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The Metallicity and Carbon-to-oxygen Ratio of the Ultrahot Jupiter WASP-76b from Gemini-S/IGRINS

Articolo
Data di Pubblicazione:
2024
Abstract:
Measurements of the carbon-to-oxygen (C/O) ratios of exoplanet atmospheres can reveal details about their formation and evolution. Recently, high-resolution cross-correlation analysis has emerged as a method of precisely constraining the C/O ratios of hot Jupiter atmospheres. We present two transits of the ultrahot Jupiter WASP-76b observed between 1.4 and 2.4 mu m with the high-resolution Immersion GRating INfrared Spectrometer on the Gemini-S telescope. We detected the presence of H2O, CO, and OH at signal-to-noise ratios of 6.93, 6.47, and 3.90, respectively. We performed two retrievals on this data set. A free retrieval for abundances of these three species retrieved a volatile metallicity of C + O H = - 0.70 - 0.93 + 1.27 , consistent with the stellar value, and a supersolar carbon-to-oxygen ratio of C/O = 0.80 - 0.11 + 0.07 . We also ran a chemically self-consistent grid retrieval, which agreed with the free retrieval within 1 sigma but favored a slightly more substellar metallicity and solar C/O ratio ( C + O H = - 0.74 - 0.17 + 0.23 and C/O = 0.59 - 0.14 + 0.13 ). A variety of formation pathways may explain the composition of WASP-76b. Additionally, we found systemic (V sys) and Keplerian (K p ) velocity offsets which were broadly consistent with expectations from 3D general circulation models of WASP-76b, with the exception of a redshifted V sys for H2O. Future observations to measure the phase-dependent velocity offsets and limb differences at high resolution on WASP-76b will be necessary to understand the H2O velocity shift. Finally, we find that the population of exoplanets with precisely constrained C/O ratios generally trends toward super-solar C/O ratios. More results from high-resolution observations or JWST will serve to further elucidate any population-level trends.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Weiner Mansfield, Megan; Line, Michael R.; Wardenier, Joost P.; Brogi, Matteo; Bean, Jacob L.; Beltz, Hayley; Smith, Peter; Zalesky, Joseph A.; Batalha, Natasha; Kempton, Eliza M.-R.; Montet, Benjamin T.; Owen, James E.; Plavchan, Peter; Rauscher, Emily
Autori di Ateneo:
BROGI Matteo
Link alla scheda completa:
https://iris.unito.it/handle/2318/2024030
Pubblicato in:
THE ASTRONOMICAL JOURNAL
Journal
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Settori (2)


PE9_3 - Exoplanetary science, formation and characterization of extrasolar planets - (2024)

SCIENZE MATEMATICHE, CHIMICHE, FISICHE - Cosmologia e Universo
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