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

January 2024 • 2024MNRAS.527.8768F

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

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 $4.74_{-0.14}^{+0.16}$ and $3.86_{-0.16}^{+0.17}$ R_⊕ with $5.4588385_{-0.0000072}^{+0.0000070}$ 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 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 (T_eq = ${1442}_{-40}^{+46}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (T_eq = $971_{-27}^{+31}$ 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.

Links

• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2024MNRAS.527.8768F
• PDF https://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/stad3036
• PREPRINT http://arxiv.org/abs/2310.08890
• DATA https://irsa.ipac.caltech.edu/bibdata/2024/F/2024MNRAS.527.8768F.html
• ELECTR https://doi.org/10.1093%2Fmnras%2Fstad3036