Understanding eccentric temperate giants: an in-depth study of the architecture and stellar obliquity of the TOI-2134 system
Federica Rescigno, Manu Stalport, Ancy Anna John, Tiger Lu, Daisy A. Turner, Lorena Acuña-Aguirre, Anand Bhongade, Anjali A. A. Piette, Vedad Kunovac, Michael Cretignier, Andrew Vanderburg, Ken Rice, Annelies Mortier, Rishikesh Sharma, Guillaume Hébrard, Abhijit Chakraborty, Alessandro Sozzetti, Andrew Collier Cameron, Pía Cortés-Zuleta, Rosario Cosentino, Florian Destriez, Mercedes López-Morales, Luca Malavolta, Jesús Maldonado, Giacomo Mantovan, Francesco Pepe, Matteo Pinamonti, André M. Silva, Stephane Udry, Shreyas Vissapragada, Thomas G. Wilson
astro-ph.EP, astro-ph.SR
Submitted: 2026-07-01
Comments: 26 pages, accepted at MNRAS
Code: https://github.com/lkreidberg/batman
License: http://creativecommons.org/licenses/by/4.0/
The gist: We revisit the TOI-2134 planetary system with three new high-cadence TESS sectors and 98 more spectra.
Terminology
Abstract
We revisit the TOI-2134 planetary system with three new high-cadence TESS sectors and 98 more spectra. This new analysis confirms the two orbiting planets by simultaneously modelling a total of eight sectors of corrected TESS photometry and 280 HARPS-N and SOPHIE radial velocities: an inner mini-Neptune in a near-circular 9.229198 plus or minus0.000003 days orbit, and an outer temperate sub-Saturn orbiting with a 95.852840 plus or minus0.000042 days period and eccentricity of 0.31 plus or minus0.01. The masses and radii of the planets were computed to be 9.37 plus or minus0.54 Me and 2.735 plus or minus0.068 Re for planet b, and 58.3 plus or minus1.9 Me and 7.35 plus or minus0.18 Re for planet c. The new data not only improves the detection significance and precisions on the planetary orbits, but also breaks the original multimodality in the eccentricity solution for the outer planet. We also detect a long-term trend in the radial velocity data, which we attribute to a stellar magnetic cycle. We investigate the spin-orbit alignment of the system via observations of the Rossiter-McLaughlin effect for TOI-2134 b with EXPRES and TOI-2134 c with PARAS-2. No RM effect was detected for planet b, but we find a 4.7 sigma detection of a 59 plus or minus31 obliquity for planet c. Finally, we examine the architecture of the system, assess its completeness, investigate the planetary interior, and their suitability for follow-up atmospheric analysis.
Sources
- Methane on the temperate exo-Saturn TOI-199b
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