BOWIE-ALIGN: Sub-solar C/O ratio and metallicity atmosphere of the misaligned hot Jupiter HAT-P-30 b
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
We present the JWST NIRSpec/G395H transmission spectrum of the misaligned hot Jupiter HAT-P-30b from 2.8–5.2 μm as part of the BOWIE-ALIGN survey, a comparative survey designed to probe the link between planet formation and atmospheric composition in samples of misaligned and aligned hot Jupiters orbiting F-type stars. Through independent data reductions and retrieval analyses, we find evidence for absorption features of H₂O and C O₂ in the atmosphere of HAT-P-30 b. Our retrieved abundances are consistent with equilibrium chemistry, from which we infer a sub-solar C/O ratio (0.16–0.45), and sub-solar and sub-stellar metallicity (0.2–0.8×solar, compared to a stellar metallicity of 1.1–1.6×solar), with muted spectral features. This composition challenges formation models of continuous migration and accretion within a steady disc of stellar metallicity, and could be the result of low C/O ratio gas accretion within the water ice line, low metallicity accretion due to the trapping of volatiles further out in the disc, or the combined accretion of low metallicity gas and carbon-poor solids.
Date Issued
2026-03-01
Date Acceptance
2026-01-13
Citation
Monthly Notices of the Royal Astronomical Society, 2026, 546 (4)
ISSN
0035-8711
Publisher
Oxford University Press (OUP)
Journal / Book Title
Monthly Notices of the Royal Astronomical Society
Volume
546
Issue
4
Copyright Statement
© The Author(s) 2026. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
License URL
Publication Status
Published
Article Number
stag143
Date Publish Online
2026-01-21