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Description
We present the confirmation and characterisation of GJ 3473 b (G 50-16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal (P=1.1980035+/-0.0000018d) was first detected by the Transiting Exoplanet Survey Satellite (TESS). Through a joint modelling of follow-up radial velocity observations with CARMENES, IRD, and HARPS together with extensive ground-based photometric follow-up observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise planetary mass, M_b_=1.86+/-0.30M_{sun}_, and radius, R_b_=1.264+/-0.050R_{sun}_. Additionally, we report the discovery of a second, temperate, non-transiting planet in the system, GJ 3473 c, which has a minimum mass, M_c_sini=7.41+/-0.91M_{sun}_ and orbital period, P_c_=15.509+/-0.033d. The inner planet of the system, GJ 3473 b, is one of the hottest transiting Earth- sized planets known thus far, accompanied by a dynamical mass measurement, which makes it a particularly attractive target for thermal emission spectroscopy.
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