IGRINS observations of WASP-127 b: H$_2$O, CO, and super-Solar atmospheric metallicity in the inflated sub-Saturn

Krishna Kanumalla; Michael R. Line; Megan Weiner Mansfield; Luis Welbanks; Peter C. B. Smith; Jacob L. Bean; Lorenzo Pino; Matteo Brogi; Vatsal Panwar

doi:10.3847/1538-3881/ad72f3

paper

IGRINS observations of WASP-127 b: H $_{2}$ O, CO, and super-Solar atmospheric metallicity in the inflated sub-Saturn

arXiv:2406.14072 · doi:10.3847/1538-3881/ad72f3

Abstract

High resolution spectroscopy of exoplanet atmospheres provides insights into their composition and dynamics from the resolved line shape and depth of thousands of spectral lines. WASP-127 b is an extremely inflated sub-Saturn (R $_{p}$ = 1.311 R $_{Jup}$ , M $_{p}$ = 0.16 M $_{Jup}$ ) with previously reported detections of H $_{2}$ O, CO $_{2}$ , and Na. However, the seeming absence of the primary carbon reservoir expected at WASP-127 b temperatures (T $_{e q}$ $\sim$ 1400 K) from chemical equilibrium, CO, posed a mystery. In this manuscript, we present the analysis of high resolution observations of WASP-127 b with the Immersion GRating INfrared Spectrometer (IGRINS) on Gemini South. We confirm the presence of H $_{2}$ O (8.67 $σ$ ) and report the detection of CO (4.34 $σ$ ). Additionally, we conduct a suite of Bayesian retrieval analyses covering a hierarchy of model complexity and self-consistency. When freely fitting for the molecular gas volume mixing ratios, we obtain super-solar metal enrichment for H $_{2}$ O abundance of log $_{10}$ X $_{H_{2} O}$ = --1.23 $_{- 0.49}^{+ 0.29}$ and a lower limit on the CO abundance of log $_{10}$ X $_{CO}$ $\geq$ --2.20 at 2 $σ$ confidence. We also report a tentative evidence of photochemistry in WASP-127 b based upon the indicative depletion of H $_{2}$ S. This is also supported by the data preferring models with photochemistry over free-chemistry and thermochemistry. The overall analysis implies a super-solar ( $\sim$ 39 $\times$ Solar; [M/H] = $1.5 9_{- 0.30}^{+ 0.30}$ ) metallicity for the atmosphere of WASP-127 b and an upper limit on its atmospheric C/O ratio as $<$ 0.68.

18 pages, 15 figures, submitted to AJ, poster at Exo5 conference area-A

IGRINS observations of WASP-127 b: H $_{2}$ O, CO, and super-Solar atmospheric metallicity in the inflated sub-Saturn

Abstract

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IGRINS observations of WASP-127 b: H2​O, CO, and super-Solar atmospheric metallicity in the inflated sub-Saturn

Abstract

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Cited by in corpus (6)

IGRINS observations of WASP-127 b: H $_{2}$ O, CO, and super-Solar atmospheric metallicity in the inflated sub-Saturn