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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742438.0, MPI für Astronomie / Publikationen_mpia
Detection of the atmosphere of the 1.6 MΘ exoplanet GJ 1132 b
Authors:Southworth, J.; Mancini, L.; Madhusudhan, N.; Mollière, P.; Ciceri, S.; Henning, T.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astronomical Journal
Issue / Number:4
Start Page:id. 191 (14 pp)
Audience:Not Specified
Abstract / Description: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}\oplus 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}\oplus for the planet, averaged over all the passbands, and a radius of 0.255 ± 0.023 {R}ȯ 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}\oplus 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}\oplus 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.
Free Keywords:planetary systems; stars: fundamental parameters; stars: individual: GJ 1132
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6256 %R 10.3847/1538-3881/aa6477
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