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

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

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


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.

Original languageEnglish (US)
Article numberA100
JournalAstronomy and Astrophysics
StatePublished - Mar 1 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planets and satellites: detection
  • Planets and satellites: individual: 394137592
  • Planets and satellites: individual: HD 1397b
  • Planets and satellites: individual: TOI-120


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