The star's brightness continues to change, increasing by around 15% per century caused by a reduction of the star's temperature by 6% per century.<ref name=illinois/> Although this means the total energy radiated by the star is reduced, it means less is emitted in the [[ultraviolet]] and instead radiated in the [[visible light|visible]]. There are still small fluctuations up and down, though only at most by 0.2 magnitudes.<ref name=aavso/> These variations can generally occur with a period of 0.156 days or 3.75 hours, though they can be fairly irregular and are thought to be due to possibly pulsation or flares on the star's surface.<ref name=universeguide/> P Cygni's fluctuation history place it in a very exclusive group of variable stars known as S Doradus star. Other members include [[Eta Carinae]] and [[S Doradus]] in the [[Magellanic Clouds]]. | The star's brightness continues to change, increasing by around 15% per century caused by a reduction of the star's temperature by 6% per century.<ref name=illinois/> Although this means the total energy radiated by the star is reduced, it means less is emitted in the [[ultraviolet]] and instead radiated in the [[visible light|visible]]. There are still small fluctuations up and down, though only at most by 0.2 magnitudes.<ref name=aavso/> These variations can generally occur with a period of 0.156 days or 3.75 hours, though they can be fairly irregular and are thought to be due to possibly pulsation or flares on the star's surface.<ref name=universeguide/> P Cygni's fluctuation history place it in a very exclusive group of variable stars known as S Doradus star. Other members include [[Eta Carinae]] and [[S Doradus]] in the [[Magellanic Clouds]]. |