Recent MHD 3D modelling of the Proxima system predicts that the interaction of the planet Proxima b with its host star, Proxima, would be proceeding in the supra-Alfvénic regime. In this case, no radio emission from the star-planet interaction should be observed. In this talk, we present multi-epoch radio observations of the Proxima Centauri system obtained with the Australia Telescope Compact Array (ATCA) and the MeerKAT radio interferometers in 2017 and 2021, at frequencies between from 1.0 to 3.0 GHz (ATCA) and 0.9 to 1.7 GHz (MeerKAT). We also present a relatively simple modelling, which indicates that Proxima b is in the sub-Alfvénic regime, and therefore can induce radio emission from the interaction with its host star. We find that the radio emission is highly circularly polarized in many epochs, with the maxima of emission happening at about twice per orbital period of Proxima b. The radio emission is consistent with being produced by the electron-cyclotron maser emission mechanism, and we suggest it is originated as a consequence of the interaction between Proxima b and its host star, Proxima. If confirmed, this result would validate the use of radio observations to detect new exoplanets. In addition, this would contradict the predictions from some 3D MHD modelling. This could in turn suggest that some of the stellar wind parameters in the region where Proxima b is located may need to be revised.

Centros de Excelencia «Severo Ochoa» y Unidades de Excelencia «María de Maeztu» 2015 – 2021: Grant PRE2020-095421 funded by MCIN/AEI/10.13039/501100011033 Ayudas para contratos predoctorales 2016 – 2021: Grant PRE2020-095421 funded by MCIN/AEI /10.13039/501100011033 and by FSE invierte en tu futuro We also acknowledge financial support through through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709)" and through grants CEX2021-001131-S and PID2020-117404GB-C21 funded by MCIN/AEI/ 10.13039/501100011033

{"references": ["Kavanagh, R et al. (2022), Monthly Notices of the Royal Astronomical Society, Volume 504, Issue 1, June 2021, Pages 1511\u20131518, https://doi.org/10.1093/mnras/stab929"]}