Exploring How Fossil Magnetic Fields Can Influence Massive Star Evolution*

There is an ever-mysterious subpopulation (10%) of massive stars in our galaxy that hosts strong, large-scale, surface magnetic fields. Due to the presence of these magnetic fields, the stars' structures and evolution can be significantly impacted. Though massive stars do not possess convective envelopes, they can host shallow convection-zones just beneath the stellar surface. One of the more recently studied effects is the interaction between the magnetic fields and these subsurface convection zones. Under the assumption that the fields are fossil in origin, there is a proposed magnetic threshold (critical field) above which strong magnetic fields could suppress convection. Fields that fall below this threshold are hypothesized to be destroyed and reprocessed into much weaker ones. With surviving fields, the other established magnetic effects are allowed to proceed in their typical fashion. Interestingly, the critical field varies with mass and the star's evolution. Thus, we are interested in this effect acting alongside the field's ability to effectively reduce the star's mass-loss rate (mass-loss quenching) and the field's loss in strength (via magnetic-flux conservation) as the star evolves. Using the 1D stellar evolution code MESA, we study 40 solar mass models evolving with the magnetic effects acting simultaneously. Our goal is to examine the interplay between these three effects and study their collective impact on the host star's evolution.