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The Astronomical Journal


We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC 44792534, V = 10.343, T = 9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC 246193072, V = 12.70, K = 10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954 b has a radius of ${0.852}_{-0.062}^{+0.053}\,{R}_{{\rm{J}}}$and a mass of ${0.174}_{-0.017}^{+0.018}$MJ and is in a 3.68 day orbit, while K2-329 b has a radius of ${0.774}_{-0.024}^{+0.026}\,{R}_{{\rm{J}}}$and a mass of ${0.260}_{-0.022}^{+0.020}$MJ and is in a 12.46 day orbit. As TOI-954 b is 30 times more irradiated than K2-329 b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.


Exoplanet systems, Photometry, Transit photometry, Spectroscopy, High resolution spectroscopy, RV, G stars, G dwarf stars, G subgiant stars, Hot Jupiters


This work is a preprint that is freely available courtesy of IOP Publishing and the American Astronomical Society. The final published version is available online.