  The coherent low-frequency radio emission detected by LOFAR from Gliese 1151,
a quiescent M4.5 dwarf star, has radio emission properties consistent with
theoretical expectations of star-planet interactions for an Earth-sized planet
on a 1-5 day orbit. New near-infrared radial velocities from the Habitable-zone
Planet Finder (HPF) spectrometer on the 10m Hobby-Eberly Telescope at McDonald
Observatory, combined with previous velocities from HARPS-N, reveal a periodic
Doppler signature consistent with an $m\sin i = 2.5 \pm 0.5 M_\oplus$ exoplanet
on a 2.02-day orbit. Precise photometry from the Transiting Exoplanet Survey
Satellite (TESS) shows no flares or activity signature, consistent with a
quiescent M dwarf. While no planetary transit is detected in the TESS data, a
weak photometric modulation is detectable in the photometry at a $\sim2$ day
period. This independent detection of a candidate planet signal with the
Doppler radial-velocity technique adds further weight to the claim of the first
detection of star-exoplanet interactions at radio wavelengths, and helps
validate this emerging technique for the detection of exoplanets.
