Show simple item record

dc.contributor.authorDesert, J.-M.
dc.contributor.authorLecavelier des Etangs, A.
dc.contributor.authorHebrard, G.
dc.contributor.authorSing, David K.
dc.contributor.authorEhrenreich, D.
dc.contributor.authorFerlet, R.
dc.contributor.authorVidal-Madjar, A.
dc.date.accessioned2014-12-17T13:55:30Z
dc.date.issued2009
dc.description.abstractWater, methane, and carbon monoxide are expected to be among the most abundant molecules besides molecular hydrogen in the hot atmosphere of close-in extrasolar giant planets. Atmospheric models for these planets predict that the strongest spectrophotometric features of those molecules are located at wavelengths ranging from 1 to 10 μm making this region of particular interest. Consequently, transit observations in the mid-infrared (mid-IR) allow the atmospheric content of transiting planets to be determined. We present new primary transit observations of the hot-Jupiter HD 189733b, obtained simultaneously at 4.5 and 8 μm with the Infrared Array Camera onboard the Spitzer Space Telescope. Together with a new refined analysis of previous observations at 3.6 and 5.8 μm using the same instrument, we are able to derive the system parameters, including planet-to-star radius ratio, impact parameter, scale of the system, and central time of the transit from fits of the transit light curves at these four wavelengths. We measure the four planet-to-star radius ratios, to be (Rp/R★)3.6 μm = 0.1545 ± 0.0003, (Rp/R★)4.5 μm = 0.1557 ± 0.0003, (Rp/R★)5.8 μm = 0.1547 ± 0.0005, and (Rp/R★)8 μm = 0.1544 ± 0.0004. The high accuracy of the planet radii measurement allows the search for atmospheric molecular absorbers. Contrary to a previous analysis of the same data set, our study is robust against systematics and reveals that water vapor absorption at 5.8 μm is not detected in this photometric data set. Furthermore, in the band centered around 4.5 μm we find a hint of excess absorption with an apparent planetary radius ΔRp /R * = 0.00128 ± 0.00056 larger (2.3σ) than the one measured simultaneously at 8 μm. This value is 4σ above what would be expected for an atmosphere where water vapor is the only absorbing species in the near-IR. This shows that an additional species absorbing around 4.5 μm could be present in the atmosphere. Carbon monoxide (CO) being a strong absorber at this wavelength is a possible candidate and this may suggest a large CO/H2O ratio between 5 and 60.en_GB
dc.description.sponsorshipCNESen_GB
dc.description.sponsorshipAgence Nationale pour la Rechercheen_GB
dc.identifier.citationVol. 699 (1), pp. 478-485en_GB
dc.identifier.doi10.1088/0004-637X/699/1/478
dc.identifier.grantnumberNT05-4_44463en_GB
dc.identifier.urihttp://hdl.handle.net/10871/16077
dc.language.isoenen_GB
dc.publisherIOP Publishing for American Astronomical Societyen_GB
dc.relation.urlhttp://dx.doi.org/10.1088/0004-637X/699/1/478en_GB
dc.subjecteclipsesen_GB
dc.subjectplanetary systemsen_GB
dc.subjectstars: individual (HD189733b)en_GB
dc.subjecttechniques: photometricen_GB
dc.titleSearch for Carbon Monoxide in the Atmosphere of the Transiting Exoplanet HD 189733ben_GB
dc.typeArticleen_GB
dc.date.available2014-12-17T13:55:30Z
dc.identifier.issn0004-637X
dc.descriptionCopyright © 2009 IOP Publishing / American Astronomical Societyen_GB
dc.identifier.eissn1538-4357
dc.identifier.journalAstrophysical Journalen_GB


Files in this item

This item appears in the following Collection(s)

Show simple item record