Atmospheric composition and circulation of the ultra-hot Jupiter WASP-121b with joint NIRPS, HARPS and CRIRES+ transit spectroscopy
Year: 2025
Type: preprint
Abstract: Ultra-hot Jupiters like WASP-121b provide unique laboratories for studying atmospheric chemistry and dynamics under extreme irradiation. Constraining their composition and circulation is key to tracing planet formation pathways. We present a comprehensive characterisation of WASP-121b using high-resolution transit spectroscopy from HARPS, NIRPS, and CRIRES+ across nine transits, complemented by five TESS sectors, two EulerCam light curves simultaneous with HARPS/NIRPS, and an extensive RV dataset refining orbital parameters. Cross-correlation detects Fe, CO, and V with SNRs of 5.8, 5.0, and 4.7, respectively. Retrieval analysis constrains H$_2$O to $-6.52^{+0.49}_{-0.68}$ dex, though its signal might be muted by the H$^-$ continuum. We measure volatile/refractory ratios, key to uncover planetary chemistry, evolution, and formation. Retrieved values align with solar composition in chemical equilibrium, suggesting minimal disequilibrium chemistry at the probed pressures (around $10^{-4}$-$10^{-3}$ bar). We update WASP-121b's orbital parameters analysing its largest RV dataset to date. Comparing orbital velocities from RVs and atmospheric retrieval reveals a non-zero circulation offset, $\mathrm{ΔK}_{\mathrm{p}} = -15 \pm 3 \ \mathrm{km}\mathrm{s}^{-1}$ (assuming $\mathrm{M}_{\star} = 1.38 \pm 0.02 \ \mathrm{M}_{\odot}$), consistent with drag-free or weak-drag 3D GCM predictions, though sensitive to stellar mass. These results provide new constraints on WASP-121b's thermal structure, dynamics, and chemistry, underscoring the power of multi-instrument and multi-wavelength high-resolution spectroscopy to probe exoplanet atmospheres.
Source: arXiv (Cornell University)
Authors: Vaulato, Valentina, Hobson, Melissa J., Allart, Romain, Pelletier, Stefan, Wardenier, Joost P., Chakraborty, Hritam, Ehrenreich, David, Nari, Nicola, Steiner, Michal, Dumusque, Xavier, Hoeijmakers, H. Jens, Artigau, Étienne, Baron, Frédérique, Barros, Susana C. C., Benneke, Björn, Bonfils, Xavier, Bouchy, François, Bryan, Marta, Martins, Bruno L. Canto, Cloutier, Ryan, Cook, Neil J., Cowan, Nicolas B., De Medeiros, Jose Renan, Delfosse, Xavier, Delgado-Mena, Elisa, Doyon, René, Hernández, Jonay I. González, Lafrenière, David, Leão, Izan de Castro, Lovis, Christophe, Malo, Lison, Melo, Claudio, Mignon, Lucile, Mordasini, Christoph, Pepe, Francesco, Rebolo, Rafael, Rowe, Jason, Santos, Nuno C., Ségransan, Damien, Mascareño, Alejandro Suárez, Udry, Stéphane, Valencia, Diana, Wade, Gregg, Aguiar, José L. A., Moulla, Khaled Al, Akinsanmi, Babatunde, Borsato, Nicholas W., Cadieux, Charles, Carteret, Yann, Silva, Ana Rita Costa, Cristo, Eduardo A. S., Forveille, Thierry, Frensch, Yolanda G. C., Gromek, Nicole, Lendl, Monika, Prinoth, Bibiana, Psaridi, Angelica, Stefanov, Atanas K., Thorsbro, Brian, Weisserman, Drew
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7080044841
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