Retrieval Survey of Metals in Six Ultrahot Jupiters: Trends in Chemistry, Rain-out, Ionization, and Atmospheric Dynamics
Abstract
Ground-based high-resolution spectroscopy (HRS) has detected numerous chemical species and atmospheric dynamics in exoplanets, most notably ultrahot Jupiters (UHJs). However, quantitative estimates on abundances have been challenging but are essential for accurate comparative characterization and to determine formation scenarios. In this work, we retrieve the atmospheres of six UHJs (WASP-76 b, MASCARA-4 b, MASCARA-2 b, WASP-121 b, HAT-P-70 b, and WASP-189 b) with ESPRESSO and HARPS-N/HARPS observations, exploring trends in eleven neutral species and dynamics. While Fe abundances agree well with stellar values, Mg, Ni, Cr, Mn, and V show more variation, highlighting the difficulty in using a single species as a proxy for metallicity. We find that Ca, Na, Ti, and TiO are underabundant, potentially due to ionization and/or nightside rain-out. Our retrievals also show that relative abundances between species are more robust, consistent with previous works. We perform spatially resolved and phase-resolved retrievals for WASP-76 b and WASP-121 b given their high signal-to-noise observations, and find the chemical abundances in each of the terminator regions are broadly consistent. We additionally constrain dynamics for our sample through Doppler shifts and broadening of the planetary signals during the primary eclipse, with median blueshifts between ∼0.9 and 9.0 km s⁻¹ due to day–night winds. Furthermore, we constrain spectroscopic masses for MASCARA-2 b and HAT-P-70 b consistent with their known upper limits, but we note that these may be biased due to degeneracies. This work highlights the importance of future HRS studies to further probe differences and trends between exoplanets.
Additional Information
© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. S.G. is grateful to Leiden Observatory at Leiden University for the award of the Oort Fellowship. This work was performed using the computer resources from the Academic Leiden Interdisciplinary Cluster Environment (ALICE) provided by Leiden University. We also utilize the Avon high-performance computing cluster managed by the Scientific Computing Research Technology Platform (SCRTP) at the University of Warwick. Y.Z. and I.S. acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No. 694513. M.B. acknowledges support from the STFC research grant ST/T000406/1. N.P.G. and C.M. gratefully acknowledge support from Science Foundation Ireland and the Royal Society via a University Research Fellowship and Enhancement Award. We thank the anonymous referee for a careful review of our manuscript. Facilities: VLT (ESPRESSO) - , TNG (HARPS-N) - , La Silla (HARPS). -Attached Files
Published - Gandhi_2023_AJ_165_242.pdf
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Additional details
- Eprint ID
- 121623
- Resolver ID
- CaltechAUTHORS:20230530-441768000.56
- Leiden University
- 694513
- European Research Council (ERC)
- ST/T000406/1
- Science and Technology Facilities Council (STFC)
- Science Foundation, Ireland
- Royal Society
- Created
-
2023-07-14Created from EPrint's datestamp field
- Updated
-
2023-07-14Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)