# Calculate the neutrino flux from the sun

warfreak131

## Homework Statement

Every reaction in the sun has the energy equivalent to 0.03 mp, and generates 2 neutrinos per reaction. Calculate the number of neutrinos per second, and calculate the neutrino flux at Earth.

Astronomy generally uses the CGS (centimeter gram second) system, so just be aware of that when I do my calculations.

## The Attempt at a Solution

nreactions * Ereaction = Luminositysun

nreactions * mc2 = Luminositysun

nreactions * (.03 * mp)(3*1010)2 = Luminositysun

nreactions * (.03 * 1.67*10-24)(3*1010)2 = Luminositysun

nreactions * (.03 * 1.67*10-24)(3*1010)2 = 3.9*1033

nreactions * 4.51*10-5 erg = 3.9*1033 erg s-1

nreactions = 3.9*1033 erg s-1 / 4.51*10-5 erg

nreactions = 8.67*1037 reactions/s

nreactions / s * 2 neutrinos / reaction = 1.73*1038 neutrinos

Nneutrinos / Area = Fneutrino

Area = 4*pi*R2 [R = 1 AU = 1.5*1013cm]

Area = 2.83*1027cm2

So divide Nneutrinos and Area, and I get 6.1*1010 neutrinos/cm2

I looked online, and found answers which were also approx 6, but were a different order of magnitude. Did I do anything wrong?

## Answers and Replies

Homework Helper
Your answer's right. Where did you find the values online?

warfreak131

Homework Helper
That link gives 6.296541*10^14 /(m^2*s). Your answer is in /(cm^2*s).

warfreak131
That link gives 6.296541*10^14 /(m^2*s). Your answer is in /(cm^2*s).

right right, right you are, thanks