Turbulence and magnetic spots at the surface of hot massive stars

TL;DR

This paper uses 3D MHD simulations to investigate how subsurface iron convection zones in hot massive stars can lead to surface turbulence and magnetic spots, explaining observed stellar phenomena.

Contribution

It demonstrates that subsurface convection can produce surface turbulence and magnetic spots, providing a physical explanation for observed phenomena in hot massive stars.

Findings

Subsurface iron convection zones induce surface turbulence.

Localized magnetic spots are likely caused by subsurface convection.

Simulations support the link between convection and observed stellar phenomena.

Abstract

Hot luminous stars show a variety of phenomena in their photospheres and in their winds which still lack clear physical explanations at this time. Among these phenomena are non-thermal line broadening, line profile variability (LPVs), discrete absorption components (DACs), wind clumping and stochastically excited pulsations. Cantiello et al. (2009) argued that a convection zone close to the surface of hot, massive stars, could be responsible for some of these phenomena. This convective zone is caused by a peak in the opacity due to iron recombination and for this reason is referred as the "iron convection zone" (FeCZ). 3D MHD simulations are used to explore the possible effects of such subsurface convection on the surface properties of hot, massive stars. We argue that turbulence and localized magnetic spots at the surface are the likely consequence of subsurface convection in early type stars.