Three super-Earths and a possible water world from TESS and ESPRESSO

Since 2018, the ESPRESSO spectrograph at the VLT has been hunting for planets in the Southern skies via the RV method. One of its goals is to follow up candidate planets from transit surveys such as the TESS mission, particularly small planets. We analyzed photometry from TESS and ground-based facilities, high-resolution imaging, and RVs from ESPRESSO, HARPS, and HIRES, to confirm and characterize three new planets: TOI-260 b, transiting a late K-dwarf, and TOI-286 b and c, orbiting an early K-dwarf. We also update parameters for the known super-Earth TOI-134 b, hosted by an M-dwarf. TOI-260 b has a 13. 475853^+0. 000013-₀. ₀₀₀₀₁₁ d period, 4. 23 1. 60 M_ mass and 1. 710. 08R_ radius. For TOI-286 b we find a 4. 5117244^+0. 0000031-₀. ₀₀₀₀₀₂₇ d period, 4. 530. 78M_ mass and 1. 420. 10R_ radius; for TOI-286 c, a 39. 361826^+0. 000070-₀. ₀₀₀₀₈₁ d period, 3. 722. 22M_ mass and 1. 88 0. 12R_ radius. For TOI-134 b we obtain a 1. 40152604^+0. 00000074-₀. ₀₀₀₀₀₀₈₂ d period, 4. 070. 45M_ mass, and 1. 630. 14R_ radius. Circular models are preferred for all, although for TOI-260 b the eccentricity is not well-constrained. We compute bulk densities and place the planets in the context of composition models. TOI-260 b lies within the radius valley, and is most likely a rocky planet. However, the uncertainty on the eccentricity and thus on the mass renders its composition hard to determine. TOI-286 b and c span the radius valley, with TOI-286 b lying below it and having a likely rocky composition, while TOI-286 c is within the valley, close to the upper border, and probably has a significant water fraction. With our updated parameters for TOI-134 b, we obtain a lower density than previous findings, giving a rocky or Earth-like composition.