A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS

March 2019 • 2019A&A...623A.100N

Authors • Nielsen, L. D. • Bouchy, F. • Turner, O. • Giles, H. • Suárez Mascareño, A. • Lovis, C. • Marmier, M. • Pepe, F. • Ségransan, D. • Udry, S. • Otegi, J. F. • Ottoni, G. • Stalport, M. • Ricker, G. • Vanderspek, R. • Latham, D. W. • Seager, S. • Winn, J. N. • Jenkins, J. M. • Kane, S. R. • Wittenmyer, R. A. • Bowler, B. • Crossfield, I. • Horner, J. • Kielkopf, J. • Morton, T. • Plavchan, P. • Tinney, C. G. • Zhang, Hui • Wright, D. J. • Mengel, M. W. • Clark, J. T. • Okumura, J. • Addison, B. • Caldwell, D. A. • Cartwright, S. M. • Collins, K. A. • Francis, J. • Guerrero, N. • Huang, C. X. • Matthews, E. C. • Pepper, J. • Rose, M. • Villaseñor, J. • Wohler, B. • Stassun, K. • Howell, S. • Ciardi, D. • Gonzales, E. • Matson, R. • Beichman, C. • Schlieder, J.

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 M_J and a radius of 1.026 ± 0.026 R_J. 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.

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David Ciardi

Senior Scientist