Precise mass and radius determination for two new and one known Neptune-sized planets around G Dwarf hosts

Abstract As part of the KESPRINT collaboration, we present the discovery and characterization of three exoplanets in the sub-Neptune to super-Neptune regime, spanning key regions of the exo-Neptunian landscape. TOI-1472 c and TOI-1648 b are newly discovered sub-Neptunes, while TOI-1472 b is a previously known super-Neptune for which we provide an improved mass measurement. These planets have orbital periods of 6–15 days and radii of 2.5–4.1 R⊕, probing regions where planet formation and atmospheric evolution remain poorly understood. We combine TESS transit photometry with ground-based radial velocities to determine precise masses, radii, and orbital properties. TOI-1472 b has a mass of $18.0^{+0.84}_{-0.85}$ M⊕ and a radius of 4.06 ± 0.10 R⊕, TOI-1472 c has a mass of $21.1^{+0.96}_{-0.99}$ M⊕ and a radius of 3.33 ± 0.08 R⊕, and TOI-1648 b has a mass of $7.4^{+1.1}_{-1.3}$ M⊕ and a radius of $2.54^{+0.14}_{-0.12}$ R⊕. The planets exhibit a range of eccentricities (0.041–0.178), indicating diverse evolutionary histories. TOI-1648 b, with a high Transmission Spectroscopy Metric (TSM ∼59), is a promising target for atmospheric characterization. Together, these three planets provide precise constraints on the structure, composition, and dynamical evolution of small to intermediate-sized exoplanets, enriching our understanding of the exo-Neptunian landscape.