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 \pm 50 K , a mass of M _ { \star } = 1.128 ^ { +0.065 } _ { -0.061 } M _ { \odot } , radius of R _ { \star } = 1.777 ^ { +0.047 } _ { -0.044 } R _ { \odot } , a surface gravity of \log g _ { \star } = 3.993 ^ { +0.027 } _ { -0.028 } , and an age of 7.4 ^ { +1.6 } _ { -1.5 } Gyr .
Its planetary companion ( TOI-172 b ) has a radius of R _ { P } = 0.965 ^ { +0.032 } _ { -0.029 } R _ { J } , a mass of M _ { P } = 5.42 ^ { +0.22 } _ { -0.20 } M _ { J } , and is on an eccentric orbit ( e = 0.3806 ^ { +0.0093 } _ { -0.0090 } ) .
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 .