An Earth-sized Planet around an M5 Dwarf Star at 22 pc

We report on the discovery of an Earth-sized transiting planet ($R_p=1.015\pm0.051\,R_\oplus$) in a $P=4.02$ day orbit around K2-415 (EPIC 211414619), M5V star at 22 pc. The candidate was first identified by analyzing light curve data K2 mission, and is here shown to exist most recent from TESS. Combining curves with secured our follow-up observations including high-resolution imaging near infrared spectroscopy IRD, we rule out false positive scenarios, finding low probability $2\times 10^{-4}$. Based IRD's radial velocities K2-415, which were sparsely taken over three years, obtain mass $3.0\pm 2.7\,M_\oplus$ ($M_p<7.5\,M_\oplus$ $95\,\%$ confidence) for K2-415b. Being one lowest stars ($\approx 0.16\,M_\odot$) known host planet, will be interesting target further observations, additional velocity monitoring transit spectroscopy.