite subjects. This is not dark matter, right. Apparently
2:52
black holes do not have a sucking everything everything that's something to the black hole.
3:00
However, we do see these enormous jets being ejected from quasards one hundreds
3:04
of thousand bagsish long. Obviously they do have some sort of poles. Of
3:08
these poles. The only time I see that the reality is with neutron stars,
3:13
white Horse. The Tory stars a sort of thing and it's always due
3:16
to a magnetic field. So how can this be? Maybe black holes do
3:22
have magnetic field, and you know the sertains that are disc around it would
3:28
be able to create this thing. However, that would not be responsible for
3:30
poles on the object itself, I would think. However, maybe I'm wrong.
3:37
So what do you think, guys? The MA they of any hole
3:39
in it? Where is it a hole in one? I'll hear it,
3:44
uh jokes jud jokes from all corners. Thank you, Robert. And in
3:49
conjunction with that, we've got a text email, a quick one from Lachlan
3:53
saying, is black hole radiation the electromagnetic field. This SEMs to be a
4:01
point of contention. We get a lot, We've had a lot of questions
4:04
about black holes, but this one seems to come up semi regularly for it.
4:10
Yeah, it does, and it's kind of connected with if I remember
4:16
rightly, it's called the no hair theorem, which I really like, actually
4:21
the no hair theme I'm sure you do, which is that there's only a
4:28
few parameters that you can learn about a black hole. And I did write
4:34
about the no yeah, no hair theorem in Cosmic Chronicles. I should read
4:38
it again and find out what I said. But yes, because you know,
4:43
there's just a very few parameters, and the idea of magnetism is that
4:48
magnetism isn't one of them, which is kind of what Robert is alluding to.
4:54
So if you have, you know, no hair black the fact that
5:00
there's no hair there tells you that there's no magnetism. However, however,
5:08
clearly do have magnetic fields, because that is what focuses the jets of radiation
5:15
and material that are exactly the cause, as Roberts alluded to, of quasars.
5:21
Active galaxies Delinquent galaxies are sometimes called them because they're all youthful galaxies.
5:28
We're looking back in time a long way and see the seeing these quasars.
5:32
So there is clearly some way in which magnetism can occur. And you basically
5:43
what you do to get the magnetic field of your black hole is you rotate
5:48
it. So it's got to be a rotating black hole and give it an
5:53
electric charge. And those two things together, an electric charge and angular moments,
6:00
which is just a fancy word for rotation, produce what is known as
6:05
a ker Newman black hole k double R Newman black hole. A curR black
6:12
hole is one that routates. I think a black hole is probably one with
6:15
electric charge. One with both of those things is a kur Newman black hole,
6:18
and it does have a magnetic diephole, which tells you it's got a
6:24
magnetic field. So yes, a black hole can have a magnetic field,
6:29
all right. And Laplin's question, is black hole radiation the electromagnetic field that's
6:34
somewhat different angle on it? It is. That's partly true because what happens
6:42
is that you know, you've got a Kerr Newman black hole that's got a
6:46
strong magnetic field, it's got an accretion disc of material around it, stuff
6:50
that's been gobbled into the black hole. That material is swept up or some
6:56
of it is swept up by the magnetic field and squirted out at the poles
7:00
of the black hole, the rotation poles to make these jets of material,
7:05
which themselves also generate radiation because you've got highly energetic particles moving through you know,
7:15
a medium, non vacuum medium. And so yes, the jets are
7:23
basically the radiation that arises because of the magnetic field of the black hole.
7:32
Question. I think so yes, but I don't really know. We just
7:42
get so many questions about them. I note that there's been a new image
7:46
released of a black hole at which was revealed in the last few weeks.
7:55
Actually, so they've got a bit of a better understand ending of it from
8:01
the image of environment and that was I think was James Webb image, if
8:07
I remember rightly. But yeah, that's we're starting to get more and more
8:11
information about them, so maybe more of their secrets will start to be unraveled.
8:16
Or was it Sagittarius a star that we're talking about. There was one
8:20
that that published information about earlier this year. It was the twentieth of March
8:26
and it is Sagittarius, so there is a marvelous rendering. And again it
8:31
comes back to something we talked about in the last main issue of Space Arts
8:39
about polarized light. How you detect magnetism via polarized light. The Event Horizon
8:45
Telescope collaboration, which looks at the structure of black black hole accretion discs,
8:50
has indeed detected the polarization of that doughnut shaped disc around the black hole at
8:56
the center of our galaxy. And it's a picture that you can find online.
9:00
It's pretty easy to find, but dated day March this year. Space
9:05
dot com is a good place to start, but there are plenty of articles
9:09
on it, but space dot com. Thanks Robert and thanks Lachlan. I
9:13
hope we helped you out there. Let's move on to our next question.
9:18
This one comes from Pete. Hello, Fred and Andrew. This is Pete
9:24
Alinga from Sunny Sheffield in the UK. I have three questions for you,
9:31
all related to the mnemonic obi A fine Girl kiss Me, which I use
9:37
to remember the different types of stars. Question one, what are the proportions
9:43
of these star types in the Milky Way? Question two? Do these proportions
9:50
hold through for all galaxies. Questions three, If the proportions are different across
9:58
the universe, what does that tell us? Thank you for the great show,
10:07
which is all the better for splitting out the Q and AS into a
10:09
separate recording All the best, Eat Manager Pete. It is lovely to hear
10:16
from you. Thanks for the endorsement on doing two shows a week instead of
10:20
one. It seems to be well accepted, so that's good. Different kinds
10:28
of stars, yes, we know there are. How many of each in
10:33
the milky way? Do those proportions correlate across galaxies? And if they're different?
10:37
Why? I think that's a price of his entire question load. It
10:43
is, that's right, so you know what we're looking at here is the
10:50
be a fine girl kiss me is well known actually these days is also be
10:56
a fine guy kiss me. It was a mnemonic that was conjured up back
11:01
in the day for the what we call the spectral classes of Just a minute,
11:07
let me deal with this. I find the phone. That's no good.
11:15
I'm not going to say that's. Get rid of that. Yes,
11:20
sorry about that. I don't know who that was from somewhere, probably trying
11:24
to sell you cladding or solar pals while they're in Queensland, so it could
11:31
be either of those. As you can tell you, I do apologize for
11:35
that, apologize to all our listeners. I meant to put the phone on
11:37
silent and I clearly forgot. I actually forget to do it on the radio
11:43
sometimes, so yeah, I can sympathize, Yeah, but I won't.
11:48
So we were unless it was somebody responding to my exhortation or be a fine
11:56
girl, kiss me. It could have been that, I guess, coming
11:58
in by phone. But it's a mnemonic for the spectra classes of stars.
12:05
And the reason why it's so totally counter intuitive. You know why isn't it
12:13
in straightforward alphabetical order, is because it goes back to the very early days
12:20
at the beginning of the last century of people doing this spectral classification working out
12:26
what the different kinds of spectra of stars meant. So when you look at
12:31
the spectrum of a star, you get this barcode of information and they're different,
12:35
and that we now know a lot of the difference depends on temperature,
12:39
some of it depends on age. These are all factors that are in that
12:45
and so they did classify them originally A, B, C, D,
12:48
E, F, G, et cetera. And then eventually it was worked
12:52
out what it was that these things were telling you. And it's now in
12:56
temperature order going downward, so O stars are the very very hot ones surface
13:03
temperatures twenty thirty thousand degrees kelvin down to the M stars the me of the
13:11
mnemonic so ob A f G k M M stars are the red dwarfs with
13:18
surface temperatures region of three thousand degrees kelvin, that sort of sort of temperature.
13:26
And so that distribution has been you know, we know that those are
13:31
the classes. And Pete tasking an ip fellow Yorkshireman, Pete asking about what
13:41
the relative numbers are of those, and it's pretty easy to find them on
13:46
the interweb. I just d good so you can answer the question. The
13:52
bottom line is, you know the essentially that obfgk M is out the A.
14:03
I think it is an order of decreasing temperature and its order of decreasing
14:09
numbers, sorry, increasing numbers, because the stars are the rarest and the
14:13
M stars are the commonest. In fact, they're by far theless common type
14:18
of stars in our galaxy. Sou and as as is is as a G,
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so they sort of rank in the middle to higher end of numbers.
14:35
Yes, but they're nowhere near as common. M stars are ms accounting for
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seventy six and a half percent of all stars, and G is seven point
14:46
six, so it's a lot less, whereas O stars are rare still aren't
14:52
they point zero zero zero zero three percent of all stars? There you go,
14:58
So that's the perfect answer to the question. You see, you don't
15:01
really need me, however you might need yes, yes, which was about
15:09
whether you know this. The same is true for other galaxies, and there
15:16
are subtle differences. Basically it's the same distribution, but there are some subtle
15:22
differences. And in Pete's next question was if there are differences, what causes
15:30
them, and it's things like differences in the amount of metals which are in
15:37
those stars. So metallicity the amount of basically the amount of iron in a
15:43
star, although as you know, Andrew, astronomers think of everything except hydrogen
15:50
and helium as being a metal, which ismical, but anyway, so the
15:54
metallicity can vary in a galaxy and that would give slightly different numbers, but
16:00
really the marginal by far the communist types of stars in the universe or Amy
16:03
stars, these dwarf stars type the am of kiss me indeed, so yeah,
16:14
easy to find on the internet if you want to have a look at
16:17
those various star types and the well, all these statistics, their vital statistics,
16:25
I think would be the best way to describe it. Pete, thank
16:27
you. I love those questions because they sort of get into the nuts and
16:30
bolts of stars and it sounds like it's pretty much the same across galaxies,
16:36
give or take, which is good because that would have been if they weren't,
16:40
it would have been a much longer explanation. This is space Nuts.
16:45
Andrew Dunkley here with Professor Fred Nuts. Okay, Fred, let's move on
16:53
to our next question, which comes from Michael. I. Just Michael from
17:00
Kent to the UK. Just a question you guys. If there was a
17:06
project that you could have worked on past or president, what would it be
17:11
more exclusively Professor Watson, what projects stood up for you the most that you've
17:18
worked on and why enjoy your show? Guys? Thank you so much.
17:25
Maybe a bit selfish, but I enjoy your long episodes because it helped makes
17:29
my micro shifts a lot of you. Thank you so much and enjoy it.
17:34
Thank you, Michael. We just said someone saying we love he you
17:37
split them up, and now Michaels saying I like them when they're long.
17:41
You could save it up and just running back to back. It would be
17:45
my advice because you can do that. Personal projects, I mean for me,
17:51
I mean I work in radio and so I haven't had direct involvement with
17:56
astronomy except with Fred, but gosh, and I think for me it'd be
18:03
more space, space science related. I'd want to be working on maybe a
18:08
mission to the Moon. I would love to have been involved in if I
18:15
was old enough and clever enough working on the Apollo missions, actually being hands
18:19
on getting those missions off the ground. If there was some way of turning
18:25
back the clock and being in the right place at the right time, that
18:29
would be something I would have adored working on, probably because it was so
18:34
very much synonymous with my childhood. It all started when I was pretty well.
18:38
When I was born, I could send home from school to watch the
18:44
moonwalk Apollo eleven Moonwalk on TV, which happened in the early afternoon our time,
18:49
if I recall correctly, on my families black and white TV. That
18:57
to me was probably one of the most inspiring things that I saw as a
19:02
kid, and it's still with me today. Going down after the missions to
19:07
Parliament House in Canberra with my family on holiday and walking into the foyer and
19:11
they had a glass cabinet, a glass box and inside the box was a
19:17
little claw, and on the top of the claw was a rock. And
19:19
that was a rock they brought back from the Moon. And I was absolutely
19:26
mesmerized by that. I couldn't believe that I was seeing a rock from another
19:29
world. It was just a piece of basshold, but that's beside the point.
19:33
There was a piece of another world, and that just blew the lid
19:38
off my brain. So if I could do anything again, or do anything
19:44
in the past astronomy, space science related, that would probably be one that
19:49
I would want to work on, a bit more sort of nuts and bolts
19:53
than something Fred might be about to talk about. But I went over and
19:59
I saw the Apilow eight control room that they set up in Florida at the
20:07
NASA base there, got to see the Satin five rocket hanging from the ceiling,
20:14
got to see Neil Armstrong's uniform, his spacesuit. Yeah, all of
20:19
that is it's probably what tickles my fancy most of all in terms of space
20:27
sen So that would be it for me. Michael Paul Shaw. What about
20:32
you, Fred, Well, yeah, I mean I endorsed all that completely,
20:38
but just to come a little bit further down to earth, if I
20:42
may. I do have friends who have worked on projects which really we're milestone
20:49
projects, and one of them is the Kirby Mission, the Cosmic Background Explorer,
20:59
which was a base mission designed to measure for the first time the cosmic
21:03
microwave background radiation. It's that was I think in the nineties. Yes,
21:10
it was the nineties where that was happening. It's been superseded by since then
21:15
by W. Matt the Wilkinson Microwave and Issotropy Probe and PLANK and a European
21:22
spacecraft that measured the cosmic microwave background. So what we're doing here is putting
21:27
a satellite into space to look for the after glow of the Big Bang,
21:33
which is a pretty neat thing to do, you know, the cosmic wallpaper,
21:37
the thing beyond which we can see because we're looking back in time so
21:40
far that we can see the glow of the Big Bang, and it's got
21:42
this structure on it, which was imposed on it by sound waves in the
21:47
early universe. That's the really, you know, almost spooky bit of this.
21:52
But the colleague guy had who worked on that, I always thought,
21:56
what a way to start your career. I think it was his PhD topic.
22:00
He was part of the Kobe team, and he did a lot of
22:03
work on that. He's now an astrobiologist, so he changed tech completely.
22:07
And then the other one, it's a similar sort of thing and epoch making
22:11
discovery and maybe there are two. Actually yes, One would be imagine being
22:18
part of the team that first detected gravitational waves back in twenty fifteen, Attigo.
22:25
You know, you really be absolutely blown away by the fact that for
22:30
the first time you've detected a gravitational wave from impact. I think it was
22:34
neutron star collisions that first one, if I remember rightly, it was.
22:40
It's a date that I can easily remember, fourteenth of September twenty fifteen,
22:44
because that's Marny's birthday. So it's stuck in my mind that it was on
22:48
her birthday. And the other one guests similar because it involves a huge,
22:52
huge collaboration. It would have been great to have worked on the event horizon
22:56
telescope to produce that very first picture of a black hole event horizon, the
23:02
one from eighty seven just a few years ago as well. So those are
23:06
really big ticket projects which it would have been great to work on. The
23:11
big projects that I've worked on, in a way, the one that I
23:17
had most to do with in it was actually my project which was developing wide
23:22
angle spectroscopic instruments for the United Kingdom. Siret Telescopture's a wide angle telescope one
23:29
point two meter diameter aperture, and I built three generations with a lot of
23:34
help, of course, of fiber optic instruments, three or four. It
23:42
was three. The fourth generation was actually nothing to do with me, but
23:48
I was kind of cheering it on. So what that meant using this fiber
23:52
optic technology was that you could measure the spectrum of many objects simultaneously, up
24:02
to one hundred and fifty in the end, and we in fact it was
24:08
four generations. The fifth generation was the one I wasn't involved with, so
24:12
I did a lot of work on this. The fourth generation one we did
24:17
surveys of stars in our galaxy, half a million stars and also surveys of
24:25
about one hundred and sixty thousand galaxies. We made a map of the nearby
24:30
universe with these galaxies. And those two surveys were also big projects that I
24:37
worked on. One was called the sixty f Galaxy Survey sixty FGS, which
24:44
wound up actually in two thousand and three. The other was the RAVE Survey,
24:47
the Radial Velocity Experiment, which wound up two well, they observing wound
24:52
up in twenty thirteen. So they were big projects which gave me a lot
24:56
of a lot of anks, I can tell you. That's why i've hairstyle
25:00
here. But nevertheless, they were also very very rewarding and you know,
25:06
made me think. I think they did quite a lot for my astronomical street
25:08
credit booth of them. Yeah. Indeed, another one I remember, and
25:14
you and I did a little documentary piece on this was the two degree field
25:19
instrument that that was a big sort of leap forward and it was a sort
25:25
of an add on to the existing telescope as far as I remember, wasn't
25:29
it, Fred. It's a bit like it is add on to the Angle
25:33
Australian Telescope HPPY that we're talking about in the last episode. Yeah, yeah,
25:38
yes, thank you, Michael. I hope that filled the breach in
25:42
terms of personal projects that we would love to have worked on. Final question,
25:48
Fred comes from Rusty and Johnny Brook. I've paraphrased this because Rusty asks
25:53
questions in chapters, but I'll break it down. Why a fog bow's white?
26:00
Now? When I first read his question, I thought, what's a
26:03
fog bow? I'd never heard the term before. I know that sounds strange,
26:07
but I've never heard a reference to a fog bow before. So I
26:12
had to have a close look at his photo and try to figure out what
26:15
he meant. And he's talking about a rainbow effect in fog. But they're
26:19
not a rainbow because they're white. They're just white. He is suggesting that
26:23
it's water droplet size that might be a factor here. What are we talking
26:29
about, Fred, Yeah, So sunlights lighting up a bank of fog,
26:33
and I'm supposed you've never seen one, because I used to see them a
26:37
lot when I was driving to your town back in the day when I used
26:40
to commute from kinder Burbon to talk on the NBC. So sunlight, it
26:47
illuminates a bank of fog, and if you're at a position where the sun's
26:51
behind you, it forms what amounts to a rainbow. But exactly as you
26:57
say, the colors are washed out. They're just white. Now, Rusty
27:03
did send an image of a fog bow, which was a beautiful image,
27:07
and yes it's white, but if you look carefully, you can just see
27:10
a slight red tinge on the outside of it and a slight bluish tinge on
27:14
the inside of it. And that's Those are the colors that you see in
27:17
an normal rainbow. So it's a kind of rainbow, but with the colors
27:21
washed out. And that's exactly what happens. What's happening, and Rusty is
27:27
perfectly right. It's called it's all to do with droplet size. So fog
27:33
bow droplets are much much smaller than rain drops that form a rainbow. The
27:38
raindrops forming a rainbow could be half a millimeter in diameter. The ones for
27:42
a fog bow much smaller. It's an aerosol almost where you're talking about your
27:48
fifty microns or something like that, rather than half a millimeter, so much
27:52
smaller, so there is a rainbow effect. Rainbows are caused by refract refraction
27:56
and dispersion of light in a globe of water, dispersion being the spreading out
28:02
into the spectrum that happens in a fog boat droplet as well, but because
28:07
they're so small, it's swamped out by another effect called diffraction, and diffraction
28:12
is to do with the wave nature of light. Because these things are so
28:15
small, you got to take the fact that light is a wave motion into
28:19
account. And what it does is it just washes out the colors. So
28:23
every color, rather than being a single color in a specific part of the
28:27
rainbow, just gets washed out to be much broader. So the colors are
28:33
all there, but they're swamped by each other until they become white, exactly
28:37
like you know, if you're pushing it back through a prism, all these
28:41
colors they will turn white. That's not the reason. It's because of diffractions
28:45
spreading out the being, but they look white. So yeah, a lovely
28:48
photograph from Rusty. We should put that one on the website. I think
28:52
I will send it to Hugh so that he's got something to do. Yeah,
28:56
I'll do that, Yes, yes, thanks Rusty, and always good
29:03
to hear from you. Rusty often sends photos through of his astronomical images and
29:11
it gives me photographic tips. I haven't tried them yet, but I will
29:15
when I get into some dark space. It's a bit too much light around
29:17
my new place, so I don't have much luck with astrophotography in my backyard.
29:22
But forgbos, yes, I can't believe I've never heard that term before.
29:27
Maybe I was just so ignorant to it it never stuck in my brain,
29:30
which is basically my entire education. So thank you, Rusty. Lovely
29:36
to hear from you, and Michael and Pete and Lachlan and Robert. Thanks
29:38
for sending your questions in, and don't forget. If you've got questions,
29:41
we'd love to get them from you, send them in right now. We'll
29:45
wait or we'll look later. You can send them via our website, spacenuts
29:51
podcast dot com or space nuts dot io. Just click on the links on
29:55
the page and you can send us audio or text questions. Text questions through
30:00
the AMA tab, audio questions through AMA and the send us your audio question
30:06
on the right hand side under that weird purple color. That's it, Fred,
30:11
Thanks again so much, lovely to catch up. We'll see you soon,
30:14
so great. Take care on you you too, Fred Watson Astronomer at
30:18
Large, and thanks to Hue in the studio for not asking us any questions
30:22
at all ever, and from me Andrew uncle, it is goodbye until next
30:26
time on Space Nuts see you then bye bye snus. You'll be to the
30:32
Space Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite
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