Large Interferometer For Exoplanets (LIFE)

X. Detectability of currently known exoplanets and synergies with future IR/O/UV reflected-starlight imaging missions^★

¹ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, 5 place Jules Janssen, 92195 Meudon, France
e-mail: oscar.carrion@obspm.fr; oscar.carrion.gonzalez@gmail.com
² Space Telescope Science Institute (STScI), 3700 San Martin Dr, Baltimore, MD 21218, USA
³ ETH Zurich, Institute for Particle Physics & Astrophysics, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland
⁴ National Center of Competence in Research PlanetS, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
⁵ Université Paris-Saclay, Université Paris-Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France
⁶ STAR Institute, Université de Liège, Allé du Six-Août 19C, 4000 Liège, Belgium
⁷ NASA Exoplanet Science Institute, Jet Propulsion Laboratory, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125, USA
⁸ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁹ Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA

Received: 26 May 2023
Accepted: 7 August 2023

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 (t_int) 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 t_int < 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 M_p < 5M_⊕ and eight have 5M_⊕ < M_p < 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.