Editing Proxima Centauri (section)

=== Alpha Centauri ===
{{Main|Alpha Centauri}}
Proxima Centauri has been suspected to be a companion of the Alpha Centauri [[binary star]] system since its discovery in 1915. For this reason, it is sometimes referred to as Alpha Centauri&nbsp;C. Data from the [[Hipparcos]] satellite, combined with ground-based observations, were consistent with the hypothesis that the three stars are a [[gravitationally bound]] system. Kervella et al. (2017) used high-precision radial velocity measurements to determine with a high degree of confidence that Proxima and Alpha Centauri are gravitationally bound.<ref name="KervellaThévenin2017" /> Proxima Centauri's orbital period around the Alpha Centauri&nbsp;AB [[barycenter]] is {{val|547000|6600|4000|fmt=commas}} years with an eccentricity of {{val|0.5|0.08}}; it approaches Alpha Centauri to {{val|4300|1100|900|u=AU|fmt=commas}} at [[periastron]] and retreats to {{val|13000|300|100|u=AU|fmt=commas}} at [[apastron]].<ref name="KervellaThévenin2017" /> At present, Proxima Centauri is {{convert|12947|±|260|AU|e12km|2|abbr=unit}} from the Alpha Centauri&nbsp;AB barycenter, nearly to the furthest point in its orbit.<ref name="KervellaThévenin2017" />

Six single stars, two binary star systems, and a triple star share a common motion through space with Proxima Centauri and the Alpha Centauri system. (The co-moving stars include [[HD 4391]], [[Gamma2 Normae|γ<sup>2</sup> Normae]], and [[Gliese 676]].) The [[space velocity (astronomy)|space velocities]] of these stars are all within 10&nbsp;km/s of Alpha Centauri's [[peculiar motion]]. Thus, they may form a [[moving group]] of stars, which would indicate a common point of origin, such as in a [[star cluster]].<ref>{{cite journal |last1=Anosova |first1=J. |last2=Orlov |first2=V. V. |last3=Pavlova |first3=N. A. |year=1994 |title=Dynamics of nearby multiple stars. The α Centauri system |journal=Astronomy and Astrophysics |volume=292 |issue=1 |pages=115–118 |bibcode=1994A&A...292..115A}}</ref>
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