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Detection of the Atmosphere of the 1.6 M Exoplanet GJ 1132 b

cam.issuedOnline2017-03-31
cam.orpheus.successTue Mar 31 10:43:16 BST 2020 - The item has an open VoR version.
dc.contributor.authorSouthworth, J
dc.contributor.authorMancini, L
dc.contributor.authorMadhusudhan, N
dc.contributor.authorMollière, P
dc.contributor.authorCiceri, S
dc.contributor.authorHenning, T
dc.contributor.orcidNikku, Madhusudhan [0000-0002-4869-000X]
dc.date.accessioned2018-09-05T12:48:21Z
dc.date.available2018-09-05T12:48:21Z
dc.date.issued2017-04-01
dc.description.abstract© 2017. The American Astronomical Society. All rights reserved. Detecting the atmospheres of low-mass, low-temperature exoplanets is a high-priority goal on the path to ultimately detecting biosignatures in the atmospheres of habitable exoplanets. High-precision HST observations of several super-Earths with equilibrium temperatures below 1000 K have to date all resulted in featureless transmission spectra, which have been suggested to be due to high-altitude clouds. We report the detection of an atmospheric feature in the atmosphere of a 1.6 M⊕ transiting exoplanet, GJ 1132 b, with an equilibrium temperature of ∼600 K and orbiting a nearby M dwarf. We present observations of nine transits of the planet obtained simultaneously in the griz and JHK passbands. We find an average radius of 1.43 ±0.16 R⊕ for the planet, averaged over all the passbands, and a radius of 0.255 ±0.023 R⊙for the star, both of which are significantly greater than previously found. The planet radius can be decomposed into a "surface radius" at ∼1.375 R⊕ overlaid by atmospheric features that increase the observed radius in the z and K bands. The z-band radius is 4σ higher than the continuum, suggesting a strong detection of an atmosphere. We deploy a suite of tests to verify the reliability of the transmission spectrum, which are greatly helped by the existence of repeat observations. The large z-band transit depth indicates strong opacity from H2O and/or CH4 or a hitherto-unconsidered opacity. A surface radius of 1.375 ±0.16 R⊕ allows for a wide range of interior compositions ranging from a nearly Earth-like rocky interior, with ∼70% silicate and ∼30% Fe, to a substantially H2O-rich water world.
dc.identifier.doi10.17863/CAM.26936
dc.identifier.eissn1538-3881
dc.identifier.issn0004-6256
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/279564
dc.language.isoeng
dc.publisherAmerican Astronomical Society
dc.publisher.urlhttp://dx.doi.org/10.3847/1538-3881/aa6477
dc.subjectplanetary systems
dc.subjectstars: fundamental parameters
dc.subjectstars: individual
dc.titleDetection of the Atmosphere of the 1.6 M<inf>⊕</inf> Exoplanet GJ 1132 b
dc.typeArticle
dcterms.dateAccepted2017-02-28
prism.issueIdentifier4
prism.publicationDate2017
prism.publicationNameAstronomical Journal
prism.volume153
pubs.funder-project-idScience and Technology Facilities Council (ST/N000927/1)
rioxxterms.licenseref.startdate2017-04-01
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.typeJournal Article/Review
rioxxterms.versionofrecord10.3847/1538-3881/aa6477

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