A predictive framework for realistic star-planet radio emission in compact systems

Context . Radio emission from star-planet interactions (SPIs) beyond our Solar System has yet to be firmly detected, primarily due to weak signals, directional beaming effects, and low-frequency emissions blocked by Earth’s ionosphere. Addressing these obstacles calls for strategic target selection. Aims . This proof-of-concept study aims to improve SPI target prioritization by simulating SPI-induced radio emission frequencies and estimating associated radio power to identify systems that are most likely to produce detectable signals. Methods . We combined Zeeman–Doppler Imaging (ZDI) maps with 3D magnetohydrodynamic (MHD) stellar wind simulations and used the ExPRES code to model SPI-driven radio emissions. We also estimated the intensity of these emissions using the radio-magnetic scaling law, based on the magnetic field and plasma density parameters from the 3D wind models. We applied this approach to systems such as Tau Boo, HD 179949, and HD 189733 to assess their detectability with current and future radio telescopes. Conclusion . This framework, tested on benchmark systems, is applicable to any star-planet system with available ZDI maps and wind models. As magnetic field reconstructions and wind simulations improve, the method will become more robust. It provides a data-driven approach to prioritize targets and optimize telescope scheduling. This approach will enable systematic exploration of magnetic SPI radio emissions across a wide range of exoplanetary systems.