Radio stars and exoplanets: Discovering the space weather of other worlds

A fundamental goal of astronomy in the coming decades is to determine whether a planet around another star could be habitable. An important piece in this habitability puzzle is the environmental conditions of an exoplanet: the 'space weather' it experiences. However, determining the space weather conditions around a star has been challenging because of the limited sensitivity of low-frequency radio telescopes. A low-frequency radio detection of a star or exoplanet can provide evidence of plasma ejection from the star, or a direct measurement of an exoplanet's magnetic field strength. Such information determines if a planet's atmosphere can survive the onslaught of stellar activity. Recently, I achieved the first low-frequency detections of quiescent stars via a novel polarisation technique using the telescope LOFAR. The radio emission is likely generated by star-planet interactions -- representing a new way to discover exoplanets and characterise their space weather environment. These first detections represent the tip of the iceberg in terms of other detectable stellar systems as I expand my observations over the northern sky. I am on the precipice of conducting the first ever population analysis of the types of stars that emit at low frequencies, revealing whether they are orbited by exoplanets, and what environmental conditions such planets experience.This grant will allow me to scale my new low-frequency calibration and polarimetric techniques to determine the space weather of stars and exoplanets via: 1) determining the radio periodicity from star-exoplanet interactions; 2) directly detecting radio emission from an exoplanet; and 3) tracing the kinematics of ejected stellar plasma.Such information will facilitate a leap in our understanding of the plasma environments around stars and the underlying laws governing the generation of planetary magnetic fields -- information that will guide us in the coming revolution in exoplanet habitability.