H{sub 2}O ABUNDANCES IN THE ATMOSPHERES OF THREE HOT JUPITERS
- Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA (United Kingdom)
- Space Telescope Science Institute, Baltimore, MD 21218 (United States)
- Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
The core accretion theory for giant planet formation predicts enrichment of elemental abundances in planetary envelopes caused by runaway accretion of planetesimals, which is consistent with measured super-solar abundances of C, N, P, S, Xe, and Ar in Jupiter's atmosphere. However, the abundance of O, which is expected to be the most dominant constituent of planetesimals, is unknown for solar system giant planets, owing to the condensation of water in their ultra-cold atmospheres, thereby posing a key unknown in solar system formation. On the other hand, hundreds of extrasolar ''hot Jupiters'' are known with very high temperatures (≥1000 K), making them excellent targets to measure H{sub 2}O abundances and, hence, oxygen in their atmospheres. We constrain the atmospheric H{sub 2}O abundances in three hot Jupiters (HD 189733b, HD 209458b, and WASP-12b), spanning a wide temperature range (1200-2500 K), using their near-infrared transmission spectra obtained using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We report conclusive measurements of H{sub 2}O in HD 189733b and HD 209458b, while that in WASP-12b is not well constrained by present data. The data allow nearly solar as well as significantly sub-solar abundances in HD 189733b and WASP-12b. However, for HD 209458b, we report the most precise H{sub 2}O measurement in an exoplanet to date that suggests a ∼20-135 × sub-solar H{sub 2}O abundance. We discuss the implications of our results on the formation conditions of hot Jupiters and on the likelihood of clouds in their atmospheres. Our results highlight the critical importance of high-precision spectra of hot Jupiters for deriving their H{sub 2}O abundances.
- OSTI ID:
- 22365393
- Journal Information:
- Astrophysical Journal Letters, Vol. 791, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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