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The core of the Sun is radiative. That means that energy is transported outwards primarily by photons and is stable to convection. This means, to first-order, that the centre of the Sun is not mixed up by convection. As the hydrogen in the core is burned, it forms helium, which has a larger atomic mass. The helium sinks towards the middle and the core fills ...


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In about four billion years the sun will have used up most of the hydrogen in its core and fuse helium into heavier elements. The fusion of helium releases more energy than the fusion of hydrogen. This will cause the sun to expand to, at least, the orbit of Venus and likely the Earth. Both planets will, of course, be vaporized.There was a similar question ...


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His name was Robert Bussard. This is what you probably saw: https://www.youtube.com/watch?v=rk6z1vP4Eo8 He passed away a few years ago. EMC2 was carrying on the work but it looks like they stalled in 2014. Lookup www.emc2fusion.org Fun Fact: Those red tips on the end of warp nacelles in Star Trek are called "Bussard Collectors" from a paper Robert Bussard ...


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By "consume" we mean "convert into helium." That $6\times10^{11}\ \mathrm{kg}$ of hydrogen is part of the Sun (specifically it is found in the core of the Sun), and it is converted into $6\times10^{11}\ \mathrm{kg}$ of helium. The Sun doesn't need to suck up material from space. Note that this amount of material is miniscule compared to the $2\times10^{30}\ ...


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To make fusion occur, large amount of activation energy is required. Once running, it will keep going. The reason why the surface of a star of a large mass is a suitable place for fusion to occur is its large gravitational force on small atoms like hydrogen. This strong gravitational force makes for a strong pressure on the gas, and according to the ideal ...


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The Coulomb barrier for protons is on the order of $10^6$ eV. Treating the Sun's core as a gas at 15.7 million kelvins, the mean kinetic energy of the protons is $2\times10^3$ eV. A quick partition function estimate of the probability of protons having enough kinetic energy to overcome the Coulomb barrier yields a probability of $10^{-257}$. Considering the ...


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Think of 2 hydrogen atoms or, protons more accurately since at those temperature the atoms don't have electrons, it's more of a soup. So, 2 protons, both positively charged so they repel each other, crash into each other pretty rarely, cause it's still a lot of empty space, but they do make contact every so often. The energy required to get 2 protons or ...


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Its just a consequence of what concentrates the fuel/contents of a star together in the first place, I think? Stars usually form by the collapse of gas clouds onto themselves. These collapses generate high temperature and density and are ideal places for nuclei to 'bump' into each other and also, the high amount of energy nuclei can possess in such a ...


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Heavy elements couldn't form right after the Big Bang because there aren't any stable nuclei with 5 or 8 nucleons. Source: Wikipedia (user Pamputt) In the Big Bang nucleosynthesis, the main product was $^4He$, because it is the most stable light isotope: 20 minutes after the Big Bang, helium-4 represented about 25% of the mass of the Universe, and the ...


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In the case of a supernova explosion it is possible to create heavy elements through fusion. Supernovae have a tremendous amount of energy in a very small volume but not as much energy per volume as there was in our early universe. So, what is the major difference? Why didn't the Big Bang create heavy elements? I just want to point out, too much ...


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This question is answered in detail by the so-called "Big Bang Nucleosynthesis", the theory about the creation of the nuclei in the early Universe. Almost out of nothing, it allows one to determine that 75% of the nuclear mass was coming in hydrogen, 25% in helium, and some small traces of lithium appeared, too. Even though Gamow used to think that all ...


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The lithium test has an ambiguity because it also depends on the age of the objects. Li is depleted once the cores of fully convective objects reach temperatures of about $3\times 10^{6}$ K. The time at which this occurs depends on the contraction timescale of newly formed objects. This timescale is longer for lower mass objects. Thus we can say that ...


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Lithium and other light elements (e.g. beryllium) can be formed indirectly from supernovae via cosmic ray spallation, a process where protons and neutrons are ejected when a cosmic ray collides with another atom. The nucleons can then form new elements. Nakamura & Shigeyama (2004) were able to calculate yields for 6Li, 7Li, and isotopes of Beryllium and ...



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