1. The problem statement, all variables and given/known data Find the reaction rate of a star purely of Hydrogen at temperature of 15MK, density of 150gm/cm^3, most of the reactions take place at R0=0.25R. Each reaction released energy of 25MeV 2. Relevant equations This is the part I'm lacking. I've got the number of protons in the sun calculated by; VolSun = (4/3)*pi*(0.25R)^3 Divided that by molar mass of Hydrogen (1) and left with number of moles of Hydrogen, thus Proton in the sun at its core. 3. The attempt at a solution So from there, I went to ORNL and got the reaction rate data for H1(P,E+NU)H2 reaction at 15MK which is about RDensity = 50*10^-20 (cm^3*moles^-1*s^-1) Now, I need to find <σv> which is the reaction rate. I tried using <σv> = RDensity * NH(Number of moles of Hydrogen) / Volume Which cancels out all the units and leaves me with s^-1 But when I take that number, multiply by 1.6*10^-19 to account going from MeV to Joules and calculate the power and thus, flux, it comes out to be a very small number which makes me feel like I'm missing something big here.