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Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3

Damiano, M; Morello, G; Tsiaras, A; Zingales, T; Tinetti, G; (2017) Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3. The Astronomical Journal , 154 (1) , Article 39. 10.3847/1538-3881/aa738b. Green open access

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Abstract

We report here the analysis of the near-infrared transit spectrum of the hot Jupiter HAT-P-32b, which was recorded with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. HAT-P-32b is one of the most inflated exoplanets discovered, making it an excellent candidate for transit spectroscopic measurements. To obtain the transit spectrum, we have adopted different analysis methods, both parametric and non-parametric (Independent Component Analysis, ICA), and compared the results. The final spectra are all consistent within 0.5σ. The uncertainties obtained with ICA are larger than those obtained with the parametric method by a factor of ∼1.6–1.8. This difference is the tradeoff for higher objectivity due to the lack of any assumption about the instrument systematics compared to the parametric approach. The ICA error bars are therefore worst-case estimates. To interpret the spectrum of HAT-P-32b we used  -REx, our fully Bayesian spectral retrieval code. As for other hot Jupiters, the results are consistent with the presence of water vapor (log H O 3.45 2 1.65 1.83 = - - + ), clouds (top pressure between 5.16 and 1.73 bar). Spectroscopic data over a broader wavelength range are needed to de-correlate the mixing ratio of water vapor from clouds and identify other possible molecular species in the atmosphere of HAT-P-32b.

Type: Article
Title: Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-3881/aa738b
Publisher version: http://dx.doi.org/10.3847/1538-3881/aa738b
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, methods: data analysis, planets and satellites: atmospheres, planets and satellites: individual (HAT-P-32 b), techniques: spectroscopic, INDEPENDENT COMPONENT ANALYSIS, HUBBLE-SPACE-TELESCOPE, EXOMOL LINE LISTS, EXTRASOLAR PLANET ATMOSPHERE, HD 189733B, EXOPLANET ATMOSPHERE, TRANSIT OBSERVATIONS, WATER ABUNDANCE, HOT, ABSORPTION
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/1569170
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