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(3 pts) Assume that the entire solar luminosity, Lo, is due to the fusion of hyd

ID: 3308422 • Letter: #

Question

(3 pts) Assume that the entire solar luminosity, Lo, is due to the fusion of hydrogen via the p-p chain as illustrated in Figure 4.3 in the textbook (Prialnik). The expected flux of neutrinos from the reactions in branch I of the p-p chain is then almost fixed if the relative importance of branch I and branch II is known. a. Imagine instead that we don't know the relative importance of branch I and branch II. You may assume branch III's contribution is negligible. Using the average neutrino energies for branches I and II found in Table 9.3 in the textbook, determine the relative percentage contribution of branches I and II to Lo if we assume a hypothetical total flux of solar neutrinos of Rv = 1.85 × 1038 neutrinos per second. b. In the hypothetical case in part a, find the neutrino luminosity expressed as a percentage of Lo-

Explanation / Answer

(a)...Proton/proton fusion into deuterium accounts for 40% of the reaction releasing 1.44 MeV of energy which is 10.4 of sun's total energy cause luminosity.

Deuterium/proton fusion into helium 3 accounts for 40% of the reaction releasing 5.49 MeV which is 39.5% Sun's total energy.

Helium 3/ helium 3 fusion into helium 4 accounts for 17% reaction releasing 12.86% MeV which is 39.3% of sun's total energy.

He3/he4 fusion into 2 helium 4S accounts for 3% of reaction releasing 19.99 MeV which is 10.8% of sun's total energy.

As lithium and beryllium delays much faster the entire luminosity is due to I and II branches only. That is 99.99%.