Monitoring the radio emission of Proxima Centauri

Abstract

We present results from the most comprehensive radio monitoring campaign towards the closest star to our Sun, Proxima Centauri. We report 1.1 to 3.1 GHz observations with the Australian Telescope Compact Array over 18 consecutive days in April 2017. We detect radio emission from Proxima Centauri for most of the observing sessions, which spanned $\sim$1.6 orbital periods of the planet Proxima b. The radio emission is stronger at the low-frequency band, centered around 1.6 GHz, and is consistent with the expected electron-cyclotron frequency for the known star's magnetic field intensity of about 600 Gauss. The 1.6 GHz light curve shows an emission pattern that is consistent with the orbital period of the planet Proxima b around the star Proxima, with its maxima of emission happening near the quadratures. We also observed two short-duration (a few minutes) flares and a long-duration (about three days) burst whose peaks happened close to the quadratures. We find that the frequency, large degree of circular polarization, change of the sign of circular polarization, and intensity of the observed radio emission are all consistent with expectations from electron cyclotron-maser emission arising from sub-Alfvénic star-planet interaction. We interpret our radio observations as signatures of interaction between the planet Proxima b and its host star Proxima. We advocate for monitoring other dwarf stars with planets to eventually reveal periodic radio emission due to star-planet interaction, thus opening a new avenue for exoplanet hunting and the study of a new field of exoplanet-star plasma interaction.

14 pages, 11 figures. Accepted on December 2, 2020 in A&A (main journal), several typos corrected

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Cited by in corpus (11)

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• Coherent radio bursts from known M-dwarf planet host YZ Ceti
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• The CARMENES search for exoplanets around M dwarfs: Stable radial-velocity variations at the rotation period of AD~Leonis -- A test case study of current limitations to treating stellar activity
• The CARMENES search for exoplanets around M dwarfs, Wolf 1069 b: Earth-mass planet in the habitable zone of a nearby, very low-mass star
• The CARMENES search for exoplanets around M dwarfs. A long-period planet around GJ 1151 measured with CARMENES and HARPS-N data
• The CARMENES search for exoplanets around M dwarfs. Two terrestrial planets orbiting G 264-012 and one terrestrial planet orbiting Gl 393
• MHD study of extreme space weather conditions for exoplanets with Earth-like magnetospheres: On habitability conditions and radio-emission
• Testing a scaling relation between coherent radio emission and physical parameters of hot magnetic stars
• The Mouse that Squeaked: A small flare from Proxima Cen observed in the millimeter, optical, and soft X-ray with Chandra and ALMA
• Star-Planet Interaction: Wave Structures and Wing-Wing Interaction