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arXiv · 2610.24776

Mid-infrared Imaging of SR 12 c with JWST/MIRI: Grain Growth in an Evolved Circumplanetary Disk

Ya-Lin Wu·Claire O. Finley·Brendan P. Bowler·Ning Chen·Yuhiko Aoyama·Gregory J. Herczeg·Catherine C. Espaillat·William Best·Ian Czekala·Katherine B. Follette·Adam L. Kraus·Raquel A. Martinez·Connor E. Robinson·Quang H. Tran·Kimberly Ward-Duong·Yifan Zhou
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Abstract

The physical properties of circumplanetary disks offer insights into the formation of giant planets and their satellites. The circumbinary planetary-mass companion SR 12 c (1200 au from SR 12 AB) hosts an isolated dust disk directly detected with ALMA. We present JWST/MIRI imaging of SR 12 c from 5.6 to 21 $μ$m and analyze its spectral energy distribution from infrared to submillimeter wavelengths. Phenomenologically, the dust disk can be described by a two-component blackbody with large contrasts in characteristic temperatures and radii. Physically motivated models with varied geometries and heating mechanisms suggest a predominantly flat, irradiation-heated disk with a smaller contribution from viscous dissipation. The disk is inferred to be compact, with an inner radius of ~3 $R_{\rm Jup}$. The outer radius is only loosely constrained, with a characteristic value of ~3 au. The lack of strong 10 $μ$m excess emission suggests significant grain growth and dust settling. We also find that SR 12 c is broadly consistent with the empirical star-disk scaling relations, providing context for its possible formation pathway. These results demonstrate the power of combining mid-infrared and submillimeter observations with disk modeling to better understand the physical properties of circumplanetary disks.

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Ya-Lin Wu, Claire O. Finley, Brendan P. Bowler, Ning Chen, Yuhiko Aoyama, Gregory J. Herczeg, Catherine C. Espaillat, William Best, Ian Czekala, Katherine B. Follette, Adam L. Kraus, Raquel A. Martinez, Connor E. Robinson, Quang H. Tran, Kimberly Ward-Duong, Yifan Zhou. 2026-10-17. Mid-infrared Imaging of SR 12 c with JWST/MIRI: Grain Growth in an Evolved Circumplanetary Disk. https://arxiv.org/abs/2610.24776

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