Searching for Planets Orbiting α Cen A with the James Webb Space Telescope
Sayson, Jorge Llop
Lissauer, Jack J.
AffiliationUniv Arizona, Steward Observ
planetary systems planetary systems planets and satellites
detection space vehicles
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationCharles Beichman et al 2020 PASP 132 015002
Rights© 2019. The Astronomical Society of the Pacific. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
Abstracta 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 1-3 au (1"-2") region around a Cen A which is predicted to be stable within the a 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 pm 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) observations set a limit of 50-100 Mjs, at 1-3 au for planets orbiting a Cen A, there is a broad range of exoplanet radii up to 10 Rjs, consistent with these mass limits. A carefully planned observing sequence along with state-of-the-art postprocessing analysis could reject the light from a Cen A at the level of 10-5 at 1"-2" and minimize the influence of a 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, a Cen A is our closest sibling star and certainly merits close scrutiny.
Note12 month embargo; published online: 12 December 2019
VersionFinal accepted manuscript
SponsorsJet Propulsion Laboratory