Editing Alpha Persei (section)

== Physical properties ==

[[File:PerseusCC.jpg|thumb|left|upright|Mirfak is the brightest star in the constellation of Perseus (top center).]]

The [[stellar spectrum|spectrum]] of Alpha Persei matches a [[stellar classification]] of F5&nbsp;Ib,<ref name=mnras402_2_1369/> revealing it to be a [[supergiant]] star in the latter stages of its [[stellar evolution|evolution]]. It has a similar spectrum to [[Procyon]] A, though the latter star is much less luminous. This difference is highlighted in their spectral designation under the [[Yerkes spectral classification]], published in 1943, where stars are ranked on luminosity as well as spectral typing. Procyon A is thus F5&nbsp;IV,<ref name=ramanamurthy2007/> a [[subgiant]] star. Since 1943, the spectrum of Alpha Persei has served as one of the stable anchor points by which other stars are classified.<ref name=baas25_1319/>

Alpha Persei has about 7.3<ref name=mnras402_2_1369/> times the [[Sun's mass]] and has expanded to roughly 53 times the [[Solar radius|size of the Sun]].<ref name="baines"/> It is radiating 3,800<ref name=tycho-gaia/> times the [[Solar luminosity|luminosity of the Sun]] from its [[photosphere]] at an [[effective temperature]] of {{Val|6350|fmt=commas|ul=K}},<ref name=mnras402_2_1369/> which creates the yellow-white glow of an [[F-type star]]. 

In the [[Hertzsprung–Russell diagram]], Alpha Persei lies inside the region in which [[Cepheid variable]]s are found.<ref name=apj664_2_1093/> It is thus useful in the study of these stars, which are important [[standard candle]]s.<ref name=kaler/> Despite Mirfak being not a Cepheid, [[Hipparcos]] photometry show a 0.006-[[magnitude (astronomy)|magnitude]] variation with a period of 9.5 days.<ref name=Beng2025/>