On the Detection Of Exorings in Reflected Light With JWST NIRCam

When directly imaging a cold giant exoplanet hosting a ring system, the reflected light from the rings can outshine the planet’s thermal emission and reflected-light in the near-infrared.

Consequently, an exoring may be detectable at a significantly lower contrasts than is required to image the exoplanet itself. Here we investigate the detectability of exorings in near-infrared reflected light using NIRCam coronagraphy PanCAKE simulations of two nearby mature stars, Proxima Centauri and Tau Ceti.

Under the most favorable assumptions, we find JWST 2μm NIRCam coronagraphy (F200W + MASK335R) is capable of detecting an exoring system with a radius of 2.8 times that of Saturn’s A-ring for planets on an orbit with a = 1.3-1.9 AU. Broader simulations indicate that NIRCam can probe large planetary ring systems around mature exoplanets comparable in size to circumplanetary disks, which can reach up to 1000 times the radius of Saturn’s A-ring.

These results suggest that NIRCam F200W coronagraphy could serendipitously detect large exorings in reflected light under the right conditions. A combined analysis of F200W coronagraphic observations of confirmed exoplanets could provide the first empirical constraints on the occurrence rate of large exorings.

Confirming the existence and frequency of exorings spanning the scale between circumplanetary disks and the rings of the Solar System giant planet could offer new insight into the formation, evolution, and architecture of planetary systems.

The image of Uranus was created using data from JWST DD 2739.b — astro-ph.EP

Rachel Bowens-Rubin, Mary Anne Limbach, Sam Hopper, Klaus Subbotina Stephenson, Matson Garza, Leigh N. Fletcher, Matthew Hedman

Comments: Accepted to AJ on Aug 29 2025
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2509.07118 [astro-ph.EP] (or arXiv:2509.07118v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2509.07118
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Submission history
From: Rachel Bowens-Rubin
[v1] Mon, 8 Sep 2025 18:15:14 UTC (6,352 KB)
https://arxiv.org/abs/2509.07118

Astrobiology,