An Eccentric Massive Jupiter Orbiting a Subgiant on a 9.5-day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images

Abstract

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 o, radius of R ∗ = 1.777-0.044+0.047 R o, a surface gravity of log g ∗ = 3.993-0.028+0.027, and an age of 7.4-1.5+1.6. 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.