Abstract

Contributed Talk - Splinter Solar

Tuesday, 10 September 2024, 15:00   (S15)

Simulations of spots on cool main-sequence stars

Tanayveer Bhatia, M. Panja, R. Cameron, S. Solanki, D. Przybylski
Max Planck Institute for Solar System Research

Sunspots and starspots are some of the most visible signatures of magnetism on the sun and other stars, respectively. On the observational side, starspots play an outsized role in stellar variability and complicate the detection and characterization of exoplanets. On the theoretical side, they offer us a glimpse into the working of solar and stellar dynamos. Realistic 3D radiative MHD models of sunspots have been created and studied recently (Rempel+ 2012) as well as first models of stellar spots in a slab-like geometry (Panja+ 2020). We build on this previous work and present simulations of starspots with substantial penumbrae on cool main-sequence stars using the MURaM simulation code. The umbra, penumbra and the quiet star for all starspots are distinct, not only in intensity and temperature, but also in thermodynamic and velocity structure, calling into question the usual assumption of 2-component radiative equilibrium models generally used to model starspots in stellar lightcurves. We study the azimuthally averaged thermodynamic structure as a distance from spot axis. Finally, we discuss scaling of contrasts (increasing with $T_{ m eff}$), velocities and field strengths for the modelled starspots and implications for stellar spectra.