TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf

D. Kossakowski, J. Kemmer, P. Bluhm, S. Stock, J. A. Caballero, V. J.S. Béjar, C. Cardona Guillén, N. Lodieu, K. A. Collins, M. Oshagh, M. Schlecker, N. Espinoza, E. Pallé, Th Henning, L. Kreidberg, M. Kürster, P. J. Amado, D. R. Anderson, J. C. Morales, S. CartwrightD. Charbonneau, P. Chaturvedi, C. Cifuentes, D. M. Conti, M. Cortés-Contreras, S. Dreizler, D. Galadí-Enríquez, P. Guerra, R. Hart, C. Hellier, C. Henze, E. Herrero, S. V. Jeffers, J. M. Jenkins, E. L.N. Jensen, A. Kaminski, J. F. Kielkopf, M. Kunimoto, M. Lafarga, D. W. Latham, J. Lillo-Box, R. Luque, K. Molaverdikhani, D. Montes, G. Morello, E. H. Morgan, G. Nowak, A. Pavlov, M. Perger, E. V. Quintana, A. Quirrenbach, S. Reffert, A. Reiners, G. Ricker, I. Ribas, C. Rodríguez López, M. R.Zapatero Osorio, S. Seager, P. Schöfer, A. Schweitzer, T. Trifonov, S. Vanaverbeke, R. Vanderspek, R. West, J. Winn, M. Zechmeister

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20 Scopus citations


We present the discovery of a transiting mini-Neptune around TOI-1201, a relatively bright and moderately young early M dwarf (J ≈ 9.5 mag, ~600-800 Myr) in an equal-mass ~8 arcsecond-wide binary system, using data from the Transiting Exoplanet Survey Satellite, along with follow-up transit observations. With an orbital period of 2.49 d, TOI-1201 b is a warm mini-Neptune with a radius of Rb = 2.415 ± 0.090 R⊕. This signal is also present in the precise radial velocity measurements from CARMENES, confirming the existence of the planet and providing a planetary mass of Mb = 6.28 ± 0.88 M⊕ and, thus, an estimated bulk density of 2.45-0.42+0.48 g cm-3. The spectroscopic observations additionally show evidence of a signal with a period of 19 d and a long periodic variation of undetermined origin. In combination with ground-based photometric monitoring from WASP-South and ASAS-SN, we attribute the 19 d signal to the stellar rotation period (Prot = 19-23 d), although we cannot rule out that the variation seen in photometry belongs to the visually close binary companion. We calculate precise stellar parameters for both TOI-1201 and its companion. The transiting planet is anexcellent target for atmosphere characterization (the transmission spectroscopy metric is 97-16+21) with the upcoming James Webb Space Telescope. It is also feasible to measure its spin-orbit alignment via the Rossiter-McLaughlin effect using current state-of-the-art spectrographs with submeter per second radial velocity precision.

Original languageEnglish (US)
Article numberA124
JournalAstronomy and Astrophysics
StatePublished - 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Stars: individual: TIC-29 960 110
  • Stars: individual: TOI-1201
  • Stars: low-mass
  • Techniques: photometric
  • Techniques: radial velocities


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