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Giant Outer Transiting Exoplanet Mass (GOTEM) Survey.VII. TOI-6041: A Multi-planet System Including A Warm Neptune Exhibiting Strong TTVs

By Keith Cowing

Status Report

astro-ph.EP

December 28, 2025

Filed under astro-ph.EP, CHEOPS, exoplanet, imaging, photometry, stallar cartography, TESS, TOI-6041, TOI-6041 b, TOI-6041 c, Transit Timing Variations, warm Neptune

Giant Outer Transiting Exoplanet Mass (GOTEM) Survey.VII. TOI-6041: A Multi-planet System Including A Warm Neptune Exhibiting Strong TTVs — Stability analysis of the TOI-6041 system. The phase space of the system is explored by varying the orbital period Pi and eccentricity ei of each planet independently. For each initial condition (Table 4), the system is integrated over 10 kyr, and a stability criterion is derived with the frequency analysis of the mean longitude. The chaotic diffusion is measured by the variation in the frequencies. The color scale corresponds to the logarithmic variation in the stability index used in (Correia et al. 2010). The red zone corresponds to highly unstable orbits, while the dark blue region can be assumed to be stable on a billion-year timescale. White dashed lines indicate the nominal orbital periods reported in Table 4. — astro-ph.EP

We present the characterization of the TOI-6041 system, a bright (V=9.84±0.03) G7-type star hosting at least two planets.

The inner planet, TOI-6041b, is a warm Neptune with a radius of 4.55+0.18−0.17R_⊕, initially identified as a single-transit event in TESS photometry.

Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26.04945+0.00033−0.00034~d orbital period and the detection of significant transit timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1~hour.

Radial velocity (RV) measurements obtained with the APF spectrographs allow us to place a 3σ upper mass limit of 28.9M_⊕ on TOI-6041b. In addition, the RV data reveal a second companion, TOI-6041c, on an 88~d orbit, with a minimum mass of 0.25M_Jup.

A preliminary TTV analysis suggests that the observed variations could be caused by gravitational perturbations from planet c; however, reproducing the observed amplitudes requires a relatively high eccentricity of about 0.3 for planet c. Our dynamical stability analysis indicates that such a configuration is dynamically viable and places a 1σ upper limit on the mass of TOI-6041c at 0.8M_Jup.

An alternative is the presence of a third, low-mass planet located between planets b and c, or on an inner orbit relative to planet b — particularly near a mean-motion resonance with planet b — which could account for the observed variations. These findings remain tentative, and further RV and photometric observations are essential to better constrain the mass of planet b and to refine the TTV modeling, thereby improving our understanding of the system’s dynamical architecture.

Location of TOI-6041 b within the radius–period diagram, along with other known exoplanets whose radius precision is better than 30%, taken from the NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu/) as of June 5, 2025. The background density map illustrates the distribution of confirmed exoplanets, with regions labeled as the Desert, Ridge, and Savanna to reflect differing planet occurrence rates (Castro-González et al. 2024). TOI-6041 b (green marker) lies in the Savanna region. This plot was generated using the nep-des Python code (https://github.com/castro-gzlz/nep-des). — astro-ph.EP

N. Heidari, A. Alnajjarine, H.P. Osborn, D. Dragomir, P. Dalba, W. Benz, G. Hébrard, J. Laskar, N. Billot, M.N. Günther, T.G. Wilson, Y. Alibert, A. Bonfanti, A. Bieryla, C. Broeg, A.C.M. Correia, J.A. Egger, Z. Essack, E. Furlan, D. Gandolfi, N. Grieves, S. Howell, D. LaCourse, C. Pezzotti, T. Pritchard, S.G. Sousa, S. Ulmer-Moll, S. Villanueva, R. Alonso, J. Asquier, T. Bárczy, D. Barrado, S.C. Barros, W. Baumjohann, L. Borsato, A. Brandeker, M. Buder, A. Collier Cameron, S. Csizmadia, P.E. Cubillos, M.B. Davies, M. Deleuil, X. Delfosse, A. Deline, O.D.S. Demangeon, B. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, K. Gazeas, M. Gillon, M. Güdel, J. Hasiba, A. Heitzmann, C. Helling, J.M. Jenkins, T. Keller, K.G. Stassun, L. Kiss, J. Korth, K.W.F. Lam, D.W. Latham, A. Lecavelier des Etangs, A. Leleu, M. Lendl, P.F.L. Maxted, S. McDermott, B. Merín, C. Mordasini, V. Nascimbeni, G. Nowak, G. Olofsson, I. Pagano, E. Pallé, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, H. Rauer, I. Ribas, G. Ricker, N.C. Santos, G. Scandariato, S. Seager, D. Ségransan, A.E. Simon, A.M.S. Smith, M. Stalport, S. Striegel, S. Sulis, G.M. Szabó, S. Udry, V. Van Grootel, R. Vanderspek, J. Venturini, E. Villaver et al. (4 additional authors not shown)

Comments: Accepted for publication in A&A, 22 pages, 8 plots
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2512.01911 [astro-ph.EP](or arXiv:2512.01911v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2512.01911
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Submission history
From: Neda Heidari
[v1] Mon, 1 Dec 2025 17:29:05 UTC (5,130 KB)
https://arxiv.org/abs/2512.01911
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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