align:start position:0% have you ever wondered how all the align:start position:0% have you ever wondered how all the align:start position:0% have you ever wondered how all the chemical elements are made then join me align:start position:0% chemical elements are made then join me align:start position:0% chemical elements are made then join me as we are lifting all the status secrets align:start position:0% as we are lifting all the status secrets align:start position:0% as we are lifting all the status secrets to understand the cosmic origin of the align:start position:0% to understand the cosmic origin of the align:start position:0% to understand the cosmic origin of the chemical elements let's look at the align:start position:0% chemical elements let's look at the align:start position:0% chemical elements let's look at the early chemical evolution align:start position:0% early chemical evolution align:start position:0% early chemical evolution [Music] align:start position:0% align:start position:0% some 14 billion years ago everything align:start position:0% some 14 billion years ago everything align:start position:0% some 14 billion years ago everything started with a big bang bang and it left align:start position:0% started with a big bang bang and it left align:start position:0% started with a big bang bang and it left behind a universe that was made from align:start position:0% behind a universe that was made from align:start position:0% behind a universe that was made from just hydrogen and helium gas I mentioned align:start position:0% just hydrogen and helium gas I mentioned align:start position:0% just hydrogen and helium gas I mentioned before there's a tiny tiny little trace align:start position:0% before there's a tiny tiny little trace align:start position:0% before there's a tiny tiny little trace of lithium but we're not going to worry align:start position:0% of lithium but we're not going to worry align:start position:0% of lithium but we're not going to worry about that so we had a universe but align:start position:0% about that so we had a universe but align:start position:0% about that so we had a universe but there were no stars yet so it was align:start position:0% there were no stars yet so it was align:start position:0% there were no stars yet so it was actually dark and some people call that align:start position:0% actually dark and some people call that align:start position:0% actually dark and some people call that the cosmic Dark Ages but structure began align:start position:0% the cosmic Dark Ages but structure began align:start position:0% the cosmic Dark Ages but structure began to form and gas began to clump and so align:start position:0% to form and gas began to clump and so align:start position:0% to form and gas began to clump and so eventually in a gas cloud the very first align:start position:0% eventually in a gas cloud the very first align:start position:0% eventually in a gas cloud the very first stars formed here are two of the first align:start position:0% stars formed here are two of the first align:start position:0% stars formed here are two of the first stars and they were made just from align:start position:0% stars and they were made just from align:start position:0% stars and they were made just from hydrogen and helium because the gas was align:start position:0% hydrogen and helium because the gas was align:start position:0% hydrogen and helium because the gas was just hydrogen helium but for energy align:start position:0% just hydrogen helium but for energy align:start position:0% just hydrogen helium but for energy generation purposes need stars needed to align:start position:0% generation purposes need stars needed to align:start position:0% generation purposes need stars needed to have nuclear fusion go on in their align:start position:0% have nuclear fusion go on in their align:start position:0% have nuclear fusion go on in their course to produce energy and so the align:start position:0% course to produce energy and so the align:start position:0% course to produce energy and so the first elements heavier than hydrogen align:start position:0% first elements heavier than hydrogen align:start position:0% first elements heavier than hydrogen helium were created inside of these align:start position:0% helium were created inside of these align:start position:0% helium were created inside of these stars and later when they exploded a align:start position:0% stars and later when they exploded a align:start position:0% stars and later when they exploded a supernova they were expelled into this align:start position:0% supernova they were expelled into this align:start position:0% supernova they were expelled into this gas cloud so we had the first elements align:start position:0% gas cloud so we had the first elements align:start position:0% gas cloud so we had the first elements here and of course they also gave the align:start position:0% here and of course they also gave the align:start position:0% here and of course they also gave the first light they lit up the universe for align:start position:0% first light they lit up the universe for align:start position:0% first light they lit up the universe for the first time and changed it in in a align:start position:0% the first time and changed it in in a align:start position:0% the first time and changed it in in a number of ways not just by bringing in align:start position:0% number of ways not just by bringing in align:start position:0% number of ways not just by bringing in light but also by producing the first align:start position:0% light but also by producing the first align:start position:0% light but also by producing the first heavier elements and that set in motion align:start position:0% heavier elements and that set in motion align:start position:0% heavier elements and that set in motion the chemical evolution of the elements align:start position:0% the chemical evolution of the elements align:start position:0% the chemical evolution of the elements that's an ongoing process until today align:start position:0% that's an ongoing process until today align:start position:0% that's an ongoing process until today now these stars here because they form align:start position:0% now these stars here because they form align:start position:0% now these stars here because they form from just hydrogen and helium gas were align:start position:0% from just hydrogen and helium gas were align:start position:0% from just hydrogen and helium gas were very massive rather large maybe align:start position:0% very massive rather large maybe align:start position:0% very massive rather large maybe something like a hundred solar masses so align:start position:0% something like a hundred solar masses so align:start position:0% something like a hundred solar masses so we use the unit here of solar mass this align:start position:0% we use the unit here of solar mass this align:start position:0% we use the unit here of solar mass this is the symbol for the Sun here as a unit align:start position:0% is the symbol for the Sun here as a unit align:start position:0% is the symbol for the Sun here as a unit so a hundred times more hundred times as align:start position:0% so a hundred times more hundred times as align:start position:0% so a hundred times more hundred times as heavy as the Sun and align:start position:0% align:start position:0% the reason for that is that hydrogen align:start position:0% the reason for that is that hydrogen align:start position:0% the reason for that is that hydrogen helium gas has trouble getting really align:start position:0% helium gas has trouble getting really align:start position:0% helium gas has trouble getting really cold align:start position:0% cold align:start position:0% cold making small stars the the important align:start position:0% making small stars the the important align:start position:0% making small stars the the important thing with massive stars is that they align:start position:0% thing with massive stars is that they align:start position:0% thing with massive stars is that they have really short lifetime so they have align:start position:0% have really short lifetime so they have align:start position:0% have really short lifetime so they have a short lifetime of maybe a few a few align:start position:0% a short lifetime of maybe a few a few align:start position:0% a short lifetime of maybe a few a few million years only a few million years align:start position:0% million years only a few million years align:start position:0% million years only a few million years is not much for on a cosmic time scale align:start position:0% is not much for on a cosmic time scale align:start position:0% is not much for on a cosmic time scale which means they exploded pretty quickly align:start position:0% which means they exploded pretty quickly align:start position:0% which means they exploded pretty quickly as gigantic supernova and as already align:start position:0% as gigantic supernova and as already align:start position:0% as gigantic supernova and as already indicated what happened at a later time align:start position:0% indicated what happened at a later time align:start position:0% indicated what happened at a later time these stars were gone but they left align:start position:0% these stars were gone but they left align:start position:0% these stars were gone but they left behind all the heavy elements that they align:start position:0% behind all the heavy elements that they align:start position:0% behind all the heavy elements that they are created and I should be specific align:start position:0% are created and I should be specific align:start position:0% are created and I should be specific here these have your elements where all align:start position:0% here these have your elements where all align:start position:0% here these have your elements where all the elements made in fusion processes up align:start position:0% the elements made in fusion processes up align:start position:0% the elements made in fusion processes up to iron so we have fusion elements in in align:start position:0% to iron so we have fusion elements in in align:start position:0% to iron so we have fusion elements in in the gas and with the onset of these align:start position:0% the gas and with the onset of these align:start position:0% the gas and with the onset of these little other elements being in the gas align:start position:0% little other elements being in the gas align:start position:0% little other elements being in the gas now the gas could for a clump much align:start position:0% now the gas could for a clump much align:start position:0% now the gas could for a clump much better and actually make small stars so align:start position:0% better and actually make small stars so align:start position:0% better and actually make small stars so the next generation of stars so this was align:start position:0% the next generation of stars so this was align:start position:0% the next generation of stars so this was the first generation first generation align:start position:0% the first generation first generation align:start position:0% the first generation first generation and here now we have the formation of align:start position:0% and here now we have the formation of align:start position:0% and here now we have the formation of second-generation stars here as a align:start position:0% second-generation stars here as a align:start position:0% second-generation stars here as a second-generation star here's a second align:start position:0% second-generation star here's a second align:start position:0% second-generation star here's a second generation starts off small stars align:start position:0% generation starts off small stars align:start position:0% generation starts off small stars similar to the Sun and perhaps a little align:start position:0% similar to the Sun and perhaps a little align:start position:0% similar to the Sun and perhaps a little bit less massive than the Sun actually align:start position:0% bit less massive than the Sun actually align:start position:0% bit less massive than the Sun actually but of course you're not going to make align:start position:0% but of course you're not going to make align:start position:0% but of course you're not going to make just small stars you're also gonna make align:start position:0% just small stars you're also gonna make align:start position:0% just small stars you're also gonna make big stars so we have a few big stars align:start position:0% big stars so we have a few big stars align:start position:0% big stars so we have a few big stars here again a few intermediate ones align:start position:0% here again a few intermediate ones align:start position:0% here again a few intermediate ones and the big ones the massive ones will align:start position:0% and the big ones the massive ones will align:start position:0% and the big ones the massive ones will again explode on a pretty fast timescale align:start position:0% again explode on a pretty fast timescale align:start position:0% again explode on a pretty fast timescale and make more elements but these little align:start position:0% and make more elements but these little align:start position:0% and make more elements but these little guys and that's the interesting part for align:start position:0% guys and that's the interesting part for align:start position:0% guys and that's the interesting part for us here now so the low mass second align:start position:0% us here now so the low mass second align:start position:0% us here now so the low mass second generations to us they have very long align:start position:0% generations to us they have very long align:start position:0% generations to us they have very long lifetimes long lifetimes of something align:start position:0% lifetimes long lifetimes of something align:start position:0% lifetimes long lifetimes of something like 15 to 20 billion years because they align:start position:0% like 15 to 20 billion years because they align:start position:0% like 15 to 20 billion years because they have I can just write that here solo me align:start position:0% have I can just write that here solo me align:start position:0% have I can just write that here solo me as they had maybe masters or at least align:start position:0% as they had maybe masters or at least align:start position:0% as they had maybe masters or at least some of them had masses between 0.6 to align:start position:0% some of them had masses between 0.6 to align:start position:0% some of them had masses between 0.6 to 0.8 solar masses so less massive than align:start position:0% 0.8 solar masses so less massive than align:start position:0% 0.8 solar masses so less massive than our Sun and as a good rule of thumb I align:start position:0% our Sun and as a good rule of thumb I align:start position:0% our Sun and as a good rule of thumb I can write this here the Sun has by align:start position:0% can write this here the Sun has by align:start position:0% can write this here the Sun has by definition a one solar mass and that has align:start position:0% definition a one solar mass and that has align:start position:0% definition a one solar mass and that has a lifetime or the Sun has a lifetime of align:start position:0% a lifetime or the Sun has a lifetime of align:start position:0% a lifetime or the Sun has a lifetime of 10 billion years and so everything that align:start position:0% 10 billion years and so everything that align:start position:0% 10 billion years and so everything that has less mass will have a longer align:start position:0% has less mass will have a longer align:start position:0% has less mass will have a longer lifetime and everything that is more align:start position:0% lifetime and everything that is more align:start position:0% lifetime and everything that is more massive than one so let me ask will have align:start position:0% massive than one so let me ask will have align:start position:0% massive than one so let me ask will have a much shorter lifetime yeah now what align:start position:0% a much shorter lifetime yeah now what align:start position:0% a much shorter lifetime yeah now what does this imply having a long lifetime align:start position:0% does this imply having a long lifetime align:start position:0% does this imply having a long lifetime it means that these stars are still align:start position:0% it means that these stars are still align:start position:0% it means that these stars are still around they are around today we can align:start position:0% around they are around today we can align:start position:0% around they are around today we can observe them today we can see them today align:start position:0% observe them today we can see them today align:start position:0% observe them today we can see them today and that means that we can use them to align:start position:0% and that means that we can use them to align:start position:0% and that means that we can use them to study the composition of this early gas align:start position:0% study the composition of this early gas align:start position:0% study the composition of this early gas here because that's when they're formed align:start position:0% here because that's when they're formed align:start position:0% here because that's when they're formed they have incorporated in in all their align:start position:0% they have incorporated in in all their align:start position:0% they have incorporated in in all their layers throughout the composition of align:start position:0% layers throughout the composition of align:start position:0% layers throughout the composition of this gas cloud it has what that was align:start position:0% this gas cloud it has what that was align:start position:0% this gas cloud it has what that was enriched by these very first stars so we align:start position:0% enriched by these very first stars so we align:start position:0% enriched by these very first stars so we have means to study the first stars and align:start position:0% have means to study the first stars and align:start position:0% have means to study the first stars and what came out of their supernova align:start position:0% what came out of their supernova align:start position:0% what came out of their supernova explosions and what happened at this align:start position:0% explosions and what happened at this align:start position:0% explosions and what happened at this very early phase of star formation align:start position:0% very early phase of star formation align:start position:0% very early phase of star formation galaxy formation and formation of all align:start position:0% galaxy formation and formation of all align:start position:0% galaxy formation and formation of all the chemical elements align:start position:0% the chemical elements align:start position:0% the chemical elements if you then wind the clock forward many align:start position:0% if you then wind the clock forward many align:start position:0% if you then wind the clock forward many things happened after well of course align:start position:0% things happened after well of course align:start position:0% things happened after well of course more stories formed many many more cells align:start position:0% more stories formed many many more cells align:start position:0% more stories formed many many more cells more supernovae and with every align:start position:0% more supernovae and with every align:start position:0% more supernovae and with every generation of supernovae more of all the align:start position:0% generation of supernovae more of all the align:start position:0% generation of supernovae more of all the elements was provided more of all the align:start position:0% elements was provided more of all the align:start position:0% elements was provided more of all the elements because as we will see later in align:start position:0% elements because as we will see later in align:start position:0% elements because as we will see later in some of these very early processes align:start position:0% some of these very early processes align:start position:0% some of these very early processes nuclear physics processes all the align:start position:0% nuclear physics processes all the align:start position:0% nuclear physics processes all the elements from the periodic table could align:start position:0% elements from the periodic table could align:start position:0% elements from the periodic table could have been were created already at the align:start position:0% have been were created already at the align:start position:0% have been were created already at the earliest times then with time more and align:start position:0% earliest times then with time more and align:start position:0% earliest times then with time more and more of all of them were created it's align:start position:0% more of all of them were created it's align:start position:0% more of all of them were created it's not like that the universe because it align:start position:0% not like that the universe because it align:start position:0% not like that the universe because it was just hydrogen and helium in the align:start position:0% was just hydrogen and helium in the align:start position:0% was just hydrogen and helium in the beginning then it took time to build up align:start position:0% beginning then it took time to build up align:start position:0% beginning then it took time to build up all the elements and march through the align:start position:0% all the elements and march through the align:start position:0% all the elements and march through the periodic table with time that is not the align:start position:0% periodic table with time that is not the align:start position:0% periodic table with time that is not the case align:start position:0% case align:start position:0% case everything was produced from early on align:start position:0% everything was produced from early on align:start position:0% everything was produced from early on and then just more and more and so well align:start position:0% and then just more and more and so well align:start position:0% and then just more and more and so well we have more stories and more chemical align:start position:0% we have more stories and more chemical align:start position:0% we have more stories and more chemical and enrichment but also the formation of align:start position:0% and enrichment but also the formation of align:start position:0% and enrichment but also the formation of the first bigger structures larger align:start position:0% the first bigger structures larger align:start position:0% the first bigger structures larger structures including the the Milky Way align:start position:0% structures including the the Milky Way align:start position:0% structures including the the Milky Way just going to breathe yet in like this align:start position:0% just going to breathe yet in like this align:start position:0% just going to breathe yet in like this because this all happened in in small align:start position:0% because this all happened in in small align:start position:0% because this all happened in in small gravitationally bound systems and they align:start position:0% gravitationally bound systems and they align:start position:0% gravitationally bound systems and they were then gobbled up later by slightly align:start position:0% were then gobbled up later by slightly align:start position:0% were then gobbled up later by slightly bigger neighbors and then those who may align:start position:0% bigger neighbors and then those who may align:start position:0% bigger neighbors and then those who may be gobbled up by the proton Milky Way align:start position:0% be gobbled up by the proton Milky Way align:start position:0% be gobbled up by the proton Milky Way and eventually the Milky Way formed and align:start position:0% and eventually the Milky Way formed and align:start position:0% and eventually the Milky Way formed and formed from from the remnants of all align:start position:0% formed from from the remnants of all align:start position:0% formed from from the remnants of all these little metal systems and so all of align:start position:0% these little metal systems and so all of align:start position:0% these little metal systems and so all of this here happened as time went on and align:start position:0% this here happened as time went on and align:start position:0% this here happened as time went on and until today today we have a universe align:start position:0% until today today we have a universe align:start position:0% until today today we have a universe that's full of structure and and full of align:start position:0% that's full of structure and and full of align:start position:0% that's full of structure and and full of all the elements well a whole two align:start position:0% all the elements well a whole two align:start position:0% all the elements well a whole two percent but I think we can consider this align:start position:0% percent but I think we can consider this align:start position:0% percent but I think we can consider this for at least you know if you're an align:start position:0% for at least you know if you're an align:start position:0% for at least you know if you're an astronomer and this and chemical align:start position:0% astronomer and this and chemical align:start position:0% astronomer and this and chemical evolution is is an ongoing align:start position:0% evolution is is an ongoing align:start position:0% evolution is is an ongoing so in the following we're going to look align:start position:0% so in the following we're going to look align:start position:0% so in the following we're going to look in more detail at chemical enrichment align:start position:0% in more detail at chemical enrichment align:start position:0% in more detail at chemical enrichment and chemical evolution and also stellar align:start position:0% and chemical evolution and also stellar align:start position:0% and chemical evolution and also stellar archaeology which is the way how we use align:start position:0% archaeology which is the way how we use align:start position:0% archaeology which is the way how we use old stars to trace these different early align:start position:0% old stars to trace these different early align:start position:0% old stars to trace these different early stages of chemical evolution align:start position:0% align:start position:0% you