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Telling twins apart: exo-Earths and Venuses with transit spectroscopy

Barstow, JK; Aigrain, S; Irwin, PGJ; Kendrew, S; Fletcher, LN; (2016) Telling twins apart: exo-Earths and Venuses with transit spectroscopy. Monthly Notices of the Royal Astronomical Society , 458 (3) pp. 2657-2666. 10.1093/mnras/stw489. Green open access

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The planned launch of the James Webb Space Telescope (JWST) in 2018 will herald a new era of exoplanet spectroscopy. JWST will be the first telescope sensitive enough to potentially characterize terrestrial planets from their transmission spectra. In this work, we explore the possibility that terrestrial planets with Venus-type and Earth-type atmospheres could be distinguished from each other using spectra obtained by JWST. If we find a terrestrial planet close to the liquid water habitable zone of an M5 star within a distance of 10 parsec, it would be possible to detect atmospheric ozone if present in large enough quantities, which would enable an oxygen-rich atmosphere to be identified. However, the cloudiness of a Venus-type atmosphere would inhibit our ability to draw firm conclusions about the atmospheric composition, making any result ambiguous. Observing small, temperate planets with JWST requires significant investment of resources, with single targets requiring of the order of 100 transits to achieve sufficient signal to noise. The possibility of detecting a crucial feature such as the ozone signature would need to be carefully weighed against the likelihood of clouds obscuring gas absorption in the spectrum.

Type: Article
Title: Telling twins apart: exo-Earths and Venuses with transit spectroscopy
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stw489
Publisher version: https://doi.org/10.1093/mnras/stw489
Language: English
Additional information: Radiative transfer, methods: data analysis, planets and satellites: atmospheres
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, Radiative Transfer, Methods: Data Analysis, Planets And Satellites: Atmospheres, Webb-Space-Telescope, Habitable Zone, HD 189733B, GJ 1214B, Atmospheres, Planets, Oxygen, Retrieval, Biosignatures, Absorption
URI: http://discovery.ucl.ac.uk/id/eprint/10054179
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