CaltechAUTHORS
Published January 2020 | Version Accepted Version + Published
Journal Article Open

Searching for Planets Orbiting α Cen A with the James Webb Space Telescope

Creators

  • 1. ROR icon Jet Propulsion Lab
  • 2. ROR icon NASA Exoplanet Science Institute
  • 3. ROR icon California Institute of Technology
  • 4. ROR icon French National Centre for Scientific Research
  • 5. ROR icon Sorbonne University
  • 6. ROR icon Ames Research Center
  • 7. ROR icon Georgia Institute of Technology
  • 8. ROR icon Astrophysique, Instrumentation et Modélisation
  • 9. ROR icon University of Arizona
  • 10. ROR icon Space Telescope Science Institute

Abstract

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 JWST can search the 1-3 AU (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 um 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 M⊕ at 1-3 AU for planets orbiting α Cen A, there is a broad range of exoplanet radii up to 10 RE 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.

Additional Information

© 2019. The Astronomical Society of the Pacific. Received 2019 August 25; accepted 2019 October 14; published 2019 December 12. Some of the research described in this publication was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2019 California Inst of Technology. All rights reserved.

Attached Files

Published - Beichman_2020_PASP_132_015002.pdf

Accepted Version - 1910.09709.pdf

Files

1910.09709.pdf

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Additional details

Additional titles

Alternative title
Searching for Planets Orbiting Alpha Centauri A with the James Webb Space Telescope

Identifiers

Eprint ID
100002
Resolver ID
CaltechAUTHORS:20191121-152416477

Related works

Describes
http://arxiv.org/abs/1910.09709 (URL)

Funding

NASA/JPL/Caltech

Dates

Created
2019-11-21
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Infrared Processing and Analysis Center (IPAC), Astronomy Department, Division of Geological and Planetary Sciences (GPS)