2017ApJ...844..139S

X-ray burst model predictions of light curves and the final composition of the nuclear ashes are affected by uncertain nuclear masses. However, not all of these masses are determined experimentally with sufficient accuracy. Here we identify the remaining nuclear mass uncertainties in X-ray burst models using a one-zone model that takes into account the changes in temperature and density evolution caused by changes in the nuclear physics. Two types of bursts are investigated-a typical mixed H/He burst with a limited rapid proton capture process (rp-process) and an extreme mixed H/He burst with an extended rp-process. When allowing for a 3σ variation, only three remaining nuclear mass uncertainties affect the light-curve predictions of a typical H/He burst (²⁷P, ⁶¹Ga, and ⁶⁵As), and only three additional masses affect the composition strongly (⁸⁰Zr, ⁸¹Zr, and ⁸²Nb). A larger number of mass uncertainties remain to be addressed for the extreme H/He burst, with the most important being ⁵⁸Zn, ⁶¹Ga, ⁶²Ge, ⁶⁵As, ⁶⁶Se, ⁷⁸Y, ⁷⁹Y, ⁷⁹Zr, ⁸⁰Zr, ⁸¹Zr, ⁸²Zr, ⁸²Nb, ⁸³Nb, ⁸⁶Tc, ⁹¹Rh, ⁹⁵Ag, ⁹⁸Cd, ⁹⁹In, ¹⁰⁰In, and ¹⁰¹In. The smallest mass uncertainty that still impacts composition significantly when varied by 3σ is ⁸⁵Mo with 16 keV uncertainty. For one of the identified masses, ²⁷P, we use the isobaric mass multiplet equation to improve the mass uncertainty, obtaining an atomic mass excess of -716(7) keV. The results provide a roadmap for future experiments at advanced rare isotope beam facilities, where all the identified nuclides are expected to be within reach for precision mass measurements.