TOI-2322: Two Transiting Rocky Planets Close To The Stellar Rotation Period And Its First Harmonic

Context. Active regions on the stellar surface can induce quasi-periodic radial velocity (RV) variations that can mimic planets and mask true planetary signals. These spurious signals can be problematic for RV surveys such as those carried out by the ESPRESSO consortium.

Aims. Using ESPRESSO and HARPS RVs and activity indicators, we aim to confirm and characterize two candidate transiting planets from TESS orbiting a K4 star with strong activity signals.

Methods. From the ESPRESSO FWHM, TESS photometry, and ASAS-SN photometry, we measure a stellar rotation period of 21.28 ± 0.08 d. We jointly model the TESS photometry, ESPRESSO and HARPS RVs, and activity indicators, applying a multivariate Gaussian Process (GP) framework to the spectroscopic data.

Results. We are able to disentangle the planetary and activity components, finding that TOI-2322 b has a 11.307170+0.000085−0.000079 d period, close to the first harmonic of the rotation period, a ≤2.03M_⊕ mass upper limit and a 0.994+0.057−0.059 R_⊕ radius. TOI-2322 c orbits close to the stellar rotation period, with a 20.225528+0.000039−0.000044 d period; it has a 18.10+4.34−5.36 M_⊕ mass and a 1.874+0.066−0.057 R_⊕ radius.

Conclusions. The multivariate GP framework is crucial to separating the stellar and planetary signals, significantly outperforming a one-dimensional GP. Likewise, the transit data is fundamental to constraining the periods and epochs, enabling the retrieval of the planetary signals in the RVs. The internal structure of TOI-2322 c is very similar to that of Earth, making it one of the most massive planets with an Earth-like composition known.

M. J. Hobson (1), A. Suárez Mascareño (2 and 3), C. Lovis (1), F. Bouchy (1), B. Lavie (1), M. Cretignier (4), A. M. Silva (5 and 6), S. G. Sousa (5 and 6), H. M. Tabernero (7and 8), V. Adibekyan (5 and 6), C. Allende Prieto (2 and 3), Y. Alibert (9 and 10), S. C. C. Barros (5 and 6), A. Castro-González (11), K. A. Collins (12), S. Cristiani (13 and 14), V. D’Odorico (13), M. Damasso (15), D. Dragomir (16), X. Dumusque (1), D. Ehrenreich (1), P. Figueira (5 and 6 and 17), R. Génova Santos (2), B. Goeke (18), J. I. González Hernández (2 and 3), K. Hesse (18), J. Lillo-Box (11), G. Lo Curto (17), C. J. A. P. Martins (19 and 5), A. Mehner (17), G. Micela (20), P. Molaro (13), N. J. Nunes (21), E. Palle (2 and 3), V. M. Passegger (23 and 2 and 3 and 22), F. Pepe (1), R. Rebolo (2), J. Rodrigues (5 and 6), N. Santos (5 and 6), A. Sozzetti (15), B. M. Tofflemire (24), S. Udry (1), C. Watkins (12), M.-R. Zapatero Osorio (11), C. Ziegler (25) ((1) Observatoire de Genève, Département d’Astronomie, Université de Genève, (2) Instituto de Astrofísica de Canarias, (3) Departamento de Astrofísica, Universidad de La Laguna, (4) Department of Physics, University of Oxford, (5) Instituto de Astrofísica e Ciências do Espaço, CAUP, Universidade do Porto, (6) Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, (7) Institut d’Estudis Espacials de Catalunya (IEEC),(8) Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, (9) Physics Institute, University of Bern, (10) Center for Space and Habitability, University of Bern, (11) Centro de Astrobiología, CSIC-INTA, (12) Center for Astrophysics | Harvard & Smithsonian, (13) INAF- Osservatorio Astronomico di Trieste, (14) IFPU-Institute for Fundamental Physics of the Universe, (15) INAF – Osservatorio Astrofisico di Torino, (16) Department of Physics and Astronomy, University of New Mexico, (17) European Southern Observatory, (18) Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, (19) Centro de Astrofísica da Universidade do Porto, (20) INAF – Osservatorio Astronomico di Palermo, (21) Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, (22) Hamburger Sternwarte, (23) Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), (24) SETI Institute, USA/NASA Ames Research Center, (25) Department of Physics, Engineering and Astronomy, Stephen F. Austin State University)

Comments: 22 pages, 20 figures. Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2508.18094 [astro-ph.EP] (or arXiv:2508.18094v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.18094
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Submission history
From: Melissa Hobson
[v1] Mon, 25 Aug 2025 14:55:35 UTC (8,412 KB)
https://arxiv.org/abs/2508.18094
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