 Stars can also vary in luminosity because of extrinsic factors , such as eclipsing binaries , as well as rotating stars that produce extreme starspots . A notable example of an eclipsing binary is Algol , which regularly varies in magnitude from 2 @.@ 3 to 3 @.@ 5 over a period of 2 @.@ 87 days . 
 Stars can also vary in luminosity because of extrinsic factors , such as eclipsing binaries , as well as rotating stars <a href='null_relcl' title='1'><mark>that</mark></a>produce extreme starspots . A notable example of an eclipsing binary <a href='drop_aux' title='2'><mark>is</mark></a>Algol , which regularly <a href='uninflect' title='3'><mark>varies</mark></a> in magnitude from 2 @.@ 3 to 3 @.@ 5 over a period of 2 @.@ 87 days . 
Stars can also vary in luminosity because of extrinsic factors , such as eclipsing binaries , as well as rotating stars produce extreme starspots . A notable example of an eclipsing binary Algol , which regularly vary in magnitude from 2 @.@ 3 to 3 @.@ 5 over a period of 2 @.@ 87 days .