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dc.contributor.authorWakeford, HR
dc.contributor.authorLewis, NK
dc.contributor.authorFowler, J
dc.contributor.authorBruno, G
dc.contributor.authorWilson, TJ
dc.contributor.authorMoran, SE
dc.contributor.authorValenti, J
dc.contributor.authorBatalha, NE
dc.contributor.authorFilippazzo, J
dc.contributor.authorBourrier, V
dc.contributor.authorHörst, SM
dc.contributor.authorLederer, SM
dc.contributor.authorde Wit, J
dc.date.accessioned2022-01-18T19:29:35Z
dc.date.available2021-10-27T19:56:34Z
dc.date.available2022-01-18T19:29:35Z
dc.date.issued2018-12
dc.date.submitted2018-11
dc.identifier.issn1538-3881
dc.identifier.urihttps://hdl.handle.net/1721.1/133773.2
dc.description.abstract© 2018. The American Astronomical Society. All rights reserved. The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets because of the presence of strong molecular features in the stellar atmosphere. TRAPPIST-1 is an ultracool dwarf, host to seven transiting planets, and contains its own molecular signatures that can potentially be imprinted on planetary transit lightcurves as a result of inhomogeneities in the occulted stellar photosphere. We present a case study on TRAPPIST-1g, the largest planet in the system, using a new observation together with previous data, to disentangle the atmospheric transmission of the planet from that of the star. We use the out-of-transit stellar spectra to reconstruct the stellar flux on the basis of one, two, and three temperature components. We find that TRAPPIST-1 is a 0.08 M ∗, 0.117 R ∗, M8V star with a photospheric effective temperature of 2400 K, with ∼35% 3000 K spot coverage and a very small fraction, <3%, of ∼5800 K hot spot. We calculate a planetary radius for TRAPPIST-1g to be R p = 1.124 R ⊕with a planetary density of ρ p = 0.8214 ρ ⊕. On the basis of the stellar reconstruction, there are 11 plausible scenarios for the combined stellar photosphere and planet transit geometry; in our analysis, we are able to rule out eight of the 11 scenarios. Using planetary models, we evaluate the remaining scenarios with respect to the transmission spectrum of TRAPPIST-1g. We conclude that the planetary transmission spectrum is likely not contaminated by any stellar spectral features and are able to rule out a clear solar H2/He-dominated atmosphere at greater than 3σ.en_US
dc.language.isoen
dc.publisherAmerican Astronomical Societyen_US
dc.relation.isversionofhttp://dx.doi.org/10.3847/1538-3881/AAF04Den_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.sourceThe American Astronomical Societyen_US
dc.titleDisentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1gen_US
dc.typeArticleen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
dc.relation.journalAstronomical Journalen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dc.date.updated2021-09-14T18:00:45Z
dspace.orderedauthorsWakeford, HR; Lewis, NK; Fowler, J; Bruno, G; Wilson, TJ; Moran, SE; Valenti, J; Batalha, NE; Filippazzo, J; Bourrier, V; Hörst, SM; Lederer, SM; de Wit, Jen_US
dspace.date.submission2021-09-14T18:00:47Z
mit.journal.volume157en_US
mit.journal.issue1en_US
mit.licensePUBLISHER_POLICY
mit.metadata.statusAuthority Work Neededen_US


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