Exoplanet Modulation of Stellar Coronal Radio Emission

TL;DR

This paper introduces a new MHD-based tool to predict how close exoplanets, especially hot Jupiters, modulate stellar coronal radio emissions, revealing potential observable signatures across a broad frequency range.

Contribution

The study develops a novel modeling tool to simulate exoplanet-induced radio flux modulations in stellar coronae, expanding the understanding of exoplanet detection via radio observations.

Findings

Modulations can exceed 100% at 10-100 MHz for hot Jupiters.

Significant modulations (2-10%) occur above 250 MHz.

Modulation sensitivity depends on planetary magnetic polarity and stellar magnetic field strength.

Abstract

The search for exoplanets in the radio bands has been focused on detecting radio emissions produced by the interaction between magnetized planets and the stellar wind (auroral emission). Here we introduce a new tool, which is part of our MHD stellar corona model, to predict the ambient coronal radio emission and its modulations induced by a close planet. For simplicity, the present work assumes that the exoplanet is stationary in the frame rotating with the stellar rotation. We explore the radio flux modulations using a limited parameter space of idealized cases by changing the magnitude of the planetary field, its polarity, the planetary orbital separation, and the strength of the stellar field. We find that the modulations induced by the planet could be significant and observable in the case of hot Jupiter planets --- above 100% modulation with respect to the ambient flux in the $10-100~MHz$ range in some cases, and 2-10% in the frequency bands above $250~MHz$ for some cases. Thus, our work indicates that radio signature of exoplanets might not be limited to low-frequency radio range. We find that the intensity modulations are sensitive to the planetary magnetic field polarity for short-orbit planets, and to the stellar magnetic field strength for all cases. The new radio tool, when applied to real systems, could provide predictions for the frequency range at which the modulations can be observed by current facilities.