Radio Signatures of Star-Planet Interactions, Exoplanets, and Space Weather

TL;DR

This paper reviews recent advances in radio observations of stellar systems, highlighting how radio signatures reveal stellar activity, star-planet interactions, and exoplanet magnetospheres, with implications for understanding space weather and exoplanet environments.

Contribution

It synthesizes recent observational progress, discusses the physics of radio emissions from stars and exoplanets, and outlines future prospects and outstanding questions in the field.

Findings

Detection of auroral emissions from low-mass stars and exoplanets.

Potential to detect and characterize exoplanetary magnetospheres.

Provisional evidence of star-planet magnetic interactions.

Abstract

Radio detections of stellar systems provide a window onto stellar magnetic activity and the space weather conditions of extrasolar planets, information that is difficult to attain at other wavelengths. There have been recent advances observing auroral emissions from radio-bright low-mass stars and exoplanets largely due to the maturation of low-frequency radio instruments and the plethora of wide-field radio surveys. To guide us in placing these recent results in context, we introduce the foremost local analogues for the field: Solar bursts and the aurorae found on Jupiter. We detail how radio bursts associated with stellar flares are foundational to the study of stellar coronae, and time-resolved radio dynamic spectra offers one of the best prospects of detecting and characterising coronal mass ejections from other stars. We highlight the prospects of directly detecting coherent radio emission from exoplanetary magnetospheres, and early tentative results. We bridge this discussion to the field of brown dwarf radio emission, in which their larger and stronger magnetospheres are amenable to detailed study with current instruments. Bright, coherent radio emission is also predicted from magnetic interactions between stars and close-in planets. We discuss the underlying physics of these interactions and implications of recent provisional detections for exoplanet characterisation. We conclude with an overview of outstanding questions in theory of stellar, star-planet interaction, and exoplanet radio emission, and the prospects of future facilities in answering them.