TOI-5126: a hot super-Neptune and warm Neptune pair discovered by TESS and CHEOPS

Tyler R. Fairnington, Emma Nabbie, Chelsea X. Huang, George Zhou, Orion Foo, Sarah Millholland, Duncan Wright, Alexandre A. Belinski, Allyson Bieryla, David R. Ciardi, Karen A. Collins, Kevin I. Collins, Mark Everett, Steve B. Howell, Jack J. Lissauer, Michael B. Lund, Felipe Murgas, Enric Palle, Samuel N. Quinn, Howard M. RellesBoris S. Safonov, Richard P. Schwarz, Nicholas J. Scott, Gregor Srdoc, George Ricker, Roland Vanderspek, Sara Seager, David W. Latham, Joshua W. Winn, Jon M. Jenkins, Luke G. Bouma, Avi Shporer, Eric B. Ting, Diana Dragomir, Michelle Kunimoto, Nora L. Eisner

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the Transiting Exoplanet Survey Satellite (TESS). The two planets, observed in sectors 45, 46, and 48 of the TESS extended mission, are 4.74+−001416 and 3.86+−001617 R with 5.4588385+−0000000720000070 and 17.8999+−0000130018 d orbital periods, respectively. We also obtained precise space-based photometric follow-up of the system with ESA’s CHaracterising ExOplanets Satellite to constrain the radius and ephemeris of TOI-5126 b. TOI-5126 b is located in the ‘hot Neptune Desert’ and is an ideal candidate for follow-up transmission spectroscopy due to its high-predicted equilibrium temperature (Teq = 1442+−4046 K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (Teq = 971+−2731 K) also suitable for follow-up. Tentative transit timing variations have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.

Original languageEnglish (US)
Pages (from-to)8768-8783
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Jan 1 2024

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • planets and satellites: detection
  • stars: individual TOI-5126
  • techniques: photometric


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