A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS
Bouchy, F.; Stassun, K.; Winn, J. N.; Wittenmyer, R. A.; Ségransan, D.; Collins, K. A.; Jenkins, J. M.; Lovis, C.; Seager, S.; Udry, S.; Pepe, F.; Suárez Mascareño, A.; Rose, M.; Latham, D. W.; Ricker, G.; Vanderspek, R.; Huang, C. X.; Beichman, C.; Plavchan, P.; Gonzales, E.; Howell, S.; Kane, S. R.; Tinney, C. G.; Zhang, Hui; Stalport, M.; Guerrero, N.; Wohler, B.; Pepper, J.; Matthews, E. C.; Caldwell, D. A.; Nielsen, L. D.; Otegi, J. F.; Turner, O.; Wright, D. J.; Ottoni, G.; Horner, J.; Marmier, M.; Villaseñor, J.; Giles, H.; Crossfield, I.; Ciardi, D.; Matson, R.; Schlieder, J.; Kielkopf, J.; Mengel, M. W.; Addison, B.; Okumura, J.; Clark, J. T.; Bowler, B.; Morton, T.; Cartwright, S. M.; Francis, J.
Switzerland, United States, Australia, China
Abstract
The Transiting Exoplanet Survey Satellite TESS has begun a new age of exoplanet discoveries around bright host stars. We present the discovery of HD 1397b (TOI-120.01), a giant planet in an 11.54-day eccentric orbit around a bright (V = 7.9) G-type subgiant. We estimate both host star and planetary parameters consistently using EXOFASTv2 based on TESS time-series photometry of transits and radial velocity measurements with CORALIE and MINERVA-Australis. We also present high angular resolution imaging with NaCo to rule out any nearby eclipsing binaries. We find that HD 1397b is a Jovian planet, with a mass of 0.415 ± 0.020 MJ and a radius of 1.026 ± 0.026 RJ. Characterising giant planets in short-period eccentric orbits, such as HD 1397b, is important for understanding and testing theories for the formation and migration of giant planets as well as planet-star interactions.