Planet-induced radio emission from the coronae of M dwarfs: the case of Prox Cen and AU Mic

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, in this paper we present Alfven wave-driven stellar wind models of the two active planet-hosting M dwarfs Prox Cen and AU Mic. Our models incorporate large-scale photospheric magnetic field maps reconstructed using the Zeeman-Doppler imaging method. We obtain a mass-loss rate of 0.25 (M)over dot(circle dot) for the wind of Prox Cen. For the young dwarf AU Mic, we explore two cases: a low and a high mass-loss rate. Depending on the properties of the Alfven waves that heat the corona in our wind models, we obtain mass-loss rates of 27 and 590 (M)over dot(circle dot) for AU Mic. We use our stellar wind models to assess the generation of electron cyclotron maser instability emission in both systems, through a mechanism analogous to the sub-Alfvenic Jupiter-Io interaction. For Prox Cen, we do not find any feasible scenario where the planet can induce radio emission in the star's corona, as the planet orbits too far from the star in the super-Alfvenic regime. However, in the case that AU Mic has a stellar wind mass-loss rate of 27 (M)over dot(circle dot), we find that both planets b and c in the system can induce radio emission from similar to 10 MHz to 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of similar to 10 mJy. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star.

Automated summary

The paper presents Alfven wave-driven stellar wind models of two active planet-hosting M dwarfs Prox Cen and AU Mic. Different mass-loss rates were obtained for the winds of the two stars, and the potential generation of electron cyclotron maser instability emission in both systems was assessed. The study also found the possibility of radio emission induced by planets in the system, with implications for determining upper limits on the mass-loss rate of the star.