SiO and a super-stellar C/O ratio in the atmosphere of the giant exoplanet WASP-121b

Fuente: arXiv
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Main Authors: Evans-Soma, Thomas M., Sing, David K., Barstow, Joanna K., Piette, Anjali A. A., Taylor, Jake, Lothringer, Joshua D., Reggiani, Henrique, Goyal, Jayesh M., Ahrer, Eva-Maria, Mayne, Nathan J., Rustamkulov, Zafar, Kataria, Tiffany, Christie, Duncan A., Gapp, Cyril, Dong, Jiayin, Foreman-Mackey, Daniel, Hattori, Soichiro, Marley, Mark S.
Format: Preprint
Published: 2025
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author Evans-Soma, Thomas M.
Sing, David K.
Barstow, Joanna K.
Piette, Anjali A. A.
Taylor, Jake
Lothringer, Joshua D.
Reggiani, Henrique
Goyal, Jayesh M.
Ahrer, Eva-Maria
Mayne, Nathan J.
Rustamkulov, Zafar
Kataria, Tiffany
Christie, Duncan A.
Gapp, Cyril
Dong, Jiayin
Foreman-Mackey, Daniel
Hattori, Soichiro
Marley, Mark S.
author_facet Evans-Soma, Thomas M.
Sing, David K.
Barstow, Joanna K.
Piette, Anjali A. A.
Taylor, Jake
Lothringer, Joshua D.
Reggiani, Henrique
Goyal, Jayesh M.
Ahrer, Eva-Maria
Mayne, Nathan J.
Rustamkulov, Zafar
Kataria, Tiffany
Christie, Duncan A.
Gapp, Cyril
Dong, Jiayin
Foreman-Mackey, Daniel
Hattori, Soichiro
Marley, Mark S.
contents Refractory elements such as iron, magnesium, and silicon can be detected in the atmospheres of ultrahot giant planets. This provides an opportunity to quantify the amount of refractory material accreted during formation, along with volatile gases and ices. However, simultaneous detections of refractories and volatiles have proved challenging, as the most prominent spectral features of associated atoms and molecules span a broad wavelength range. Here, using a single JWST observation of the ultrahot giant planet WASP-121b, we report detections of H$_2$O (5.5-13.5$σ$), CO (10.8-12.8$σ$), and SiO (5.7-6.2$σ$) in the planet's dayside atmosphere, and CH$_4$ (3.1-5.1$σ$) in the nightside atmosphere. We measure super-stellar values for the atmospheric C/H, O/H, Si/H, and C/O ratios, which point to the joint importance of pebbles and planetesimals in giant planet formation. The CH$_4$-rich nightside composition is also indicative of dynamical processes, such as strong vertical mixing, having a profound influence on the chemistry of ultrahot giant planets.
format Preprint
id arxiv_https___arxiv_org_abs_2506_01771
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SiO and a super-stellar C/O ratio in the atmosphere of the giant exoplanet WASP-121b
Evans-Soma, Thomas M.
Sing, David K.
Barstow, Joanna K.
Piette, Anjali A. A.
Taylor, Jake
Lothringer, Joshua D.
Reggiani, Henrique
Goyal, Jayesh M.
Ahrer, Eva-Maria
Mayne, Nathan J.
Rustamkulov, Zafar
Kataria, Tiffany
Christie, Duncan A.
Gapp, Cyril
Dong, Jiayin
Foreman-Mackey, Daniel
Hattori, Soichiro
Marley, Mark S.
Earth and Planetary Astrophysics
Refractory elements such as iron, magnesium, and silicon can be detected in the atmospheres of ultrahot giant planets. This provides an opportunity to quantify the amount of refractory material accreted during formation, along with volatile gases and ices. However, simultaneous detections of refractories and volatiles have proved challenging, as the most prominent spectral features of associated atoms and molecules span a broad wavelength range. Here, using a single JWST observation of the ultrahot giant planet WASP-121b, we report detections of H$_2$O (5.5-13.5$σ$), CO (10.8-12.8$σ$), and SiO (5.7-6.2$σ$) in the planet's dayside atmosphere, and CH$_4$ (3.1-5.1$σ$) in the nightside atmosphere. We measure super-stellar values for the atmospheric C/H, O/H, Si/H, and C/O ratios, which point to the joint importance of pebbles and planetesimals in giant planet formation. The CH$_4$-rich nightside composition is also indicative of dynamical processes, such as strong vertical mixing, having a profound influence on the chemistry of ultrahot giant planets.
title SiO and a super-stellar C/O ratio in the atmosphere of the giant exoplanet WASP-121b
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2506.01771