M. Kretzschmar, Antonio Vecchio, V. Krasnoselskikh, M. Maksimović, J. Souček, David Píša, L. Claire Gasque, S. D. Bale, Thierry Dudok de Wit, M. Pulupa, Y. V. Khotyaintsev, T. Chust, G. Jannet, J.‐Y. Brochot, C. Revillet, Patrice Fergeau, X. Bonnin, K. Goetz
Abstract Solar radio bursts, and astrophysical radio emissions in general, are observed either in space or on the ground by measuring their fluctuating electric field. Here, we report the first measurement of the magnetic component of a solar radio wave, observed simultaneously by the Solar Orbiter and Parker Solar Probe missions. The observations were made during the type III radio burst on 2021 October 28. The analysis of the wave polarization and magnetic and electric field amplitudes allows us to estimate the refractive index and put constraints on the direction of the wave. The wave is found to be consistent with an ordinary-mode wave and with a source near the southeast limb of the Sun. These results pave the way for future observations and analyses of the magnetic field of radio waves, in particular, for solar radio bursts.