@article{b6318626374a49e6953c87b41b406567,
title = "A solar C/O and sub-solar metallicity in a hot Jupiter atmosphere",
abstract = "Measurements of the atmospheric carbon (C) and oxygen (O) relative to hydrogen (H) in hot Jupiters (relative to their host stars) provide insight into their formation location and subsequent orbital migration1,2. Hot Jupiters that form beyond the major volatile (H2O/CO/CO2) ice lines and subsequently migrate post disk-dissipation are predicted have atmospheric carbon-to-oxygen ratios (C/O) near 1 and subsolar metallicities2, whereas planets that migrate through the disk before dissipation are predicted to be heavily polluted by infalling O-rich icy planetesimals, resulting in C/O < 0.5 and super-solar metallicities1,2. Previous observations of hot Jupiters have been able to provide bounded constraints on either H2O (refs. 3–5) or CO (refs. 6,7), but not both for the same planet, leaving uncertain4 the true elemental C and O inventory and subsequent C/O and metallicity determinations. Here we report spectroscopic observations of a typical transiting hot Jupiter, WASP-77Ab. From these, we determine the atmospheric gas volume mixing ratio constraints on both H2O and CO (9.5 × 10−5–1.5 × 10−4 and 1.2 × 10−4–2.6 × 10−4, respectively). From these bounded constraints, we are able to derive the atmospheric C/H (0.35−0.10+0.17 × solar) and O/H (0.32−0.08+0.12 × solar) abundances and the corresponding atmospheric carbon-to-oxygen ratio (C/O = 0.59 ± 0.08; the solar value is 0.55). The sub-solar (C+O)/H (0.33−0.09+0.13 × solar) is suggestive of a metal-depleted atmosphere relative to what is expected for Jovian-like planets1 while the near solar value of C/O rules out the disk-free migration/C-rich2 atmosphere scenario.",
author = "Line, {Michael R.} and Matteo Brogi and Bean, {Jacob L.} and Siddharth Gandhi and Joseph Zalesky and Vivien Parmentier and Peter Smith and Mace, {Gregory N.} and Megan Mansfield and Kempton, {Eliza M.R.} and Fortney, {Jonathan J.} and Evgenya Shkolnik and Jennifer Patience and Emily Rauscher and D{\'e}sert, {Jean Michel} and Wardenier, {Joost P.}",
note = "Funding Information: Acknowledgements M.R.L., J.J.F., J.L.B. and P.S. acknowledge support from NASA XRP grant 80NSSC19K0293. M.R.L. and E.S. acknowledge support from the Nexus for Exoplanet System Science and NASA Astrobiology Institute Virtual Planetary Laboratory (no. 80NSSC18K0829). M.B. and S.G. acknowledge support from the UK Science and Technology Facilities Council (STFC) research grant ST/S000631/1. J.Z. acknowledges support from the NASA FINESST grant 80NSSC19K1420. E.M.-R.K. and E.R. thank the Heising-Simons Foundation for support. J.P.W. acknowledges support from the Wolfson Harrison UK Research Council Physics Scholarship and the UK Science and Technology Facilities Council (STFC). This work used the Immersion Grating Infrared Spectrometer (IGRINS) that was developed under a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI) with the financial support of the Mount Cuba Astronomical Foundation, of the US National Science Foundation under grants AST-1229522 and AST-1702267, of the McDonald Observatory of the University of Texas at Austin, of the Korean GMT Project of KASI, and Gemini Observatory. This program, GS-2020B-Q-249, is based on observations obtained at the international Gemini Observatory, a program of NSF{\textquoteright}s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigaci{\'o}n y Desarrollo (Chile), Ministerio de Ciencia, Tecnolog{\'i}a e Innovaci{\'o}n (Argentina), Minist{\'e}rio da Ci{\^e}ncia, Tecnologia, Inova{\c c}{\~o}es e Comunica{\c c}{\~o}es (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). Finally, we acknowledge Research Computing at Arizona State University for providing HPC and storage resources that have significantly contributed to the research results reported within this manuscript. Publisher Copyright: {\textcopyright} 2021, The Author(s), under exclusive licence to Springer Nature Limited.",
year = "2021",
month = oct,
day = "28",
doi = "10.1038/s41586-021-03912-6",
language = "English (US)",
volume = "598",
pages = "580--584",
journal = "Nature",
issn = "0028-0836",
publisher = "Nature Publishing Group",
number = "7882",
}