Fast radio bursts may originate from nearby flaring stars

Six cases of fast radio bursts (FRBs) have recently been discovered. The FRBs are bright (~0.1-1 Jy) and brief (~1ms) pulses of radio emission with dispersion measures (DMs) that exceed Galactic values, and hence FRBs have been interpreted to be at cosmological distances. We propose, instead, that FRBs are rare eruptions of flaring main-sequence stars within ~1 kpc. Rather than associating their excess DM with the intergalactic medium, we relate it to a blanket of coronal plasma around their host star. We have monitored at optical bands the stars within the radio beams of three of the known FRBs. In one field, we find a bright (V = 13.6 mag) variable star (0.2 mag peak to trough) with a main-sequence G-type spectrum and a period P = 7.8 h, likely a W-UMa-type contact binary. Analysis of our data outside of the FRB beams indicates a 5 per cent probability of finding, at random, a variable star of this brightness and amplitude within the FRB beams, but this could still be a chance coincidence. We find no unusual variable stars in the other two FRB fields. Further observations are needed to investigate if similar nearby (≲800 pc) stars are the sources of FRBs.