The TASSIE Program. II: Three Close-In Companions Orbiting Sun-Like Stars

We present three southern transiting giant planet candidates alerted by the Transiting Exoplanet Survey Satellite (TESS) mission and investigated at the University of Tasmania Greenhill Observatory (UTGO). The candidate planets are orbiting thin disk G-dwarf main-sequence stars with roughly solar metallicity, possessing orbital periods between 2.9 - 3.3 days and radii of 1.1 - 1.3 RJ. We performed ground-based follow-up photometry primarily with the UTGO Harlingten 50 cm, then gathered reconnaissance spectra, high angular resolution imaging and high-precision radial velocities to rule out false positive scenarios. We confirmed that two of these systems host true exoplanets and constrained their masses. TOI-3053b is a typical hot Jupiter, with M 3053b = 0.85 ± 0.12 MJ and a bulk density of ρ3053b = 0.64 ± 0.10 g cm–3. TOI-3278b/HATS-78b is a hot Saturn-mass planet (M 3278b = 0.30 ± 0.07 MJ) with a highly inflated atmosphere and a low density of ρ3278b = 0.21 ± 0.05 g cm–3. The other candidate (TOI-3272.01) remains unconfirmed, but appears consistent with being a hot Jupiter. TOI-3272.01 is notable as a candidate planet orbiting a potentially young to intermediate age star, with a rotational analysis indicating an age estimate of T 3272 = 1.1 ± 0.2 Gyr. These systems add to a growing sample of hot giant planets from TESS that may provide constraints on the migration pathways and radius inflation of the broader close-in exoplanet population.