On Variations Of Pre-Supernova Model Properties
  We explore the variation in single star 15-30 $\rm{M}_{\odot}$, non-rotating, solar metallicity, pre-supernova MESA models due to changes in the number of isotopes in a fully-coupled nuclear reaction network and adjustments in the mass resolution. Within this two-dimensional plane we quantitatively detail the range of core masses at various stages of evolution, mass locations of the main nuclear burning shells, electron fraction profiles, mass fraction profiles, burning lifetimes, stellar lifetimes, and compactness parameter at core-collapse for models with and without mass loss. Up to carbon burning we generally find mass resolution has a larger impact on the variations than the number of isotopes, while the number of isotopes plays a more significant role in determining the span of the variations for neon, oxygen and silicon burning. Choice of mass resolution dominates the variations in the structure of the intermediate convection zone and secondary convection zone during core and shell hydrogen burning respectively, where we find a minimum mass resolution of $\approx$ 0.01 $\rm{M}_{\odot}$ is necessary to achieve convergence in the helium core mass at the $\approx$5% level. On the other hand, at the onset of core-collapse we find $\approx$30% variations in the central electron fraction and mass locations of the main nuclear burning shells, a minimum of $\approx$127 isotopes is needed to attain convergence of these values at the $\approx$10% level. 
R. Farmer, C.E. Fields, I. Petermann, Luc Dessart, M. Cantiello, B.   Paxton, F.X. Timmes
astro-ph.SR