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Planets of Alpha Centauri A

In 2021, a candidate planet named Candidate 1 (abbreviated as C1) was detected around Alpha Centauri A, thought to orbit at approximately 1.1 AU with a period of about one year, and to have a mass between that of Neptune and one-half that of Saturn, though it may be a dust disk or an artifact. The possibility of C1 being a background star has been ruled out. If this candidate is confirmed, the temporary name C1 will most likely be replaced with the scientific designation Alpha Centauri Ab in accordance with current naming conventions.

GO Cycle 1 observations are planned for the James Webb Space Telescope (JWST) to search for planets around Alpha Centauri A, as well as observations of Epsilon Muscae. The coronographic observations, which occurred on July 26 and 27, 2023, were failures, though there are follow-up observations in March 2024. Pre-launch estimates predicted that JWST will be able to find planets with a radius of 5 R at 1–3 AU. Multiple observations every 3–6 months could push the limit down to 3 R. Post-processing techniques could push the limit down to 0.5–0.7 R. Post-launch estimates based on observations of HIP 65426 b find that JWST will be able to find planets even closer to Alpha Centauri A and could find a 5 R planet at 0.5–2.5 AU. Candidate 1 has an estimated radius between 3.3–11 R and orbits at 1.1 AU. It is therefore likely within the reach of JWST observations.