Large Interferometer For Exoplanets (LIFE): X. Detectability of currently known exoplanets and synergies with future IR/O/UV reflected-starlight imaging missions

Abstract

Context. The next generation of space-based observatories will characterize the atmospheres of low-mass, temperate exoplanets with the direct-imaging technique. This will be a major step forward in our understanding of exoplanet diversity and the prevalence of potentially habitable conditions beyond the Earth. Aims. We compute a list of currently known exoplanets detectable with the mid-infrared Large Interferometer For Exoplanets (LIFE) in thermal emission. We also compute the list of known exoplanets accessible to a notional design of the future Habitable Worlds Observatory (HWO), observing in reflected starlight. Methods. With a pre-existing statistical methodology, we processed the NASA Exoplanet Archive and computed orbital realizations for each known exoplanet. We derived their mass, radius, equilibrium temperature, and planet-star angular separation. We used the LIFEsim simulator to compute the integration time (tint) required to detect each planet with LIFE. A planet is considered detectable if a broadband signal-to-noise ratio S/N = 7 is achieved over the spectral range 4- 18.5 μm in tint < 100 h. We tested whether the planet is accessible to HWO in reflected starlight based on its notional inner and outer working angles, and minimum planet-to-star contrast. Results. LIFE's reference configuration (four 2-m telescopes with 5% throughput and a nulling baseline between 10- 100 m) can detect 212 known exoplanets within 20 pc. Of these, 49 are also accessible to HWO in reflected starlight, offering a unique opportunity for synergies in atmospheric characterization. LIFE can also detect 32 known transiting exoplanets. Furthermore, we find 38 LIFE-detectable planets orbiting in the habitable zone, of which 13 have Mp < 5M⊕ and eight have 5M⊕ < Mp < 10M⊕. Conclusions. LIFE already has enough targets to perform ground-breaking analyses of low-mass, habitable-zone exoplanets, a fraction of which will also be accessible to other instruments.