TOI-5126: A hot super-Neptune and warm Neptune pair discovered by TESS and CHEOPS
/ Authors
Tyler R. Fairnington, Emma Nabbie, Chelsea X. Huang, G. Zhou, Orion Foo, Sarah C. Millholland, Duncan J. Wright, A. Belinski, A. Bieryla, D. Ciardi
and 26 more authors
K. Collins, K. Collins, M. Everett, S. Howell, J. Lissauer, M. Lund, F. Murgas, E. Pallé, S. Quinn, H. Relles, B. Safonov, R. Schwarz, N. Scott, G. Srdoc, G. Ricker, R. Vanderspek, S. Seager, D. Latham, J. Winn, J. Jenkins, Luke G Boumay, A. Shporer, E. Ting, Diana Dragomiry, M. Kunimoto, N. Eisner
/ Abstract
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 $4.74_{-0.14}^{+0.16}$R⊕ and $3.86_{-0.16}^{+0.17}$R⊕ with $5.4588385_{-0.0000072}^{+0.0000070}$ d and $17.8999_{-0.0013}^{+0.0018}$ d orbital periods, respectively. We also obtained precise space based photometric follow-up of the system with ESA’s CHaracterising ExOplanets Satellite (CHEOPS) 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= ${1442}_{-40}^{+46}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (Teq= $971_{-27}^{+31}$ K) also suitable for follow-up. Tentative transit timing variations (TTVs) 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.
Journal: Monthly Notices of the Royal Astronomical Society