Type I X-ray bursts are thermonuclear explosions on the surface of accreting neutron stars .
Hydrogen rich X-ray bursts burn protons far from the line of stability and can release energy in the form of neutrinos from \beta -decays .
We have estimated , for the first time , the neutrino fluxes of Type I bursts for a range of initial conditions based on the predictions of a 1D implicit hydrodynamics code , Kepler , which calculates the complete nuclear reaction network .
We find that neutrino losses are between 6.7 { \times 10 ^ { -5 } } and 0.14 of the total energy per nucleon , Q _ { \mathrm { nuc } } , depending upon the hydrogen fraction in the fuel .
These values are significantly below the 35 \% value for neutrino losses often adopted in recent literature for the rp -process .
The discrepancy arises because it is only at \beta -decays that \approx 35 \% of energy is lost due to neutrino emission , whereas there are no neutrino losses in ( p, \gamma ) and ( \alpha,p ) reactions .
Using the total measured burst energies from Kepler for a range of initial conditions , we have determined an approximation formula for the total energy per nucleon released during an X-ray burst , { Q _ { \mathrm { nuc } } } = ( 1.31 + 6.95 { \mkern 1.5 mu \overline { \mkern - 1.5 muX \mkern - 1.5 % mu } \mkern 1.5 mu } -1.92 { \mkern 1.5 mu \overline { \mkern - 1.5 muX \mkern - 1.5 mu } \mkern 1 % .5 mu } ^ { 2 } ) { \mathrm { MeV } \mathrm { nucleon } ^ { -1 } } , where { \mkern 1.5 mu \overline { \mkern - 1.5 muX \mkern - 1.5 mu } \mkern 1.5 mu } is the average hydrogen mass fraction of the ignition column , with an RMS error of 0.052 { \mathrm { MeV } \mathrm { nucleon } ^ { -1 } } .
We provide a detailed analysis of the nuclear energy output of a burst and find an incomplete extraction of mass excess in the burst fuel , with 14 \% of the mass excess in the fuel not being extracted .