Exoplanet Transits with Next-Generation Radio Telescopes

TL;DR

This paper explores the potential of next-generation radio telescopes, like SKA, to detect exoplanet transits via radio emissions from host stars, offering a new method to study exoplanets and stellar activity.

Contribution

It introduces the concept of detecting exoplanet transits through radio observations, specifically focusing on the capabilities of SKA to observe starspot occultations and magnetospheric effects.

Findings

SKA2-Mid can detect transits around nearby solar-like stars and cool dwarfs.

Radio transits encode information about planetary magnetospheres.

Radio observations can help distinguish stellar activity from planetary signals.

Abstract

Nearly everything we know about extrasolar planets to date comes from optical astronomy. While exoplanetary aurorae are predicted to be bright at low radio frequencies (< 1 GHz), we consider the effect of an exoplanet transit on radio emission from the host star. As radio emission from solar-like stars is concentrated in active regions, a planet occulting a starspot can cause a disproportionately deep transit which should be detectable with major radio arrays currently under development, such as the Square Kilometre Array (SKA). We calculate the radiometric sensitivity of the SKA stages and components, finding that SKA2-Mid can expect to detect transits around the very nearest solar-like stars and many cool dwarfs. The shape of this radiometric light curve will be affected by scintillation and lensing from the planet's magnetosphere and thereby encode magnetospheric parameters. Furthermore, these transits will also probe the distribution of stellar activity across a star's surface, and will help scrub out contamination from stellar activity on exoplanet transmission spectra and radial velocity spectra. This radio window on exoplanets and their host stars is therefore a valuable complement to existing optical tools.