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dc.contributor.authorGibson, N. P.-
dc.contributor.authorAigrain, S.-
dc.contributor.authorBarstow, J. K.-
dc.contributor.authorEvans, T. M.-
dc.contributor.authorFletcher, L. N.-
dc.contributor.authorIrwin, P. G. J.-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society, 2013, 436 (4), pp. 2974-2988 (15)en
dc.description.abstractWe report Gemini-North Gemini Multi-Object Spectrograph observations of the inflated hot Jupiter HAT-P-32b during two primary transits. We simultaneously observed two comparison stars and used differential spectrophotometry to produce multiwavelength light curves. ‘White’ light curves and 29 ‘spectral’ light curves were extracted for each transit and analysed to refine the system parameters and produce transmission spectra from 520 to 930 nm in ≈14 nm bins. The light curves contain time-varying white noise as well as time-correlated noise, and we used a Gaussian process model to fit this complex noise model. Common mode corrections derived from the white light-curve fits were applied to the spectral light curves which significantly improved our precision, reaching typical uncertainties in the transit depth of ∼2 × 10−4, corresponding to about half a pressure scale height. The low-resolution transmission spectra are consistent with a featureless model, and we can confidently rule out broad features larger than about one scale height. The absence of Na/K wings or prominent TiO/VO features is most easily explained by grey absorption from clouds in the upper atmosphere, masking the spectral features. However, we cannot confidently rule out clear atmosphere models with low abundances (∼10−3 solar) of TiO, VO or even metal hydrides masking the Na and K wings. A smaller scale height or ionization could also contribute to muted spectral features, but alone are unable to account for the absence of features reported here.en
dc.description.sponsorshipJKB acknowledges the support of the John Fell Oxford University Press (OUP) Research Fund for this research. We are extremely grateful for the support provided by the Gemini staff. This work is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil) and CONICET (Argentina).en
dc.publisherOxford University Press (OUP), Royal Astronomical Societyen
dc.rightsCopyright © 2013, Oxford University Press (OUP), Royal Astronomical Society. Deposited with reference to the publisher’s open access archiving policy.en
dc.subjectScience & Technologyen
dc.subjectPhysical Sciencesen
dc.subjectAstronomy & Astrophysicsen
dc.subjectmethods: data analysisen
dc.subjecttechniques: spectroscopicen
dc.subjectstars: individual: HAT-P-32en
dc.subjectplanetary systemsen
dc.subjecttechniques: Gaussian processesen
dc.subjectEXOPLANET HD 189733Ben
dc.subjectGJ 1214Ben
dc.subjectLIGHT CURVESen
dc.titleThe optical transmission spectrum of the hot Jupiter HAT-P-32b: clouds explain the absence of broad spectral features?en
dc.typeJournal Articleen
dc.description.versionPublisher Versionen
pubs.organisational-group/Organisation/COLLEGE OF SCIENCE AND ENGINEERINGen
pubs.organisational-group/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomyen
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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