Star Stuff
Star Stuff
They keep saying that we're star stuff, but what exactly does that mean?
Stars are the progenitors of everything matter.
The reason this is true is because all of the elements that make us up are created in stars. Therefore, every atom in our bodies came from stars. How does this happen?
The early universe consisted of hydrogen, the simplest element that has one proton and one electron. If it had stayed that way, we would have had to be gas people. However, This situation was good enough for the hydrogen to form into large stars, much larger than our Sun. The giant blue stars that formed out of the primordial hydrogen burned hot (a million times as luminous as our sun) and fast and went supernova within a million years, maybe even sooner. All of the elements were created in these giant stars by a process known as nucleosynthesis either directly in their cores or when they went supernova. As a matter of fact, it takes extreme temperatures to form the higher elements by fusion, the kind of temperatures created by the higher pressures in these early giant stars. We're talking hundreds of millions of degrees.
As I've indicated in a recent essay, our sun fuses hydrogen into helium as its main core energy producing process. After a star like our sun runs out of hydrogen it begins to fuse helium into lithium and beryllium, which causes the core to produce more heat. This, in turn, expands the outer layers of the star into a red giant. When a main sequence dwarf star like our sun reaches this stage and begins to burn carbon, it blows off its outer layers and becomes a white dwarf.
In giant stars larger than 8 times the mass of our sun, further nucleosynthesis creates nitrogen, oxygen, carbon, neon, silicon, calcium, argon, titanium, chromium, zinc and magnesium. Each new nuclear synthesis requires a higher temperature. These huge stars form layers upon layer of elemental fusion reactions in their cores. These layers are like onionskins in which the lowest layer is always the hottest and as such is fusing higher atomic weight elements.
However, when a massive star begins to form an iron core, that's when trouble begins because it sucks too much energy away and all fusion ceases. When the iron core becomes larger in mass than the Chandrasekhar limit, the core collapses very quickly, causing a huge explosion known as a supernova. The very high temperatures that exist in a supernova for a brief period of time are what cause the nucleosynthesis of the heavier elements like gold, platinum and higher nucleotides, which is why these elements are rare. They only form in a supernovae explosion.
Not all elements are produced by fusion reactions or the aftermath of these reactions. Some elements, such as lithium, beryllium and boron are produced by gamma ray spallation in which protons and alpha particles smash into heavier elements. But since these gamma rays come from supernovae it's still the action of stars that form these elements.
Oh, and it's thought that a supernova may have made it possible for us to exist. Our star formed from a hydrogen and helium cloud, but the cloud was devoid of the heavier elements that were needed for life. It turns out that a nearby supernova of a large star blasted the elements into the sun's gas cloud, providing the elements needed to form planets and life. Evidence for this is found in meteorites. Older meteorites (4 billion years old) have inclusions that don't have these heavier elements. Inclusions are the earliest part of the meteorite. The rest of the meteorite does have the heavier elements such as carbon, phosphorus, sulfur and other elements needed for life.
The thing to take away from this is that all elements that make up Earth and us are created by fusion reactions in stars or in star supernovae. Thus, the reason we are made from star stuff. If you delve into the complicated nuclear chemistry and quantum effects that make all of this possible, I think you would come to the conclusion that none of this is purely accidental. It's much too complicated. How is it an accident that these nuclear reactions in stars just happened to be the correct steps to create life? Think about it!
Thanks for reading.
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