RV of TOI-4860

Using the photometric time series from TESS sectors 10, 36, 46, and 63 and near-infrared spectrophotometry from ExTrA, we measured a planetary radius of 0.77+/-0.03R_J_ and an orbital period of 1.52 days. With high-resolution spectroscopy taken by the CFHT/SPIRou and ESO/ESPRESSO spectrographs, we refined the host star parameters ([Fe/H]=0.27+/-0.12) and measured the mass of the planet (0.273+/-0.006M_J_).

Based on these measurements, TOI-4860 b joins the small set of massive planets (>80M_E_) found around mid to late M dwarfs (<0.4R_{sun}_), providing both an interesting challenge to planet formation theory and a favourable target for further atmospheric studies with transmission spectroscopy. We identified an additional signal in the radial velocity data that we attribute to an eccentric planet candidate (e=0.66+/-0.09) with an orbital period of 427+/-7 days and a minimum mass of 1.66+/-0.26M_J_, but additional data would be needed to confirm this.