Upper limit of stellar masses is not predictively determined

Establish an unambiguous theoretical prediction for the upper limit of stellar masses within models of stellar formation and structure, resolving the current ambiguity in these theories.

Background

The paper opens by noting that theoretical models of stellar formation and structure do not yield a clear, agreed-upon upper bound on stellar masses. This uncertainty complicates interpretation of observations and comparisons across studies, as illustrated by widely varying mass estimates for extremely massive stars in clusters such as RMC 136.

The authors frame their analysis of the massive binary WR 20a against this broader context, where determining extreme stellar masses remains theoretically unsettled, and emphasize the importance of robust mass determinations from eclipsing binaries.