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Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-resolution Data

Wang, Ji and Wang, Jason J. and Ruffio, Jean-Baptiste and Blake, Geoffrey A. and Mawet, Dimitri and Baker, Ashley and Bartos, Randall and Bond, Charlotte Z. and Calvin, Benjamin and Cetre, Sylvain and Delorme, Jacques-Robert and Doppmann, Greg and Echeverri, Daniel and Finnerty, Luke and Fitzgerald, Michael P. and Jovanovic, Nemanja and Lopez, Ronald and Martin, Emily C. and Morris, Evan and Pezzato, Jacklyn and Ragland, Sam and Ruane, Garreth and Sappey, Ben and Schofield, Tobias and Skemer, Andrew and Venenciano, Taylor and Wallace, J. Kent and Wizinowich, Peter and Xuan, Jerry W. and Bryan, Marta L. and Roy, Arpita and Wallack, Nicole L. (2023) Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-resolution Data. Astronomical Journal, 165 (1). Art. No. 4. ISSN 0004-6256. doi:10.3847/1538-3881/ac9f19.

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The formation and evolution pathway for the directly imaged multiplanetary system HR 8799 remains mysterious. Accurate constraints on the chemical composition of the planetary atmosphere(s) are key to solving the mystery. We perform a detailed atmospheric retrieval on HR 8799 c to infer the chemical abundances and abundance ratios using a combination of photometric data along with low- and high-resolution spectroscopic data (R ∼ 20–35,000). We specifically retrieve [C/H], [O/H], and C/O and find them to be 0.55_(-0.39)^(+0.36), 0.47_(-0.32)^(+0.31), and 0.67_(-0.15)^(+0.12) at 68% confidence. The superstellar C and O abundances, yet a stellar C/O ratio, reveal a potential formation pathway for HR 8799 c. Planet c, and likely the other gas giant planets in the system, formed early on (likely within ∼1 Myr), followed by further atmospheric enrichment in C and O through the accretion of solids beyond the CO ice line. The enrichment either preceded or took place during the early phase of the inward migration to the current planet locations.

Item Type:Article
Related URLs:
URLURL TypeDescription
Wang, Ji0000-0002-4361-8885
Wang, Jason J.0000-0003-0774-6502
Ruffio, Jean-Baptiste0000-0003-2233-4821
Blake, Geoffrey A.0000-0003-0787-1610
Mawet, Dimitri0000-0002-8895-4735
Baker, Ashley0000-0002-6525-7013
Calvin, Benjamin0000-0003-4737-5486
Delorme, Jacques-Robert0000-0001-8953-1008
Echeverri, Daniel0000-0002-1583-2040
Finnerty, Luke0000-0002-1392-0768
Fitzgerald, Michael P.0000-0002-0176-8973
Jovanovic, Nemanja0000-0001-5213-6207
Martin, Emily C.0000-0002-0618-5128
Pezzato, Jacklyn0000-0002-6769-2035
Ragland, Sam0000-0002-0696-1780
Ruane, Garreth0000-0003-4769-1665
Sappey, Ben0000-0003-1399-3593
Skemer, Andrew0000-0001-6098-3924
Wallace, J. Kent0000-0001-5299-6899
Wizinowich, Peter0000-0002-1646-442X
Xuan, Jerry W.0000-0002-6618-1137
Bryan, Marta L.0000-0002-6076-5967
Roy, Arpita0000-0001-8127-5775
Wallack, Nicole L.0000-0003-0354-0187
Additional Information:This work is supported by the National Science Foundation under grant No. 2143400. We thank Andrew Youdin, Joan Najita, and Kaitlin Kratter for insightful discussions on gravitational instability versus pebble accretion. We thank the anonymous referee for constructive comments and suggestions that significantly improved the Paper. Funding for KPIC has been provided by the California Institute of Technology, the Jet Propulsion Laboratory, the Heising-Simons Foundation (grant Nos. 2015-129, 2017-318, and 2019-1312), the Simons Foundation (through the Caltech Center for Comparative Planetary Evolution), and NSF under grant AST-1611623. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We thank the Heising-Simons Foundation for supporting the workshop on combining high-resolution spectroscopy and high-contrast imaging for exoplanet characterization, where the idea originated on combining photometric data and spectral data of different resolutions.
Group:Astronomy Department, Division of Geological and Planetary Sciences, Caltech Center for Comparative Planetary Evolution
Funding AgencyGrant Number
Heising-Simons Foundation2015-129
Heising-Simons Foundation2017-318
Heising-Simons Foundation2019-1312
Simons FoundationUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20221221-398072700.2
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118578
Deposited By: Research Services Depository
Deposited On:25 Jan 2023 16:26
Last Modified:25 Jan 2023 18:25

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