Editing Alpha Centauri (section)

=== Planets of Proxima Centauri ===
{{Main|Proxima Centauri b|Proxima Centauri c|l2=c|Proxima Centauri d|l3=d}}
{{See also|Proxima Centauri#Planetary system}}

Proxima Centauri b is a terrestrial planet discovered in 2016 by astronomers at the [[European Southern Observatory]] (ESO). It has an estimated [[minimum mass]] of 1.17 {{Earth mass|link=y}} ([[Earth mass]]es) and orbits approximately 0.049 [[Astronomical unit|AU]] from Proxima Centauri, placing it in the star's [[Circumstellar habitable zone|habitable zone]].<ref name="proxima b discovery paper">{{cite journal|bibcode=2016Natur.536..437A|title=A terrestrial planet candidate in a temperate orbit around Proxima Centauri|journal=Nature|volume=536|issue=7617|pages=437–440|last1=Anglada-Escudé |first1=Guillem|last2=Amado|first2=Pedro J.|last3=Barnes|first3=John|last4=Berdiñas|first4=Zaira M.|last5=Butler|first5=R. Paul|last6=Coleman|first6=Gavin A. L.|last7=de la Cueva|first7=Ignacio|last8=Dreizler
|first8=Stefan|last9=Endl|first9=Michael|last10=Giesers|first10=Benjamin|last11=Jeffers|first11=Sandra V.|last12=Jenkins|first12=James S.|last13=Jones|first13=Hugh R. A.|last14=Kiraga|first14=Marcin |last15=Kürster|first15=Martin|last16=López-González|first16=María J.|last17=Marvin|first17=Christopher J.|last18=Morales|first18=Nicolás|last19=Morin|first19=Julien|last20=Nelson|first20=Richard P. |last21=Ortiz|first21=José L.|last22=Ofir|first22=Aviv|last23=Paardekooper|first23=Sijme-Jan|last24=Reiners|first24=Ansgar|last25=Rodríguez|first25=Eloy|last26=Rodríguez-López|first26=Cristina|last27=Sarmiento
|first27=Luis F.|last28=Strachan|first28=John P.|last29=Tsapras|first29=Yiannis|last30=Tuomi|first30=Mikko|first31=Mathias|last31=Zechmeister|display-authors=3|year=2016|arxiv=1609.03449|doi=10.1038/nature19106
|pmid=27558064|s2cid=4451513|url=https://www.nature.com/articles/nature19106}}</ref><ref name=Mascareno2020>{{cite journal|arxiv=2005.12114|last1=Suárez Mascareño|first1=A.|last2=Faria|first2=J. P. |last3=Figueira|first3=P.|title=Revisiting Proxima with ESPRESSO|journal=Astronomy & Astrophysics|year=2020|volume=639|page=A77|doi=10.1051/0004-6361/202037745|bibcode=2020A&A...639A..77S|s2cid=218869742 |display-authors=et al.}}</ref>

The discovery of Proxima Centauri c was formally published in 2020 and could be a [[super-Earth]] or [[mini-Neptune]].<ref name="proxima c scientific american">{{cite magazine|title=A Second Planet May Orbit Earth's Nearest Neighboring Star|url=https://www.scientificamerican.com/article/a-second-planet-may-orbit-earths-nearest-neighboring-star/|magazine=Scientific American|first=Lee|last=Billings|date=12 April 2019|access-date=2 August 2020}}</ref><ref name="proxima c discovery paper">{{cite journal|last1=Damasso|first1=Mario|last2=Del Sordo|first2=Fabio |display-authors=et al. |title=A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5&nbsp;AU |journal=Science Advances |date=January 2020 |volume=6 |issue=3 |page=eaax7467|doi=10.1126/sciadv.aax7467|pmid=31998838|pmc=6962037 |bibcode=2020SciA....6.7467D|doi-access=free}}</ref> It has a mass of roughly 7 {{Earth mass}} and orbits about {{nobr|1.49 AU}} from Proxima Centauri with a period of {{convert|1928|days|years}}.<ref name="proxima c mass">{{cite journal|last1=Benedict|first1=G. Fritz|last2=McArthur|first2=Barbara E.|title=A Moving Target — Revising the Mass of Proxima Centauri c|journal=Research Notes of the AAS|date=June 2020|volume=4|issue=6|page=86|doi=10.3847/2515-5172/ab9ca9|bibcode=2020RNAAS...4...86B|s2cid=225798015 |doi-access=free }}</ref> In June 2020, a possible direct imaging detection of the planet hinted at the presence of a large ring system.<ref name="proxima c imaging">{{cite journal|last1=Gratton |first1=Raffaele|last2=Zurlo|first2=Alice|last3=Le Coroller|first3=Hervé|display-authors=et al.|title=Searching for the near-infrared counterpart of Proxima c using multi-epoch high-contrast SPHERE data at VLT |journal=Astronomy & Astrophysics|date=June 2020|volume=638|page=A120|doi=10.1051/0004-6361/202037594 |bibcode=2020A&A...638A.120G |arxiv=2004.06685|s2cid=215754278}}</ref> However, a 2022 study disputed the existence of this planet.<ref name="Artigau2022">{{cite journal |bibcode=2022AJ....164...84A |title=Line-by-line Velocity Measurements: An Outlier-resistant Method for Precision Velocimetry |last1=Artigau |first1=Étienne |last2=Cadieux |first2=Charles |last3=Cook |first3=Neil J. |last4=Doyon |first4=René |last5=Vandal |first5=Thomas |last6=Donati |first6=Jean-François |last7=Moutou |first7=Claire |last8=Delfosse |first8=Xavier |last9=Fouqué |first9=Pascal |last10=Martioli |first10=Eder |last11=Bouchy |first11=François |last12=Parsons |first12=Jasmine |last13=Carmona |first13=Andres |last14=Dumusque |first14=Xavier |last15=Astudillo-Defru |first15=Nicola |last16=Bonfils |first16=Xavier |last17=Mignon |first17=Lucille |journal=The Astronomical Journal |date=2022 |volume=164 |issue=3 |page=84 |doi=10.3847/1538-3881/ac7ce6 |doi-access=free |arxiv=2207.13524 }}</ref>

A 2020 paper refining Proxima b's mass excludes the presence of extra companions with masses above {{Earth mass|0.6}} at periods shorter than 50 days, but the authors detected a radial-velocity curve with a periodicity of 5.15 days, suggesting the presence of a planet with a mass of about {{Earth mass|0.29}}.<ref name=Mascareno2020/> This planet, Proxima Centauri d, was detected in 2022.<ref name="Faria2022">{{cite journal |last1=Faria |first1=J. P. |last2=Suárez Mascareño |first2=A. |last3=Figueira |first3=P. |last4=Silva |first4=A. M. |last5=Damasso |first5=M. |last6=Demangeon |first6=O. |last7=Pepe |first7=F. |last8=Santos |first8=N. C. |last9=Rebolo |first9=R. |last10=Cristiani |first10=S. |last11=Adibekyan |first11=V. |display-authors=2 |date=January 4, 2022 |title=A candidate short-period sub-Earth orbiting Proxima Centauri |url=https://www.eso.org/public/archives/releases/sciencepapers/eso2202/eso2202a.pdf |journal=Astronomy & Astrophysics |publisher=European Southern Observatory |volume=658 |pages=17 |arxiv=2202.05188 |bibcode=2022A&A...658A.115F |doi=10.1051/0004-6361/202142337 |doi-access=free |last35=Tabernero |last23=Lo Curto |first18=X. |last19=Ehrenreich |first19=D. |last20=González Hernández |first20=J. I. |last21=Hara |last15=Cabral |first22=J. |first28=G. |last24=Lovis |first23=G. |first17=P. |first24=C. |last25=Martins |first25=C. J. A. P. |last26=Mégevand |first26=D. |last27=Mehner |first27=A. |last28=Micela |first21=N. |last18=Dumusque |last17=Di Marcantonio |first30=N. J. |first36=S. |last31=Pallé |first31=E. |last32=Poretti |first32=E. |last33=Sousa |first33=S. G. |last34=Sozzetti |first34=A. |last36=Udry |first15=A. |first29=P. |last37=Zapatero Osorio |first16=V. |first37=M. R. |first14=S. C. C. |last14=Barros |first13=R. |last13=Allart |first12=Y. |last12=Alibert |last30=Nunes |last29=Molaro |last16=D'Odorico |last22=Lillo-Box |first35=H.}}</ref><ref name="Artigau2022"/>