The ¹³CO-rich atmosphere of a young accreting super-Jupiter
Abstract
Isotope abundance ratios have an important role in astronomy and planetary sciences, providing insights into the origin and evolution of the Solar System, interstellar chemistry and stellar nucleosynthesis. In contrast to deuterium/hydrogen ratios, carbon isotope ratios are found to be roughly constant (around 89) in the Solar System, but do vary on galactic scales with a ¹²C/¹³C isotopologue ratio of around 68 in the current local interstellar medium. In molecular clouds and protoplanetary disks, ¹²CO/¹³CO ratios can be altered by ice and gas partitioning, low-temperature isotopic ion-exchange reactions and isotope-selective photodissociation. Here we report observations of ¹³CO in the atmosphere of the young, accreting super-Jupiter TYC 8998-760-1 b, at a statistical significance of more than six sigma. Marginalizing over the planet's atmospheric temperature structure, chemical composition and spectral calibration uncertainties suggests a ¹²CO/¹³CO ratio of 31⁺¹⁷₋₁₀(90% confidence), a substantial enrichment in ¹³C with respect to the terrestrial standard and the local interstellar value. As the current location of TYC 8998-760-1 b at greater than or equal to 160 astronomical units is far beyond the CO snowline, we postulate that it accreted a substantial fraction of its carbon from ices enriched in ¹³C through fractionation.
Additional Information
© The Author(s), under exclusive licence to Springer Nature Limited 2021. Received 30 October 2020; Accepted 05 May 2021; Published 14 July 2021. We thank E. van Dishoeck, A. Cridland and A. Miotello for discussions on carbon fractionation in protoplanetary disks. We thank K. Chubb for a 13CO line list comparison. Based on observations collected at the European Southern Observatory (ESO) under ESO programme 2103.C-5012(C). Y.Z. and I.A.G.S. acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement number 694513. The research of A.J.B. and F.S. leading to these results has received funding from the European Research Council under ERC Starting Grant agreement 678194 (FALCONER). P.M. acknowledges support from the European Research Council under the European Union's Horizon 2020 research and innovation programme under grant agreement number 832428. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Data availability: The data are publicly available from the ESO Science Archive with the programme ID 2103.C-5012(C). Code availability: The data analysis was performed with custom Python scripts following the standard procedure. The code and reduced spectrum are available from https://gitlab.strw.leidenuniv.nl/yzhang/yses1b-sinfoni. The atmospheric retrieval models use petitRADTRANS, which is available from https://petitradtrans.readthedocs.io/, and the nested sampling tool PyMultiNest, which is available from https://johannesbuchner.github.io/PyMultiNest/. Author Contributions: Y.Z. and I.A.G.S. performed the data analysis and wrote the manuscript. A.J.B. led the SINFONI proposal, planned the observations and commented on the manuscript, and is the principal investigator of the Young Suns Exoplanet Survey (YSES) that led to the discovery of the TYC 8998 system. P.M. developed the retrieval models and assisted the data analysis. C.G., M.A.K., E.E.M., T.M., M.R. and F.S. constitute the core team of YSES, contributed to the SINFONI proposal and commented on the manuscript. H.J.H. helped the preparations of the observations and commented on the manuscript. The authors declare no competing interests. Peer review information: Nature thanks Drake Deming and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.Attached Files
Accepted Version - 2107.06297.pdf
Supplemental Material - 41586_2021_3616_Fig4_ESM.webp
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Additional details
- Alternative title
- The 13CO-rich atmosphere of a young accreting super-Jupiter
- Eprint ID
- 109915
- Resolver ID
- CaltechAUTHORS:20210719-203550633
- 694513
- European Research Council (ERC)
- 678194
- European Research Council (ERC)
- 832428
- European Research Council (ERC)
- NASA/JPL/Caltech
- Created
-
2021-07-19Created from EPrint's datestamp field
- Updated
-
2021-09-16Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)