Editing Alpha Centauri (section)

=== Planets of Alpha Centauri A ===
{{Main|2 = Alpha Centauri Ab}}
[[File:Candidate1 Discovery.png|thumb|upright=1.6|The discovery image of Alpha Centauri's candidate Neptunian planet, marked here as "C1"]]
{{Orbitbox planet begin
|name=Alpha Centauri A
|period_unit=day
}}
{{OrbitboxPlanet hypothetical
|exoplanet=[[Alpha Centauri Ab|b]]
|semimajor= 1.1
|period= ~360
|mass_earth= 9~35{{efn|
These mass limits are calculated from the observed radius of {{nobr|{{math| 3.3~7}} {{Earth radius|link=n}}}} applied to the equation quoted, and presumably used, to calculate the planet mass from the planet radius in the Wagner ''et al'' 2021 paper:<ref name="WagnerBoehle2021"/> {{nobr|{{math| ''R'' ∝ ''M''{{sup|&thinsp;0.55}} }} }} (although this radius-mass relationship is for low-mass planets and not for larger gas giants). Therefore {{nobr| {{math| 3.3{{sup|1.82}} {{=}} 8.77 }} {{Earth mass|link=n}} }} and {{nobr|{{math| 7{{sup|1.82}} {{=}} 34.52}} {{Earth mass|link=n}}.}} The {{nobr| {{mvar|M}}{{sub|{{math|sin ''i''}}}} ≥ 53 {{Earth mass|link=n}} }} is for a planet at the outer edge of the conservative habitable zone, {{nobr|2.1 AU}}, and so the upper mass limit is lower than that for the C{{sub|1}} planet at just {{nobr|1.1 AU}}.
}}
|radius_earth= 3.3~7
|inclination= ~65 ± 25
}}
{{Orbitbox end}}

In 2021, a candidate planet named Candidate 1 (or C1) was detected around Alpha Centauri A, thought to orbit at approximately {{nobr|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.<ref>{{cite web | url = https://www.theguardian.com/science/2021/feb/10/astronomers-hopes-raised-by-glimpse-of-possible-new-planet-alpha-centauri| title = Astronomers' hopes raised by glimpse of possible new planet? |access-date=2022-01-16| work=[[The Guardian]] | date=10 February 2021 |first=Ian |last=Sample}}</ref><ref name="WagnerBoehle2021">{{cite journal |last1=Wagner |first1=K. |last2=Boehle |first2=A. |last3=Pathak |first3=P.|last4=Kasper |first4=M.|last5=Arsenault|first5=R. |last6=Jakob|first6=G.|last7=Käufl|first7=U. |last8=Leveratto|first8=S.|last9=Maire|first9=A.-L.|last10=Pantin |first10=E.|last11=Siebenmorgen |first11=R.|last12=Zins|first12=G. |last13=Absil|first13=O. |last14=Ageorges |first14=N. |last15=Apai |first15=D. |last16=Carlotti|first16=A. |last17=Choquet|first17=É.|last18=Delacroix|first18=C.|last19=Dohlen|first19=K.|last20=Duhoux|first20=P.|last21=Forsberg|first21=P.|last22=Fuenteseca|first22=E.|last23=Gutruf|first23=S.|last24=Guyon|first24=O.|last25=Huby|first25=E.|last26=Kampf|first26=D.|last27=Karlsson|first27=M.|last28=Kervella|first28=P.|last29=Kirchbauer|first29=J.-P.|last30=Klupar|first30=P. |last31=Kolb|first31=J.|last32=Mawet|first32=D.|last33=N'Diaye|first33=M.|last34=Orban de Xivry|first34=G.|last35=Quanz|first35=S. P.|last36=Reutlinger|first36=A.|last37=Ruane|first37=G.|last38=Riquelme |first38=M. |last39=Soenke|first39=C.|last40=Sterzik|first40=M.|last41=Vigan|first41=A.|last42=de Zeeuw|first42=T. |display-authors=6 |title=Imaging low-mass planets within the habitable zone of α Centauri |journal=Nature Communications|date=10 February 2021|volume=12|issue=1|page=922|doi=10.1038/s41467-021-21176-6|pmid=33568657|pmc=7876126|doi-access=free|arxiv=2102.05159|bibcode=2021NatCo..12..922W}} [https://www.youtube.com/watch?v=Da2EMPuGu00&feature=youtu.be Kevin Wagner's (lead author of paper?) video of discovery]</ref> 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.<ref name="IAUNamingRules">{{cite web|url=https://www.iau.org/public/themes/naming_exoplanets/|title=Naming of Exoplanets|publisher=International Astronomical Union|access-date=24 July 2021}}</ref>

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]].<ref name=":0">{{Cite web |title=1618 Program Information |url=https://www.stsci.edu/cgi-bin/get-proposal-info?observatory=JWST&id=1618 |access-date=2022-09-01 |website=www.stsci.edu |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901094214/https://www.stsci.edu/cgi-bin/get-proposal-info?observatory=JWST&id=1618 |url-status=dead }}</ref> The coronographic observations, which occurred on July 26 and 27, 2023, were failures, though there are follow-up observations in March 2024.<ref>{{Cite web |title=Visit Information |url=https://www.stsci.edu/cgi-bin/get-visit-status?id=1618&markupFormat=html&observatory=JWST |access-date=2022-09-01 |website=www.stsci.edu |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901094234/https://www.stsci.edu/cgi-bin/get-visit-status?id=1618&markupFormat=html&observatory=JWST |url-status=dead }}</ref> Pre-launch estimates predicted that JWST will be able to find planets with a radius of 5 {{Earth radius|link=true}} at {{nobr|1–3 AU}}. Multiple observations every 3–6 months could push the limit down to 3 {{Earth radius}}.<ref>{{Cite journal |last1=Beichman |first1=Charles |last2=Ygouf |first2=Marie |last3=Llop Sayson |first3=Jorge |last4=Mawet |first4=Dimitri |last5=Yung |first5=Yuk |last6=Choquet |first6=Elodie |last7=Kervella |first7=Pierre |last8=Boccaletti |first8=Anthony |last9=Belikov |first9=Ruslan |last10=Lissauer |first10=Jack J. |last11=Quarles |first11=Billy |last12=Lagage |first12=Pierre-Olivier |last13=Dicken |first13=Daniel |last14=Hu |first14=Renyu |last15=Mennesson |first15=Bertrand |date=2020-01-01 |title=Searching for Planets Orbiting α Cen A with the James Webb Space Telescope |url=https://ui.adsabs.harvard.edu/abs/2020PASP..132a5002B |journal=Publications of the Astronomical Society of the Pacific |volume=132 |issue=1007 |pages=015002 |doi=10.1088/1538-3873/ab5066 |arxiv=1910.09709 |bibcode=2020PASP..132a5002B |s2cid=204823856 |issn=0004-6280}}</ref> 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 {{Earth radius}} planet at {{nobr|0.5–2.5 AU}}.<ref>{{Cite journal |last1=Carter |first1=Aarynn L. |last2=Hinkley |first2=Sasha |last3=Kammerer |first3=Jens |last4=Skemer |first4=Andrew |last5=Biller |first5=Beth A. |last6=Leisenring |first6=Jarron M. |last7=Millar-Blanchaer |first7=Maxwell A. |last8=Petrus |first8=Simon |last9=Stone |first9=Jordan M. |last10=Ward-Duong |first10=Kimberly |last11=Wang |first11=Jason J. |last12=Girard |first12=Julien H. |last13=Hines |first13=Dean C. |last14=Perrin |first14=Marshall D. |last15=Pueyo |first15=Laurent |date=2023 |title=The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High-contrast Imaging of the Exoplanet HIP 65426 b from 2 to 16 μm |journal=The Astrophysical Journal Letters |volume=951 |issue=1 |pages=L20 |doi=10.3847/2041-8213/acd93e |arxiv=2208.14990 |bibcode=2023ApJ...951L..20C |doi-access=free }}</ref> Candidate&nbsp;1 has an estimated radius between {{nobr|3.3–11 {{Earth radius}}}}<ref name=WagnerBoehle2021/> and orbits at {{nobr|1.1 AU}}. It is therefore likely within the reach of JWST observations.