Produção Nacional
Revisado por pares
Where Is the Water? Jupiter-like C/H Ratio but Strong H 2 O Depletion Found on τ Boötis b Using SPIRou
2021; Institute of Physics; Volume: 162; Issue: 2 Linguagem: Inglês
10.3847/1538-3881/ac0428
ISSN1538-3881
AutoresStefan Pelletier, Björn Benneke, Antoine Darveau-Bernier, Anne Boucher, Neil J. Cook, Caroline Piaulet, Louis-Philippe Coulombe, Étienne Artigau, David Lafrenière, Simon Delisle, R. Allart, René Doyon, J.‐F. Donati, P. Fouqué, C. Moutou, Charles Cadieux, X. Delfosse, G. Hébrard, J. H. C. Martins, Eder Martioli, Thomas Vandal,
Tópico(s)Spectroscopy and Laser Applications
ResumoAbstract The present-day envelope of gaseous planets is a relic of how these giant planets originated and evolved. Measuring their elemental composition therefore presents a powerful opportunity to answer long-standing questions regarding planet formation. Obtaining precise observational constraints on the elemental inventory of giant exoplanets has, however, remained challenging owing to the limited simultaneous wavelength coverage of current space-based instruments. Here, we present thermal emission observations of the nontransiting hot Jupiter τ Boo b using the new wide wavelength coverage (0.95–2.50 μ m) and high spectral resolution ( R = 70,000) CFHT/SPIRou spectrograph. By combining a total of 20 hr of SPIRou data obtained over five nights in a full atmospheric retrieval framework designed for high-resolution data, we constrain the abundances of all the major oxygen- and carbon-bearing molecules and recover a noninverted temperature structure using a new free-shape, nonparametric temperature–pressure profile retrieval approach. We find a volume mixing ratio of log(CO) = − <?CDATA ${2.46}_{-0.29}^{+0.25}$?> 2.46 − 0.29 + 0.25 and a highly depleted water abundance of less than 0.0072 times the expected value for a solar composition envelope. Combined with upper limits on the abundances of CH 4 , CO 2 , HCN, TiO, and C 2 H 2 , this results in a gas-phase C/H ratio of <?CDATA ${5.85}_{-2.82}^{+4.44}$?> 5.85 − 2.82 + 4.44 × solar, consistent with the value of Jupiter, and an envelope C/O ratio robustly greater than 0.60, even when taking into account the oxygen that may be sequestered out of the gas phase. Combined, the inferred supersolar C/H, O/H, and C/O ratios on τ Boo b support a formation scenario beyond the water snowline in a disk enriched in CO owing to pebble drift.
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