Mod-01 Lec-41 Nucleosynthesis of elements in Stars

Previous lecture, we talked about what is going on inside the core of the sun, how nuclear fusion is taking place, and how hydrogen is being converted into helium. So, we saw that the temperatures are about 1.4 into 10 to the power 7 K and so at these temperatures in the core, and the density is also very high, density of that hydrogen

core around 160 grams per centimeter cube. And corresponding pressure and which that the reactions p p I, then p p II, p p III main reactions, and the result of all this is that 4 hydrogen nuclei get converted into 4 helium nucleus, and you have 2 positrons and these nucleons formed and plus energy of course.

Same is the case with C N O cycle same final result, this happens around say 2 percent of the time, and this happens about 98 percent of the times and of this is 85 percent, this is almost 15 percent and this is 0.1 percent. The neutrino is which come out of these reactions,

these neutrinos have different energies in different cycles p p I, p p II, p p III C N O etcetera. And these neutrinos in fact, give us and almost live update of what is going on inside the core of the sun, with an 8 minutes of delay. Because, the photons that are created or energy that is created in fusion, that takes long

long time to come to the surface, and get emitted to the earth and other surrounding space. But, neutrinos which are produced in these fusion reactions, they almost without interacting with the material, they come out with almost the same speed as the speed of light. And therefore, by studying these neutrinos, we know the details of these fusion reactions.

Now, today's topic is making of newer elements inside these stars, here helium is being made from hydrogen, so one element is getting converted into another element. And in the sun itself if we see apart from this hydrogen and helium, we have a varieties of other elements, some 64 other elements have been detected. And if we look for the whole universe, in the