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Description
We report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of only the TESS full frame images, because the host star was not chosen as a two-minute cadence target. From a global analysis of the TESS photometry and follow-up observations carried out by the TESS Follow-up Observing Program Working Group, TOI-172 (TIC 29857954) is a slightly evolved star with an effective temperature of T_eff_=5645+/-50 K, a mass of M_*_=1.128_-0.061_^+0.065^ M_{sun}_, radius of R_*_=1.777_-0.044_^+0.047^ R_{sun}_, a surface gravity of log g_*_=3.993_-0.028_^+0.027^, and an age of 7.4_-1.5_^+1.6^ Gyr. Its planetary companion (TOI-172 b) has a radius of R_P_=0.965_-0.029_^+0.032^ R_J_, a mass of M_P_=5.42_-0.20_^+0.22^ M_J_, and is on an eccentric orbit (e=0.3806_-0.0090_^+0.0093^). TOI-172 b is one of the few known massive giant planets on a highly eccentric short-period orbit. Future study of the atmosphere of this planet and its system architecture offer opportunities to understand the formation and evolution of similar systems.
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