星场与星云图

since we've been talking about how stars form and the evolution of stars I thought it was about time that we looked at some cool pictures of stars forming or stars themselves or evolution of stars so this right here is from the Eagle Nebula eagle I should capitalize the e this right here is from the eagle the Eagle Nebula and just so you know the word nebula is kind of a general word for any interstellar cloud of gas or dust so when we're talking about the Eagle Nebula we talked about a huge nebula and it says actually it's a it's a nebula that spans and just so you have a sense this is just one of the pillars in the this is called the pillars of creation you've probably seen this image before there's these three pillars here and this is just a small part of the actual Eagle Nebula and just this pillar right over here just this pillar here just so that you have a sense of how large it is how large it is just this pillar itself is seven light years it is seven light years tall so this is an enormous amount of distance remember the distance from Earth to the nearest star was about four light years it would take Voyager if it was pointed in the right direction at moving at 60,000 kilometers per hour it would take Voyager 80,000 years to go four light years just this pillar is seven light years but I wanted to show you this because these type of nebula is the plural of nebula are where stars can form so this right here you actually see this is actually a kind of a breeding ground for the birth of new stars this gas is condensing just like we talked about a couple of videos ago until it gets to that critical temperature that critical density where you can actually get fusion where you could actually get fusion of hydrogen so this is just a huge interstellar cloud of hydrogen gas and over here you could say well you can just see it's just this just this breeding ground for stars and we don't even we actually think that this structure doesn't even exist anymore because remember this thing is very very far away from us in fact it is just so you have the number this is seven thousand light years away seven thousand light light-years away which means that what what we are seeing now the photons that are reaching us right now reaching our eyes are reaching our telescopes right now left this region of space 7,000 years ago so we're seeing it as it was 7,000 years ago so a lot of this gas a lot of this hydrogen may have already condensed into many many many more stars so the structure might not be the way it looks right now and actually there was another supernova that happened that we think might have kind of blown away a lot of this dust and we won't even be able to see what the effects of that supernova were for another thousand years but anyway this is just a pretty amazing photograph in my opinion especially and it's beautiful at any scale but it's even more mind-blowing when you think that this is 7 this is a structure that is seven light years tall and this is really just part of the Eagle Nebula one of the pillars of creation this right here is a star field and this is as we're looking towards the center of our galaxy the Milky Way so this is the Sagittarius star field and what I just want to the neat thing here you just see is such a diversity in stars and this is also kind of mind-numbing because every one of these stars are inside of our galaxy this is looking towards the center of our galaxy we're not looking at this isn't one of those we're looking beyond our galaxy or and working at clusters of galaxies this is just stars here but let's see here's you see a huge variety you see some stars that are shining red right over here and obviously the apparent size you cannot completely tell because the stars are different distances and at different intensities but the the redder stars these are stars they're red giant phase or they're probably at the red giant phase I haven't done specific research on these stars but that's what we suspect those are that the red giant phase the ones that are kind of in the yellowish white part of the spectrum these are stars probably in their main sequence probably not too different than our own Sun the ones that are in the yellowish white or closer to orange yellowish white part of the spectrum and the ones that look a little bit more bluish the ones that look a little bit more bluish or a little bit more greenish these are burning super fast let me see if I can find this one looks a little bit blue to me these are burning so I had to pause the video for a coffee these are burning super super fast and so the the supermassive stars they burn kind of fast and furious and then just die out while the smaller the the smaller star is the ones that less mass they burn slower over many many over a much much much longer period of time so the ones that are burning really fast or meeting a lot of energy at the at the the smaller wavelength part of the light spectrum and that's why they look bluer or greener and these are going to be more massive stars the ones that look whiter or blue or green err while the redder ones the redder ones are are less massive stars that are in kind of their supergiant phase and so they are at this point cooler than kind of the main sequence stars this right here this right here is the cat's eye nebula and the word nebula this is actually a planetary nebula and I want to differentiate this right here is a planetary this is a planetary nebula and it's you it's called a nebula because it is kind of this gas that's that's kind of floating out in space but it's at a completely different scale than this nebula then the Eagle Nebula that we drew over here so normally when people just talk about nebula they're talking about something like the Eagle Nebula this huge masses of interstellar gas when people talk about planetary nebula this is still actually a huge huge radius but nowhere near seven light years it's but it's still a huge but this is the byproduct of a star shedding off all of its outer material so this is at the center of this we see a fairly mature star here and it's shed off kind of its outer layers and it did that while it was in this red giant phase so the core would keep flaring up keep having these hot explosions and every now every time you had one of those hot explosions you had more and more of its outer layers getting pushed off pushed off into space forming this planetary nebula so this as we see it right now it's still not yet a white dwarf it is still an active star Fusion is still occurring in the star but it's well on its way to becoming a white dwarf it once all the fuel runs out so it's passed the red giant phase it's throwing all of this material into space and it's on its way to becoming a white dwarf anyway hopefully you enjoyed that I actually find all of these all of these images to be pretty captivating especially the starfield one because this is just inside of our galaxy hopefully gives even more appreciation for how many stars there are I mean this is just a small fraction of the 200 to 400 billion stars inside the Milky Way