Nonlinear Alfvén Wave Model of Stellar Coronae and Winds from the Sun to M Dwarfs

Abstract

An M dwarf’s atmosphere and wind are expected to be highly magnetized. The nonlinear propagation of Alfvén waves could play a key role in both heating the stellar atmosphere and driving the stellar wind. Using this Alfvén wave scenario, we carried out a one-dimensional compressive magnetohydrodynamic simulation to examine the nonlinear propagation of Alfvén waves from the M dwarf’s photosphere, chromosphere to the corona, and interplanetary space. Based on the simulation results, we developed a semi-empirical method describing the solar and M dwarf’s coronal temperature, stellar wind velocity, and wind’s mass-loss rate. We find that M dwarfs’ coronae tend to be cooler than the solar corona, and that M dwarfs’ stellar winds can be characterized as having a faster velocity and much smaller mass-loss rate compared to those of the solar wind.