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Journal Articles Experimental Astronomy Year : 2021

Observability of temperate exoplanets with Ariel

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While the Ariel mission is primarily designed for the study of warm and hot objects, with an equilibrium temperature above 500 K, in this paper we want to explore a larger sample of possible colder targets. We thus investigate the detectability with Ariel of “temperate” exoplanets (with an equilibrium temperature of 400 K). We first consider the case of hydrogen-rich exoplanets (from Jupiters to sub-Neptunes) and we calculate their infrared transmission spectrum for several classes of stars. We consider the Tier 2 mode of Ariel, for which the resolving power (R = 50 for λ < 4 μm and R = 15 for λ > 4 μm) is sufficient to get information about the chemical composition of the objects. Results show that temperate Jupiters and sub-Neptunes around all types of stars from G2 to M8, with revolution periods of a few tens of days and transit durations of a few hours, could be observed with Ariel, up to distances of about 50 pc for Jupiters and 25 pc for sub-Neptunes. In the case of temperate super-Earths, we estimate that they will not be observable in the Ariel Tier 2 mode. In a study of currently available target candidates, we find one sub-Neptune (TOI-178 g) as possibly observable in Ariel’s Tier 2. This on-going study is a follow-up of “Transit spectroscopy of temperate Jupiters with ARIEL: A feasibility study” (Encrenaz et al., Exp. Astr. 46:31–44, 2018).
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Dates and versions

insu-03341114 , version 1 (10-09-2021)



Thérèse Encrenaz, Athena Coustenis, G. Gilli, Emmanuel Marcq, Karan Molaverdikhani, et al.. Observability of temperate exoplanets with Ariel. Experimental Astronomy, 2021, 53, pp.375-390. ⟨10.1007/s10686-021-09793-x⟩. ⟨insu-03341114⟩
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