JWST/NIRSpec Detects Warm CO Emission In The Terrestrial-Planet Zone Of HD 131488

We have obtained a high-resolution, JWST NIRSpec 2.87 — 5.14 μm spectrum of the debris disk around HD 131488.

We discover CO fundamental emission indicating the presence of warm fluorescent gas within ∼10 AU of the star. The large discrepancy in CO’s vibrational and rotational temperature indicates that CO is out of thermal equilibrium and is excited with UV fluorescence.

Our UV fluorescence model gives a best fit of 1150K with an effective temperature of 450, 332, and 125K for the warm CO gas kinetic temperature within 0.5, 1, and 10AU to the star and a gas vibrational temperature of 8800K.

The newly discovered warm CO gas population likely resides between sub-AU scales and ∼10AU, interior to the cold CO reservoir detected beyond 35AU with HST STIS and ALMA. The discovery of warm, fluorescent gas in a debris disk is the first such detection ever made. The detection of warm CO raises the possibility of unseen molecules (H₂O, H₂, etc) as collisional partners to excite the warm gas.

We estimated a lower mass limit for CO of 1.25×10−7M_⊕, which is 10−5 of the cold CO mass detected with ALMA and HST. We demonstrate that UV fluorescence emerges as a promising avenue for detecting tenuous gas at 10⁻⁷ Earth-mass level in debris disks with JWST.

Worthen, Joan Najita, Chen Xie, Aoife Brennan, Amaya Moro-Martin, John Debes, Kevin France, Luca Matrà, Marshall Perrin, Aki Roberge

Comments: 30 Pages, 15 Figures, 6 Tables; Accepted to ApJ; Data Behind Figure 2 Available on the Journal Publisher Site
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2512.11972 [astro-ph.EP] (or arXiv:2512.11972v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2512.11972
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Related DOI:
https://doi.org/10.3847/1538-4357/ae2797
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Submission history
From: Cicero Lu
[v1] Fri, 12 Dec 2025 19:00:10 UTC (3,249 KB)
https://arxiv.org/abs/2512.11972

Astrobiology, exoplanet,