Life and death of stars
Star Field and Nebula Images Star Field and Nebula Images
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- since we've been talking how stars formed 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,
- 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're actually talking about a huge nebula
- and actually, it's a nebula that expands.
- and so that you have a sense, this is just one of the pillars of the "Pillars of creation"
- This is just a small part of the actual Eagle Nebula
- And just this pillar right over here, just this pillar here
- so that you have a sense of how large it is, just this pillar itself is 7 light years
- it is 7 light years talls
- so this is an enormous amount of distance
- remember, the distance from earth to the nearest star was about 4 light years
- it would take voyager, if it were pointed in the right direction
- moving at 60 thousand kilometers per hour
- it would take Voyager 80 thousand years to go 4 light years
- just this pillar is 7 light years
- but i wanted to show you this because these type of nebulae, the plural of nebula
- are where stars can form.
- so this right here, you actually see, is actually 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, the critical density, where you can actually get
- fusion of hydrogen
- so this is just a huge interstellar cloud of hydrogen gas
- and over here you can see its just this breeding ground for stars
- and we don't even, we think that this structure doesn't even exist anymore
- because remember, this thing is very very far away from us
- in fact is, just so you have the number, this thing is 7000 light years away
- 7000 light years away
- which means that what we are seeing now, the photons that are reaching our eyes or telescopes right now
- left this region of space 7000 years ago
- so we're seeing it as it was 7000 years ago
- so a lot of this gas, a lot of this hydrogen, may have already condensed into many many more stars
- so the structure might not be the way it looks right now
- and actually there was another
- super nova that happened that might have blown away a lot of this stuff
- and we won't even be able to see the effects of this super nova
- for another thousand years
- but anyway, this is just a pretty amazing photograph in my opinion
- especially, and its beautiful at any scale
- and it's even more mindblowing when you think that this is 7, this is a structure
- that is 7 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 milkyway
- this is the Sagittarius star field
- the neat thing here you see is such a diversity in stars
- 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
- this isn't one of those where we're looking beyond our galaxy or looking at clusters of galaxies
- this is just stars here
- but the thing here is that 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 different stars are at different distances and at difference intensities
- but the redder stars, these are stars in their red giant phase
- or they're probably at their red giant phase
- i haven't done specific research on these stars
- but that's what we suspect
- those are in their red giant phase
- the ones that are kind of in the yellowish white part of the spectrum
- these are stars that are probably in their main sequence
- probably not too different than own sun
- the ones that are in the yellowish white, closer to orange-yellowish-white part of the spectrum
- and the ones that look a little 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 big bluish to me,
- these are burning super super fast, and so
- the super massive stars, they burn kind of fast and furious and then just die out
- but the smaller stars, the ones with less mass
- they burn slower over a much much longer period of time
- so the ones that are burning fast
- are emitting a lot of energy at the smaller wavelength part of the light spectrum
- that's why they look bluer or greener and these are going to be more massive stars
- the ones that look white or bluer or greener
- while the redder ones
- the redder ones are less massive stars that are kind of in their super giant phase
- and so they are at this point cooler than 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
- this one here is a planetary nebula
- and it's called a nebula because it is kind of this gas that's kinda floating out in space
- but it's at a completely different kind of scale than this Eagle nebula
- that we drew over here
- so when people talk about nebulas, they normally talking about something like the eagle nebula
- these huge masses of interstella gas
- when people talk about planetary nebulas; this is actually still a huge radius
- but no where near 7 light years
- but this is the bi-product of a star shedding all of its outer material
- so at the center of this, we see kind of a mature star here
- and it's shed of kind of its outer layers
- and it did that in its red giant phase
- so the core would keep flaring up, having these hot explosions
- and every time you have one of these 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
- its still not yet a white dwarf, it is still an active star
- fusion is still occurring in this star, but it is well on its way onto becoming a a white dwarf
- once all its fuel runs out
- it's past its red giant phase, it's thrown all of this material into space and it's on its way onto becoming
- a white dwarf
- anyway hopefully you enjoyed that
- i actually find all of these images to be pretty captivating
- especially the star field one
- because this just inside of our galaxy
- hopefully it gives more appreciation for how many stars there are
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At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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