Search For Exoplanetary Ring Systems With TESS

Photometric surveys for exoplanetary ring systems have not confirmed any object with Saturn-sized ring.

We systematically analyse 308 TESS planet candidates, mainly comprised of giant short-period planets orbiting nearby bright stars. These targets are selected based on the optimistic detectability of rings, assuming a favourable ring orientation.

We develop a pipeline with a two-step noise reduction and compare the fitting results of both ringless and ringed transit models to the resulting phase-folded light curves. Although we identify six systems where ringed models are statistically favoured, visual inspection of the signals suggests that none of them is conclusively attributed to the presence of rings. Assuming the ring orientation favourable for detection, we determine the 3σ upper limits on ring sizes for 125 objects.

Using these ring size limits, we derive upper limits on the ring occurrence rate, such as rings with an outer radius larger than 1.8 times the planetary radii occurring at rates lower than 2%. However, these limits can be relaxed if tidal alignment between the spin and orbital axes holds.

We explore an alternative detection method using transit depth variations by ring precession and estimate that 10 and 13 systems are likely detectable in TESS and Kepler data, respectively.

IMAGE

Detailed procedure from initial processing of each transit data to the derivation of the significance of ring signals in the case of
TOI-102.01.

Tsubasa Umetani, Masataka Aizawa, Yuichiro Ezoe, Yoshitaka Ishisaki

Comments: 25 pages, 21 figures, accepted for publication in PASJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2505.05948 [astro-ph.EP] (or arXiv:2505.05948v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2505.05948
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Journal reference: Publ. Astron. Soc. Japan 77 (2025) 86-104
Related DOI:
https://doi.org/10.1093/pasj/psae101
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Submission history
From: Tsubasa Umetani
[v1] Fri, 9 May 2025 10:46:42 UTC (4,155 KB)
https://arxiv.org/abs/2505.05948

Astrobiology