Starspots as the origin of ultrafast drifting radio bursts from an active M dwarf
arXiv:2510.17547 · doi:10.1126/sciadv.adw6116
Abstract
Detecting coherent radio bursts from nearby M dwarfs provides opportunities for exploring their magnetic activity and interaction with orbiting exoplanets. However, it remains uncertain if the emission is related to flare-like activity similar to the Sun or magnetospheric process akin to magnetized planets. Using observations (1.0 - 1.5 GHz) taken by the Five-hundred-meter Aperture Spherical radio Telescope, we found a type of millisecond-scale radio bursts with exceptionally high frequency drift rates () from an active M dwarf, AD Leo. The ultrafast drift rates point to a source region with a notably low magnetic scale height (, as the stellar radius), a feature not expected in a commonly assumed dipole-like global field but highly possible in localized strong-field structures, i.e. starspots. Our findings suggest that a concentrated magnetic field above starspots could be responsible for some of the most intense radio bursts from M dwarfs, supporting a solar-like electron acceleration mechanism.
Published on Science Advances, the authors' version
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