Detection of Radio Emission from Superflaring Solar-type Stars in the VLA Sky Survey

Solar-type stars have been observed to flare at optical wavelengths with energies much higher than is observed for the Sun. To date, no counterparts have been observed at longer wavelengths. We searched the Very Large Array Sky Survey (VLASS) for radio emission associated with a sample of 150 solar-type stars that exhibit superflares in the Transiting Exoplanet Survey Satellite (TESS) data. Counterparts to six of these stars were present in VLASS as transient or highly variable radio sources. One star is detected in all three VLASS epochs, exhibiting an extreme level of apparently persistent radio emission. The engine for this radio emission is unclear, but may be related to accretion, a binary companion, or the presence of large-scale magnetic fields. Two stars show radio emission with a >50% circular polarization fraction, which likely indicates a coherent emission process. Overall, the VLASS-detected stars likely predominantly emit nonthermal, incoherent emission and tend to have higher flare rates and energies than the rest of our TESS sample. This, in addition to the VLASS-detected stars adhering to the Güdel–Benz relation, suggests that the radio emission may be associated with superflares and that the superflare phenomenon on solar-type stars extends to radio wavelengths, tracing particle acceleration. These data provide the first window into the luminosity function of radio superflares for solar-type stars and highlight the need for coordinated, multiwavelength monitoring of such stars to fully illustrate the stellar flare–particle acceleration relation.