![In top panels transits of TOI1408 b (left) and c (right) are shown along with their best fitting models (computed for one of likelihood maxima). In panels below the corresponding binned residuals and their uncertainties are plotted. Notice that there are a few occurrences when planets b and c transits partly overlapped with each other; in such a case all transit curves are plotted in the same graph. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/TOI-1408.png?fit=1200%2C680&ssl=1)
[astro-ph.EP] We perform a self-consistent analysis of Doppler and photometric TESS and ground-based transit observations available for TOI-1408, known to host a system with two planets orbiting near 2:1 mean-motion commensurability and a distant companion.
In general we confirm its orbital configuration derived in previous studies, however we found that the likelihood function contains multiple local maxima spread over a wider parametric domain, thus making some model uncertainties significantly larger than deemed before.
In particular, the planet b radius still appears poorly constrained (from ∼1.2RJup to ∼3.5RJup) because of the near-tangential transit geometry. We also show that the derived model is very prior-dependent regarding the astrophysical (spectrum-derived) constraints on the stellar mass M⋆ and radius R⋆.
While such estimations may potentially contribute a significant information to the fit, their prior distribution must be accurately specified to be useful. Presently so accurate characterization (e.g. the correlation between M⋆ and R⋆) is not available in the literature.
Roman V. Baluev
Comments: 23 pages, 11 figures, 2 tables; accepted by Research in Astronomy & Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2610.02434 [astro-ph.EP] (or arXiv:2610.02434v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2610.02434
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Submission history
From: Roman Baluev
[v1] Thu, 1 Oct 2026 20:01:28 UTC (1,267 KB)
https://arxiv.org/abs/2610.02434
Astrobiology, exoplanet,
