A star initially has `10^40` deuterons. It produces energy via the processes `_1^2H+_1^2Hrarr_1^3H+p` and `_1^2H+_1^3Hrarr_2^4He+n`. Where the masses of the nuclei are
`m(`^2H)=2.014` amu, `m(p)=1.007` amu, `m(n)=1.008` amu and `m(`^4He)=4.001` amu. If the average power radiated by the star is `10^16 W`, the deuteron supply of the star is exhausted in a time of the order of