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

Beichman, Charles and Ygouf, Marie and Llop Sayson, Jorge and Mawet, Dimitri and Yung, Yuk and Choquet, Élodie and Kervella, Pierre and Boccaletti, Anthony and Belikov, Ruslan and Lissauer, Jack J. and Quarles, Billy and Lagage, Pierre-Olivier and Dicken, Daniel and Hu, Renyu and Mennesson, Bertrand and Ressler, Mike and Serabyn, Eugene and Krist, John and Bendek, Eduardo and Leisenring, Jarron and Pueyo, Laurent (2020) Searching for Planets Orbiting α Cen A with the James Webb Space Telescope. Publications of the Astronomical Society of the Pacific, 132 (1007). Art. No. 015002. ISSN 0004-6280. doi:10.1088/1538-3873/ab5066.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Beichman, Charles0000-0002-5627-5471
Ygouf, Marie0000-0001-7591-2731
Mawet, Dimitri0000-0002-8895-4735
Yung, Yuk0000-0002-4263-2562
Choquet, Élodie0000-0002-9173-0740
Kervella, Pierre0000-0003-0626-1749
Boccaletti, Anthony0000-0001-9353-2724
Lissauer, Jack J.0000-0001-6513-1659
Hu, Renyu0000-0003-2215-8485
Mennesson, Bertrand0000-0003-4205-4800
Leisenring, Jarron0000-0002-0834-6140
Pueyo, Laurent0000-0003-3818-408X
Alternate Title:Searching for Planets Orbiting Alpha Centauri A with the James Webb Space Telescope
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.
Group:Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Subject Keywords:infrared: planetary systems – planetary systems – planets and satellites: detection – space vehicles: instruments
Issue or Number:1007
Record Number:CaltechAUTHORS:20191121-152416477
Persistent URL:
Official Citation:Charles Beichman et al 2020 PASP 132 015002
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100002
Deposited By: Tony Diaz
Deposited On:21 Nov 2019 23:34
Last Modified:16 Nov 2021 17:50

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