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TESS is revolutionising the search for planets orbiting bright and nearbystars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a brightV=9.1 K1 dwarf also known as HD 15337, and found two transiting signals withperiod of 4.76 and 17.18 days and radius of 1.90 and 2.21\,\Rearth. This starwas observed as part of the radial-velocity search for planets using the HARPSspectrometer, and 85 precise radial-velocity measurements were obtained over aperiod of 14 years. In this paper, we analyse the HARPS radial-velocitymeasurements in hand to confirm the planetary nature of these two signals. Byreanalysing TESS photometry and host star parameters using EXOFASTv2, we findthat TOI-402.01 and TOI-402.02 have periods of 4.75642$\pm$0.00021 and17.1784$\pm$0.0016 days and radii of 1.70$\pm$0.06 and2.52$\pm$0.11\,\Rearth\,(precision 3.6 and 4.2\%), respectively. By analysingthe HARPS radial-velocity measurements, we find that those planets are bothsuper-Earths with masses of 7.20$\pm$0.81 and8.79$\pm$1.67\,\Mearth\,(precision 11.3 and 19.0\%), and small eccentricitiescompatible with zero at 2$\sigma$. Although having rather similar masses, theradius of these two planets is really different, putting them on differentsides of the radius gap. With stellar irradiation 160 times more important thanEarth for TOI-402.01 and only 29 times more for TOI-402.02, it is likely thatphoto-evaporation is at the origin of this radius difference. Those twoplanets, being in the same system and therefore being in the same irradiationenvironment are therefore extremely important to perform comparativeexoplanetology across the evaporation valley and thus bring constraints on themechanisms responsible for the radius gap.

Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337)