Massive star evolution is dominated by key physical processes such as mass loss , convection and rotation , yet these effects are poorly constrained , even on the main sequence .
We utilise a detached , eclipsing binary HD166734 as a testbed for single star evolution to calibrate new MESA stellar evolution grids .
We introduce a novel method of comparing theoretical models with observations in the ’ Mass-Luminosity Plane ’ , as an equivalent to the HRD ( see Higgins & Vink , 2018 ) .
We reproduce stellar parameters and abundances of HD166734 with enhanced overshooting ( \alpha _ { ov } = 0.5 ) , mass loss and rotational mixing .
When comparing the constraints of our testbed to the systematic grid of models we find that a higher value of \alpha _ { ov } = 0.5 ( rather than \alpha _ { ov } = 0.1 ) results in a solution which is more likely to evolve to a neutron star than a black hole , due to a lower value of the compactness parameter .