Studying planetary interactions in exoplanet systems informs theories of planet formation and evolution, providing essential context for understanding our own solar system. We combine spectroscopy, transit photometry, transit timing variations, and astrometry to characterize the TOI-201 system. The co-transiting system consists of a super-Earth, warm Jupiter, and massive companion at 5.8, 53, and 2900 day orbital periods, respectively. We perform dynamical simulations to study the past and future of the system. von-Zeipel-Kozai-Lidov oscillations emerge as the most plausible scenario to explain the outer companion's high orbital eccentricity, with planet-planet scattering a possible but less likely contender. Due to non-zero mutual inclinations between the planets, the system is visibly evolving on very short timescales, with the current co-transiting configuration ending in 200 years.
@article{arxiv.2604.23929,
title = {Uncovering the Rapidly Evolving Orbits of the Dynamic TOI-201 System},
author = {Ismael Mireles and Solène Ulmer-Moll and Donald Liveoak and Diana Dragomir and Judith Korth and Alexander Venner and Karen A. Collins and Amaury H. M. J. Triaud and Tristan Guillot and Antoine Petit and Theron Carmichael and Sarah Millholland and Tim Hallatt and Hannu Parviainen and Hugh P. Osborn and David Rapetti and Thomas A. Baycroft and Siddharth Bhatnagar and François Bouchy and Radka Dancikova and Pedro Figueira and Monika Lendl and Stéphane Udry and Peter Wheatley and Lyu Abe and Abdelkrim Agabi and Matteo Beltrame and Philippe Bendjoya and Vincent Deloupy and Djamel Mékarnia and François-Xavier Schmider and Olga Suárez and Khalid Barkaoui and Keith Horne and Felipe Murgas and Enric Palle and Richard P. Schwarz and Ramotholo Sefako and Avi Shporer and Gregor Srdoc and Chris Stockdale and Francis P. Wilkin and Joel D. Hartman and Lauren A. Sgro and Thiam-Guan Tan and Jon M. Jenkins and Attila Bódi and David Havell and Darren Rivett and Ian Transom},
journal= {arXiv preprint arXiv:2604.23929},
year = {2026}
}