Planet-induced radio emission from the coronae of M dwarfs

TL;DR

This study models star-planet interactions in the M dwarf AU Mic, predicting radio emissions caused by planets that could help determine stellar mass-loss rates, based on recent detections and magnetic field reconstructions.

Contribution

It introduces detailed stellar wind models incorporating magnetic field data to predict planet-induced radio emissions in AU Mic's corona, a novel approach for this star system.

Findings

Planets b and c can induce radio emission from 10 MHz to 3 GHz.

Predicted peak flux densities reach up to 10 mJy.

Radio emission detection can constrain the star's mass-loss rate.

Abstract

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, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfv\'enic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of 27 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz to 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star.