M63 - Sunflower Galaxy - Deep Sky Videos

so we've been working our way through the messier catalogue making videos about every single Messier object and it turns out there aren't very many pretty ones there are lots of rather boring looking clusters of stars and things but once in a while you hit a really beautiful galaxy and this is one of those it's Messier 63 otherwise known as the sunflower galaxy here is a glorious looking thing I mean it's a spiral galaxy it's about 50 50 million light years away it's actually part of a group with various other galaxies of which actually another of Messier it's more famous and beautiful galaxies Messier 51 the Whirlpool Galaxy is a member of the same group Messier 51 is a beautiful grand design so it has sort of two big spiral arms but as this is what's known as a flocculent spiral in that apparently it doesn't have grand design structure we'll come back to it in a bit it has these kind of little bits of spiral arms which I guess is why it ends up being called the sunflower galaxy because they look like the little petals of a sunflower so this is a good opportunity to talk a little bit about the nature of spiral structure the classic picture people have of spiral structure is you've got a galaxy and it's got these beautiful spiral arms coming out of it and that's what galaxies like the Whirlpool Galaxy and various other grand design spiral look like famously there's a problem with understanding how this structure is there at least how it stays there in that if you look at how fast the galaxy's rotating what you find is that the bits on the outside are going around almost exactly the same speed as the bits at the inside and the reason why that is a bit weird is because if you think about it it's as if you had all the stars running long distance race where they all stay in lane and if you really ran a long distance race that way the people in the outside lanes would be hugely disadvantaged because they've got a whole lot further to go the stars the material near the middle would have gone round dozens of times and this lot in the outside lanes would still be panting their way around the first lap and so it would very rapidly get wound up as the stars on the inside went round and round and round and the stars on the outside hadn't yet completed one circuit it's a thing called the winding paradox and we sort of understand it because we don't think that the spiral arms and these grand design spiral are really kind of physical entities they're more like waves that are working their way around so just like in a water wave the individual molecules of water don't follow the wave they stay more or less where they are same here that the wave will propagate through the galaxies but the stars are just traveling along at their own particular speed as they orbit around so that's grand design spiral structure here we have the other extreme which is this stuff flocculants bio strategy you know you can't pick out two arms here there's just lots of little tiny bits of spiral structure and here we think there might be a different piece of physics as to what's going on so in this case we got the center of our galaxy and what we think probably happens in systems like this is some star start to form at some point and what happens is the very massive stars will very quickly go supernova and they'll compress gas around them and so you'll end up with other stars forming and other little clusters of stars forming and so you end up with these little sort of collections of star formation occurring and of course all this stuff is all waiting around the galaxy but again remember the stuff at the inside is going at the same speed as the stuff at the outside which essentially means the stuff further out gets left behind and so what'll happen is although they might have originally formed in a circular blob if we look at them a bit later on the one on the inside will have gone further and then the stuff a bit further out wouldn't have got quite so far and so you end up forming these little bits of a spiral arm so we think probably in cases like this a lot of what we're seeing is little bits of star formation happening and then then getting stretched out by this mechanism into these little sections of spiral arm which sort of form the petals of our sunflower now it is further complicated by the fact that the other thing you can see in this picture is there are lots of dark bits and the dark bits are where there's dust lanes so as well as the stars getting stretched out there's also dust lanes that can be getting stretched out as well and are obscuring stars and just complicating the picture so what's happening is that this light being emitted in the optical in the ultraviolet by the stars and it's being absorbed by the dust but that really just makes the dust warm up a bit right the energy doesn't disappear what happens is that light gets absorbed that energy gets absorbed by the dust the dust then warms up a bit and then reradiates it in the far infrared so although in this in the optical picture here we see the dust that's kind of absorbing stuff if we were to take a mid to far infrared image of this galaxy we'd see that the slowing and so here's a picture of the same galaxy as seen in the fit too far infrared so what we're seeing here is actually these dust glowing as it's warmed up to this relatively cool temperatures tens to hundreds of Kelvin so low temperatures but still warm enough for it to be radiating and so we can actually see these dust lines which were previously obscuring things actually radiating their infrared energy away and the other intriguing thing is when we looked in the optical picture there really wasn't any evidence of any grand design but here we start seeing much longer features so it looks like there's something else going on in this galaxy beside those little bits of star formation getting stretched out that there does appear to be more kind of something closer to grand design structure in the optical part of the spectrum you have struggled to see the stars because they're being obscured by the dust in the far infrared the light that you see is dominated by the dust itself in between in the near infrared you can see the light from the star still and actually in the near infrared the dust is pretty bad at obscuring that starlight so actually the star light gets through the dust so we can actually see the stars in a fairly unobscured fashion by looking in the near-infrared so somewhere I have a near infrared picture of this galaxy yeah here we go so the title this is uncovering spiral structure and flocculent galaxies Messier 63 is a classic example of a flock 10 galaxies and sure enough it's one of the ones that made it into their sample and they looked in the near-infrared and here's their picture of it so this is a negative image which means that the dark bits you can see is actually where the stars are and if you look at this closely you can actually see that actually the flocculent structure has largely disappeared and really what you see in the slightly older but unobscured stars is just two spiral arms they're quite faint but they're definitely there so underlying all the stuff about what's going on in the recent star formation and creating these flocculent spiral or structure partly obscured by the dust it looks like the other story of spiral structure the grand design thing is also going on in this galaxy that there is a wave of these slightly older stars which we can see when we look in the near-infrared and we end up seeing this grand design spiral structure as well this is a really beautiful galaxy how have you waited so long because we were really good and actually I was I was really straight so several of us are making these videos and I was pretty strict saying look we got to do lots of the boring objects cuz the trouble is a Messier catalogue has got lots of boring objects in it as well as a few of these real gems only so it turns out that no sorry I shouldn't call them boring objects they're all interesting but they're not all necessarily pretty and so there were a few of these pretty objects and lots of objects which don't look so inspiring so we've been pretty good in that for every you know pretty object we do we do two or three that don't look very pretty it turns out we've slightly overdone it so we've actually got quite a few of the really nice ones left to do at this point right where the S is is us right which means that in any direction you look you'll see more star say this way than you do in if you were looking this way and so actually any direction you look in the plane of that slab which is kind of this ring around the sky you will see the Milky Way which is exactly what we see and you see the Milky Way is kind of a band across the sky

Channel: DeepSkyVideos

Views: 26,132

Rating: 4.9808955 out of 5

Keywords: astronomy

Id: S0N98fMLkbU

Length: 6min 56sec (416 seconds)

Published: Wed Apr 15 2020