Searching for planets orbiting αcen a with the james webb space telescope

Charles Beichman, Marie Ygouf, Jorge Llop Sayson, Dimitri Mawet, Yuk Yung, Elodie Choquet, Pierre Kervella, Anthony Boccaletti, Ruslan Belikov, Jack J. Lissauer, Billy Quarles, Pierre Olivier Lagage, Daniel Dicken, Renyu Hu, Bertrand Mennesson, Mike Ressler, Eugene Serabyn, John Krist, Eduardo Bendek, Jarron LeisenringLaurent Pueyo

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


α Centauri A is the closest solar-type star to the Sun and offers an excellent opportunity to detect the thermal emission of a mature planet heated by its host star. The MIRI coronagraph on the James Webb Space Telescope can search the 1–3au (1″–2″) region around α Cen A which is predicted to be stable within the α Cen AB system. We demonstrate that with reasonable performance of the telescope and instrument, a 20 hr program combining on-target and reference star observations at 15.5 μm could detect thermal emission from planets as small as ∼5 R. Multiple visits every 3–6 months would increase the geometrical completeness, provide astrometric confirmation of detected sources, and push the radius limit down to ∼3 R. An exozodiacal cloud only a few times brighter than our own should also be detectable, although a sufficiently bright cloud might obscure any planet present in the system. While current precision radial velocity (PRV) observationssetalimitof50–100 M at 1–3 au for planets orbiting α Cen A, there is a broad range of exoplanet radii up to 10 R consistent with these mass limits. A carefully planned observing sequence along with state-of-the-art post-processing analysis could reject the light from α Cen A at the level of ∼10−5 at 1″–2″ and minimize the influence of α Cen B located 7″–8″ away in the 2022–2023 timeframe. These space-based observations would complement on-going imaging experiments at shorter wavelengths as well as PRV and astrometric experiments to detect planets dynamically. Planetary demographics suggest that the likelihood of directly imaging a planet whose mass and orbit are consistent with present PRV limits is small, ∼5%, and possibly lower if the presence of a binary companion further reduces occurrence rates. However, at a distance of just 1.34 pc, α Cen A is our closest sibling star and certainly merits close scrutiny.

Original languageEnglish (US)
Article number015002
JournalPublications of the Astronomical Society of the Pacific
Issue number1007
StatePublished - Jan 2020


  • Infrared: planetary systems
  • Planetary systems
  • Planets and satellites: detection
  • Space vehicles: instruments

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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