TY - JOUR
T1 - Atmospheric carbon depletion as a tracer of water oceans and biomass on temperate terrestrial exoplanets
AU - Triaud, Amaury H.M.J.
AU - de Wit, Julien
AU - Klein, Frieder
AU - Turbet, Martin
AU - Rackham, Benjamin V.
AU - Niraula, Prajwal
AU - Glidden, Ana
AU - Jagoutz, Oliver E.
AU - Peč, Matej
AU - Petkowski, Janusz J.
AU - Seager, Sara
AU - Selsis, Franck
N1 - Publisher Copyright:
© 2023, Springer Nature Limited.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - The conventional observables to identify a habitable or inhabited environment in exoplanets, such as an ocean glint or abundant atmospheric O2, will be challenging to detect with present or upcoming observatories. Here we suggest a new signature. A low carbon abundance in the atmosphere of a temperate rocky planet, relative to other planets of the same system, traces the presence of a substantial amount of liquid water, plate tectonics and/or biomass. Here we show that JWST can already perform such a search in some selected systems such as TRAPPIST-1 via the CO2 band at 4.3 μm, which falls in a spectral sweet spot where the overall noise budget and the effect of cloud and/or hazes are optimal. We propose a three-step strategy for transiting exoplanets: detection of an atmosphere around temperate terrestrial planets in about 10 transits for the most favourable systems; assessment of atmospheric carbon depletion in about 40 transits; and measurements of O3 abundance to disentangle between a water- versus biomass-supported carbon depletion in about 100 transits. The concept of carbon depletion as a signature for habitability is also applicable for next-generation direct-imaging telescopes.
AB - The conventional observables to identify a habitable or inhabited environment in exoplanets, such as an ocean glint or abundant atmospheric O2, will be challenging to detect with present or upcoming observatories. Here we suggest a new signature. A low carbon abundance in the atmosphere of a temperate rocky planet, relative to other planets of the same system, traces the presence of a substantial amount of liquid water, plate tectonics and/or biomass. Here we show that JWST can already perform such a search in some selected systems such as TRAPPIST-1 via the CO2 band at 4.3 μm, which falls in a spectral sweet spot where the overall noise budget and the effect of cloud and/or hazes are optimal. We propose a three-step strategy for transiting exoplanets: detection of an atmosphere around temperate terrestrial planets in about 10 transits for the most favourable systems; assessment of atmospheric carbon depletion in about 40 transits; and measurements of O3 abundance to disentangle between a water- versus biomass-supported carbon depletion in about 100 transits. The concept of carbon depletion as a signature for habitability is also applicable for next-generation direct-imaging telescopes.
U2 - 10.1038/s41550-023-02157-9
DO - 10.1038/s41550-023-02157-9
M3 - Article
AN - SCOPUS:85180909098
SN - 2397-3366
VL - 8
SP - 17
EP - 29
JO - Nature Astronomy
JF - Nature Astronomy
IS - 1
ER -