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This content will become publicly available on December 6, 2023

Title: Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-resolution Data
Abstract 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.
Authors:
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Award ID(s):
2143400
Publication Date:
NSF-PAR ID:
10399488
Journal Name:
The Astronomical Journal
Volume:
165
Issue:
1
Page Range or eLocation-ID:
4
ISSN:
0004-6256
Sponsoring Org:
National Science Foundation
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